From 786d5994da79151180cb14a6cf157ebbba61c0cc Mon Sep 17 00:00:00 2001 From: "djm@openbsd.org" Date: Wed, 30 Nov 2016 03:07:37 +0000 Subject: [PATCH] upstream commit add a whitelist of paths from which ssh-agent will load (via ssh-pkcs11-helper) a PKCS#11 module; ok markus@ Upstream-ID: fe79769469d9cd6d26fe0dc15751b83ef2a06e8f --- ssh-agent.1 | 17 +++++++++++++++-- ssh-agent.c | 43 +++++++++++++++++++++++++++++++++++-------- 2 files changed, 50 insertions(+), 10 deletions(-) diff --git a/ssh-agent.1 b/ssh-agent.1 index c4b50bbdf..372adbe7c 100644 --- a/ssh-agent.1 +++ b/ssh-agent.1 @@ -1,4 +1,4 @@ -.\" $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 .\" Copyright (c) 1995 Tatu Ylonen , Espoo, Finland @@ -34,7 +34,7 @@ .\" (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 @@ -47,6 +47,7 @@ .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 @@ -121,6 +122,18 @@ The default is 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 . diff --git a/ssh-agent.c b/ssh-agent.c index fd5f2b35d..395213553 100644 --- a/ssh-agent.c +++ b/ssh-agent.c @@ -1,4 +1,4 @@ -/* $OpenBSD: ssh-agent.c,v 1.214 2016/09/12 01:22:38 deraadt Exp $ */ +/* $OpenBSD: ssh-agent.c,v 1.215 2016/11/30 03:07:37 djm Exp $ */ /* * Author: Tatu Ylonen * Copyright (c) 1995 Tatu Ylonen , Espoo, Finland @@ -82,11 +82,16 @@ #include "misc.h" #include "digest.h" #include "ssherr.h" +#include "match.h" #ifdef ENABLE_PKCS11 #include "ssh-pkcs11.h" #endif +#ifndef DEFAULT_PKCS11_WHITELIST +# define DEFAULT_PKCS11_WHITELIST "/usr/lib/*,/usr/local/lib/*" +#endif + typedef enum { AUTH_UNUSED, AUTH_SOCKET, @@ -134,6 +139,9 @@ pid_t cleanup_pid = 0; 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 @@ -737,7 +745,7 @@ no_identities(SocketEntry *e, u_int type) 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; @@ -769,10 +777,21 @@ process_add_smartcard_key(SocketEntry *e) 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; @@ -780,8 +799,8 @@ process_add_smartcard_key(SocketEntry *e) 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); @@ -1172,7 +1191,7 @@ 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); } @@ -1213,7 +1232,7 @@ main(int ac, char **av) __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); @@ -1228,6 +1247,11 @@ main(int ac, char **av) 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(); @@ -1262,6 +1286,9 @@ main(int ac, char **av) 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 && @@ -1409,7 +1436,7 @@ skip: 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();