1 files changed, 276 insertions, 468 deletions

diff --git a/ssh-agent.c b/ssh-agent.c
index b987562b9..0c6c36592 100644
--- a/ssh-agent.c
+++ b/ssh-agent.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh-agent.c,v 1.218 2017/03/15 03:52:30 deraadt Exp $ */
+/* $OpenBSD: ssh-agent.c,v 1.224 2017/07/24 04:34:28 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -60,6 +60,9 @@
 #ifdef HAVE_PATHS_H
 # include <paths.h>
 #endif
+#ifdef HAVE_POLL_H
+# include <poll.h>
+#endif
 #include <signal.h>
 #include <stdarg.h>
 #include <stdio.h>
@@ -73,7 +76,6 @@
 
 #include "xmalloc.h"
 #include "ssh.h"
-#include "rsa.h"
 #include "sshbuf.h"
 #include "sshkey.h"
 #include "authfd.h"
@@ -92,6 +94,9 @@
 # define DEFAULT_PKCS11_WHITELIST "/usr/lib*/*,/usr/local/lib*/*"
 #endif
 
+/* Maximum accepted message length */
+#define AGENT_MAX_LEN   (256*1024)
+
 typedef enum {
         AUTH_UNUSED,
         AUTH_SOCKET,
@@ -118,13 +123,13 @@ typedef struct identity {
         u_int confirm;
 } Identity;
 
-typedef struct {
+struct idtable {
         int nentries;
         TAILQ_HEAD(idqueue, identity) idlist;
-} Idtab;
+};
 
-/* private key table, one per protocol version */
-Idtab idtable[3];
+/* private key table */
+struct idtable *idtab;
 
 int max_fd = 0;
 
@@ -171,21 +176,9 @@ close_socket(SocketEntry *e)
 static void
 idtab_init(void)
 {
-        int i;
-
-        for (i = 0; i <=2; i++) {
-                TAILQ_INIT(&idtable[i].idlist);
-                idtable[i].nentries = 0;
-        }
-}
-
-/* return private key table for requested protocol version */
-static Idtab *
-idtab_lookup(int version)
-{
-        if (version < 1 || version > 2)
-                fatal("internal error, bad protocol version %d", version);
-        return &idtable[version];
+        idtab = xcalloc(1, sizeof(*idtab));
+        TAILQ_INIT(&idtab->idlist);
+        idtab->nentries = 0;
 }
 
 static void
@@ -199,12 +192,11 @@ free_identity(Identity *id)
 
 /* return matching private key for given public key */
 static Identity *
-lookup_identity(struct sshkey *key, int version)
+lookup_identity(struct sshkey *key)
 {
         Identity *id;
 
-        Idtab *tab = idtab_lookup(version);
-        TAILQ_FOREACH(id, &tab->idlist, next) {
+        TAILQ_FOREACH(id, &idtab->idlist, next) {
                 if (sshkey_equal(key, id->key))
                         return (id);
         }
@@ -241,135 +233,30 @@ send_status(SocketEntry *e, int success)
 
 /* send list of supported public keys to 'client' */
 static void
-process_request_identities(SocketEntry *e, int version)
+process_request_identities(SocketEntry *e)
 {
-        Idtab *tab = idtab_lookup(version);
         Identity *id;
         struct sshbuf *msg;
         int r;
 
         if ((msg = sshbuf_new()) == NULL)
                 fatal("%s: sshbuf_new failed", __func__);
-        if ((r = sshbuf_put_u8(msg, (version == 1) ?
-            SSH_AGENT_RSA_IDENTITIES_ANSWER :
-            SSH2_AGENT_IDENTITIES_ANSWER)) != 0 ||
-            (r = sshbuf_put_u32(msg, tab->nentries)) != 0)
-                fatal("%s: buffer error: %s", __func__, ssh_err(r));
-        TAILQ_FOREACH(id, &tab->idlist, next) {
-                if (id->key->type == KEY_RSA1) {
-#ifdef WITH_SSH1
-                        if ((r = sshbuf_put_u32(msg,
-                            BN_num_bits(id->key->rsa->n))) != 0 ||
-                            (r = sshbuf_put_bignum1(msg,
-                            id->key->rsa->e)) != 0 ||
-                            (r = sshbuf_put_bignum1(msg,
-                            id->key->rsa->n)) != 0)
-                                fatal("%s: buffer error: %s",
-                                    __func__, ssh_err(r));
-#endif
-                } else {
-                        u_char *blob;
-                        size_t blen;
-
-                        if ((r = sshkey_to_blob(id->key, &blob, &blen)) != 0) {
-                                error("%s: sshkey_to_blob: %s", __func__,
-                                    ssh_err(r));
-                                continue;
-                        }
-                        if ((r = sshbuf_put_string(msg, blob, blen)) != 0)
-                                fatal("%s: buffer error: %s",
-                                    __func__, ssh_err(r));
-                        free(blob);
-                }
-                if ((r = sshbuf_put_cstring(msg, id->comment)) != 0)
-                        fatal("%s: buffer error: %s", __func__, ssh_err(r));
-        }
-        if ((r = sshbuf_put_stringb(e->output, msg)) != 0)
-                fatal("%s: buffer error: %s", __func__, ssh_err(r));
-        sshbuf_free(msg);
-}
-
-#ifdef WITH_SSH1
-/* ssh1 only */
-static void
-process_authentication_challenge1(SocketEntry *e)
-{
-        u_char buf[32], mdbuf[16], session_id[16];
-        u_int response_type;
-        BIGNUM *challenge;
-        Identity *id;
-        int r, len;
-        struct sshbuf *msg;
-        struct ssh_digest_ctx *md;
-        struct sshkey *key;
-
-        if ((msg = sshbuf_new()) == NULL)
-                fatal("%s: sshbuf_new failed", __func__);
-        if ((key = sshkey_new(KEY_RSA1)) == NULL)
-                fatal("%s: sshkey_new failed", __func__);
-        if ((challenge = BN_new()) == NULL)
-                fatal("%s: BN_new failed", __func__);
-
-        if ((r = sshbuf_get_u32(e->request, NULL)) != 0 || /* ignored */
-            (r = sshbuf_get_bignum1(e->request, key->rsa->e)) != 0 ||
-            (r = sshbuf_get_bignum1(e->request, key->rsa->n)) != 0 ||
-            (r = sshbuf_get_bignum1(e->request, challenge)))
-                fatal("%s: buffer error: %s", __func__, ssh_err(r));
-
-        /* Only protocol 1.1 is supported */
-        if (sshbuf_len(e->request) == 0)
-                goto failure;
-        if ((r = sshbuf_get(e->request, session_id, sizeof(session_id))) != 0 ||
-            (r = sshbuf_get_u32(e->request, &response_type)) != 0)
+        if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 ||
+            (r = sshbuf_put_u32(msg, idtab->nentries)) != 0)
                 fatal("%s: buffer error: %s", __func__, ssh_err(r));
-        if (response_type != 1)
-                goto failure;
-
-        id = lookup_identity(key, 1);
-        if (id != NULL && (!id->confirm || confirm_key(id) == 0)) {
-                struct sshkey *private = id->key;
-                /* Decrypt the challenge using the private key. */
-                if ((r = rsa_private_decrypt(challenge, challenge,
-                    private->rsa) != 0)) {
-                        fatal("%s: rsa_public_encrypt: %s", __func__,
+        TAILQ_FOREACH(id, &idtab->idlist, next) {
+                if ((r = sshkey_puts(id->key, msg)) != 0 ||
+                    (r = sshbuf_put_cstring(msg, id->comment)) != 0) {
+                        error("%s: put key/comment: %s", __func__,
                             ssh_err(r));
-                        goto failure;   /* XXX ? */
+                        continue;
                 }
-
-                /* The response is MD5 of decrypted challenge plus session id */
-                len = BN_num_bytes(challenge);
-                if (len <= 0 || len > 32) {
-                        logit("%s: bad challenge length %d", __func__, len);
-                        goto failure;
-                }
-                memset(buf, 0, 32);
-                BN_bn2bin(challenge, buf + 32 - len);
-                if ((md = ssh_digest_start(SSH_DIGEST_MD5)) == NULL ||
-                    ssh_digest_update(md, buf, 32) < 0 ||
-                    ssh_digest_update(md, session_id, 16) < 0 ||
-                    ssh_digest_final(md, mdbuf, sizeof(mdbuf)) < 0)
-                        fatal("%s: md5 failed", __func__);
-                ssh_digest_free(md);
-
-                /* Send the response. */
-                if ((r = sshbuf_put_u8(msg, SSH_AGENT_RSA_RESPONSE)) != 0 ||
-                    (r = sshbuf_put(msg, mdbuf, sizeof(mdbuf))) != 0)
-                        fatal("%s: buffer error: %s", __func__, ssh_err(r));
-                goto send;
         }
-
- failure:
-        /* Unknown identity or protocol error.  Send failure. */
-        if ((r = sshbuf_put_u8(msg, SSH_AGENT_FAILURE)) != 0)
-                fatal("%s: buffer error: %s", __func__, ssh_err(r));
- send:
         if ((r = sshbuf_put_stringb(e->output, msg)) != 0)
                 fatal("%s: buffer error: %s", __func__, ssh_err(r));
-        sshkey_free(key);
-        BN_clear_free(challenge);
         sshbuf_free(msg);
 }
-#endif
+
 
 static char *
 agent_decode_alg(struct sshkey *key, u_int flags)
@@ -387,27 +274,24 @@ agent_decode_alg(struct sshkey *key, u_int flags)
 static void
 process_sign_request2(SocketEntry *e)
 {
-        u_char *blob, *data, *signature = NULL;
-        size_t blen, dlen, slen = 0;
+        const u_char *data;
+        u_char *signature = NULL;
+        size_t dlen, slen = 0;
         u_int compat = 0, flags;
         int r, ok = -1;
         struct sshbuf *msg;
-        struct sshkey *key;
+        struct sshkey *key = NULL;
         struct identity *id;
 
         if ((msg = sshbuf_new()) == NULL)
                 fatal("%s: sshbuf_new failed", __func__);
-        if ((r = sshbuf_get_string(e->request, &blob, &blen)) != 0 ||
-            (r = sshbuf_get_string(e->request, &data, &dlen)) != 0 ||
+        if ((r = sshkey_froms(e->request, &key)) != 0 ||
+            (r = sshbuf_get_string_direct(e->request, &data, &dlen)) != 0 ||
             (r = sshbuf_get_u32(e->request, &flags)) != 0)
                 fatal("%s: buffer error: %s", __func__, ssh_err(r));
         if (flags & SSH_AGENT_OLD_SIGNATURE)
                 compat = SSH_BUG_SIGBLOB;
-        if ((r = sshkey_from_blob(blob, blen, &key)) != 0) {
-                error("%s: cannot parse key blob: %s", __func__, ssh_err(r));
-                goto send;
-        }
-        if ((id = lookup_identity(key, 2)) == NULL) {
+        if ((id = lookup_identity(key)) == NULL) {
                 verbose("%s: %s key not found", __func__, sshkey_type(key));
                 goto send;
         }
@@ -435,90 +319,52 @@ process_sign_request2(SocketEntry *e)
                 fatal("%s: buffer error: %s", __func__, ssh_err(r));
 
         sshbuf_free(msg);
-        free(data);
-        free(blob);
         free(signature);
 }
 
 /* shared */
 static void
-process_remove_identity(SocketEntry *e, int version)
+process_remove_identity(SocketEntry *e)
 {
-        size_t blen;
         int r, success = 0;
         struct sshkey *key = NULL;
-        u_char *blob;
-#ifdef WITH_SSH1
-        u_int bits;
-#endif /* WITH_SSH1 */
-
-        switch (version) {
-#ifdef WITH_SSH1
-        case 1:
-                if ((key = sshkey_new(KEY_RSA1)) == NULL) {
-                        error("%s: sshkey_new failed", __func__);
-                        return;
-                }
-                if ((r = sshbuf_get_u32(e->request, &bits)) != 0 ||
-                    (r = sshbuf_get_bignum1(e->request, key->rsa->e)) != 0 ||
-                    (r = sshbuf_get_bignum1(e->request, key->rsa->n)) != 0)
-                        fatal("%s: buffer error: %s", __func__, ssh_err(r));
+        Identity *id;
 
-                if (bits != sshkey_size(key))
-                        logit("Warning: identity keysize mismatch: "
-                            "actual %u, announced %u",
-                            sshkey_size(key), bits);
-                break;
-#endif /* WITH_SSH1 */
-        case 2:
-                if ((r = sshbuf_get_string(e->request, &blob, &blen)) != 0)
-                        fatal("%s: buffer error: %s", __func__, ssh_err(r));
-                if ((r = sshkey_from_blob(blob, blen, &key)) != 0)
-                        error("%s: sshkey_from_blob failed: %s",
-                            __func__, ssh_err(r));
-                free(blob);
-                break;
+        if ((r = sshkey_froms(e->request, &key)) != 0) {
+                error("%s: get key: %s", __func__, ssh_err(r));
+                goto done;
         }
-        if (key != NULL) {
-                Identity *id = lookup_identity(key, version);
-                if (id != NULL) {
-                        /*
-                         * We have this key.  Free the old key.  Since we
-                         * don't want to leave empty slots in the middle of
-                         * the array, we actually free the key there and move
-                         * all the entries between the empty slot and the end
-                         * of the array.
-                         */
-                        Idtab *tab = idtab_lookup(version);
-                        if (tab->nentries < 1)
-                                fatal("process_remove_identity: "
-                                    "internal error: tab->nentries %d",
-                                    tab->nentries);
-                        TAILQ_REMOVE(&tab->idlist, id, next);
-                        free_identity(id);
-                        tab->nentries--;
-                        success = 1;
-                }
-                sshkey_free(key);
+        if ((id = lookup_identity(key)) == NULL) {
+                debug("%s: key not found", __func__);
+                goto done;
         }
+        /* We have this key, free it. */
+        if (idtab->nentries < 1)
+                fatal("%s: internal error: nentries %d",
+                    __func__, idtab->nentries);
+        TAILQ_REMOVE(&idtab->idlist, id, next);
+        free_identity(id);
+        idtab->nentries--;
+        sshkey_free(key);
+        success = 1;
+ done:
         send_status(e, success);
 }
 
 static void
-process_remove_all_identities(SocketEntry *e, int version)
+process_remove_all_identities(SocketEntry *e)
 {
-        Idtab *tab = idtab_lookup(version);
         Identity *id;
 
         /* Loop over all identities and clear the keys. */
-        for (id = TAILQ_FIRST(&tab->idlist); id;
-            id = TAILQ_FIRST(&tab->idlist)) {
-                TAILQ_REMOVE(&tab->idlist, id, next);
+        for (id = TAILQ_FIRST(&idtab->idlist); id;
+            id = TAILQ_FIRST(&idtab->idlist)) {
+                TAILQ_REMOVE(&idtab->idlist, id, next);
                 free_identity(id);
         }
 
         /* Mark that there are no identities. */
-        tab->nentries = 0;
+        idtab->nentries = 0;
 
         /* Send success. */
         send_status(e, 1);
@@ -530,24 +376,19 @@ reaper(void)
 {
         time_t deadline = 0, now = monotime();
         Identity *id, *nxt;
-        int version;
-        Idtab *tab;
-
-        for (version = 1; version < 3; version++) {
-                tab = idtab_lookup(version);
-                for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
-                        nxt = TAILQ_NEXT(id, next);
-                        if (id->death == 0)
-                                continue;
-                        if (now >= id->death) {
-                                debug("expiring key '%s'", id->comment);
-                                TAILQ_REMOVE(&tab->idlist, id, next);
-                                free_identity(id);
-                                tab->nentries--;
-                        } else
-                                deadline = (deadline == 0) ? id->death :
-                                    MINIMUM(deadline, id->death);
-                }
+
+        for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) {
+                nxt = TAILQ_NEXT(id, next);
+                if (id->death == 0)
+                        continue;
+                if (now >= id->death) {
+                        debug("expiring key '%s'", id->comment);
+                        TAILQ_REMOVE(&idtab->idlist, id, next);
+                        free_identity(id);
+                        idtab->nentries--;
+                } else
+                        deadline = (deadline == 0) ? id->death :
+                            MINIMUM(deadline, id->death);
         }
         if (deadline == 0 || deadline <= now)
                 return 0;
@@ -555,54 +396,9 @@ reaper(void)
                 return (deadline - now);
 }
 
-/*
- * XXX this and the corresponding serialisation function probably belongs
- * in key.c
- */
-#ifdef WITH_SSH1
-static int
-agent_decode_rsa1(struct sshbuf *m, struct sshkey **kp)
-{
-        struct sshkey *k = NULL;
-        int r = SSH_ERR_INTERNAL_ERROR;
-
-        *kp = NULL;
-        if ((k = sshkey_new_private(KEY_RSA1)) == NULL)
-                return SSH_ERR_ALLOC_FAIL;
-
-        if ((r = sshbuf_get_u32(m, NULL)) != 0 ||               /* ignored */
-            (r = sshbuf_get_bignum1(m, k->rsa->n)) != 0 ||
-            (r = sshbuf_get_bignum1(m, k->rsa->e)) != 0 ||
-            (r = sshbuf_get_bignum1(m, k->rsa->d)) != 0 ||
-            (r = sshbuf_get_bignum1(m, k->rsa->iqmp)) != 0 ||
-            /* SSH1 and SSL have p and q swapped */
-            (r = sshbuf_get_bignum1(m, k->rsa->q)) != 0 ||      /* p */
-            (r = sshbuf_get_bignum1(m, k->rsa->p)) != 0)        /* q */
-                goto out;
-
-        /* Generate additional parameters */
-        if ((r = rsa_generate_additional_parameters(k->rsa)) != 0)
-                goto out;
-        /* enable blinding */
-        if (RSA_blinding_on(k->rsa, NULL) != 1) {
-                r = SSH_ERR_LIBCRYPTO_ERROR;
-                goto out;
-        }
-
-        r = 0; /* success */
- out:
-        if (r == 0)
-                *kp = k;
-        else
-                sshkey_free(k);
-        return r;
-}
-#endif /* WITH_SSH1 */
-
 static void
-process_add_identity(SocketEntry *e, int version)
+process_add_identity(SocketEntry *e)
 {
-        Idtab *tab = idtab_lookup(version);
         Identity *id;
         int success = 0, confirm = 0;
         u_int seconds;
@@ -612,17 +408,8 @@ process_add_identity(SocketEntry *e, int version)
         u_char ctype;
         int r = SSH_ERR_INTERNAL_ERROR;
 
-        switch (version) {
-#ifdef WITH_SSH1
-        case 1:
-                r = agent_decode_rsa1(e->request, &k);
-                break;
-#endif /* WITH_SSH1 */
-        case 2:
-                r = sshkey_private_deserialize(e->request, &k);
-                break;
-        }
-        if (r != 0 || k == NULL ||
+        if ((r = sshkey_private_deserialize(e->request, &k)) != 0 ||
+            k == NULL ||
             (r = sshbuf_get_cstring(e->request, &comment, NULL)) != 0) {
                 error("%s: decode private key: %s", __func__, ssh_err(r));
                 goto err;
@@ -658,12 +445,12 @@ process_add_identity(SocketEntry *e, int version)
         success = 1;
         if (lifetime && !death)
                 death = monotime() + lifetime;
-        if ((id = lookup_identity(k, version)) == NULL) {
+        if ((id = lookup_identity(k)) == NULL) {
                 id = xcalloc(1, sizeof(Identity));
                 id->key = k;
-                TAILQ_INSERT_TAIL(&tab->idlist, id, next);
+                TAILQ_INSERT_TAIL(&idtab->idlist, id, next);
                 /* Increment the number of identities. */
-                tab->nentries++;
+                idtab->nentries++;
         } else {
                 sshkey_free(k);
                 free(id->comment);
@@ -724,17 +511,14 @@ process_lock_agent(SocketEntry *e, int lock)
 }
 
 static void
-no_identities(SocketEntry *e, u_int type)
+no_identities(SocketEntry *e)
 {
         struct sshbuf *msg;
         int r;
 
         if ((msg = sshbuf_new()) == NULL)
                 fatal("%s: sshbuf_new failed", __func__);
-        if ((r = sshbuf_put_u8(msg,
-            (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ?
-            SSH_AGENT_RSA_IDENTITIES_ANSWER :
-            SSH2_AGENT_IDENTITIES_ANSWER)) != 0 ||
+        if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 ||
             (r = sshbuf_put_u32(msg, 0)) != 0 ||
             (r = sshbuf_put_stringb(e->output, msg)) != 0)
                 fatal("%s: buffer error: %s", __func__, ssh_err(r));
@@ -746,13 +530,12 @@ static void
 process_add_smartcard_key(SocketEntry *e)
 {
         char *provider = NULL, *pin, canonical_provider[PATH_MAX];
-        int r, i, version, count = 0, success = 0, confirm = 0;
+        int r, i, count = 0, success = 0, confirm = 0;
         u_int seconds;
         time_t death = 0;
         u_char type;
         struct sshkey **keys = NULL, *k;
         Identity *id;
-        Idtab *tab;
 
         if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 ||
             (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0)
@@ -772,8 +555,7 @@ process_add_smartcard_key(SocketEntry *e)
                         confirm = 1;
                         break;
                 default:
-                        error("process_add_smartcard_key: "
-                            "Unknown constraint type %d", type);
+                        error("%s: Unknown constraint type %d", __func__, type);
                         goto send;
                 }
         }
@@ -794,17 +576,15 @@ process_add_smartcard_key(SocketEntry *e)
         count = pkcs11_add_provider(canonical_provider, pin, &keys);
         for (i = 0; i < count; i++) {
                 k = keys[i];
-                version = k->type == KEY_RSA1 ? 1 : 2;
-                tab = idtab_lookup(version);
-                if (lookup_identity(k, version) == NULL) {
+                if (lookup_identity(k) == NULL) {
                         id = xcalloc(1, sizeof(Identity));
                         id->key = k;
                         id->provider = xstrdup(canonical_provider);
                         id->comment = xstrdup(canonical_provider); /* XXX */
                         id->death = death;
                         id->confirm = confirm;
-                        TAILQ_INSERT_TAIL(&tab->idlist, id, next);
-                        tab->nentries++;
+                        TAILQ_INSERT_TAIL(&idtab->idlist, id, next);
+                        idtab->nentries++;
                         success = 1;
                 } else {
                         sshkey_free(k);
@@ -822,9 +602,8 @@ static void
 process_remove_smartcard_key(SocketEntry *e)
 {
         char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX];
-        int r, version, success = 0;
+        int r, success = 0;
         Identity *id, *nxt;
-        Idtab *tab;
 
         if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 ||
             (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0)
@@ -838,25 +617,21 @@ process_remove_smartcard_key(SocketEntry *e)
         }
 
         debug("%s: remove %.100s", __func__, canonical_provider);
-        for (version = 1; version < 3; version++) {
-                tab = idtab_lookup(version);
-                for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
-                        nxt = TAILQ_NEXT(id, next);
-                        /* Skip file--based keys */
-                        if (id->provider == NULL)
-                                continue;
-                        if (!strcmp(canonical_provider, id->provider)) {
-                                TAILQ_REMOVE(&tab->idlist, id, next);
-                                free_identity(id);
-                                tab->nentries--;
-                        }
+        for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) {
+                nxt = TAILQ_NEXT(id, next);
+                /* Skip file--based keys */
+                if (id->provider == NULL)
+                        continue;
+                if (!strcmp(canonical_provider, id->provider)) {
+                        TAILQ_REMOVE(&idtab->idlist, id, next);
+                        free_identity(id);
+                        idtab->nentries--;
                 }
         }
         if (pkcs11_del_provider(canonical_provider) == 0)
                 success = 1;
         else
-                error("process_remove_smartcard_key:"
-                    " pkcs11_del_provider failed");
+                error("%s: pkcs11_del_provider failed", __func__);
 send:
         free(provider);
         send_status(e, success);
@@ -865,88 +640,86 @@ send:
 
 /* dispatch incoming messages */
 
-static void
-process_message(SocketEntry *e)
+static int
+process_message(u_int socknum)
 {
         u_int msg_len;
         u_char type;
         const u_char *cp;
         int r;
+        SocketEntry *e;
+
+        if (socknum >= sockets_alloc) {
+                fatal("%s: socket number %u >= allocated %u",
+                    __func__, socknum, sockets_alloc);
+        }
+        e = &sockets[socknum];
 
         if (sshbuf_len(e->input) < 5)
-                return;         /* Incomplete message. */
+                return 0;               /* Incomplete message header. */
         cp = sshbuf_ptr(e->input);
         msg_len = PEEK_U32(cp);
-        if (msg_len > 256 * 1024) {
-                close_socket(e);
-                return;
+        if (msg_len > AGENT_MAX_LEN) {
+                debug("%s: socket %u (fd=%d) message too long %u > %u",
+                    __func__, socknum, e->fd, msg_len, AGENT_MAX_LEN);
+                return -1;
         }
         if (sshbuf_len(e->input) < msg_len + 4)
-                return;
+                return 0;               /* Incomplete message body. */
 
         /* move the current input to e->request */
         sshbuf_reset(e->request);
         if ((r = sshbuf_get_stringb(e->input, e->request)) != 0 ||
-            (r = sshbuf_get_u8(e->request, &type)) != 0)
+            (r = sshbuf_get_u8(e->request, &type)) != 0) {
+                if (r == SSH_ERR_MESSAGE_INCOMPLETE ||
+                    r == SSH_ERR_STRING_TOO_LARGE) {
+                        debug("%s: buffer error: %s", __func__, ssh_err(r));
+                        return -1;
+                }
                 fatal("%s: buffer error: %s", __func__, ssh_err(r));
+        }
+
+        debug("%s: socket %u (fd=%d) type %d", __func__, socknum, e->fd, type);
 
         /* check wheter agent is locked */
         if (locked && type != SSH_AGENTC_UNLOCK) {
                 sshbuf_reset(e->request);
                 switch (type) {
-                case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
                 case SSH2_AGENTC_REQUEST_IDENTITIES:
                         /* send empty lists */
-                        no_identities(e, type);
+                        no_identities(e);
                         break;
                 default:
                         /* send a fail message for all other request types */
                         send_status(e, 0);
                 }
-                return;
+                return 0;
         }
 
-        debug("type %d", type);
         switch (type) {
         case SSH_AGENTC_LOCK:
         case SSH_AGENTC_UNLOCK:
                 process_lock_agent(e, type == SSH_AGENTC_LOCK);
                 break;
-#ifdef WITH_SSH1
-        /* ssh1 */
-        case SSH_AGENTC_RSA_CHALLENGE:
-                process_authentication_challenge1(e);
-                break;
-        case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
-                process_request_identities(e, 1);
-                break;
-        case SSH_AGENTC_ADD_RSA_IDENTITY:
-        case SSH_AGENTC_ADD_RSA_ID_CONSTRAINED:
-                process_add_identity(e, 1);
-                break;
-        case SSH_AGENTC_REMOVE_RSA_IDENTITY:
-                process_remove_identity(e, 1);
-                break;
-#endif
         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
-                process_remove_all_identities(e, 1); /* safe for !WITH_SSH1 */
+                process_remove_all_identities(e); /* safe for !WITH_SSH1 */
                 break;
         /* ssh2 */
         case SSH2_AGENTC_SIGN_REQUEST:
                 process_sign_request2(e);
                 break;
         case SSH2_AGENTC_REQUEST_IDENTITIES:
-                process_request_identities(e, 2);
+                process_request_identities(e);
                 break;
         case SSH2_AGENTC_ADD_IDENTITY:
         case SSH2_AGENTC_ADD_ID_CONSTRAINED:
-                process_add_identity(e, 2);
+                process_add_identity(e);
                 break;
         case SSH2_AGENTC_REMOVE_IDENTITY:
-                process_remove_identity(e, 2);
+                process_remove_identity(e);
                 break;
         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
-                process_remove_all_identities(e, 2);
+                process_remove_all_identities(e);
                 break;
 #ifdef ENABLE_PKCS11
         case SSH_AGENTC_ADD_SMARTCARD_KEY:
@@ -964,6 +737,7 @@ process_message(SocketEntry *e)
                 send_status(e, 0);
                 break;
         }
+        return 0;
 }
 
 static void
@@ -1005,19 +779,141 @@ new_socket(sock_type type, int fd)
 }
 
 static int
-prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, u_int *nallocp,
-    struct timeval **tvpp)
+handle_socket_read(u_int socknum)
+{
+        struct sockaddr_un sunaddr;
+        socklen_t slen;
+        uid_t euid;
+        gid_t egid;
+        int fd;
+
+        slen = sizeof(sunaddr);
+        fd = accept(sockets[socknum].fd, (struct sockaddr *)&sunaddr, &slen);
+        if (fd < 0) {
+                error("accept from AUTH_SOCKET: %s", strerror(errno));
+                return -1;
+        }
+        if (getpeereid(fd, &euid, &egid) < 0) {
+                error("getpeereid %d failed: %s", fd, strerror(errno));
+                close(fd);
+                return -1;
+        }
+        if ((euid != 0) && (getuid() != euid)) {
+                error("uid mismatch: peer euid %u != uid %u",
+                    (u_int) euid, (u_int) getuid());
+                close(fd);
+                return -1;
+        }
+        new_socket(AUTH_CONNECTION, fd);
+        return 0;
+}
+
+static int
+handle_conn_read(u_int socknum)
+{
+        char buf[1024];
+        ssize_t len;
+        int r;
+
+        if ((len = read(sockets[socknum].fd, buf, sizeof(buf))) <= 0) {
+                if (len == -1) {
+                        if (errno == EAGAIN || errno == EINTR)
+                                return 0;
+                        error("%s: read error on socket %u (fd %d): %s",
+                            __func__, socknum, sockets[socknum].fd,
+                            strerror(errno));
+                }
+                return -1;
+        }
+        if ((r = sshbuf_put(sockets[socknum].input, buf, len)) != 0)
+                fatal("%s: buffer error: %s", __func__, ssh_err(r));
+        explicit_bzero(buf, sizeof(buf));
+        process_message(socknum);
+        return 0;
+}
+
+static int
+handle_conn_write(u_int socknum)
 {
-        u_int i, sz;
-        int n = 0;
-        static struct timeval tv;
+        ssize_t len;
+        int r;
+
+        if (sshbuf_len(sockets[socknum].output) == 0)
+                return 0; /* shouldn't happen */
+        if ((len = write(sockets[socknum].fd,
+            sshbuf_ptr(sockets[socknum].output),
+            sshbuf_len(sockets[socknum].output))) <= 0) {
+                if (len == -1) {
+                        if (errno == EAGAIN || errno == EINTR)
+                                return 0;
+                        error("%s: read error on socket %u (fd %d): %s",
+                            __func__, socknum, sockets[socknum].fd,
+                            strerror(errno));
+                }
+                return -1;
+        }
+        if ((r = sshbuf_consume(sockets[socknum].output, len)) != 0)
+                fatal("%s: buffer error: %s", __func__, ssh_err(r));
+        return 0;
+}
+
+static void
+after_poll(struct pollfd *pfd, size_t npfd)
+{
+        size_t i;
+        u_int socknum;
+
+        for (i = 0; i < npfd; i++) {
+                if (pfd[i].revents == 0)
+                        continue;
+                /* Find sockets entry */
+                for (socknum = 0; socknum < sockets_alloc; socknum++) {
+                        if (sockets[socknum].type != AUTH_SOCKET &&
+                            sockets[socknum].type != AUTH_CONNECTION)
+                                continue;
+                        if (pfd[i].fd == sockets[socknum].fd)
+                                break;
+                }
+                if (socknum >= sockets_alloc) {
+                        error("%s: no socket for fd %d", __func__, pfd[i].fd);
+                        continue;
+                }
+                /* Process events */
+                switch (sockets[socknum].type) {
+                case AUTH_SOCKET:
+                        if ((pfd[i].revents & (POLLIN|POLLERR)) != 0 &&
+                            handle_socket_read(socknum) != 0)
+                                close_socket(&sockets[socknum]);
+                        break;
+                case AUTH_CONNECTION:
+                        if ((pfd[i].revents & (POLLIN|POLLERR)) != 0 &&
+                            handle_conn_read(socknum) != 0) {
+                                close_socket(&sockets[socknum]);
+                                break;
+                        }
+                        if ((pfd[i].revents & (POLLOUT|POLLHUP)) != 0 &&
+                            handle_conn_write(socknum) != 0)
+                                close_socket(&sockets[socknum]);
+                        break;
+                default:
+                        break;
+                }
+        }
+}
+
+static int
+prepare_poll(struct pollfd **pfdp, size_t *npfdp, int *timeoutp)
+{
+        struct pollfd *pfd = *pfdp;
+        size_t i, j, npfd = 0;
         time_t deadline;
 
+        /* Count active sockets */
         for (i = 0; i < sockets_alloc; i++) {
                 switch (sockets[i].type) {
                 case AUTH_SOCKET:
                 case AUTH_CONNECTION:
-                        n = MAXIMUM(n, sockets[i].fd);
+                        npfd++;
                         break;
                 case AUTH_UNUSED:
                         break;
@@ -1026,28 +922,23 @@ prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, u_int *nallocp,
                         break;
                 }
         }
+        if (npfd != *npfdp &&
+            (pfd = recallocarray(pfd, *npfdp, npfd, sizeof(*pfd))) == NULL)
+                fatal("%s: recallocarray failed", __func__);
+        *pfdp = pfd;
+        *npfdp = npfd;
 
-        sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
-        if (*fdrp == NULL || sz > *nallocp) {
-                free(*fdrp);
-                free(*fdwp);
-                *fdrp = xmalloc(sz);
-                *fdwp = xmalloc(sz);
-                *nallocp = sz;
-        }
-        if (n < *fdl)
-                debug("XXX shrink: %d < %d", n, *fdl);
-        *fdl = n;
-        memset(*fdrp, 0, sz);
-        memset(*fdwp, 0, sz);
-
-        for (i = 0; i < sockets_alloc; i++) {
+        for (i = j = 0; i < sockets_alloc; i++) {
                 switch (sockets[i].type) {
                 case AUTH_SOCKET:
                 case AUTH_CONNECTION:
-                        FD_SET(sockets[i].fd, *fdrp);
+                        pfd[j].fd = sockets[i].fd;
+                        pfd[j].revents = 0;
+                        /* XXX backoff when input buffer full */
+                        pfd[j].events = POLLIN;
                         if (sshbuf_len(sockets[i].output) > 0)
-                                FD_SET(sockets[i].fd, *fdwp);
+                                pfd[j].events |= POLLOUT;
+                        j++;
                         break;
                 default:
                         break;
@@ -1058,99 +949,17 @@ prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, u_int *nallocp,
                 deadline = (deadline == 0) ? parent_alive_interval :
                     MINIMUM(deadline, parent_alive_interval);
         if (deadline == 0) {
-                *tvpp = NULL;
+                *timeoutp = -1; /* INFTIM */
         } else {
-                tv.tv_sec = deadline;
-                tv.tv_usec = 0;
-                *tvpp = &tv;
+                if (deadline > INT_MAX / 1000)
+                        *timeoutp = INT_MAX / 1000;
+                else
+                        *timeoutp = deadline * 1000;
         }
         return (1);
 }
 
 static void
-after_select(fd_set *readset, fd_set *writeset)
-{
-        struct sockaddr_un sunaddr;
-        socklen_t slen;
-        char buf[1024];
-        int len, sock, r;
-        u_int i, orig_alloc;
-        uid_t euid;
-        gid_t egid;
-
-        for (i = 0, orig_alloc = sockets_alloc; i < orig_alloc; i++)
-                switch (sockets[i].type) {
-                case AUTH_UNUSED:
-                        break;
-                case AUTH_SOCKET:
-                        if (FD_ISSET(sockets[i].fd, readset)) {
-                                slen = sizeof(sunaddr);
-                                sock = accept(sockets[i].fd,
-                                    (struct sockaddr *)&sunaddr, &slen);
-                                if (sock < 0) {
-                                        error("accept from AUTH_SOCKET: %s",
-                                            strerror(errno));
-                                        break;
-                                }
-                                if (getpeereid(sock, &euid, &egid) < 0) {
-                                        error("getpeereid %d failed: %s",
-                                            sock, strerror(errno));
-                                        close(sock);
-                                        break;
-                                }
-                                if ((euid != 0) && (getuid() != euid)) {
-                                        error("uid mismatch: "
-                                            "peer euid %u != uid %u",
-                                            (u_int) euid, (u_int) getuid());
-                                        close(sock);
-                                        break;
-                                }
-                                new_socket(AUTH_CONNECTION, sock);
-                        }
-                        break;
-                case AUTH_CONNECTION:
-                        if (sshbuf_len(sockets[i].output) > 0 &&
-                            FD_ISSET(sockets[i].fd, writeset)) {
-                                len = write(sockets[i].fd,
-                                    sshbuf_ptr(sockets[i].output),
-                                    sshbuf_len(sockets[i].output));
-                                if (len == -1 && (errno == EAGAIN ||
-                                    errno == EWOULDBLOCK ||
-                                    errno == EINTR))
-                                        continue;
-                                if (len <= 0) {
-                                        close_socket(&sockets[i]);
-                                        break;
-                                }
-                                if ((r = sshbuf_consume(sockets[i].output,
-                                    len)) != 0)
-                                        fatal("%s: buffer error: %s",
-                                            __func__, ssh_err(r));
-                        }
-                        if (FD_ISSET(sockets[i].fd, readset)) {
-                                len = read(sockets[i].fd, buf, sizeof(buf));
-                                if (len == -1 && (errno == EAGAIN ||
-                                    errno == EWOULDBLOCK ||
-                                    errno == EINTR))
-                                        continue;
-                                if (len <= 0) {
-                                        close_socket(&sockets[i]);
-                                        break;
-                                }
-                                if ((r = sshbuf_put(sockets[i].input,
-                                    buf, len)) != 0)
-                                        fatal("%s: buffer error: %s",
-                                            __func__, ssh_err(r));
-                                explicit_bzero(buf, sizeof(buf));
-                                process_message(&sockets[i]);
-                        }
-                        break;
-                default:
-                        fatal("Unknown type %d", sockets[i].type);
-                }
-}
-
-static void
 cleanup_socket(void)
 {
         if (cleanup_pid != 0 && getpid() != cleanup_pid)
@@ -1209,9 +1018,7 @@ main(int ac, char **av)
 {
         int c_flag = 0, d_flag = 0, D_flag = 0, k_flag = 0, s_flag = 0;
         int sock, fd, ch, result, saved_errno;
-        u_int nalloc;
         char *shell, *format, *pidstr, *agentsocket = NULL;
-        fd_set *readsetp = NULL, *writesetp = NULL;
 #ifdef HAVE_SETRLIMIT
         struct rlimit rlim;
 #endif
@@ -1219,9 +1026,11 @@ main(int ac, char **av)
         extern char *optarg;
         pid_t pid;
         char pidstrbuf[1 + 3 * sizeof pid];
-        struct timeval *tvp = NULL;
         size_t len;
         mode_t prev_mask;
+        int timeout = -1; /* INFTIM */
+        struct pollfd *pfd = NULL;
+        size_t npfd = 0;
 
         ssh_malloc_init();      /* must be called before any mallocs */
         /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
@@ -1442,15 +1251,14 @@ skip:
         signal(SIGINT, (d_flag | D_flag) ? cleanup_handler : SIG_IGN);
         signal(SIGHUP, cleanup_handler);
         signal(SIGTERM, cleanup_handler);
-        nalloc = 0;
 
         if (pledge("stdio rpath cpath unix id proc exec", NULL) == -1)
                 fatal("%s: pledge: %s", __progname, strerror(errno));
         platform_pledge_agent();
 
         while (1) {
-                prepare_select(&readsetp, &writesetp, &max_fd, &nalloc, &tvp);
-                result = select(max_fd + 1, readsetp, writesetp, NULL, tvp);
+                prepare_poll(&pfd, &npfd, &timeout);
+                result = poll(pfd, npfd, timeout);
                 saved_errno = errno;
                 if (parent_alive_interval != 0)
                         check_parent_exists();
@@ -1458,9 +1266,9 @@ skip:
                 if (result < 0) {
                         if (saved_errno == EINTR)
                                 continue;
-                        fatal("select: %s", strerror(saved_errno));
+                        fatal("poll: %s", strerror(saved_errno));
                 } else if (result > 0)
-                        after_select(readsetp, writesetp);
+                        after_poll(pfd, npfd);
         }
         /* NOTREACHED */
 }