upstream: sshd: switch monitor to sshbuf API; lots of help & ok

djm@

OpenBSD-Commit-ID: d89bd02d33974fd35ca0b8940d88572227b34a48

1 files changed, 284 insertions, 201 deletions

diff --git a/monitor_wrap.c b/monitor_wrap.c
index 6bf041093..cf38b230b 100644
--- a/monitor_wrap.c
+++ b/monitor_wrap.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: monitor_wrap.c,v 1.102 2018/07/09 21:26:02 markus Exp $ */
+/* $OpenBSD: monitor_wrap.c,v 1.103 2018/07/09 21:53:45 markus Exp $ */
 /*
  * Copyright 2002 Niels Provos <provos@citi.umich.edu>
  * Copyright 2002 Markus Friedl <markus@openbsd.org>
@@ -50,7 +50,7 @@
 #ifdef WITH_OPENSSL
 #include "dh.h"
 #endif
-#include "buffer.h"
+#include "sshbuf.h"
 #include "key.h"
 #include "cipher.h"
 #include "kex.h"
@@ -93,27 +93,28 @@ extern ServerOptions options;
 void
 mm_log_handler(LogLevel level, const char *msg, void *ctx)
 {
-        Buffer log_msg;
+        struct sshbuf *log_msg;
         struct monitor *mon = (struct monitor *)ctx;
+        int r;
+        size_t len;
 
         if (mon->m_log_sendfd == -1)
                 fatal("%s: no log channel", __func__);
 
-        buffer_init(&log_msg);
-        /*
-         * Placeholder for packet length. Will be filled in with the actual
-         * packet length once the packet has been constucted. This saves
-         * fragile math.
-         */
-        buffer_put_int(&log_msg, 0);
+        if ((log_msg = sshbuf_new()) == NULL)
+                fatal("%s: sshbuf_new failed", __func__);
 
-        buffer_put_int(&log_msg, level);
-        buffer_put_cstring(&log_msg, msg);
-        put_u32(buffer_ptr(&log_msg), buffer_len(&log_msg) - 4);
-        if (atomicio(vwrite, mon->m_log_sendfd, buffer_ptr(&log_msg),
-            buffer_len(&log_msg)) != buffer_len(&log_msg))
+        if ((r = sshbuf_put_u32(log_msg, 0)) != 0 || /* length; filled below */
+            (r = sshbuf_put_u32(log_msg, level)) != 0 ||
+            (r = sshbuf_put_cstring(log_msg, msg)) != 0)
+                fatal("%s: buffer error: %s", __func__, ssh_err(r));
+        if ((len = sshbuf_len(log_msg)) < 4 || len > 0xffffffff)
+                fatal("%s: bad length %zu", __func__, len);
+        POKE_U32(sshbuf_mutable_ptr(log_msg), len - 4);
+        if (atomicio(vwrite, mon->m_log_sendfd,
+            sshbuf_mutable_ptr(log_msg), len) != len)
                 fatal("%s: write: %s", __func__, strerror(errno));
-        buffer_free(&log_msg);
+        sshbuf_free(log_msg);
 }
 
 int
@@ -127,26 +128,29 @@ mm_is_monitor(void)
 }
 
 void
-mm_request_send(int sock, enum monitor_reqtype type, Buffer *m)
+mm_request_send(int sock, enum monitor_reqtype type, struct sshbuf *m)
 {
-        u_int mlen = buffer_len(m);
+        size_t mlen = sshbuf_len(m);
         u_char buf[5];
 
         debug3("%s entering: type %d", __func__, type);
 
-        put_u32(buf, mlen + 1);
+        if (mlen >= 0xffffffff)
+                fatal("%s: bad length %zu", __func__, mlen);
+        POKE_U32(buf, mlen + 1);
         buf[4] = (u_char) type;         /* 1st byte of payload is mesg-type */
         if (atomicio(vwrite, sock, buf, sizeof(buf)) != sizeof(buf))
                 fatal("%s: write: %s", __func__, strerror(errno));
-        if (atomicio(vwrite, sock, buffer_ptr(m), mlen) != mlen)
+        if (atomicio(vwrite, sock, sshbuf_mutable_ptr(m), mlen) != mlen)
                 fatal("%s: write: %s", __func__, strerror(errno));
 }
 
 void
-mm_request_receive(int sock, Buffer *m)
+mm_request_receive(int sock, struct sshbuf *m)
 {
-        u_char buf[4];
+        u_char buf[4], *p = NULL;
         u_int msg_len;
+        int r;
 
         debug3("%s entering", __func__);
 
@@ -155,24 +159,27 @@ mm_request_receive(int sock, Buffer *m)
                         cleanup_exit(255);
                 fatal("%s: read: %s", __func__, strerror(errno));
         }
-        msg_len = get_u32(buf);
+        msg_len = PEEK_U32(buf);
         if (msg_len > 256 * 1024)
                 fatal("%s: read: bad msg_len %d", __func__, msg_len);
-        buffer_clear(m);
-        buffer_append_space(m, msg_len);
-        if (atomicio(read, sock, buffer_ptr(m), msg_len) != msg_len)
+        sshbuf_reset(m);
+        if ((r = sshbuf_reserve(m, msg_len, &p)) != 0)
+                fatal("%s: buffer error: %s", __func__, ssh_err(r));
+        if (atomicio(read, sock, p, msg_len) != msg_len)
                 fatal("%s: read: %s", __func__, strerror(errno));
 }
 
 void
-mm_request_receive_expect(int sock, enum monitor_reqtype type, Buffer *m)
+mm_request_receive_expect(int sock, enum monitor_reqtype type, struct sshbuf *m)
 {
         u_char rtype;
+        int r;
 
         debug3("%s entering: type %d", __func__, type);
 
         mm_request_receive(sock, m);
-        rtype = buffer_get_char(m);
+        if ((r = sshbuf_get_u8(m, &rtype)) != 0)
+                fatal("%s: buffer error: %s", __func__, ssh_err(r));
         if (rtype != type)
                 fatal("%s: read: rtype %d != type %d", __func__,
                     rtype, type);
@@ -183,20 +190,24 @@ DH *
 mm_choose_dh(int min, int nbits, int max)
 {
         BIGNUM *p, *g;
-        int success = 0;
-        Buffer m;
+        int r;
+        u_char success = 0;
+        struct sshbuf *m;
 
-        buffer_init(&m);
-        buffer_put_int(&m, min);
-        buffer_put_int(&m, nbits);
-        buffer_put_int(&m, max);
+        if ((m = sshbuf_new()) == NULL)
+                fatal("%s: sshbuf_new failed", __func__);
+        if ((r = sshbuf_put_u32(m, min)) != 0 ||
+            (r = sshbuf_put_u32(m, nbits)) != 0 ||
+            (r = sshbuf_put_u32(m, max)) != 0)
+                fatal("%s: buffer error: %s", __func__, ssh_err(r));
 
-        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_MODULI, &m);
+        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_MODULI, m);
 
         debug3("%s: waiting for MONITOR_ANS_MODULI", __func__);
-        mm_request_receive_expect(pmonitor->m_recvfd, MONITOR_ANS_MODULI, &m);
+        mm_request_receive_expect(pmonitor->m_recvfd, MONITOR_ANS_MODULI, m);
 
-        success = buffer_get_char(&m);
+        if ((r = sshbuf_get_u8(m, &success)) != 0)
+                fatal("%s: buffer error: %s", __func__, ssh_err(r));
         if (success == 0)
                 fatal("%s: MONITOR_ANS_MODULI failed", __func__);
 
@@ -204,11 +215,12 @@ mm_choose_dh(int min, int nbits, int max)
                 fatal("%s: BN_new failed", __func__);
         if ((g = BN_new()) == NULL)
                 fatal("%s: BN_new failed", __func__);
-        buffer_get_bignum2(&m, p);
-        buffer_get_bignum2(&m, g);
+        if ((r = sshbuf_get_bignum2(m, p)) != 0 ||
+            (r = sshbuf_get_bignum2(m, g)) != 0)
+                fatal("%s: buffer error: %s", __func__, ssh_err(r));
 
-        debug3("%s: remaining %d", __func__, buffer_len(&m));
-        buffer_free(&m);
+        debug3("%s: remaining %zu", __func__, sshbuf_len(m));
+        sshbuf_free(m);
 
         return (dh_new_group(g, p));
 }
@@ -219,21 +231,30 @@ mm_key_sign(struct sshkey *key, u_char **sigp, u_int *lenp,
     const u_char *data, u_int datalen, const char *hostkey_alg)
 {
         struct kex *kex = *pmonitor->m_pkex;
-        Buffer m;
+        struct sshbuf *m;
+        size_t xxxlen;
+        u_int ndx = kex->host_key_index(key, 0, active_state);
+        int r;
 
         debug3("%s entering", __func__);
 
-        buffer_init(&m);
-        buffer_put_int(&m, kex->host_key_index(key, 0, active_state));
-        buffer_put_string(&m, data, datalen);
-        buffer_put_cstring(&m, hostkey_alg);
+        if ((m = sshbuf_new()) == NULL)
+                fatal("%s: sshbuf_new failed", __func__);
+        if ((r = sshbuf_put_u32(m, ndx)) != 0 ||
+            (r = sshbuf_put_string(m, data, datalen)) != 0 ||
+            (r = sshbuf_put_cstring(m, hostkey_alg)) != 0)
+                fatal("%s: buffer error: %s", __func__, ssh_err(r));
 
-        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_SIGN, &m);
+        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_SIGN, m);
 
         debug3("%s: waiting for MONITOR_ANS_SIGN", __func__);
-        mm_request_receive_expect(pmonitor->m_recvfd, MONITOR_ANS_SIGN, &m);
-        *sigp  = buffer_get_string(&m, lenp);
-        buffer_free(&m);
+        mm_request_receive_expect(pmonitor->m_recvfd, MONITOR_ANS_SIGN, m);
+        if ((r = sshbuf_get_string(m, sigp, &xxxlen)) != 0)
+                fatal("%s: buffer error: %s", __func__, ssh_err(r));
+        if (xxxlen > 0xffffffff)
+                fatal("%s: bad length %zu", __func__, xxxlen);
+        *lenp = xxxlen; /* XXX fix API: size_t vs u_int */
+        sshbuf_free(m);
 
         return (0);
 }
@@ -242,54 +263,80 @@ struct passwd *
 mm_getpwnamallow(const char *username)
 {
         struct ssh *ssh = active_state;         /* XXX */
-        Buffer m;
+        struct sshbuf *m;
         struct passwd *pw;
-        u_int len, i;
+        size_t len;
+        u_int i;
         ServerOptions *newopts;
+        int r;
+        u_char ok;
+        const u_char *p;
 
         debug3("%s entering", __func__);
 
-        buffer_init(&m);
-        buffer_put_cstring(&m, username);
+        if ((m = sshbuf_new()) == NULL)
+                fatal("%s: sshbuf_new failed", __func__);
+        if ((r = sshbuf_put_cstring(m, username)) != 0)
+                fatal("%s: buffer error: %s", __func__, ssh_err(r));
 
-        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_PWNAM, &m);
+        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_PWNAM, m);
 
         debug3("%s: waiting for MONITOR_ANS_PWNAM", __func__);
-        mm_request_receive_expect(pmonitor->m_recvfd, MONITOR_ANS_PWNAM, &m);
+        mm_request_receive_expect(pmonitor->m_recvfd, MONITOR_ANS_PWNAM, m);
 
-        if (buffer_get_char(&m) == 0) {
+        if ((r = sshbuf_get_u8(m, &ok)) != 0)
+                fatal("%s: buffer error: %s", __func__, ssh_err(r));
+        if (ok == 0) {
                 pw = NULL;
                 goto out;
         }
-        pw = buffer_get_string(&m, &len);
-        if (len != sizeof(struct passwd))
+
+        /* XXX don't like passing struct passwd like this */
+        pw = xcalloc(sizeof(*pw), 1);
+        if ((r = sshbuf_get_string_direct(m, &p, &len)) != 0)
+                fatal("%s: buffer error: %s", __func__, ssh_err(r));
+        if (len != sizeof(*pw))
                 fatal("%s: struct passwd size mismatch", __func__);
-        pw->pw_name = buffer_get_string(&m, NULL);
-        pw->pw_passwd = buffer_get_string(&m, NULL);
+        memcpy(pw, p, sizeof(*pw));
+
+        if ((r = sshbuf_get_cstring(m, &pw->pw_name, NULL)) != 0 ||
+            (r = sshbuf_get_cstring(m, &pw->pw_passwd, NULL)) != 0 ||
 #ifdef HAVE_STRUCT_PASSWD_PW_GECOS
-        pw->pw_gecos = buffer_get_string(&m, NULL);
+            (r = sshbuf_get_cstring(m, &pw->pw_gecos, NULL)) != 0 ||
 #endif
 #ifdef HAVE_STRUCT_PASSWD_PW_CLASS
-        pw->pw_class = buffer_get_string(&m, NULL);
+            (r = sshbuf_get_cstring(m, &pw->pw_class, NULL)) != 0 ||
 #endif
-        pw->pw_dir = buffer_get_string(&m, NULL);
-        pw->pw_shell = buffer_get_string(&m, NULL);
+            (r = sshbuf_get_cstring(m, &pw->pw_dir, NULL)) != 0 ||
+            (r = sshbuf_get_cstring(m, &pw->pw_shell, NULL)) != 0)
+                fatal("%s: buffer error: %s", __func__, ssh_err(r));
 
 out:
         /* copy options block as a Match directive may have changed some */
-        newopts = buffer_get_string(&m, &len);
+        if ((r = sshbuf_get_string_direct(m, &p, &len)) != 0)
+                fatal("%s: buffer error: %s", __func__, ssh_err(r));
         if (len != sizeof(*newopts))
                 fatal("%s: option block size mismatch", __func__);
+        newopts = xcalloc(sizeof(*newopts), 1);
+        memcpy(newopts, p, sizeof(*newopts));
 
 #define M_CP_STROPT(x) do { \
-                if (newopts->x != NULL) \
-                        newopts->x = buffer_get_string(&m, NULL); \
+                if (newopts->x != NULL) { \
+                        if ((r = sshbuf_get_cstring(m, \
+                            &newopts->x, NULL)) != 0) \
+                                fatal("%s: buffer error: %s", \
+                                    __func__, ssh_err(r)); \
+                } \
         } while (0)
 #define M_CP_STRARRAYOPT(x, nx) do { \
                 newopts->x = newopts->nx == 0 ? \
                     NULL : xcalloc(newopts->nx, sizeof(*newopts->x)); \
-                for (i = 0; i < newopts->nx; i++) \
-                        newopts->x[i] = buffer_get_string(&m, NULL); \
+                for (i = 0; i < newopts->nx; i++) { \
+                        if ((r = sshbuf_get_cstring(m, \
+                            &newopts->x[i], NULL)) != 0) \
+                                fatal("%s: buffer error: %s", \
+                                    __func__, ssh_err(r)); \
+                } \
         } while (0)
         /* See comment in servconf.h */
         COPY_MATCH_STRING_OPTS();
@@ -301,7 +348,7 @@ out:
         process_permitopen(ssh, &options);
         free(newopts);
 
-        buffer_free(&m);
+        sshbuf_free(m);
 
         return (pw);
 }
@@ -309,19 +356,22 @@ out:
 char *
 mm_auth2_read_banner(void)
 {
-        Buffer m;
+        struct sshbuf *m;
         char *banner;
+        int r;
 
         debug3("%s entering", __func__);
 
-        buffer_init(&m);
-        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_AUTH2_READ_BANNER, &m);
-        buffer_clear(&m);
+        if ((m = sshbuf_new()) == NULL)
+                fatal("%s: sshbuf_new failed", __func__);
+        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_AUTH2_READ_BANNER, m);
+        sshbuf_reset(m);
 
         mm_request_receive_expect(pmonitor->m_recvfd,
-            MONITOR_ANS_AUTH2_READ_BANNER, &m);
-        banner = buffer_get_string(&m, NULL);
-        buffer_free(&m);
+            MONITOR_ANS_AUTH2_READ_BANNER, m);
+        if ((r = sshbuf_get_cstring(m, &banner, NULL)) != 0)
+                fatal("%s: buffer error: %s", __func__, ssh_err(r));
+        sshbuf_free(m);
 
         /* treat empty banner as missing banner */
         if (strlen(banner) == 0) {
@@ -336,41 +386,50 @@ mm_auth2_read_banner(void)
 void
 mm_inform_authserv(char *service, char *style)
 {
-        Buffer m;
+        struct sshbuf *m;
+        int r;
 
         debug3("%s entering", __func__);
 
-        buffer_init(&m);
-        buffer_put_cstring(&m, service);
-        buffer_put_cstring(&m, style ? style : "");
+        if ((m = sshbuf_new()) == NULL)
+                fatal("%s: sshbuf_new failed", __func__);
+        if ((r = sshbuf_put_cstring(m, service)) != 0 ||
+            (r = sshbuf_put_cstring(m, style ? style : "")) != 0)
+                fatal("%s: buffer error: %s", __func__, ssh_err(r));
 
-        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_AUTHSERV, &m);
+        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_AUTHSERV, m);
 
-        buffer_free(&m);
+        sshbuf_free(m);
 }
 
 /* Do the password authentication */
 int
 mm_auth_password(struct ssh *ssh, char *password)
 {
-        Buffer m;
-        int authenticated = 0;
+        struct sshbuf *m;
+        int r, maxtries = 0, authenticated = 0;
 
         debug3("%s entering", __func__);
 
-        buffer_init(&m);
-        buffer_put_cstring(&m, password);
-        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_AUTHPASSWORD, &m);
+        if ((m = sshbuf_new()) == NULL)
+                fatal("%s: sshbuf_new failed", __func__);
+        if ((r = sshbuf_put_cstring(m, password)) != 0)
+                fatal("%s: buffer error: %s", __func__, ssh_err(r));
+        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_AUTHPASSWORD, m);
 
         debug3("%s: waiting for MONITOR_ANS_AUTHPASSWORD", __func__);
-        mm_request_receive_expect(pmonitor->m_recvfd, MONITOR_ANS_AUTHPASSWORD, &m);
+        mm_request_receive_expect(pmonitor->m_recvfd,
+            MONITOR_ANS_AUTHPASSWORD, m);
 
-        authenticated = buffer_get_int(&m);
+        if ((r = sshbuf_get_u32(m, &authenticated)) != 0)
+                fatal("%s: buffer error: %s", __func__, ssh_err(r));
 #ifdef USE_PAM
-        sshpam_set_maxtries_reached(buffer_get_int(&m));
+        if ((r = sshbuf_get_u32(m, &maxtries)) != 0)
+                fatal("%s: buffer error: %s", __func__, ssh_err(r));
+        sshpam_set_maxtries_reached(maxtries);
 #endif
 
-        buffer_free(&m);
+        sshbuf_free(m);
 
         debug3("%s: user %sauthenticated",
             __func__, authenticated ? "" : "not ");
@@ -396,9 +455,7 @@ int
 mm_key_allowed(enum mm_keytype type, const char *user, const char *host,
     struct sshkey *key, int pubkey_auth_attempt, struct sshauthopt **authoptp)
 {
-        Buffer m;
-        u_char *blob;
-        u_int len;
+        struct sshbuf *m;
         int r, allowed = 0;
         struct sshauthopt *opts = NULL;
 
@@ -407,31 +464,29 @@ mm_key_allowed(enum mm_keytype type, const char *user, const char *host,
         if (authoptp != NULL)
                 *authoptp = NULL;
 
-        /* Convert the key to a blob and the pass it over */
-        if (!key_to_blob(key, &blob, &len))
-                return 0;
-
-        buffer_init(&m);
-        buffer_put_int(&m, type);
-        buffer_put_cstring(&m, user ? user : "");
-        buffer_put_cstring(&m, host ? host : "");
-        buffer_put_string(&m, blob, len);
-        buffer_put_int(&m, pubkey_auth_attempt);
-        free(blob);
+        if ((m = sshbuf_new()) == NULL)
+                fatal("%s: sshbuf_new failed", __func__);
+        if ((r = sshbuf_put_u32(m, type)) != 0 ||
+            (r = sshbuf_put_cstring(m, user ? user : "")) != 0 ||
+            (r = sshbuf_put_cstring(m, host ? host : "")) != 0 ||
+            (r = sshkey_puts(key, m)) != 0 ||
+            (r = sshbuf_put_u32(m, pubkey_auth_attempt)) != 0)
+                fatal("%s: buffer error: %s", __func__, ssh_err(r));
 
-        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_KEYALLOWED, &m);
+        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_KEYALLOWED, m);
 
         debug3("%s: waiting for MONITOR_ANS_KEYALLOWED", __func__);
         mm_request_receive_expect(pmonitor->m_recvfd,
-            MONITOR_ANS_KEYALLOWED, &m);
+            MONITOR_ANS_KEYALLOWED, m);
 
-        allowed = buffer_get_int(&m);
+        if ((r = sshbuf_get_u32(m, &allowed)) != 0)
+                fatal("%s: buffer error: %s", __func__, ssh_err(r));
         if (allowed && type == MM_USERKEY) {
-                if ((r = sshauthopt_deserialise(&m, &opts)) != 0)
+                if ((r = sshauthopt_deserialise(m, &opts)) != 0)
                         fatal("%s: sshauthopt_deserialise: %s",
                             __func__, ssh_err(r));
         }
-        buffer_free(&m);
+        sshbuf_free(m);
 
         if (authoptp != NULL) {
                 *authoptp = opts;
@@ -452,32 +507,31 @@ int
 mm_sshkey_verify(const struct sshkey *key, const u_char *sig, size_t siglen,
     const u_char *data, size_t datalen, const char *sigalg, u_int compat)
 {
-        Buffer m;
-        u_char *blob;
-        u_int len;
+        struct sshbuf *m;
         u_int encoded_ret = 0;
+        int r;
 
         debug3("%s entering", __func__);
 
-        /* Convert the key to a blob and the pass it over */
-        if (!key_to_blob(key, &blob, &len))
-                return (0);
 
-        buffer_init(&m);
-        buffer_put_string(&m, blob, len);
-        buffer_put_string(&m, sig, siglen);
-        buffer_put_string(&m, data, datalen);
-        buffer_put_cstring(&m, sigalg == NULL ? "" : sigalg);
-        free(blob);
+        if ((m = sshbuf_new()) == NULL)
+                fatal("%s: sshbuf_new failed", __func__);
+        if ((r = sshkey_puts(key, m)) != 0 ||
+            (r = sshbuf_put_string(m, sig, siglen)) != 0 ||
+            (r = sshbuf_put_string(m, data, datalen)) != 0 ||
+            (r = sshbuf_put_cstring(m, sigalg == NULL ? "" : sigalg)) != 0)
+                fatal("%s: buffer error: %s", __func__, ssh_err(r));
 
-        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_KEYVERIFY, &m);
+        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_KEYVERIFY, m);
 
         debug3("%s: waiting for MONITOR_ANS_KEYVERIFY", __func__);
-        mm_request_receive_expect(pmonitor->m_recvfd, MONITOR_ANS_KEYVERIFY, &m);
+        mm_request_receive_expect(pmonitor->m_recvfd,
+            MONITOR_ANS_KEYVERIFY, m);
 
-        encoded_ret = buffer_get_int(&m);
+        if ((r = sshbuf_get_u32(m, &encoded_ret)) != 0)
+                fatal("%s: buffer error: %s", __func__, ssh_err(r));
 
-        buffer_free(&m);
+        sshbuf_free(m);
 
         if (encoded_ret != 0)
                 return SSH_ERR_SIGNATURE_INVALID;
@@ -504,7 +558,7 @@ mm_send_keystate(struct monitor *monitor)
 int
 mm_pty_allocate(int *ptyfd, int *ttyfd, char *namebuf, size_t namebuflen)
 {
-        Buffer m;
+        struct sshbuf *m;
         char *p, *msg;
         int success = 0, tmp1 = -1, tmp2 = -1, r;
 
@@ -521,21 +575,24 @@ mm_pty_allocate(int *ptyfd, int *ttyfd, char *namebuf, size_t namebuflen)
         close(tmp1);
         close(tmp2);
 
-        buffer_init(&m);
-        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_PTY, &m);
+        if ((m = sshbuf_new()) == NULL)
+                fatal("%s: sshbuf_new failed", __func__);
+        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_PTY, m);
 
         debug3("%s: waiting for MONITOR_ANS_PTY", __func__);
-        mm_request_receive_expect(pmonitor->m_recvfd, MONITOR_ANS_PTY, &m);
+        mm_request_receive_expect(pmonitor->m_recvfd, MONITOR_ANS_PTY, m);
 
-        success = buffer_get_int(&m);
+        if ((r = sshbuf_get_u32(m, &success)) != 0)
+                fatal("%s: buffer error: %s", __func__, ssh_err(r));
         if (success == 0) {
                 debug3("%s: pty alloc failed", __func__);
-                buffer_free(&m);
+                sshbuf_free(m);
                 return (0);
         }
-        p = buffer_get_string(&m, NULL);
-        msg = buffer_get_string(&m, NULL);
-        buffer_free(&m);
+        if ((r = sshbuf_get_cstring(m, &p, NULL)) != 0 ||
+            (r = sshbuf_get_cstring(m, &msg, NULL)) != 0)
+                fatal("%s: buffer error: %s", __func__, ssh_err(r));
+        sshbuf_free(m);
 
         strlcpy(namebuf, p, namebuflen); /* Possible truncation */
         free(p);
@@ -555,14 +612,17 @@ mm_pty_allocate(int *ptyfd, int *ttyfd, char *namebuf, size_t namebuflen)
 void
 mm_session_pty_cleanup2(Session *s)
 {
-        Buffer m;
+        struct sshbuf *m;
+        int r;
 
         if (s->ttyfd == -1)
                 return;
-        buffer_init(&m);
-        buffer_put_cstring(&m, s->tty);
-        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_PTYCLEANUP, &m);
-        buffer_free(&m);
+        if ((m = sshbuf_new()) == NULL)
+                fatal("%s: sshbuf_new failed", __func__);
+        if ((r = sshbuf_put_cstring(m, s->tty)) != 0)
+                fatal("%s: buffer error: %s", __func__, ssh_err(r));
+        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_PTYCLEANUP, m);
+        sshbuf_free(m);
 
         /* closed dup'ed master */
         if (s->ptymaster != -1 && close(s->ptymaster) < 0)
@@ -710,11 +770,12 @@ mm_sshpam_free_ctx(void *ctxtp)
 void
 mm_terminate(void)
 {
-        Buffer m;
+        struct sshbuf *m;
 
-        buffer_init(&m);
-        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_TERM, &m);
-        buffer_free(&m);
+        if ((m = sshbuf_new()) == NULL)
+                fatal("%s: sshbuf_new failed", __func__);
+        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_TERM, m);
+        sshbuf_free(m);
 }
 
 static void
@@ -733,27 +794,31 @@ int
 mm_bsdauth_query(void *ctx, char **name, char **infotxt,
    u_int *numprompts, char ***prompts, u_int **echo_on)
 {
-        Buffer m;
+        struct sshbuf *m;
         u_int success;
         char *challenge;
+        int r;
 
         debug3("%s: entering", __func__);
 
-        buffer_init(&m);
-        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_BSDAUTHQUERY, &m);
+        if ((m = sshbuf_new()) == NULL)
+                fatal("%s: sshbuf_new failed", __func__);
+        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_BSDAUTHQUERY, m);
 
-        mm_request_receive_expect(pmonitor->m_recvfd, MONITOR_ANS_BSDAUTHQUERY,
-            &m);
-        success = buffer_get_int(&m);
+        mm_request_receive_expect(pmonitor->m_recvfd,
+            MONITOR_ANS_BSDAUTHQUERY, m);
+        if ((r = sshbuf_get_u32(m, &success)) != 0)
+                fatal("%s: buffer error: %s", __func__, ssh_err(r));
         if (success == 0) {
                 debug3("%s: no challenge", __func__);
-                buffer_free(&m);
+                sshbuf_free(m);
                 return (-1);
         }
 
         /* Get the challenge, and format the response */
-        challenge  = buffer_get_string(&m, NULL);
-        buffer_free(&m);
+        if ((r = sshbuf_get_cstring(m, &challenge, NULL)) != 0)
+                fatal("%s: buffer error: %s", __func__, ssh_err(r));
+        sshbuf_free(m);
 
         mm_chall_setup(name, infotxt, numprompts, prompts, echo_on);
         (*prompts)[0] = challenge;
@@ -766,22 +831,25 @@ mm_bsdauth_query(void *ctx, char **name, char **infotxt,
 int
 mm_bsdauth_respond(void *ctx, u_int numresponses, char **responses)
 {
-        Buffer m;
-        int authok;
+        struct sshbuf *m;
+        int r, authok;
 
         debug3("%s: entering", __func__);
         if (numresponses != 1)
                 return (-1);
 
-        buffer_init(&m);
-        buffer_put_cstring(&m, responses[0]);
-        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_BSDAUTHRESPOND, &m);
+        if ((m = sshbuf_new()) == NULL)
+                fatal("%s: sshbuf_new failed", __func__);
+        if ((r = sshbuf_put_cstring(m, responses[0])) != 0)
+                fatal("%s: buffer error: %s", __func__, ssh_err(r));
+        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_BSDAUTHRESPOND, m);
 
         mm_request_receive_expect(pmonitor->m_recvfd,
-            MONITOR_ANS_BSDAUTHRESPOND, &m);
+            MONITOR_ANS_BSDAUTHRESPOND, m);
 
-        authok = buffer_get_int(&m);
-        buffer_free(&m);
+        if ((r = sshbuf_get_u32(m, &authok)) != 0)
+                fatal("%s: buffer error: %s", __func__, ssh_err(r));
+        sshbuf_free(m);
 
         return ((authok == 0) ? -1 : 0);
 }
@@ -881,45 +949,55 @@ mm_audit_run_command(const char *command)
 OM_uint32
 mm_ssh_gssapi_server_ctx(Gssctxt **ctx, gss_OID goid)
 {
-        Buffer m;
+        struct sshbuf *m;
         OM_uint32 major;
+        int r;
 
         /* Client doesn't get to see the context */
         *ctx = NULL;
 
-        buffer_init(&m);
-        buffer_put_string(&m, goid->elements, goid->length);
+        if ((m = sshbuf_new()) == NULL)
+                fatal("%s: sshbuf_new failed", __func__);
+        if ((r = sshbuf_put_string(m, goid->elements, goid->length)) != 0)
+                fatal("%s: buffer error: %s", __func__, ssh_err(r));
 
-        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_GSSSETUP, &m);
-        mm_request_receive_expect(pmonitor->m_recvfd, MONITOR_ANS_GSSSETUP, &m);
+        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_GSSSETUP, m);
+        mm_request_receive_expect(pmonitor->m_recvfd, MONITOR_ANS_GSSSETUP, m);
 
-        major = buffer_get_int(&m);
+        if ((r = sshbuf_get_u32(m, &major)) != 0)
+                fatal("%s: buffer error: %s", __func__, ssh_err(r));
 
-        buffer_free(&m);
+        sshbuf_free(m);
         return (major);
 }
 
 OM_uint32
 mm_ssh_gssapi_accept_ctx(Gssctxt *ctx, gss_buffer_desc *in,
-    gss_buffer_desc *out, OM_uint32 *flags)
+    gss_buffer_desc *out, OM_uint32 *flagsp)
 {
-        Buffer m;
+        struct sshbuf *m;
         OM_uint32 major;
-        u_int len;
+        u_int flags;
+        int r;
 
-        buffer_init(&m);
-        buffer_put_string(&m, in->value, in->length);
+        if ((m = sshbuf_new()) == NULL)
+                fatal("%s: sshbuf_new failed", __func__);
+        if ((r = sshbuf_put_string(m, in->value, in->length)) != 0)
+                fatal("%s: buffer error: %s", __func__, ssh_err(r));
 
-        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_GSSSTEP, &m);
-        mm_request_receive_expect(pmonitor->m_recvfd, MONITOR_ANS_GSSSTEP, &m);
+        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_GSSSTEP, m);
+        mm_request_receive_expect(pmonitor->m_recvfd, MONITOR_ANS_GSSSTEP, m);
 
-        major = buffer_get_int(&m);
-        out->value = buffer_get_string(&m, &len);
-        out->length = len;
-        if (flags)
-                *flags = buffer_get_int(&m);
+        if ((r = sshbuf_get_u32(m, &major)) != 0 ||
+            (r = sshbuf_get_string(m, &out->value, &out->length)) != 0)
+                fatal("%s: buffer error: %s", __func__, ssh_err(r));
+        if (flagsp != NULL) {
+                if ((r = sshbuf_get_u32(m, &flags)) != 0)
+                        fatal("%s: buffer error: %s", __func__, ssh_err(r));
+                *flagsp = flags;
+        }
 
-        buffer_free(&m);
+        sshbuf_free(m);
 
         return (major);
 }
@@ -927,39 +1005,44 @@ mm_ssh_gssapi_accept_ctx(Gssctxt *ctx, gss_buffer_desc *in,
 OM_uint32
 mm_ssh_gssapi_checkmic(Gssctxt *ctx, gss_buffer_t gssbuf, gss_buffer_t gssmic)
 {
-        Buffer m;
+        struct sshbuf *m;
         OM_uint32 major;
+        int r;
 
-        buffer_init(&m);
-        buffer_put_string(&m, gssbuf->value, gssbuf->length);
-        buffer_put_string(&m, gssmic->value, gssmic->length);
+        if ((m = sshbuf_new()) == NULL)
+                fatal("%s: sshbuf_new failed", __func__);
+        if ((r = sshbuf_put_string(m, gssbuf->value, gssbuf->length)) != 0 ||
+            (r = sshbuf_put_string(m, gssmic->value, gssmic->length)) != 0)
+                fatal("%s: buffer error: %s", __func__, ssh_err(r));
 
-        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_GSSCHECKMIC, &m);
-        mm_request_receive_expect(pmonitor->m_recvfd, MONITOR_ANS_GSSCHECKMIC,
-            &m);
+        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_GSSCHECKMIC, m);
+        mm_request_receive_expect(pmonitor->m_recvfd,
+            MONITOR_ANS_GSSCHECKMIC, m);
 
-        major = buffer_get_int(&m);
-        buffer_free(&m);
+        if ((r = sshbuf_get_u32(m, &major)) != 0)
+                fatal("%s: buffer error: %s", __func__, ssh_err(r));
+        sshbuf_free(m);
         return(major);
 }
 
 int
 mm_ssh_gssapi_userok(char *user)
 {
-        Buffer m;
-        int authenticated = 0;
+        struct sshbuf *m;
+        int r, authenticated = 0;
 
-        buffer_init(&m);
+        if ((m = sshbuf_new()) == NULL)
+                fatal("%s: sshbuf_new failed", __func__);
 
-        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_GSSUSEROK, &m);
-        mm_request_receive_expect(pmonitor->m_recvfd, MONITOR_ANS_GSSUSEROK,
-                                  &m);
+        mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_GSSUSEROK, m);
+        mm_request_receive_expect(pmonitor->m_recvfd,
+            MONITOR_ANS_GSSUSEROK, m);
 
-        authenticated = buffer_get_int(&m);
+        if ((r = sshbuf_get_u32(m, &authenticated)) != 0)
+                fatal("%s: buffer error: %s", __func__, ssh_err(r));
 
-        buffer_free(&m);
+        sshbuf_free(m);
         debug3("%s: user %sauthenticated",__func__, authenticated ? "" : "not ");
         return (authenticated);
 }
 #endif /* GSSAPI */
-