/* $OpenBSD: packet.c,v 1.236 2016/09/06 09:22:56 markus Exp $ */ /* * Author: Tatu Ylonen * Copyright (c) 1995 Tatu Ylonen , Espoo, Finland * All rights reserved * This file contains code implementing the packet protocol and communication * with the other side. This same code is used both on client and server side. * * As far as I am concerned, the code I have written for this software * can be used freely for any purpose. Any derived versions of this * software must be clearly marked as such, and if the derived work is * incompatible with the protocol description in the RFC file, it must be * called by a name other than "ssh" or "Secure Shell". * * * SSH2 packet format added by Markus Friedl. * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ #include "includes.h" #include /* MIN roundup */ #include #include "openbsd-compat/sys-queue.h" #include #ifdef HAVE_SYS_TIME_H # include #endif #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "buffer.h" /* typedefs XXX */ #include "key.h" /* typedefs XXX */ #include "xmalloc.h" #include "crc32.h" #include "deattack.h" #include "compat.h" #include "ssh1.h" #include "ssh2.h" #include "cipher.h" #include "sshkey.h" #include "kex.h" #include "digest.h" #include "mac.h" #include "log.h" #include "canohost.h" #include "misc.h" #include "channels.h" #include "ssh.h" #include "packet.h" #include "ssherr.h" #include "sshbuf.h" #ifdef PACKET_DEBUG #define DBG(x) x #else #define DBG(x) #endif #define PACKET_MAX_SIZE (256 * 1024) struct packet_state { u_int32_t seqnr; u_int32_t packets; u_int64_t blocks; u_int64_t bytes; }; struct packet { TAILQ_ENTRY(packet) next; u_char type; struct sshbuf *payload; }; struct session_state { /* * This variable contains the file descriptors used for * communicating with the other side. connection_in is used for * reading; connection_out for writing. These can be the same * descriptor, in which case it is assumed to be a socket. */ int connection_in; int connection_out; /* Protocol flags for the remote side. */ u_int remote_protocol_flags; /* Encryption context for receiving data. Only used for decryption. */ struct sshcipher_ctx *receive_context; /* Encryption context for sending data. Only used for encryption. */ struct sshcipher_ctx *send_context; /* Buffer for raw input data from the socket. */ struct sshbuf *input; /* Buffer for raw output data going to the socket. */ struct sshbuf *output; /* Buffer for the partial outgoing packet being constructed. */ struct sshbuf *outgoing_packet; /* Buffer for the incoming packet currently being processed. */ struct sshbuf *incoming_packet; /* Scratch buffer for packet compression/decompression. */ struct sshbuf *compression_buffer; /* Incoming/outgoing compression dictionaries */ z_stream compression_in_stream; z_stream compression_out_stream; int compression_in_started; int compression_out_started; int compression_in_failures; int compression_out_failures; /* * Flag indicating whether packet compression/decompression is * enabled. */ int packet_compression; /* default maximum packet size */ u_int max_packet_size; /* Flag indicating whether this module has been initialized. */ int initialized; /* Set to true if the connection is interactive. */ int interactive_mode; /* Set to true if we are the server side. */ int server_side; /* Set to true if we are authenticated. */ int after_authentication; int keep_alive_timeouts; /* The maximum time that we will wait to send or receive a packet */ int packet_timeout_ms; /* Session key information for Encryption and MAC */ struct newkeys *newkeys[MODE_MAX]; struct packet_state p_read, p_send; /* Volume-based rekeying */ u_int64_t max_blocks_in, max_blocks_out, rekey_limit; /* Time-based rekeying */ u_int32_t rekey_interval; /* how often in seconds */ time_t rekey_time; /* time of last rekeying */ /* Session key for protocol v1 */ u_char ssh1_key[SSH_SESSION_KEY_LENGTH]; u_int ssh1_keylen; /* roundup current message to extra_pad bytes */ u_char extra_pad; /* XXX discard incoming data after MAC error */ u_int packet_discard; size_t packet_discard_mac_already; struct sshmac *packet_discard_mac; /* Used in packet_read_poll2() */ u_int packlen; /* Used in packet_send2 */ int rekeying; /* Used in packet_set_interactive */ int set_interactive_called; /* Used in packet_set_maxsize */ int set_maxsize_called; /* One-off warning about weak ciphers */ int cipher_warning_done; /* SSH1 CRC compensation attack detector */ struct deattack_ctx deattack; TAILQ_HEAD(, packet) outgoing; }; struct ssh * ssh_alloc_session_state(void) { struct ssh *ssh = NULL; struct session_state *state = NULL; if ((ssh = calloc(1, sizeof(*ssh))) == NULL || (state = calloc(1, sizeof(*state))) == NULL || (state->input = sshbuf_new()) == NULL || (state->output = sshbuf_new()) == NULL || (state->outgoing_packet = sshbuf_new()) == NULL || (state->incoming_packet = sshbuf_new()) == NULL) goto fail; TAILQ_INIT(&state->outgoing); TAILQ_INIT(&ssh->private_keys); TAILQ_INIT(&ssh->public_keys); state->connection_in = -1; state->connection_out = -1; state->max_packet_size = 32768; state->packet_timeout_ms = -1; state->p_send.packets = state->p_read.packets = 0; state->initialized = 1; /* * ssh_packet_send2() needs to queue packets until * we've done the initial key exchange. */ state->rekeying = 1; ssh->state = state; return ssh; fail: if (state) { sshbuf_free(state->input); sshbuf_free(state->output); sshbuf_free(state->incoming_packet); sshbuf_free(state->outgoing_packet); free(state); } free(ssh); return NULL; } /* Returns nonzero if rekeying is in progress */ int ssh_packet_is_rekeying(struct ssh *ssh) { return compat20 && (ssh->state->rekeying || (ssh->kex != NULL && ssh->kex->done == 0)); } /* * Sets the descriptors used for communication. Disables encryption until * packet_set_encryption_key is called. */ struct ssh * ssh_packet_set_connection(struct ssh *ssh, int fd_in, int fd_out) { struct session_state *state; const struct sshcipher *none = cipher_by_name("none"); int r; if (none == NULL) { error("%s: cannot load cipher 'none'", __func__); return NULL; } if (ssh == NULL) ssh = ssh_alloc_session_state(); if (ssh == NULL) { error("%s: cound not allocate state", __func__); return NULL; } state = ssh->state; state->connection_in = fd_in; state->connection_out = fd_out; if ((r = cipher_init(&state->send_context, none, (const u_char *)"", 0, NULL, 0, CIPHER_ENCRYPT)) != 0 || (r = cipher_init(&state->receive_context, none, (const u_char *)"", 0, NULL, 0, CIPHER_DECRYPT)) != 0) { error("%s: cipher_init failed: %s", __func__, ssh_err(r)); free(ssh); /* XXX need ssh_free_session_state? */ return NULL; } state->newkeys[MODE_IN] = state->newkeys[MODE_OUT] = NULL; deattack_init(&state->deattack); /* * Cache the IP address of the remote connection for use in error * messages that might be generated after the connection has closed. */ (void)ssh_remote_ipaddr(ssh); return ssh; } void ssh_packet_set_timeout(struct ssh *ssh, int timeout, int count) { struct session_state *state = ssh->state; if (timeout <= 0 || count <= 0) { state->packet_timeout_ms = -1; return; } if ((INT_MAX / 1000) / count < timeout) state->packet_timeout_ms = INT_MAX; else state->packet_timeout_ms = timeout * count * 1000; } int ssh_packet_stop_discard(struct ssh *ssh) { struct session_state *state = ssh->state; int r; if (state->packet_discard_mac) { char buf[1024]; size_t dlen = PACKET_MAX_SIZE; if (dlen > state->packet_discard_mac_already) dlen -= state->packet_discard_mac_already; memset(buf, 'a', sizeof(buf)); while (sshbuf_len(state->incoming_packet) < dlen) if ((r = sshbuf_put(state->incoming_packet, buf, sizeof(buf))) != 0) return r; (void) mac_compute(state->packet_discard_mac, state->p_read.seqnr, sshbuf_ptr(state->incoming_packet), dlen, NULL, 0); } logit("Finished discarding for %.200s port %d", ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); return SSH_ERR_MAC_INVALID; } static int ssh_packet_start_discard(struct ssh *ssh, struct sshenc *enc, struct sshmac *mac, size_t mac_already, u_int discard) { struct session_state *state = ssh->state; int r; if (enc == NULL || !cipher_is_cbc(enc->cipher) || (mac && mac->etm)) { if ((r = sshpkt_disconnect(ssh, "Packet corrupt")) != 0) return r; return SSH_ERR_MAC_INVALID; } /* * Record number of bytes over which the mac has already * been computed in order to minimize timing attacks. */ if (mac && mac->enabled) { state->packet_discard_mac = mac; state->packet_discard_mac_already = mac_already; } if (sshbuf_len(state->input) >= discard) return ssh_packet_stop_discard(ssh); state->packet_discard = discard - sshbuf_len(state->input); return 0; } /* Returns 1 if remote host is connected via socket, 0 if not. */ int ssh_packet_connection_is_on_socket(struct ssh *ssh) { struct session_state *state = ssh->state; struct sockaddr_storage from, to; socklen_t fromlen, tolen; if (state->connection_in == -1 || state->connection_out == -1) return 0; /* filedescriptors in and out are the same, so it's a socket */ if (state->connection_in == state->connection_out) return 1; fromlen = sizeof(from); memset(&from, 0, sizeof(from)); if (getpeername(state->connection_in, (struct sockaddr *)&from, &fromlen) < 0) return 0; tolen = sizeof(to); memset(&to, 0, sizeof(to)); if (getpeername(state->connection_out, (struct sockaddr *)&to, &tolen) < 0) return 0; if (fromlen != tolen || memcmp(&from, &to, fromlen) != 0) return 0; if (from.ss_family != AF_INET && from.ss_family != AF_INET6) return 0; return 1; } void ssh_packet_get_bytes(struct ssh *ssh, u_int64_t *ibytes, u_int64_t *obytes) { if (ibytes) *ibytes = ssh->state->p_read.bytes; if (obytes) *obytes = ssh->state->p_send.bytes; } int ssh_packet_connection_af(struct ssh *ssh) { struct sockaddr_storage to; socklen_t tolen = sizeof(to); memset(&to, 0, sizeof(to)); if (getsockname(ssh->state->connection_out, (struct sockaddr *)&to, &tolen) < 0) return 0; #ifdef IPV4_IN_IPV6 if (to.ss_family == AF_INET6 && IN6_IS_ADDR_V4MAPPED(&((struct sockaddr_in6 *)&to)->sin6_addr)) return AF_INET; #endif return to.ss_family; } /* Sets the connection into non-blocking mode. */ void ssh_packet_set_nonblocking(struct ssh *ssh) { /* Set the socket into non-blocking mode. */ set_nonblock(ssh->state->connection_in); if (ssh->state->connection_out != ssh->state->connection_in) set_nonblock(ssh->state->connection_out); } /* Returns the socket used for reading. */ int ssh_packet_get_connection_in(struct ssh *ssh) { return ssh->state->connection_in; } /* Returns the descriptor used for writing. */ int ssh_packet_get_connection_out(struct ssh *ssh) { return ssh->state->connection_out; } /* * Returns the IP-address of the remote host as a string. The returned * string must not be freed. */ const char * ssh_remote_ipaddr(struct ssh *ssh) { const int sock = ssh->state->connection_in; /* Check whether we have cached the ipaddr. */ if (ssh->remote_ipaddr == NULL) { if (ssh_packet_connection_is_on_socket(ssh)) { ssh->remote_ipaddr = get_peer_ipaddr(sock); ssh->remote_port = get_peer_port(sock); ssh->local_ipaddr = get_local_ipaddr(sock); ssh->local_port = get_local_port(sock); } else { ssh->remote_ipaddr = strdup("UNKNOWN"); ssh->remote_port = 65535; ssh->local_ipaddr = strdup("UNKNOWN"); ssh->local_port = 65535; } } return ssh->remote_ipaddr; } /* Returns the port number of the remote host. */ int ssh_remote_port(struct ssh *ssh) { (void)ssh_remote_ipaddr(ssh); /* Will lookup and cache. */ return ssh->remote_port; } /* * Returns the IP-address of the local host as a string. The returned * string must not be freed. */ const char * ssh_local_ipaddr(struct ssh *ssh) { (void)ssh_remote_ipaddr(ssh); /* Will lookup and cache. */ return ssh->local_ipaddr; } /* Returns the port number of the local host. */ int ssh_local_port(struct ssh *ssh) { (void)ssh_remote_ipaddr(ssh); /* Will lookup and cache. */ return ssh->local_port; } /* Closes the connection and clears and frees internal data structures. */ void ssh_packet_close(struct ssh *ssh) { struct session_state *state = ssh->state; u_int mode; if (!state->initialized) return; state->initialized = 0; if (state->connection_in == state->connection_out) { shutdown(state->connection_out, SHUT_RDWR); close(state->connection_out); } else { close(state->connection_in); close(state->connection_out); } sshbuf_free(state->input); sshbuf_free(state->output); sshbuf_free(state->outgoing_packet); sshbuf_free(state->incoming_packet); for (mode = 0; mode < MODE_MAX; mode++) kex_free_newkeys(state->newkeys[mode]); if (state->compression_buffer) { sshbuf_free(state->compression_buffer); if (state->compression_out_started) { z_streamp stream = &state->compression_out_stream; debug("compress outgoing: " "raw data %llu, compressed %llu, factor %.2f", (unsigned long long)stream->total_in, (unsigned long long)stream->total_out, stream->total_in == 0 ? 0.0 : (double) stream->total_out / stream->total_in); if (state->compression_out_failures == 0) deflateEnd(stream); } if (state->compression_in_started) { z_streamp stream = &state->compression_out_stream; debug("compress incoming: " "raw data %llu, compressed %llu, factor %.2f", (unsigned long long)stream->total_out, (unsigned long long)stream->total_in, stream->total_out == 0 ? 0.0 : (double) stream->total_in / stream->total_out); if (state->compression_in_failures == 0) inflateEnd(stream); } } cipher_free(state->send_context); cipher_free(state->receive_context); state->send_context = state->receive_context = NULL; free(ssh->remote_ipaddr); ssh->remote_ipaddr = NULL; free(ssh->state); ssh->state = NULL; } /* Sets remote side protocol flags. */ void ssh_packet_set_protocol_flags(struct ssh *ssh, u_int protocol_flags) { ssh->state->remote_protocol_flags = protocol_flags; } /* Returns the remote protocol flags set earlier by the above function. */ u_int ssh_packet_get_protocol_flags(struct ssh *ssh) { return ssh->state->remote_protocol_flags; } /* * Starts packet compression from the next packet on in both directions. * Level is compression level 1 (fastest) - 9 (slow, best) as in gzip. */ static int ssh_packet_init_compression(struct ssh *ssh) { if (!ssh->state->compression_buffer && ((ssh->state->compression_buffer = sshbuf_new()) == NULL)) return SSH_ERR_ALLOC_FAIL; return 0; } static int start_compression_out(struct ssh *ssh, int level) { if (level < 1 || level > 9) return SSH_ERR_INVALID_ARGUMENT; debug("Enabling compression at level %d.", level); if (ssh->state->compression_out_started == 1) deflateEnd(&ssh->state->compression_out_stream); switch (deflateInit(&ssh->state->compression_out_stream, level)) { case Z_OK: ssh->state->compression_out_started = 1; break; case Z_MEM_ERROR: return SSH_ERR_ALLOC_FAIL; default: return SSH_ERR_INTERNAL_ERROR; } return 0; } static int start_compression_in(struct ssh *ssh) { if (ssh->state->compression_in_started == 1) inflateEnd(&ssh->state->compression_in_stream); switch (inflateInit(&ssh->state->compression_in_stream)) { case Z_OK: ssh->state->compression_in_started = 1; break; case Z_MEM_ERROR: return SSH_ERR_ALLOC_FAIL; default: return SSH_ERR_INTERNAL_ERROR; } return 0; } int ssh_packet_start_compression(struct ssh *ssh, int level) { int r; if (ssh->state->packet_compression && !compat20) return SSH_ERR_INTERNAL_ERROR; ssh->state->packet_compression = 1; if ((r = ssh_packet_init_compression(ssh)) != 0 || (r = start_compression_in(ssh)) != 0 || (r = start_compression_out(ssh, level)) != 0) return r; return 0; } /* XXX remove need for separate compression buffer */ static int compress_buffer(struct ssh *ssh, struct sshbuf *in, struct sshbuf *out) { u_char buf[4096]; int r, status; if (ssh->state->compression_out_started != 1) return SSH_ERR_INTERNAL_ERROR; /* This case is not handled below. */ if (sshbuf_len(in) == 0) return 0; /* Input is the contents of the input buffer. */ if ((ssh->state->compression_out_stream.next_in = sshbuf_mutable_ptr(in)) == NULL) return SSH_ERR_INTERNAL_ERROR; ssh->state->compression_out_stream.avail_in = sshbuf_len(in); /* Loop compressing until deflate() returns with avail_out != 0. */ do { /* Set up fixed-size output buffer. */ ssh->state->compression_out_stream.next_out = buf; ssh->state->compression_out_stream.avail_out = sizeof(buf); /* Compress as much data into the buffer as possible. */ status = deflate(&ssh->state->compression_out_stream, Z_PARTIAL_FLUSH); switch (status) { case Z_MEM_ERROR: return SSH_ERR_ALLOC_FAIL; case Z_OK: /* Append compressed data to output_buffer. */ if ((r = sshbuf_put(out, buf, sizeof(buf) - ssh->state->compression_out_stream.avail_out)) != 0) return r; break; case Z_STREAM_ERROR: default: ssh->state->compression_out_failures++; return SSH_ERR_INVALID_FORMAT; } } while (ssh->state->compression_out_stream.avail_out == 0); return 0; } static int uncompress_buffer(struct ssh *ssh, struct sshbuf *in, struct sshbuf *out) { u_char buf[4096]; int r, status; if (ssh->state->compression_in_started != 1) return SSH_ERR_INTERNAL_ERROR; if ((ssh->state->compression_in_stream.next_in = sshbuf_mutable_ptr(in)) == NULL) return SSH_ERR_INTERNAL_ERROR; ssh->state->compression_in_stream.avail_in = sshbuf_len(in); for (;;) { /* Set up fixed-size output buffer. */ ssh->state->compression_in_stream.next_out = buf; ssh->state->compression_in_stream.avail_out = sizeof(buf); status = inflate(&ssh->state->compression_in_stream, Z_PARTIAL_FLUSH); switch (status) { case Z_OK: if ((r = sshbuf_put(out, buf, sizeof(buf) - ssh->state->compression_in_stream.avail_out)) != 0) return r; break; case Z_BUF_ERROR: /* * Comments in zlib.h say that we should keep calling * inflate() until we get an error. This appears to * be the error that we get. */ return 0; case Z_DATA_ERROR: return SSH_ERR_INVALID_FORMAT; case Z_MEM_ERROR: return SSH_ERR_ALLOC_FAIL; case Z_STREAM_ERROR: default: ssh->state->compression_in_failures++; return SSH_ERR_INTERNAL_ERROR; } } /* NOTREACHED */ } /* Serialise compression state into a blob for privsep */ static int ssh_packet_get_compress_state(struct sshbuf *m, struct ssh *ssh) { struct session_state *state = ssh->state; struct sshbuf *b; int r; if ((b = sshbuf_new()) == NULL) return SSH_ERR_ALLOC_FAIL; if (state->compression_in_started) { if ((r = sshbuf_put_string(b, &state->compression_in_stream, sizeof(state->compression_in_stream))) != 0) goto out; } else if ((r = sshbuf_put_string(b, NULL, 0)) != 0) goto out; if (state->compression_out_started) { if ((r = sshbuf_put_string(b, &state->compression_out_stream, sizeof(state->compression_out_stream))) != 0) goto out; } else if ((r = sshbuf_put_string(b, NULL, 0)) != 0) goto out; r = sshbuf_put_stringb(m, b); out: sshbuf_free(b); return r; } /* Deserialise compression state from a blob for privsep */ static int ssh_packet_set_compress_state(struct ssh *ssh, struct sshbuf *m) { struct session_state *state = ssh->state; struct sshbuf *b = NULL; int r; const u_char *inblob, *outblob; size_t inl, outl; if ((r = sshbuf_froms(m, &b)) != 0) goto out; if ((r = sshbuf_get_string_direct(b, &inblob, &inl)) != 0 || (r = sshbuf_get_string_direct(b, &outblob, &outl)) != 0) goto out; if (inl == 0) state->compression_in_started = 0; else if (inl != sizeof(state->compression_in_stream)) { r = SSH_ERR_INTERNAL_ERROR; goto out; } else { state->compression_in_started = 1; memcpy(&state->compression_in_stream, inblob, inl); } if (outl == 0) state->compression_out_started = 0; else if (outl != sizeof(state->compression_out_stream)) { r = SSH_ERR_INTERNAL_ERROR; goto out; } else { state->compression_out_started = 1; memcpy(&state->compression_out_stream, outblob, outl); } r = 0; out: sshbuf_free(b); return r; } void ssh_packet_set_compress_hooks(struct ssh *ssh, void *ctx, void *(*allocfunc)(void *, u_int, u_int), void (*freefunc)(void *, void *)) { ssh->state->compression_out_stream.zalloc = (alloc_func)allocfunc; ssh->state->compression_out_stream.zfree = (free_func)freefunc; ssh->state->compression_out_stream.opaque = ctx; ssh->state->compression_in_stream.zalloc = (alloc_func)allocfunc; ssh->state->compression_in_stream.zfree = (free_func)freefunc; ssh->state->compression_in_stream.opaque = ctx; } /* * Causes any further packets to be encrypted using the given key. The same * key is used for both sending and reception. However, both directions are * encrypted independently of each other. */ void ssh_packet_set_encryption_key(struct ssh *ssh, const u_char *key, u_int keylen, int number) { #ifndef WITH_SSH1 fatal("no SSH protocol 1 support"); #else /* WITH_SSH1 */ struct session_state *state = ssh->state; const struct sshcipher *cipher = cipher_by_number(number); int r; const char *wmsg; if (cipher == NULL) fatal("%s: unknown cipher number %d", __func__, number); if (keylen < 20) fatal("%s: keylen too small: %d", __func__, keylen); if (keylen > SSH_SESSION_KEY_LENGTH) fatal("%s: keylen too big: %d", __func__, keylen); memcpy(state->ssh1_key, key, keylen); state->ssh1_keylen = keylen; if ((r = cipher_init(&state->send_context, cipher, key, keylen, NULL, 0, CIPHER_ENCRYPT)) != 0 || (r = cipher_init(&state->receive_context, cipher, key, keylen, NULL, 0, CIPHER_DECRYPT) != 0)) fatal("%s: cipher_init failed: %s", __func__, ssh_err(r)); if (!state->cipher_warning_done && ((wmsg = cipher_warning_message(state->send_context)) != NULL || (wmsg = cipher_warning_message(state->send_context)) != NULL)) { error("Warning: %s", wmsg); state->cipher_warning_done = 1; } #endif /* WITH_SSH1 */ } /* * Finalizes and sends the packet. If the encryption key has been set, * encrypts the packet before sending. */ int ssh_packet_send1(struct ssh *ssh) { struct session_state *state = ssh->state; u_char buf[8], *cp; int r, padding, len; u_int checksum; /* * If using packet compression, compress the payload of the outgoing * packet. */ if (state->packet_compression) { sshbuf_reset(state->compression_buffer); /* Skip padding. */ if ((r = sshbuf_consume(state->outgoing_packet, 8)) != 0) goto out; /* padding */ if ((r = sshbuf_put(state->compression_buffer, "\0\0\0\0\0\0\0\0", 8)) != 0) goto out; if ((r = compress_buffer(ssh, state->outgoing_packet, state->compression_buffer)) != 0) goto out; sshbuf_reset(state->outgoing_packet); if ((r = sshbuf_putb(state->outgoing_packet, state->compression_buffer)) != 0) goto out; } /* Compute packet length without padding (add checksum, remove padding). */ len = sshbuf_len(state->outgoing_packet) + 4 - 8; /* Insert padding. Initialized to zero in packet_start1() */ padding = 8 - len % 8; if (!cipher_ctx_is_plaintext(state->send_context)) { cp = sshbuf_mutable_ptr(state->outgoing_packet); if (cp == NULL) { r = SSH_ERR_INTERNAL_ERROR; goto out; } arc4random_buf(cp + 8 - padding, padding); } if ((r = sshbuf_consume(state->outgoing_packet, 8 - padding)) != 0) goto out; /* Add check bytes. */ checksum = ssh_crc32(sshbuf_ptr(state->outgoing_packet), sshbuf_len(state->outgoing_packet)); POKE_U32(buf, checksum); if ((r = sshbuf_put(state->outgoing_packet, buf, 4)) != 0) goto out; #ifdef PACKET_DEBUG fprintf(stderr, "packet_send plain: "); sshbuf_dump(state->outgoing_packet, stderr); #endif /* Append to output. */ POKE_U32(buf, len); if ((r = sshbuf_put(state->output, buf, 4)) != 0) goto out; if ((r = sshbuf_reserve(state->output, sshbuf_len(state->outgoing_packet), &cp)) != 0) goto out; if ((r = cipher_crypt(state->send_context, 0, cp, sshbuf_ptr(state->outgoing_packet), sshbuf_len(state->outgoing_packet), 0, 0)) != 0) goto out; #ifdef PACKET_DEBUG fprintf(stderr, "encrypted: "); sshbuf_dump(state->output, stderr); #endif state->p_send.packets++; state->p_send.bytes += len + sshbuf_len(state->outgoing_packet); sshbuf_reset(state->outgoing_packet); /* * Note that the packet is now only buffered in output. It won't be * actually sent until ssh_packet_write_wait or ssh_packet_write_poll * is called. */ r = 0; out: return r; } int ssh_set_newkeys(struct ssh *ssh, int mode) { struct session_state *state = ssh->state; struct sshenc *enc; struct sshmac *mac; struct sshcomp *comp; struct sshcipher_ctx **ccp; struct packet_state *ps; u_int64_t *max_blocks; const char *wmsg, *dir; int r, crypt_type; debug2("set_newkeys: mode %d", mode); if (mode == MODE_OUT) { dir = "output"; ccp = &state->send_context; crypt_type = CIPHER_ENCRYPT; ps = &state->p_send; max_blocks = &state->max_blocks_out; } else { dir = "input"; ccp = &state->receive_context; crypt_type = CIPHER_DECRYPT; ps = &state->p_read; max_blocks = &state->max_blocks_in; } if (state->newkeys[mode] != NULL) { debug("%s: rekeying after %llu %s blocks" " (%llu bytes total)", __func__, (unsigned long long)ps->blocks, dir, (unsigned long long)ps->bytes); cipher_free(*ccp); *ccp = NULL; enc = &state->newkeys[mode]->enc; mac = &state->newkeys[mode]->mac; comp = &state->newkeys[mode]->comp; mac_clear(mac); explicit_bzero(enc->iv, enc->iv_len); explicit_bzero(enc->key, enc->key_len); explicit_bzero(mac->key, mac->key_len); free(enc->name); free(enc->iv); free(enc->key); free(mac->name); free(mac->key); free(comp->name); free(state->newkeys[mode]); } /* note that both bytes and the seqnr are not reset */ ps->packets = ps->blocks = 0; /* move newkeys from kex to state */ if ((state->newkeys[mode] = ssh->kex->newkeys[mode]) == NULL) return SSH_ERR_INTERNAL_ERROR; ssh->kex->newkeys[mode] = NULL; enc = &state->newkeys[mode]->enc; mac = &state->newkeys[mode]->mac; comp = &state->newkeys[mode]->comp; if (cipher_authlen(enc->cipher) == 0) { if ((r = mac_init(mac)) != 0) return r; } mac->enabled = 1; DBG(debug("cipher_init_context: %d", mode)); if ((r = cipher_init(ccp, enc->cipher, enc->key, enc->key_len, enc->iv, enc->iv_len, crypt_type)) != 0) return r; if (!state->cipher_warning_done && (wmsg = cipher_warning_message(*ccp)) != NULL) { error("Warning: %s", wmsg); state->cipher_warning_done = 1; } /* Deleting the keys does not gain extra security */ /* explicit_bzero(enc->iv, enc->block_size); explicit_bzero(enc->key, enc->key_len); explicit_bzero(mac->key, mac->key_len); */ if ((comp->type == COMP_ZLIB || (comp->type == COMP_DELAYED && state->after_authentication)) && comp->enabled == 0) { if ((r = ssh_packet_init_compression(ssh)) < 0) return r; if (mode == MODE_OUT) { if ((r = start_compression_out(ssh, 6)) != 0) return r; } else { if ((r = start_compression_in(ssh)) != 0) return r; } comp->enabled = 1; } /* * The 2^(blocksize*2) limit is too expensive for 3DES, * blowfish, etc, so enforce a 1GB limit for small blocksizes. */ if (enc->block_size >= 16) *max_blocks = (u_int64_t)1 << (enc->block_size*2); else *max_blocks = ((u_int64_t)1 << 30) / enc->block_size; if (state->rekey_limit) *max_blocks = MIN(*max_blocks, state->rekey_limit / enc->block_size); debug("rekey after %llu blocks", (unsigned long long)*max_blocks); return 0; } #define MAX_PACKETS (1U<<31) static int ssh_packet_need_rekeying(struct ssh *ssh, u_int outbound_packet_len) { struct session_state *state = ssh->state; u_int32_t out_blocks; /* XXX client can't cope with rekeying pre-auth */ if (!state->after_authentication) return 0; /* Haven't keyed yet or KEX in progress. */ if (ssh->kex == NULL || ssh_packet_is_rekeying(ssh)) return 0; /* Peer can't rekey */ if (ssh->compat & SSH_BUG_NOREKEY) return 0; /* * Permit one packet in or out per rekey - this allows us to * make progress when rekey limits are very small. */ if (state->p_send.packets == 0 && state->p_read.packets == 0) return 0; /* Time-based rekeying */ if (state->rekey_interval != 0 && state->rekey_time + state->rekey_interval <= monotime()) return 1; /* Always rekey when MAX_PACKETS sent in either direction */ if (state->p_send.packets > MAX_PACKETS || state->p_read.packets > MAX_PACKETS) return 1; /* Rekey after (cipher-specific) maxiumum blocks */ out_blocks = roundup(outbound_packet_len, state->newkeys[MODE_OUT]->enc.block_size); return (state->max_blocks_out && (state->p_send.blocks + out_blocks > state->max_blocks_out)) || (state->max_blocks_in && (state->p_read.blocks > state->max_blocks_in)); } /* * Delayed compression for SSH2 is enabled after authentication: * This happens on the server side after a SSH2_MSG_USERAUTH_SUCCESS is sent, * and on the client side after a SSH2_MSG_USERAUTH_SUCCESS is received. */ static int ssh_packet_enable_delayed_compress(struct ssh *ssh) { struct session_state *state = ssh->state; struct sshcomp *comp = NULL; int r, mode; /* * Remember that we are past the authentication step, so rekeying * with COMP_DELAYED will turn on compression immediately. */ state->after_authentication = 1; for (mode = 0; mode < MODE_MAX; mode++) { /* protocol error: USERAUTH_SUCCESS received before NEWKEYS */ if (state->newkeys[mode] == NULL) continue; comp = &state->newkeys[mode]->comp; if (comp && !comp->enabled && comp->type == COMP_DELAYED) { if ((r = ssh_packet_init_compression(ssh)) != 0) return r; if (mode == MODE_OUT) { if ((r = start_compression_out(ssh, 6)) != 0) return r; } else { if ((r = start_compression_in(ssh)) != 0) return r; } comp->enabled = 1; } } return 0; } /* Used to mute debug logging for noisy packet types */ static int ssh_packet_log_type(u_char type) { switch (type) { case SSH2_MSG_CHANNEL_DATA: case SSH2_MSG_CHANNEL_EXTENDED_DATA: case SSH2_MSG_CHANNEL_WINDOW_ADJUST: return 0; default: return 1; } } /* * Finalize packet in SSH2 format (compress, mac, encrypt, enqueue) */ int ssh_packet_send2_wrapped(struct ssh *ssh) { struct session_state *state = ssh->state; u_char type, *cp, macbuf[SSH_DIGEST_MAX_LENGTH]; u_char tmp, padlen, pad = 0; u_int authlen = 0, aadlen = 0; u_int len; struct sshenc *enc = NULL; struct sshmac *mac = NULL; struct sshcomp *comp = NULL; int r, block_size; if (state->newkeys[MODE_OUT] != NULL) { enc = &state->newkeys[MODE_OUT]->enc; mac = &state->newkeys[MODE_OUT]->mac; comp = &state->newkeys[MODE_OUT]->comp; /* disable mac for authenticated encryption */ if ((authlen = cipher_authlen(enc->cipher)) != 0) mac = NULL; } block_size = enc ? enc->block_size : 8; aadlen = (mac && mac->enabled && mac->etm) || authlen ? 4 : 0; type = (sshbuf_ptr(state->outgoing_packet))[5]; if (ssh_packet_log_type(type)) debug3("send packet: type %u", type); #ifdef PACKET_DEBUG fprintf(stderr, "plain: "); sshbuf_dump(state->outgoing_packet, stderr); #endif if (comp && comp->enabled) { len = sshbuf_len(state->outgoing_packet); /* skip header, compress only payload */ if ((r = sshbuf_consume(state->outgoing_packet, 5)) != 0) goto out; sshbuf_reset(state->compression_buffer); if ((r = compress_buffer(ssh, state->outgoing_packet, state->compression_buffer)) != 0) goto out; sshbuf_reset(state->outgoing_packet); if ((r = sshbuf_put(state->outgoing_packet, "\0\0\0\0\0", 5)) != 0 || (r = sshbuf_putb(state->outgoing_packet, state->compression_buffer)) != 0) goto out; DBG(debug("compression: raw %d compressed %zd", len, sshbuf_len(state->outgoing_packet))); } /* sizeof (packet_len + pad_len + payload) */ len = sshbuf_len(state->outgoing_packet); /* * calc size of padding, alloc space, get random data, * minimum padding is 4 bytes */ len -= aadlen; /* packet length is not encrypted for EtM modes */ padlen = block_size - (len % block_size); if (padlen < 4) padlen += block_size; if (state->extra_pad) { tmp = state->extra_pad; state->extra_pad = roundup(state->extra_pad, block_size); /* check if roundup overflowed */ if (state->extra_pad < tmp) return SSH_ERR_INVALID_ARGUMENT; tmp = (len + padlen) % state->extra_pad; /* Check whether pad calculation below will underflow */ if (tmp > state->extra_pad) return SSH_ERR_INVALID_ARGUMENT; pad = state->extra_pad - tmp; DBG(debug3("%s: adding %d (len %d padlen %d extra_pad %d)", __func__, pad, len, padlen, state->extra_pad)); tmp = padlen; padlen += pad; /* Check whether padlen calculation overflowed */ if (padlen < tmp) return SSH_ERR_INVALID_ARGUMENT; /* overflow */ state->extra_pad = 0; } if ((r = sshbuf_reserve(state->outgoing_packet, padlen, &cp)) != 0) goto out; if (enc && !cipher_ctx_is_plaintext(state->send_context)) { /* random padding */ arc4random_buf(cp, padlen); } else { /* clear padding */ explicit_bzero(cp, padlen); } /* sizeof (packet_len + pad_len + payload + padding) */ len = sshbuf_len(state->outgoing_packet); cp = sshbuf_mutable_ptr(state->outgoing_packet); if (cp == NULL) { r = SSH_ERR_INTERNAL_ERROR; goto out; } /* packet_length includes payload, padding and padding length field */ POKE_U32(cp, len - 4); cp[4] = padlen; DBG(debug("send: len %d (includes padlen %d, aadlen %d)", len, padlen, aadlen)); /* compute MAC over seqnr and packet(length fields, payload, padding) */ if (mac && mac->enabled && !mac->etm) { if ((r = mac_compute(mac, state->p_send.seqnr, sshbuf_ptr(state->outgoing_packet), len, macbuf, sizeof(macbuf))) != 0) goto out; DBG(debug("done calc MAC out #%d", state->p_send.seqnr)); } /* encrypt packet and append to output buffer. */ if ((r = sshbuf_reserve(state->output, sshbuf_len(state->outgoing_packet) + authlen, &cp)) != 0) goto out; if ((r = cipher_crypt(state->send_context, state->p_send.seqnr, cp, sshbuf_ptr(state->outgoing_packet), len - aadlen, aadlen, authlen)) != 0) goto out; /* append unencrypted MAC */ if (mac && mac->enabled) { if (mac->etm) { /* EtM: compute mac over aadlen + cipher text */ if ((r = mac_compute(mac, state->p_send.seqnr, cp, len, macbuf, sizeof(macbuf))) != 0) goto out; DBG(debug("done calc MAC(EtM) out #%d", state->p_send.seqnr)); } if ((r = sshbuf_put(state->output, macbuf, mac->mac_len)) != 0) goto out; } #ifdef PACKET_DEBUG fprintf(stderr, "encrypted: "); sshbuf_dump(state->output, stderr); #endif /* increment sequence number for outgoing packets */ if (++state->p_send.seqnr == 0) logit("outgoing seqnr wraps around"); if (++state->p_send.packets == 0) if (!(ssh->compat & SSH_BUG_NOREKEY)) return SSH_ERR_NEED_REKEY; state->p_send.blocks += len / block_size; state->p_send.bytes += len; sshbuf_reset(state->outgoing_packet); if (type == SSH2_MSG_NEWKEYS) r = ssh_set_newkeys(ssh, MODE_OUT); else if (type == SSH2_MSG_USERAUTH_SUCCESS && state->server_side) r = ssh_packet_enable_delayed_compress(ssh); else r = 0; out: return r; } /* returns non-zero if the specified packet type is usec by KEX */ static int ssh_packet_type_is_kex(u_char type) { return type >= SSH2_MSG_TRANSPORT_MIN && type <= SSH2_MSG_TRANSPORT_MAX && type != SSH2_MSG_SERVICE_REQUEST && type != SSH2_MSG_SERVICE_ACCEPT && type != SSH2_MSG_EXT_INFO; } int ssh_packet_send2(struct ssh *ssh) { struct session_state *state = ssh->state; struct packet *p; u_char type; int r, need_rekey; if (sshbuf_len(state->outgoing_packet) < 6) return SSH_ERR_INTERNAL_ERROR; type = sshbuf_ptr(state->outgoing_packet)[5]; need_rekey = !ssh_packet_type_is_kex(type) && ssh_packet_need_rekeying(ssh, sshbuf_len(state->outgoing_packet)); /* * During rekeying we can only send key exchange messages. * Queue everything else. */ if ((need_rekey || state->rekeying) && !ssh_packet_type_is_kex(type)) { if (need_rekey) debug3("%s: rekex triggered", __func__); debug("enqueue packet: %u", type); p = calloc(1, sizeof(*p)); if (p == NULL) return SSH_ERR_ALLOC_FAIL; p->type = type; p->payload = state->outgoing_packet; TAILQ_INSERT_TAIL(&state->outgoing, p, next); state->outgoing_packet = sshbuf_new(); if (state->outgoing_packet == NULL) return SSH_ERR_ALLOC_FAIL; if (need_rekey) { /* * This packet triggered a rekey, so send the * KEXINIT now. * NB. reenters this function via kex_start_rekex(). */ return kex_start_rekex(ssh); } return 0; } /* rekeying starts with sending KEXINIT */ if (type == SSH2_MSG_KEXINIT) state->rekeying = 1; if ((r = ssh_packet_send2_wrapped(ssh)) != 0) return r; /* after a NEWKEYS message we can send the complete queue */ if (type == SSH2_MSG_NEWKEYS) { state->rekeying = 0; state->rekey_time = monotime(); while ((p = TAILQ_FIRST(&state->outgoing))) { type = p->type; /* * If this packet triggers a rekex, then skip the * remaining packets in the queue for now. * NB. re-enters this function via kex_start_rekex. */ if (ssh_packet_need_rekeying(ssh, sshbuf_len(p->payload))) { debug3("%s: queued packet triggered rekex", __func__); return kex_start_rekex(ssh); } debug("dequeue packet: %u", type); sshbuf_free(state->outgoing_packet); state->outgoing_packet = p->payload; TAILQ_REMOVE(&state->outgoing, p, next); memset(p, 0, sizeof(*p)); free(p); if ((r = ssh_packet_send2_wrapped(ssh)) != 0) return r; } } return 0; } /* * Waits until a packet has been received, and returns its type. Note that * no other data is processed until this returns, so this function should not * be used during the interactive session. */ int ssh_packet_read_seqnr(struct ssh *ssh, u_char *typep, u_int32_t *seqnr_p) { struct session_state *state = ssh->state; int len, r, ms_remain; fd_set *setp; char buf[8192]; struct timeval timeout, start, *timeoutp = NULL; DBG(debug("packet_read()")); setp = calloc(howmany(state->connection_in + 1, NFDBITS), sizeof(fd_mask)); if (setp == NULL) return SSH_ERR_ALLOC_FAIL; /* * Since we are blocking, ensure that all written packets have * been sent. */ if ((r = ssh_packet_write_wait(ssh)) != 0) goto out; /* Stay in the loop until we have received a complete packet. */ for (;;) { /* Try to read a packet from the buffer. */ r = ssh_packet_read_poll_seqnr(ssh, typep, seqnr_p); if (r != 0) break; if (!compat20 && ( *typep == SSH_SMSG_SUCCESS || *typep == SSH_SMSG_FAILURE || *typep == SSH_CMSG_EOF || *typep == SSH_CMSG_EXIT_CONFIRMATION)) if ((r = sshpkt_get_end(ssh)) != 0) break; /* If we got a packet, return it. */ if (*typep != SSH_MSG_NONE) break; /* * Otherwise, wait for some data to arrive, add it to the * buffer, and try again. */ memset(setp, 0, howmany(state->connection_in + 1, NFDBITS) * sizeof(fd_mask)); FD_SET(state->connection_in, setp); if (state->packet_timeout_ms > 0) { ms_remain = state->packet_timeout_ms; timeoutp = &timeout; } /* Wait for some data to arrive. */ for (;;) { if (state->packet_timeout_ms != -1) { ms_to_timeval(&timeout, ms_remain); gettimeofday(&start, NULL); } if ((r = select(state->connection_in + 1, setp, NULL, NULL, timeoutp)) >= 0) break; if (errno != EAGAIN && errno != EINTR && errno != EWOULDBLOCK) break; if (state->packet_timeout_ms == -1) continue; ms_subtract_diff(&start, &ms_remain); if (ms_remain <= 0) { r = 0; break; } } if (r == 0) return SSH_ERR_CONN_TIMEOUT; /* Read data from the socket. */ len = read(state->connection_in, buf, sizeof(buf)); if (len == 0) { r = SSH_ERR_CONN_CLOSED; goto out; } if (len < 0) { r = SSH_ERR_SYSTEM_ERROR; goto out; } /* Append it to the buffer. */ if ((r = ssh_packet_process_incoming(ssh, buf, len)) != 0) goto out; } out: free(setp); return r; } int ssh_packet_read(struct ssh *ssh) { u_char type; int r; if ((r = ssh_packet_read_seqnr(ssh, &type, NULL)) != 0) fatal("%s: %s", __func__, ssh_err(r)); return type; } /* * Waits until a packet has been received, verifies that its type matches * that given, and gives a fatal error and exits if there is a mismatch. */ int ssh_packet_read_expect(struct ssh *ssh, u_int expected_type) { int r; u_char type; if ((r = ssh_packet_read_seqnr(ssh, &type, NULL)) != 0) return r; if (type != expected_type) { if ((r = sshpkt_disconnect(ssh, "Protocol error: expected packet type %d, got %d", expected_type, type)) != 0) return r; return SSH_ERR_PROTOCOL_ERROR; } return 0; } /* Checks if a full packet is available in the data received so far via * packet_process_incoming. If so, reads the packet; otherwise returns * SSH_MSG_NONE. This does not wait for data from the connection. * * SSH_MSG_DISCONNECT is handled specially here. Also, * SSH_MSG_IGNORE messages are skipped by this function and are never returned * to higher levels. */ int ssh_packet_read_poll1(struct ssh *ssh, u_char *typep) { struct session_state *state = ssh->state; u_int len, padded_len; const char *emsg; const u_char *cp; u_char *p; u_int checksum, stored_checksum; int r; *typep = SSH_MSG_NONE; /* Check if input size is less than minimum packet size. */ if (sshbuf_len(state->input) < 4 + 8) return 0; /* Get length of incoming packet. */ len = PEEK_U32(sshbuf_ptr(state->input)); if (len < 1 + 2 + 2 || len > 256 * 1024) { if ((r = sshpkt_disconnect(ssh, "Bad packet length %u", len)) != 0) return r; return SSH_ERR_CONN_CORRUPT; } padded_len = (len + 8) & ~7; /* Check if the packet has been entirely received. */ if (sshbuf_len(state->input) < 4 + padded_len) return 0; /* The entire packet is in buffer. */ /* Consume packet length. */ if ((r = sshbuf_consume(state->input, 4)) != 0) goto out; /* * Cryptographic attack detector for ssh * (C)1998 CORE-SDI, Buenos Aires Argentina * Ariel Futoransky(futo@core-sdi.com) */ if (!cipher_ctx_is_plaintext(state->receive_context)) { emsg = NULL; switch (detect_attack(&state->deattack, sshbuf_ptr(state->input), padded_len)) { case DEATTACK_OK: break; case DEATTACK_DETECTED: emsg = "crc32 compensation attack detected"; break; case DEATTACK_DOS_DETECTED: emsg = "deattack denial of service detected"; break; default: emsg = "deattack error"; break; } if (emsg != NULL) { error("%s", emsg); if ((r = sshpkt_disconnect(ssh, "%s", emsg)) != 0 || (r = ssh_packet_write_wait(ssh)) != 0) return r; return SSH_ERR_CONN_CORRUPT; } } /* Decrypt data to incoming_packet. */ sshbuf_reset(state->incoming_packet); if ((r = sshbuf_reserve(state->incoming_packet, padded_len, &p)) != 0) goto out; if ((r = cipher_crypt(state->receive_context, 0, p, sshbuf_ptr(state->input), padded_len, 0, 0)) != 0) goto out; if ((r = sshbuf_consume(state->input, padded_len)) != 0) goto out; #ifdef PACKET_DEBUG fprintf(stderr, "read_poll plain: "); sshbuf_dump(state->incoming_packet, stderr); #endif /* Compute packet checksum. */ checksum = ssh_crc32(sshbuf_ptr(state->incoming_packet), sshbuf_len(state->incoming_packet) - 4); /* Skip padding. */ if ((r = sshbuf_consume(state->incoming_packet, 8 - len % 8)) != 0) goto out; /* Test check bytes. */ if (len != sshbuf_len(state->incoming_packet)) { error("%s: len %d != sshbuf_len %zd", __func__, len, sshbuf_len(state->incoming_packet)); if ((r = sshpkt_disconnect(ssh, "invalid packet length")) != 0 || (r = ssh_packet_write_wait(ssh)) != 0) return r; return SSH_ERR_CONN_CORRUPT; } cp = sshbuf_ptr(state->incoming_packet) + len - 4; stored_checksum = PEEK_U32(cp); if (checksum != stored_checksum) { error("Corrupted check bytes on input"); if ((r = sshpkt_disconnect(ssh, "connection corrupted")) != 0 || (r = ssh_packet_write_wait(ssh)) != 0) return r; return SSH_ERR_CONN_CORRUPT; } if ((r = sshbuf_consume_end(state->incoming_packet, 4)) < 0) goto out; if (state->packet_compression) { sshbuf_reset(state->compression_buffer); if ((r = uncompress_buffer(ssh, state->incoming_packet, state->compression_buffer)) != 0) goto out; sshbuf_reset(state->incoming_packet); if ((r = sshbuf_putb(state->incoming_packet, state->compression_buffer)) != 0) goto out; } state->p_read.packets++; state->p_read.bytes += padded_len + 4; if ((r = sshbuf_get_u8(state->incoming_packet, typep)) != 0) goto out; if (*typep < SSH_MSG_MIN || *typep > SSH_MSG_MAX) { error("Invalid ssh1 packet type: %d", *typep); if ((r = sshpkt_disconnect(ssh, "invalid packet type")) != 0 || (r = ssh_packet_write_wait(ssh)) != 0) return r; return SSH_ERR_PROTOCOL_ERROR; } r = 0; out: return r; } int ssh_packet_read_poll2(struct ssh *ssh, u_char *typep, u_int32_t *seqnr_p) { struct session_state *state = ssh->state; u_int padlen, need; u_char *cp; u_int maclen, aadlen = 0, authlen = 0, block_size; struct sshenc *enc = NULL; struct sshmac *mac = NULL; struct sshcomp *comp = NULL; int r; *typep = SSH_MSG_NONE; if (state->packet_discard) return 0; if (state->newkeys[MODE_IN] != NULL) { enc = &state->newkeys[MODE_IN]->enc; mac = &state->newkeys[MODE_IN]->mac; comp = &state->newkeys[MODE_IN]->comp; /* disable mac for authenticated encryption */ if ((authlen = cipher_authlen(enc->cipher)) != 0) mac = NULL; } maclen = mac && mac->enabled ? mac->mac_len : 0; block_size = enc ? enc->block_size : 8; aadlen = (mac && mac->enabled && mac->etm) || authlen ? 4 : 0; if (aadlen && state->packlen == 0) { if (cipher_get_length(state->receive_context, &state->packlen, state->p_read.seqnr, sshbuf_ptr(state->input), sshbuf_len(state->input)) != 0) return 0; if (state->packlen < 1 + 4 || state->packlen > PACKET_MAX_SIZE) { #ifdef PACKET_DEBUG sshbuf_dump(state->input, stderr); #endif logit("Bad packet length %u.", state->packlen); if ((r = sshpkt_disconnect(ssh, "Packet corrupt")) != 0) return r; return SSH_ERR_CONN_CORRUPT; } sshbuf_reset(state->incoming_packet); } else if (state->packlen == 0) { /* * check if input size is less than the cipher block size, * decrypt first block and extract length of incoming packet */ if (sshbuf_len(state->input) < block_size) return 0; sshbuf_reset(state->incoming_packet); if ((r = sshbuf_reserve(state->incoming_packet, block_size, &cp)) != 0) goto out; if ((r = cipher_crypt(state->receive_context, state->p_send.seqnr, cp, sshbuf_ptr(state->input), block_size, 0, 0)) != 0) goto out; state->packlen = PEEK_U32(sshbuf_ptr(state->incoming_packet)); if (state->packlen < 1 + 4 || state->packlen > PACKET_MAX_SIZE) { #ifdef PACKET_DEBUG fprintf(stderr, "input: \n"); sshbuf_dump(state->input, stderr); fprintf(stderr, "incoming_packet: \n"); sshbuf_dump(state->incoming_packet, stderr); #endif logit("Bad packet length %u.", state->packlen); return ssh_packet_start_discard(ssh, enc, mac, 0, PACKET_MAX_SIZE); } if ((r = sshbuf_consume(state->input, block_size)) != 0) goto out; } DBG(debug("input: packet len %u", state->packlen+4)); if (aadlen) { /* only the payload is encrypted */ need = state->packlen; } else { /* * the payload size and the payload are encrypted, but we * have a partial packet of block_size bytes */ need = 4 + state->packlen - block_size; } DBG(debug("partial packet: block %d, need %d, maclen %d, authlen %d," " aadlen %d", block_size, need, maclen, authlen, aadlen)); if (need % block_size != 0) { logit("padding error: need %d block %d mod %d", need, block_size, need % block_size); return ssh_packet_start_discard(ssh, enc, mac, 0, PACKET_MAX_SIZE - block_size); } /* * check if the entire packet has been received and * decrypt into incoming_packet: * 'aadlen' bytes are unencrypted, but authenticated. * 'need' bytes are encrypted, followed by either * 'authlen' bytes of authentication tag or * 'maclen' bytes of message authentication code. */ if (sshbuf_len(state->input) < aadlen + need + authlen + maclen) return 0; /* packet is incomplete */ #ifdef PACKET_DEBUG fprintf(stderr, "read_poll enc/full: "); sshbuf_dump(state->input, stderr); #endif /* EtM: check mac over encrypted input */ if (mac && mac->enabled && mac->etm) { if ((r = mac_check(mac, state->p_read.seqnr, sshbuf_ptr(state->input), aadlen + need, sshbuf_ptr(state->input) + aadlen + need + authlen, maclen)) != 0) { if (r == SSH_ERR_MAC_INVALID) logit("Corrupted MAC on input."); goto out; } } if ((r = sshbuf_reserve(state->incoming_packet, aadlen + need, &cp)) != 0) goto out; if ((r = cipher_crypt(state->receive_context, state->p_read.seqnr, cp, sshbuf_ptr(state->input), need, aadlen, authlen)) != 0) goto out; if ((r = sshbuf_consume(state->input, aadlen + need + authlen)) != 0) goto out; if (mac && mac->enabled) { /* Not EtM: check MAC over cleartext */ if (!mac->etm && (r = mac_check(mac, state->p_read.seqnr, sshbuf_ptr(state->incoming_packet), sshbuf_len(state->incoming_packet), sshbuf_ptr(state->input), maclen)) != 0) { if (r != SSH_ERR_MAC_INVALID) goto out; logit("Corrupted MAC on input."); if (need > PACKET_MAX_SIZE) return SSH_ERR_INTERNAL_ERROR; return ssh_packet_start_discard(ssh, enc, mac, sshbuf_len(state->incoming_packet), PACKET_MAX_SIZE - need); } /* Remove MAC from input buffer */ DBG(debug("MAC #%d ok", state->p_read.seqnr)); if ((r = sshbuf_consume(state->input, mac->mac_len)) != 0) goto out; } if (seqnr_p != NULL) *seqnr_p = state->p_read.seqnr; if (++state->p_read.seqnr == 0) logit("incoming seqnr wraps around"); if (++state->p_read.packets == 0) if (!(ssh->compat & SSH_BUG_NOREKEY)) return SSH_ERR_NEED_REKEY; state->p_read.blocks += (state->packlen + 4) / block_size; state->p_read.bytes += state->packlen + 4; /* get padlen */ padlen = sshbuf_ptr(state->incoming_packet)[4]; DBG(debug("input: padlen %d", padlen)); if (padlen < 4) { if ((r = sshpkt_disconnect(ssh, "Corrupted padlen %d on input.", padlen)) != 0 || (r = ssh_packet_write_wait(ssh)) != 0) return r; return SSH_ERR_CONN_CORRUPT; } /* skip packet size + padlen, discard padding */ if ((r = sshbuf_consume(state->incoming_packet, 4 + 1)) != 0 || ((r = sshbuf_consume_end(state->incoming_packet, padlen)) != 0)) goto out; DBG(debug("input: len before de-compress %zd", sshbuf_len(state->incoming_packet))); if (comp && comp->enabled) { sshbuf_reset(state->compression_buffer); if ((r = uncompress_buffer(ssh, state->incoming_packet, state->compression_buffer)) != 0) goto out; sshbuf_reset(state->incoming_packet); if ((r = sshbuf_putb(state->incoming_packet, state->compression_buffer)) != 0) goto out; DBG(debug("input: len after de-compress %zd", sshbuf_len(state->incoming_packet))); } /* * get packet type, implies consume. * return length of payload (without type field) */ if ((r = sshbuf_get_u8(state->incoming_packet, typep)) != 0) goto out; if (ssh_packet_log_type(*typep)) debug3("receive packet: type %u", *typep); if (*typep < SSH2_MSG_MIN || *typep >= SSH2_MSG_LOCAL_MIN) { if ((r = sshpkt_disconnect(ssh, "Invalid ssh2 packet type: %d", *typep)) != 0 || (r = ssh_packet_write_wait(ssh)) != 0) return r; return SSH_ERR_PROTOCOL_ERROR; } if (*typep == SSH2_MSG_NEWKEYS) r = ssh_set_newkeys(ssh, MODE_IN); else if (*typep == SSH2_MSG_USERAUTH_SUCCESS && !state->server_side) r = ssh_packet_enable_delayed_compress(ssh); else r = 0; #ifdef PACKET_DEBUG fprintf(stderr, "read/plain[%d]:\r\n", *typep); sshbuf_dump(state->incoming_packet, stderr); #endif /* reset for next packet */ state->packlen = 0; /* do we need to rekey? */ if (ssh_packet_need_rekeying(ssh, 0)) { debug3("%s: rekex triggered", __func__); if ((r = kex_start_rekex(ssh)) != 0) return r; } out: return r; } int ssh_packet_read_poll_seqnr(struct ssh *ssh, u_char *typep, u_int32_t *seqnr_p) { struct session_state *state = ssh->state; u_int reason, seqnr; int r; u_char *msg; for (;;) { msg = NULL; if (compat20) { r = ssh_packet_read_poll2(ssh, typep, seqnr_p); if (r != 0) return r; if (*typep) { state->keep_alive_timeouts = 0; DBG(debug("received packet type %d", *typep)); } switch (*typep) { case SSH2_MSG_IGNORE: debug3("Received SSH2_MSG_IGNORE"); break; case SSH2_MSG_DEBUG: if ((r = sshpkt_get_u8(ssh, NULL)) != 0 || (r = sshpkt_get_string(ssh, &msg, NULL)) != 0 || (r = sshpkt_get_string(ssh, NULL, NULL)) != 0) { free(msg); return r; } debug("Remote: %.900s", msg); free(msg); break; case SSH2_MSG_DISCONNECT: if ((r = sshpkt_get_u32(ssh, &reason)) != 0 || (r = sshpkt_get_string(ssh, &msg, NULL)) != 0) return r; /* Ignore normal client exit notifications */ do_log2(ssh->state->server_side && reason == SSH2_DISCONNECT_BY_APPLICATION ? SYSLOG_LEVEL_INFO : SYSLOG_LEVEL_ERROR, "Received disconnect from %s port %d:" "%u: %.400s", ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), reason, msg); free(msg); return SSH_ERR_DISCONNECTED; case SSH2_MSG_UNIMPLEMENTED: if ((r = sshpkt_get_u32(ssh, &seqnr)) != 0) return r; debug("Received SSH2_MSG_UNIMPLEMENTED for %u", seqnr); break; default: return 0; } } else { r = ssh_packet_read_poll1(ssh, typep); switch (*typep) { case SSH_MSG_NONE: return SSH_MSG_NONE; case SSH_MSG_IGNORE: break; case SSH_MSG_DEBUG: if ((r = sshpkt_get_string(ssh, &msg, NULL)) != 0) return r; debug("Remote: %.900s", msg); free(msg); break; case SSH_MSG_DISCONNECT: if ((r = sshpkt_get_string(ssh, &msg, NULL)) != 0) return r; error("Received disconnect from %s port %d: " "%.400s", ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), msg); free(msg); return SSH_ERR_DISCONNECTED; default: DBG(debug("received packet type %d", *typep)); return 0; } } } } /* * Buffers the given amount of input characters. This is intended to be used * together with packet_read_poll. */ int ssh_packet_process_incoming(struct ssh *ssh, const char *buf, u_int len) { struct session_state *state = ssh->state; int r; if (state->packet_discard) { state->keep_alive_timeouts = 0; /* ?? */ if (len >= state->packet_discard) { if ((r = ssh_packet_stop_discard(ssh)) != 0) return r; } state->packet_discard -= len; return 0; } if ((r = sshbuf_put(ssh->state->input, buf, len)) != 0) return r; return 0; } int ssh_packet_remaining(struct ssh *ssh) { return sshbuf_len(ssh->state->incoming_packet); } /* * Sends a diagnostic message from the server to the client. This message * can be sent at any time (but not while constructing another message). The * message is printed immediately, but only if the client is being executed * in verbose mode. These messages are primarily intended to ease debugging * authentication problems. The length of the formatted message must not * exceed 1024 bytes. This will automatically call ssh_packet_write_wait. */ void ssh_packet_send_debug(struct ssh *ssh, const char *fmt,...) { char buf[1024]; va_list args; int r; if (compat20 && (ssh->compat & SSH_BUG_DEBUG)) return; va_start(args, fmt); vsnprintf(buf, sizeof(buf), fmt, args); va_end(args); if (compat20) { if ((r = sshpkt_start(ssh, SSH2_MSG_DEBUG)) != 0 || (r = sshpkt_put_u8(ssh, 0)) != 0 || /* always display */ (r = sshpkt_put_cstring(ssh, buf)) != 0 || (r = sshpkt_put_cstring(ssh, "")) != 0 || (r = sshpkt_send(ssh)) != 0) fatal("%s: %s", __func__, ssh_err(r)); } else { if ((r = sshpkt_start(ssh, SSH_MSG_DEBUG)) != 0 || (r = sshpkt_put_cstring(ssh, buf)) != 0 || (r = sshpkt_send(ssh)) != 0) fatal("%s: %s", __func__, ssh_err(r)); } if ((r = ssh_packet_write_wait(ssh)) != 0) fatal("%s: %s", __func__, ssh_err(r)); } /* * Pretty-print connection-terminating errors and exit. */ void sshpkt_fatal(struct ssh *ssh, const char *tag, int r) { switch (r) { case SSH_ERR_CONN_CLOSED: logdie("Connection closed by %.200s port %d", ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); case SSH_ERR_CONN_TIMEOUT: logdie("Connection %s %.200s port %d timed out", ssh->state->server_side ? "from" : "to", ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); case SSH_ERR_DISCONNECTED: logdie("Disconnected from %.200s port %d", ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); case SSH_ERR_SYSTEM_ERROR: if (errno == ECONNRESET) logdie("Connection reset by %.200s port %d", ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); /* FALLTHROUGH */ case SSH_ERR_NO_CIPHER_ALG_MATCH: case SSH_ERR_NO_MAC_ALG_MATCH: case SSH_ERR_NO_COMPRESS_ALG_MATCH: case SSH_ERR_NO_KEX_ALG_MATCH: case SSH_ERR_NO_HOSTKEY_ALG_MATCH: if (ssh && ssh->kex && ssh->kex->failed_choice) { logdie("Unable to negotiate with %.200s port %d: %s. " "Their offer: %s", ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), ssh_err(r), ssh->kex->failed_choice); } /* FALLTHROUGH */ default: logdie("%s%sConnection %s %.200s port %d: %s", tag != NULL ? tag : "", tag != NULL ? ": " : "", ssh->state->server_side ? "from" : "to", ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), ssh_err(r)); } } /* * Logs the error plus constructs and sends a disconnect packet, closes the * connection, and exits. This function never returns. The error message * should not contain a newline. The length of the formatted message must * not exceed 1024 bytes. */ void ssh_packet_disconnect(struct ssh *ssh, const char *fmt,...) { char buf[1024]; va_list args; static int disconnecting = 0; int r; if (disconnecting) /* Guard against recursive invocations. */ fatal("packet_disconnect called recursively."); disconnecting = 1; /* * Format the message. Note that the caller must make sure the * message is of limited size. */ va_start(args, fmt); vsnprintf(buf, sizeof(buf), fmt, args); va_end(args); /* Display the error locally */ logit("Disconnecting: %.100s", buf); /* * Send the disconnect message to the other side, and wait * for it to get sent. */ if ((r = sshpkt_disconnect(ssh, "%s", buf)) != 0) sshpkt_fatal(ssh, __func__, r); if ((r = ssh_packet_write_wait(ssh)) != 0) sshpkt_fatal(ssh, __func__, r); /* Close the connection. */ ssh_packet_close(ssh); cleanup_exit(255); } /* * Checks if there is any buffered output, and tries to write some of * the output. */ int ssh_packet_write_poll(struct ssh *ssh) { struct session_state *state = ssh->state; int len = sshbuf_len(state->output); int r; if (len > 0) { len = write(state->connection_out, sshbuf_ptr(state->output), len); if (len == -1) { if (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK) return 0; return SSH_ERR_SYSTEM_ERROR; } if (len == 0) return SSH_ERR_CONN_CLOSED; if ((r = sshbuf_consume(state->output, len)) != 0) return r; } return 0; } /* * Calls packet_write_poll repeatedly until all pending output data has been * written. */ int ssh_packet_write_wait(struct ssh *ssh) { fd_set *setp; int ret, r, ms_remain = 0; struct timeval start, timeout, *timeoutp = NULL; struct session_state *state = ssh->state; setp = calloc(howmany(state->connection_out + 1, NFDBITS), sizeof(fd_mask)); if (setp == NULL) return SSH_ERR_ALLOC_FAIL; if ((r = ssh_packet_write_poll(ssh)) != 0) { free(setp); return r; } while (ssh_packet_have_data_to_write(ssh)) { memset(setp, 0, howmany(state->connection_out + 1, NFDBITS) * sizeof(fd_mask)); FD_SET(state->connection_out, setp); if (state->packet_timeout_ms > 0) { ms_remain = state->packet_timeout_ms; timeoutp = &timeout; } for (;;) { if (state->packet_timeout_ms != -1) { ms_to_timeval(&timeout, ms_remain); gettimeofday(&start, NULL); } if ((ret = select(state->connection_out + 1, NULL, setp, NULL, timeoutp)) >= 0) break; if (errno != EAGAIN && errno != EINTR && errno != EWOULDBLOCK) break; if (state->packet_timeout_ms == -1) continue; ms_subtract_diff(&start, &ms_remain); if (ms_remain <= 0) { ret = 0; break; } } if (ret == 0) { free(setp); return SSH_ERR_CONN_TIMEOUT; } if ((r = ssh_packet_write_poll(ssh)) != 0) { free(setp); return r; } } free(setp); return 0; } /* Returns true if there is buffered data to write to the connection. */ int ssh_packet_have_data_to_write(struct ssh *ssh) { return sshbuf_len(ssh->state->output) != 0; } /* Returns true if there is not too much data to write to the connection. */ int ssh_packet_not_very_much_data_to_write(struct ssh *ssh) { if (ssh->state->interactive_mode) return sshbuf_len(ssh->state->output) < 16384; else return sshbuf_len(ssh->state->output) < 128 * 1024; } void ssh_packet_set_tos(struct ssh *ssh, int tos) { #ifndef IP_TOS_IS_BROKEN if (!ssh_packet_connection_is_on_socket(ssh)) return; switch (ssh_packet_connection_af(ssh)) { # ifdef IP_TOS case AF_INET: debug3("%s: set IP_TOS 0x%02x", __func__, tos); if (setsockopt(ssh->state->connection_in, IPPROTO_IP, IP_TOS, &tos, sizeof(tos)) < 0) error("setsockopt IP_TOS %d: %.100s:", tos, strerror(errno)); break; # endif /* IP_TOS */ # ifdef IPV6_TCLASS case AF_INET6: debug3("%s: set IPV6_TCLASS 0x%02x", __func__, tos); if (setsockopt(ssh->state->connection_in, IPPROTO_IPV6, IPV6_TCLASS, &tos, sizeof(tos)) < 0) error("setsockopt IPV6_TCLASS %d: %.100s:", tos, strerror(errno)); break; # endif /* IPV6_TCLASS */ } #endif /* IP_TOS_IS_BROKEN */ } /* Informs that the current session is interactive. Sets IP flags for that. */ void ssh_packet_set_interactive(struct ssh *ssh, int interactive, int qos_interactive, int qos_bulk) { struct session_state *state = ssh->state; if (state->set_interactive_called) return; state->set_interactive_called = 1; /* Record that we are in interactive mode. */ state->interactive_mode = interactive; /* Only set socket options if using a socket. */ if (!ssh_packet_connection_is_on_socket(ssh)) return; set_nodelay(state->connection_in); ssh_packet_set_tos(ssh, interactive ? qos_interactive : qos_bulk); } /* Returns true if the current connection is interactive. */ int ssh_packet_is_interactive(struct ssh *ssh) { return ssh->state->interactive_mode; } int ssh_packet_set_maxsize(struct ssh *ssh, u_int s) { struct session_state *state = ssh->state; if (state->set_maxsize_called) { logit("packet_set_maxsize: called twice: old %d new %d", state->max_packet_size, s); return -1; } if (s < 4 * 1024 || s > 1024 * 1024) { logit("packet_set_maxsize: bad size %d", s); return -1; } state->set_maxsize_called = 1; debug("packet_set_maxsize: setting to %d", s); state->max_packet_size = s; return s; } int ssh_packet_inc_alive_timeouts(struct ssh *ssh) { return ++ssh->state->keep_alive_timeouts; } void ssh_packet_set_alive_timeouts(struct ssh *ssh, int ka) { ssh->state->keep_alive_timeouts = ka; } u_int ssh_packet_get_maxsize(struct ssh *ssh) { return ssh->state->max_packet_size; } /* * 9.2. Ignored Data Message * * byte SSH_MSG_IGNORE * string data * * All implementations MUST understand (and ignore) this message at any * time (after receiving the protocol version). No implementation is * required to send them. This message can be used as an additional * protection measure against advanced traffic analysis techniques. */ void ssh_packet_send_ignore(struct ssh *ssh, int nbytes) { u_int32_t rnd = 0; int r, i; if ((r = sshpkt_start(ssh, compat20 ? SSH2_MSG_IGNORE : SSH_MSG_IGNORE)) != 0 || (r = sshpkt_put_u32(ssh, nbytes)) != 0) fatal("%s: %s", __func__, ssh_err(r)); for (i = 0; i < nbytes; i++) { if (i % 4 == 0) rnd = arc4random(); if ((r = sshpkt_put_u8(ssh, (u_char)rnd & 0xff)) != 0) fatal("%s: %s", __func__, ssh_err(r)); rnd >>= 8; } } void ssh_packet_set_rekey_limits(struct ssh *ssh, u_int64_t bytes, time_t seconds) { debug3("rekey after %llu bytes, %d seconds", (unsigned long long)bytes, (int)seconds); ssh->state->rekey_limit = bytes; ssh->state->rekey_interval = seconds; } time_t ssh_packet_get_rekey_timeout(struct ssh *ssh) { time_t seconds; seconds = ssh->state->rekey_time + ssh->state->rekey_interval - monotime(); return (seconds <= 0 ? 1 : seconds); } void ssh_packet_set_server(struct ssh *ssh) { ssh->state->server_side = 1; } void ssh_packet_set_authenticated(struct ssh *ssh) { ssh->state->after_authentication = 1; } void * ssh_packet_get_input(struct ssh *ssh) { return (void *)ssh->state->input; } void * ssh_packet_get_output(struct ssh *ssh) { return (void *)ssh->state->output; } /* Reset after_authentication and reset compression in post-auth privsep */ static int ssh_packet_set_postauth(struct ssh *ssh) { struct sshcomp *comp; int r, mode; debug("%s: called", __func__); /* This was set in net child, but is not visible in user child */ ssh->state->after_authentication = 1; ssh->state->rekeying = 0; for (mode = 0; mode < MODE_MAX; mode++) { if (ssh->state->newkeys[mode] == NULL) continue; comp = &ssh->state->newkeys[mode]->comp; if (comp && comp->enabled && (r = ssh_packet_init_compression(ssh)) != 0) return r; } return 0; } /* Packet state (de-)serialization for privsep */ /* turn kex into a blob for packet state serialization */ static int kex_to_blob(struct sshbuf *m, struct kex *kex) { int r; if ((r = sshbuf_put_string(m, kex->session_id, kex->session_id_len)) != 0 || (r = sshbuf_put_u32(m, kex->we_need)) != 0 || (r = sshbuf_put_u32(m, kex->hostkey_type)) != 0 || (r = sshbuf_put_u32(m, kex->kex_type)) != 0 || (r = sshbuf_put_stringb(m, kex->my)) != 0 || (r = sshbuf_put_stringb(m, kex->peer)) != 0 || (r = sshbuf_put_u32(m, kex->flags)) != 0 || (r = sshbuf_put_cstring(m, kex->client_version_string)) != 0 || (r = sshbuf_put_cstring(m, kex->server_version_string)) != 0) return r; return 0; } /* turn key exchange results into a blob for packet state serialization */ static int newkeys_to_blob(struct sshbuf *m, struct ssh *ssh, int mode) { struct sshbuf *b; struct sshcipher_ctx *cc; struct sshcomp *comp; struct sshenc *enc; struct sshmac *mac; struct newkeys *newkey; int r; if ((newkey = ssh->state->newkeys[mode]) == NULL) return SSH_ERR_INTERNAL_ERROR; enc = &newkey->enc; mac = &newkey->mac; comp = &newkey->comp; cc = (mode == MODE_OUT) ? ssh->state->send_context : ssh->state->receive_context; if ((r = cipher_get_keyiv(cc, enc->iv, enc->iv_len)) != 0) return r; if ((b = sshbuf_new()) == NULL) return SSH_ERR_ALLOC_FAIL; /* The cipher struct is constant and shared, you export pointer */ if ((r = sshbuf_put_cstring(b, enc->name)) != 0 || (r = sshbuf_put(b, &enc->cipher, sizeof(enc->cipher))) != 0 || (r = sshbuf_put_u32(b, enc->enabled)) != 0 || (r = sshbuf_put_u32(b, enc->block_size)) != 0 || (r = sshbuf_put_string(b, enc->key, enc->key_len)) != 0 || (r = sshbuf_put_string(b, enc->iv, enc->iv_len)) != 0) goto out; if (cipher_authlen(enc->cipher) == 0) { if ((r = sshbuf_put_cstring(b, mac->name)) != 0 || (r = sshbuf_put_u32(b, mac->enabled)) != 0 || (r = sshbuf_put_string(b, mac->key, mac->key_len)) != 0) goto out; } if ((r = sshbuf_put_u32(b, comp->type)) != 0 || (r = sshbuf_put_u32(b, comp->enabled)) != 0 || (r = sshbuf_put_cstring(b, comp->name)) != 0) goto out; r = sshbuf_put_stringb(m, b); out: sshbuf_free(b); return r; } /* serialize packet state into a blob */ int ssh_packet_get_state(struct ssh *ssh, struct sshbuf *m) { struct session_state *state = ssh->state; u_char *p; size_t slen, rlen; int r, ssh1cipher; if (!compat20) { ssh1cipher = cipher_ctx_get_number(state->receive_context); slen = cipher_get_keyiv_len(state->send_context); rlen = cipher_get_keyiv_len(state->receive_context); if ((r = sshbuf_put_u32(m, state->remote_protocol_flags)) != 0 || (r = sshbuf_put_u32(m, ssh1cipher)) != 0 || (r = sshbuf_put_string(m, state->ssh1_key, state->ssh1_keylen)) != 0 || (r = sshbuf_put_u32(m, slen)) != 0 || (r = sshbuf_reserve(m, slen, &p)) != 0 || (r = cipher_get_keyiv(state->send_context, p, slen)) != 0 || (r = sshbuf_put_u32(m, rlen)) != 0 || (r = sshbuf_reserve(m, rlen, &p)) != 0 || (r = cipher_get_keyiv(state->receive_context, p, rlen)) != 0) return r; } else { if ((r = kex_to_blob(m, ssh->kex)) != 0 || (r = newkeys_to_blob(m, ssh, MODE_OUT)) != 0 || (r = newkeys_to_blob(m, ssh, MODE_IN)) != 0 || (r = sshbuf_put_u64(m, state->rekey_limit)) != 0 || (r = sshbuf_put_u32(m, state->rekey_interval)) != 0 || (r = sshbuf_put_u32(m, state->p_send.seqnr)) != 0 || (r = sshbuf_put_u64(m, state->p_send.blocks)) != 0 || (r = sshbuf_put_u32(m, state->p_send.packets)) != 0 || (r = sshbuf_put_u64(m, state->p_send.bytes)) != 0 || (r = sshbuf_put_u32(m, state->p_read.seqnr)) != 0 || (r = sshbuf_put_u64(m, state->p_read.blocks)) != 0 || (r = sshbuf_put_u32(m, state->p_read.packets)) != 0 || (r = sshbuf_put_u64(m, state->p_read.bytes)) != 0) return r; } slen = cipher_get_keycontext(state->send_context, NULL); rlen = cipher_get_keycontext(state->receive_context, NULL); if ((r = sshbuf_put_u32(m, slen)) != 0 || (r = sshbuf_reserve(m, slen, &p)) != 0) return r; if (cipher_get_keycontext(state->send_context, p) != (int)slen) return SSH_ERR_INTERNAL_ERROR; if ((r = sshbuf_put_u32(m, rlen)) != 0 || (r = sshbuf_reserve(m, rlen, &p)) != 0) return r; if (cipher_get_keycontext(state->receive_context, p) != (int)rlen) return SSH_ERR_INTERNAL_ERROR; if ((r = ssh_packet_get_compress_state(m, ssh)) != 0 || (r = sshbuf_put_stringb(m, state->input)) != 0 || (r = sshbuf_put_stringb(m, state->output)) != 0) return r; return 0; } /* restore key exchange results from blob for packet state de-serialization */ static int newkeys_from_blob(struct sshbuf *m, struct ssh *ssh, int mode) { struct sshbuf *b = NULL; struct sshcomp *comp; struct sshenc *enc; struct sshmac *mac; struct newkeys *newkey = NULL; size_t keylen, ivlen, maclen; int r; if ((newkey = calloc(1, sizeof(*newkey))) == NULL) { r = SSH_ERR_ALLOC_FAIL; goto out; } if ((r = sshbuf_froms(m, &b)) != 0) goto out; #ifdef DEBUG_PK sshbuf_dump(b, stderr); #endif enc = &newkey->enc; mac = &newkey->mac; comp = &newkey->comp; if ((r = sshbuf_get_cstring(b, &enc->name, NULL)) != 0 || (r = sshbuf_get(b, &enc->cipher, sizeof(enc->cipher))) != 0 || (r = sshbuf_get_u32(b, (u_int *)&enc->enabled)) != 0 || (r = sshbuf_get_u32(b, &enc->block_size)) != 0 || (r = sshbuf_get_string(b, &enc->key, &keylen)) != 0 || (r = sshbuf_get_string(b, &enc->iv, &ivlen)) != 0) goto out; if (cipher_authlen(enc->cipher) == 0) { if ((r = sshbuf_get_cstring(b, &mac->name, NULL)) != 0) goto out; if ((r = mac_setup(mac, mac->name)) != 0) goto out; if ((r = sshbuf_get_u32(b, (u_int *)&mac->enabled)) != 0 || (r = sshbuf_get_string(b, &mac->key, &maclen)) != 0) goto out; if (maclen > mac->key_len) { r = SSH_ERR_INVALID_FORMAT; goto out; } mac->key_len = maclen; } if ((r = sshbuf_get_u32(b, &comp->type)) != 0 || (r = sshbuf_get_u32(b, (u_int *)&comp->enabled)) != 0 || (r = sshbuf_get_cstring(b, &comp->name, NULL)) != 0) goto out; if (enc->name == NULL || cipher_by_name(enc->name) != enc->cipher) { r = SSH_ERR_INVALID_FORMAT; goto out; } if (sshbuf_len(b) != 0) { r = SSH_ERR_INVALID_FORMAT; goto out; } enc->key_len = keylen; enc->iv_len = ivlen; ssh->kex->newkeys[mode] = newkey; newkey = NULL; r = 0; out: free(newkey); sshbuf_free(b); return r; } /* restore kex from blob for packet state de-serialization */ static int kex_from_blob(struct sshbuf *m, struct kex **kexp) { struct kex *kex; int r; if ((kex = calloc(1, sizeof(struct kex))) == NULL || (kex->my = sshbuf_new()) == NULL || (kex->peer = sshbuf_new()) == NULL) { r = SSH_ERR_ALLOC_FAIL; goto out; } if ((r = sshbuf_get_string(m, &kex->session_id, &kex->session_id_len)) != 0 || (r = sshbuf_get_u32(m, &kex->we_need)) != 0 || (r = sshbuf_get_u32(m, (u_int *)&kex->hostkey_type)) != 0 || (r = sshbuf_get_u32(m, &kex->kex_type)) != 0 || (r = sshbuf_get_stringb(m, kex->my)) != 0 || (r = sshbuf_get_stringb(m, kex->peer)) != 0 || (r = sshbuf_get_u32(m, &kex->flags)) != 0 || (r = sshbuf_get_cstring(m, &kex->client_version_string, NULL)) != 0 || (r = sshbuf_get_cstring(m, &kex->server_version_string, NULL)) != 0) goto out; kex->server = 1; kex->done = 1; r = 0; out: if (r != 0 || kexp == NULL) { if (kex != NULL) { sshbuf_free(kex->my); sshbuf_free(kex->peer); free(kex); } if (kexp != NULL) *kexp = NULL; } else { *kexp = kex; } return r; } /* * Restore packet state from content of blob 'm' (de-serialization). * Note that 'm' will be partially consumed on parsing or any other errors. */ int ssh_packet_set_state(struct ssh *ssh, struct sshbuf *m) { struct session_state *state = ssh->state; const u_char *ssh1key, *ivin, *ivout, *keyin, *keyout, *input, *output; size_t ssh1keylen, rlen, slen, ilen, olen; int r; u_int ssh1cipher = 0; if (!compat20) { if ((r = sshbuf_get_u32(m, &state->remote_protocol_flags)) != 0 || (r = sshbuf_get_u32(m, &ssh1cipher)) != 0 || (r = sshbuf_get_string_direct(m, &ssh1key, &ssh1keylen)) != 0 || (r = sshbuf_get_string_direct(m, &ivout, &slen)) != 0 || (r = sshbuf_get_string_direct(m, &ivin, &rlen)) != 0) return r; if (ssh1cipher > INT_MAX) return SSH_ERR_KEY_UNKNOWN_CIPHER; ssh_packet_set_encryption_key(ssh, ssh1key, ssh1keylen, (int)ssh1cipher); if (cipher_get_keyiv_len(state->send_context) != (int)slen || cipher_get_keyiv_len(state->receive_context) != (int)rlen) return SSH_ERR_INVALID_FORMAT; if ((r = cipher_set_keyiv(state->send_context, ivout)) != 0 || (r = cipher_set_keyiv(state->receive_context, ivin)) != 0) return r; } else { if ((r = kex_from_blob(m, &ssh->kex)) != 0 || (r = newkeys_from_blob(m, ssh, MODE_OUT)) != 0 || (r = newkeys_from_blob(m, ssh, MODE_IN)) != 0 || (r = sshbuf_get_u64(m, &state->rekey_limit)) != 0 || (r = sshbuf_get_u32(m, &state->rekey_interval)) != 0 || (r = sshbuf_get_u32(m, &state->p_send.seqnr)) != 0 || (r = sshbuf_get_u64(m, &state->p_send.blocks)) != 0 || (r = sshbuf_get_u32(m, &state->p_send.packets)) != 0 || (r = sshbuf_get_u64(m, &state->p_send.bytes)) != 0 || (r = sshbuf_get_u32(m, &state->p_read.seqnr)) != 0 || (r = sshbuf_get_u64(m, &state->p_read.blocks)) != 0 || (r = sshbuf_get_u32(m, &state->p_read.packets)) != 0 || (r = sshbuf_get_u64(m, &state->p_read.bytes)) != 0) return r; /* * We set the time here so that in post-auth privsep slave we * count from the completion of the authentication. */ state->rekey_time = monotime(); /* XXX ssh_set_newkeys overrides p_read.packets? XXX */ if ((r = ssh_set_newkeys(ssh, MODE_IN)) != 0 || (r = ssh_set_newkeys(ssh, MODE_OUT)) != 0) return r; } if ((r = sshbuf_get_string_direct(m, &keyout, &slen)) != 0 || (r = sshbuf_get_string_direct(m, &keyin, &rlen)) != 0) return r; if (cipher_get_keycontext(state->send_context, NULL) != (int)slen || cipher_get_keycontext(state->receive_context, NULL) != (int)rlen) return SSH_ERR_INVALID_FORMAT; cipher_set_keycontext(state->send_context, keyout); cipher_set_keycontext(state->receive_context, keyin); if ((r = ssh_packet_set_compress_state(ssh, m)) != 0 || (r = ssh_packet_set_postauth(ssh)) != 0) return r; sshbuf_reset(state->input); sshbuf_reset(state->output); if ((r = sshbuf_get_string_direct(m, &input, &ilen)) != 0 || (r = sshbuf_get_string_direct(m, &output, &olen)) != 0 || (r = sshbuf_put(state->input, input, ilen)) != 0 || (r = sshbuf_put(state->output, output, olen)) != 0) return r; if (sshbuf_len(m)) return SSH_ERR_INVALID_FORMAT; debug3("%s: done", __func__); return 0; } /* NEW API */ /* put data to the outgoing packet */ int sshpkt_put(struct ssh *ssh, const void *v, size_t len) { return sshbuf_put(ssh->state->outgoing_packet, v, len); } int sshpkt_putb(struct ssh *ssh, const struct sshbuf *b) { return sshbuf_putb(ssh->state->outgoing_packet, b); } int sshpkt_put_u8(struct ssh *ssh, u_char val) { return sshbuf_put_u8(ssh->state->outgoing_packet, val); } int sshpkt_put_u32(struct ssh *ssh, u_int32_t val) { return sshbuf_put_u32(ssh->state->outgoing_packet, val); } int sshpkt_put_u64(struct ssh *ssh, u_int64_t val) { return sshbuf_put_u64(ssh->state->outgoing_packet, val); } int sshpkt_put_string(struct ssh *ssh, const void *v, size_t len) { return sshbuf_put_string(ssh->state->outgoing_packet, v, len); } int sshpkt_put_cstring(struct ssh *ssh, const void *v) { return sshbuf_put_cstring(ssh->state->outgoing_packet, v); } int sshpkt_put_stringb(struct ssh *ssh, const struct sshbuf *v) { return sshbuf_put_stringb(ssh->state->outgoing_packet, v); } #ifdef WITH_OPENSSL #ifdef OPENSSL_HAS_ECC int sshpkt_put_ec(struct ssh *ssh, const EC_POINT *v, const EC_GROUP *g) { return sshbuf_put_ec(ssh->state->outgoing_packet, v, g); } #endif /* OPENSSL_HAS_ECC */ #ifdef WITH_SSH1 int sshpkt_put_bignum1(struct ssh *ssh, const BIGNUM *v) { return sshbuf_put_bignum1(ssh->state->outgoing_packet, v); } #endif /* WITH_SSH1 */ int sshpkt_put_bignum2(struct ssh *ssh, const BIGNUM *v) { return sshbuf_put_bignum2(ssh->state->outgoing_packet, v); } #endif /* WITH_OPENSSL */ /* fetch data from the incoming packet */ int sshpkt_get(struct ssh *ssh, void *valp, size_t len) { return sshbuf_get(ssh->state->incoming_packet, valp, len); } int sshpkt_get_u8(struct ssh *ssh, u_char *valp) { return sshbuf_get_u8(ssh->state->incoming_packet, valp); } int sshpkt_get_u32(struct ssh *ssh, u_int32_t *valp) { return sshbuf_get_u32(ssh->state->incoming_packet, valp); } int sshpkt_get_u64(struct ssh *ssh, u_int64_t *valp) { return sshbuf_get_u64(ssh->state->incoming_packet, valp); } int sshpkt_get_string(struct ssh *ssh, u_char **valp, size_t *lenp) { return sshbuf_get_string(ssh->state->incoming_packet, valp, lenp); } int sshpkt_get_string_direct(struct ssh *ssh, const u_char **valp, size_t *lenp) { return sshbuf_get_string_direct(ssh->state->incoming_packet, valp, lenp); } int sshpkt_get_cstring(struct ssh *ssh, char **valp, size_t *lenp) { return sshbuf_get_cstring(ssh->state->incoming_packet, valp, lenp); } #ifdef WITH_OPENSSL #ifdef OPENSSL_HAS_ECC int sshpkt_get_ec(struct ssh *ssh, EC_POINT *v, const EC_GROUP *g) { return sshbuf_get_ec(ssh->state->incoming_packet, v, g); } #endif /* OPENSSL_HAS_ECC */ #ifdef WITH_SSH1 int sshpkt_get_bignum1(struct ssh *ssh, BIGNUM *v) { return sshbuf_get_bignum1(ssh->state->incoming_packet, v); } #endif /* WITH_SSH1 */ int sshpkt_get_bignum2(struct ssh *ssh, BIGNUM *v) { return sshbuf_get_bignum2(ssh->state->incoming_packet, v); } #endif /* WITH_OPENSSL */ int sshpkt_get_end(struct ssh *ssh) { if (sshbuf_len(ssh->state->incoming_packet) > 0) return SSH_ERR_UNEXPECTED_TRAILING_DATA; return 0; } const u_char * sshpkt_ptr(struct ssh *ssh, size_t *lenp) { if (lenp != NULL) *lenp = sshbuf_len(ssh->state->incoming_packet); return sshbuf_ptr(ssh->state->incoming_packet); } /* start a new packet */ int sshpkt_start(struct ssh *ssh, u_char type) { u_char buf[9]; int len; DBG(debug("packet_start[%d]", type)); len = compat20 ? 6 : 9; memset(buf, 0, len - 1); buf[len - 1] = type; sshbuf_reset(ssh->state->outgoing_packet); return sshbuf_put(ssh->state->outgoing_packet, buf, len); } /* send it */ int sshpkt_send(struct ssh *ssh) { if (compat20) return ssh_packet_send2(ssh); else return ssh_packet_send1(ssh); } int sshpkt_disconnect(struct ssh *ssh, const char *fmt,...) { char buf[1024]; va_list args; int r; va_start(args, fmt); vsnprintf(buf, sizeof(buf), fmt, args); va_end(args); if (compat20) { if ((r = sshpkt_start(ssh, SSH2_MSG_DISCONNECT)) != 0 || (r = sshpkt_put_u32(ssh, SSH2_DISCONNECT_PROTOCOL_ERROR)) != 0 || (r = sshpkt_put_cstring(ssh, buf)) != 0 || (r = sshpkt_put_cstring(ssh, "")) != 0 || (r = sshpkt_send(ssh)) != 0) return r; } else { if ((r = sshpkt_start(ssh, SSH_MSG_DISCONNECT)) != 0 || (r = sshpkt_put_cstring(ssh, buf)) != 0 || (r = sshpkt_send(ssh)) != 0) return r; } return 0; } /* roundup current message to pad bytes */ int sshpkt_add_padding(struct ssh *ssh, u_char pad) { ssh->state->extra_pad = pad; return 0; }