openssh/openssh-7.2p2-restrict_pkcs11-modules.patch

# HG changeset patch
# Parent  22de9aeddbde2b36da9c23475cfa5dcd42e95287
whitelist paths for loading of PKCS#11 modules in ssh-agent

CVE-2016-10009
bsc#1016366

upstream commit 786d5994da79151180cb14a6cf157ebbba61c0cc

diff --git a/openssh-7.2p2/ssh-agent.1 b/openssh-7.2p2/ssh-agent.1
--- a/openssh-7.2p2/ssh-agent.1
+++ b/openssh-7.2p2/ssh-agent.1
@@ -1,9 +1,9 @@
-.\" $OpenBSD: ssh-agent.1,v 1.62 2015/11/15 23:54:15 jmc Exp $
+.\" $OpenBSD: ssh-agent.1,v 1.63 2016/11/30 03:07:37 djm Exp $
 .\"
 .\" Author: Tatu Ylonen <ylo@cs.hut.fi>
 .\" Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
 .\"                    All rights reserved
 .\"
 .\" 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
@@ -29,29 +29,30 @@
 .\" 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.
 .\"
-.Dd $Mdocdate: November 15 2015 $
+.Dd $Mdocdate: November 30 2016 $
 .Dt SSH-AGENT 1
 .Os
 .Sh NAME
 .Nm ssh-agent
 .Nd authentication agent
 .Sh SYNOPSIS
 .Nm ssh-agent
 .Op Fl c | s
 .Op Fl \&Dd
 .Op Fl a Ar bind_address
 .Op Fl E Ar fingerprint_hash
 .Op Fl t Ar life
+.Op Fl P Ar pkcs11_whitelist
 .Op Ar command Op Ar arg ...
 .Nm ssh-agent
 .Op Fl c | s
 .Fl k
 .Sh DESCRIPTION
 .Nm
 is a program to hold private keys used for public key authentication
 (RSA, DSA, ECDSA, Ed25519).
@@ -116,16 +117,28 @@ Valid options are:
 and
 .Dq sha256 .
 The default is
 .Dq sha256 .
 .It Fl k
 Kill the current agent (given by the
 .Ev SSH_AGENT_PID
 environment variable).
+.It Fl P
+Specify a pattern-list of acceptable paths for PKCS#11 shared libraries
+that may be added using the
+.Fl s
+option to
+.Xr ssh-add 1 .
+The default is to allow loading PKCS#11 libraries from
+.Dq /usr/lib/*,/usr/local/lib/* .
+PKCS#11 libraries that do not match the whitelist will be refused.
+See PATTERNS in
+.Xr ssh_config 5
+for a description of pattern-list syntax.
 .It Fl s
 Generate Bourne shell commands on
 .Dv stdout .
 This is the default if
 .Ev SHELL
 does not look like it's a csh style of shell.
 .It Fl t Ar life
 Set a default value for the maximum lifetime of identities added to the agent.
diff --git a/openssh-7.2p2/ssh-agent.c b/openssh-7.2p2/ssh-agent.c
--- a/openssh-7.2p2/ssh-agent.c
+++ b/openssh-7.2p2/ssh-agent.c
@@ -78,25 +78,30 @@
 #include "sshbuf.h"
 #include "sshkey.h"
 #include "authfd.h"
 #include "compat.h"
 #include "log.h"
 #include "misc.h"
 #include "digest.h"
 #include "ssherr.h"
+#include "match.h"
 
 #ifdef ENABLE_PKCS11
 #include "ssh-pkcs11.h"
 #endif
 
 #if defined(HAVE_SYS_PRCTL_H)
 #include <sys/prctl.h>	/* For prctl() and PR_SET_DUMPABLE */
 #endif
 
+#ifndef DEFAULT_PKCS11_WHITELIST
+# define DEFAULT_PKCS11_WHITELIST "/usr/lib/*,/usr/local/lib/*"
+#endif
+
 typedef enum {
 	AUTH_UNUSED,
 	AUTH_SOCKET,
 	AUTH_CONNECTION
 } sock_type;
 
 typedef struct {
 	int fd;
@@ -134,16 +139,19 @@ time_t parent_alive_interval = 0;
 
 /* pid of process for which cleanup_socket is applicable */
 pid_t cleanup_pid = 0;
 
 /* pathname and directory for AUTH_SOCKET */
 char socket_name[PATH_MAX];
 char socket_dir[PATH_MAX];
 
+/* PKCS#11 path whitelist */
+static char *pkcs11_whitelist;
+
 /* locking */
 #define LOCK_SIZE	32
 #define LOCK_SALT_SIZE	16
 #define LOCK_ROUNDS	1
 int locked = 0;
 char lock_passwd[LOCK_SIZE];
 char lock_salt[LOCK_SALT_SIZE];
 
@@ -736,17 +744,17 @@ no_identities(SocketEntry *e, u_int type
 		fatal("%s: buffer error: %s", __func__, ssh_err(r));
 	sshbuf_free(msg);
 }
 
 #ifdef ENABLE_PKCS11
 static void
 process_add_smartcard_key(SocketEntry *e)
 {
-	char *provider = NULL, *pin;
+	char *provider = NULL, *pin, canonical_provider[PATH_MAX];
 	int r, i, version, 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;
 
@@ -768,29 +776,40 @@ process_add_smartcard_key(SocketEntry *e
 			confirm = 1;
 			break;
 		default:
 			error("process_add_smartcard_key: "
 			    "Unknown constraint type %d", type);
 			goto send;
 		}
 	}
+	if (realpath(provider, canonical_provider) == NULL) {
+		verbose("failed PKCS#11 add of \"%.100s\": realpath: %s",
+		    provider, strerror(errno));
+		goto send;
+	}
+	if (match_pattern_list(canonical_provider, pkcs11_whitelist, 0) != 1) {
+		verbose("refusing PKCS#11 add of \"%.100s\": "
+		    "provider not whitelisted", canonical_provider);
+		goto send;
+	}
+	debug("%s: add %.100s", __func__, canonical_provider);
 	if (lifetime && !death)
 		death = monotime() + lifetime;
 
-	count = pkcs11_add_provider(provider, pin, &keys);
+	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) {
 			id = xcalloc(1, sizeof(Identity));
 			id->key = k;
-			id->provider = xstrdup(provider);
-			id->comment = xstrdup(provider); /* XXX */
+			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++;
 			success = 1;
 		} else {
 			sshkey_free(k);
 		}
@@ -1171,17 +1190,17 @@ check_parent_exists(void)
 	}
 }
 
 static void
 usage(void)
 {
 	fprintf(stderr,
 	    "usage: ssh-agent [-c | -s] [-Dd] [-a bind_address] [-E fingerprint_hash]\n"
-	    "                 [-t life] [command [arg ...]]\n"
+	    "                 [-P pkcs11_whitelist] [-t life] [command [arg ...]]\n"
 	    "       ssh-agent [-c | -s] -k\n");
 	exit(1);
 }
 
 int
 main(int ac, char **av)
 {
 	int c_flag = 0, d_flag = 0, D_flag = 0, k_flag = 0, s_flag = 0;
@@ -1215,31 +1234,36 @@ main(int ac, char **av)
 
 #ifdef WITH_OPENSSL
 	OpenSSL_add_all_algorithms();
 #endif
 
 	__progname = ssh_get_progname(av[0]);
 	seed_rng();
 
-	while ((ch = getopt(ac, av, "cDdksE:a:t:")) != -1) {
+	while ((ch = getopt(ac, av, "cDdksE:a:P:t:")) != -1) {
 		switch (ch) {
 		case 'E':
 			fingerprint_hash = ssh_digest_alg_by_name(optarg);
 			if (fingerprint_hash == -1)
 				fatal("Invalid hash algorithm \"%s\"", optarg);
 			break;
 		case 'c':
 			if (s_flag)
 				usage();
 			c_flag++;
 			break;
 		case 'k':
 			k_flag++;
 			break;
+		case 'P':
+			if (pkcs11_whitelist != NULL)
+				fatal("-P option already specified");
+			pkcs11_whitelist = xstrdup(optarg);
+			break;
 		case 's':
 			if (c_flag)
 				usage();
 			s_flag++;
 			break;
 		case 'd':
 			if (d_flag || D_flag)
 				usage();
@@ -1264,16 +1288,19 @@ main(int ac, char **av)
 		}
 	}
 	ac -= optind;
 	av += optind;
 
 	if (ac > 0 && (c_flag || k_flag || s_flag || d_flag || D_flag))
 		usage();
 
+	if (pkcs11_whitelist == NULL)
+		pkcs11_whitelist = xstrdup(DEFAULT_PKCS11_WHITELIST);
+
 	if (ac == 0 && !c_flag && !s_flag) {
 		shell = getenv("SHELL");
 		if (shell != NULL && (len = strlen(shell)) > 2 &&
 		    strncmp(shell + len - 3, "csh", 3) == 0)
 			c_flag = 1;
 	}
 	if (k_flag) {
 		const char *errstr = NULL;
@@ -1411,17 +1438,17 @@ skip:
 		parent_alive_interval = 10;
 	idtab_init();
 	signal(SIGPIPE, SIG_IGN);
 	signal(SIGINT, (d_flag | D_flag) ? cleanup_handler : SIG_IGN);
 	signal(SIGHUP, cleanup_handler);
 	signal(SIGTERM, cleanup_handler);
 	nalloc = 0;
 
-	if (pledge("stdio cpath unix id proc exec", NULL) == -1)
+	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);
 		saved_errno = errno;
 		if (parent_alive_interval != 0)