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openssh: fix CVE-2023-38408

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The PKCS#11 feature in ssh-agent in OpenSSH before 9.3p2 has an
insufficiently trustworthy search path, leading to remote code
execution if an agent is forwarded to an attacker-controlled system.
(Code in /usr/lib is not necessarily safe for loading into ssh-agent.)
NOTE: this issue exists because of an incomplete fix for CVE-2016-10009.

References:
https://nvd.nist.gov/vuln/detail/CVE-2023-38408

Upstream patches:
892506b136
1f2731f5d7
29ef8a0486
099cdf59ce

(From OE-Core rev: 3c01159ab6a843fc922cf779b022c965d4ecd453)

Signed-off-by: Archana Polampalli <archana.polampalli@windriver.com>
Signed-off-by: Steve Sakoman <steve@sakoman.com>
This commit is contained in:
Archana Polampalli
2023-07-28 12:28:40 +00:00
committed by Steve Sakoman
parent d198c0d738
commit e01d123ba1
5 changed files with 912 additions and 0 deletions
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585
meta/recipes-connectivity/openssh/openssh/CVE-2023-38408-0001.patch Normal file
View File

@@ -0,0 +1,585 @@
From 099cdf59ce1e72f55d421c8445bf6321b3004755 Mon Sep 17 00:00:00 2001
From: "djm@openbsd.org" <djm@openbsd.org>
Date: Wed, 19 Jul 2023 14:03:45 +0000
Subject: [PATCH 1/4] upstream: Separate ssh-pkcs11-helpers for each p11 module
Make ssh-pkcs11-client start an independent helper for each provider,
providing better isolation between modules and reliability if a single
module misbehaves.
This also implements reference counting of PKCS#11-hosted keys,
allowing ssh-pkcs11-helper subprocesses to be automatically reaped
when no remaining keys reference them. This fixes some bugs we have
that make PKCS11 keys unusable after they have been deleted, e.g.
https://bugzilla.mindrot.org/show_bug.cgi?id=3125
ok markus@
OpenBSD-Commit-ID: 0ce188b14fe271ab0568f4500070d96c5657244e
Upstream-Status: Backport [https://github.com/openssh/openssh-portable/commit/099cdf59ce1e72f55d421c8445bf6321b3004755]
CVE: CVE-2023-38408
Signed-off-by: Archana Polampalli <archana.polampalli@windriver.com>
---
ssh-pkcs11-client.c | 378 +++++++++++++++++++++++++++++++++-----------
1 file changed, 285 insertions(+), 93 deletions(-)
diff --git a/ssh-pkcs11-client.c b/ssh-pkcs11-client.c
index cfd833d..7db6c6c 100644
--- a/ssh-pkcs11-client.c
+++ b/ssh-pkcs11-client.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh-pkcs11-client.c,v 1.17 2020/10/18 11:32:02 djm Exp $ */
+/* $OpenBSD: ssh-pkcs11-client.c,v 1.18 2023/07/19 14:03:45 djm Exp $ */
/*
* Copyright (c) 2010 Markus Friedl. All rights reserved.
* Copyright (c) 2014 Pedro Martelletto. All rights reserved.
@@ -30,12 +30,11 @@
#include <string.h>
#include <unistd.h>
#include <errno.h>
+#include <limits.h>
#include <openssl/ecdsa.h>
#include <openssl/rsa.h>
-#include "openbsd-compat/openssl-compat.h"
-
#include "pathnames.h"
#include "xmalloc.h"
#include "sshbuf.h"
@@ -47,18 +46,140 @@
#include "ssh-pkcs11.h"
#include "ssherr.h"
+#include "openbsd-compat/openssl-compat.h"
+
/* borrows code from sftp-server and ssh-agent */
-static int fd = -1;
-static pid_t pid = -1;
+/*
+ * Maintain a list of ssh-pkcs11-helper subprocesses. These may be looked up
+ * by provider path or their unique EC/RSA METHOD pointers.
+ */
+struct helper {
+ char *path;
+ pid_t pid;
+ int fd;
+ RSA_METHOD *rsa_meth;
+ EC_KEY_METHOD *ec_meth;
+ int (*rsa_finish)(RSA *rsa);
+ void (*ec_finish)(EC_KEY *key);
+ size_t nrsa, nec; /* number of active keys of each type */
+};
+static struct helper **helpers;
+static size_t nhelpers;
+
+static struct helper *
+helper_by_provider(const char *path)
+{
+ size_t i;
+
+ for (i = 0; i < nhelpers; i++) {
+ if (helpers[i] == NULL || helpers[i]->path == NULL ||
+ helpers[i]->fd == -1)
+ continue;
+ if (strcmp(helpers[i]->path, path) == 0)
+ return helpers[i];
+ }
+ return NULL;
+}
+
+static struct helper *
+helper_by_rsa(const RSA *rsa)
+{
+ size_t i;
+ const RSA_METHOD *meth;
+
+ if ((meth = RSA_get_method(rsa)) == NULL)
+ return NULL;
+ for (i = 0; i < nhelpers; i++) {
+ if (helpers[i] != NULL && helpers[i]->rsa_meth == meth)
+ return helpers[i];
+ }
+ return NULL;
+
+}
+
+static struct helper *
+helper_by_ec(const EC_KEY *ec)
+{
+ size_t i;
+ const EC_KEY_METHOD *meth;
+
+ if ((meth = EC_KEY_get_method(ec)) == NULL)
+ return NULL;
+ for (i = 0; i < nhelpers; i++) {
+ if (helpers[i] != NULL && helpers[i]->ec_meth == meth)
+ return helpers[i];
+ }
+ return NULL;
+
+}
+
+static void
+helper_free(struct helper *helper)
+{
+ size_t i;
+ int found = 0;
+
+ if (helper == NULL)
+ return;
+ if (helper->path == NULL || helper->ec_meth == NULL ||
+ helper->rsa_meth == NULL)
+ fatal_f("inconsistent helper");
+ debug3_f("free helper for provider %s", helper->path);
+ for (i = 0; i < nhelpers; i++) {
+ if (helpers[i] == helper) {
+ if (found)
+ fatal_f("helper recorded more than once");
+ found = 1;
+ }
+ else if (found)
+ helpers[i - 1] = helpers[i];
+ }
+ if (found) {
+ helpers = xrecallocarray(helpers, nhelpers,
+ nhelpers - 1, sizeof(*helpers));
+ nhelpers--;
+ }
+ free(helper->path);
+ EC_KEY_METHOD_free(helper->ec_meth);
+ RSA_meth_free(helper->rsa_meth);
+ free(helper);
+}
+
+static void
+helper_terminate(struct helper *helper)
+{
+ if (helper == NULL) {
+ return;
+ } else if (helper->fd == -1) {
+ debug3_f("already terminated");
+ } else {
+ debug3_f("terminating helper for %s; "
+ "remaining %zu RSA %zu ECDSA",
+ helper->path, helper->nrsa, helper->nec);
+ close(helper->fd);
+ /* XXX waitpid() */
+ helper->fd = -1;
+ helper->pid = -1;
+ }
+ /*
+ * Don't delete the helper entry until there are no remaining keys
+ * that reference it. Otherwise, any signing operation would call
+ * a free'd METHOD pointer and that would be bad.
+ */
+ if (helper->nrsa == 0 && helper->nec == 0)
+ helper_free(helper);
+}
static void
-send_msg(struct sshbuf *m)
+send_msg(int fd, struct sshbuf *m)
{
u_char buf[4];
size_t mlen = sshbuf_len(m);
int r;
+ if (fd == -1)
+ return;
POKE_U32(buf, mlen);
if (atomicio(vwrite, fd, buf, 4) != 4 ||
atomicio(vwrite, fd, sshbuf_mutable_ptr(m),
@@ -69,12 +190,15 @@ send_msg(struct sshbuf *m)
}
static int
-recv_msg(struct sshbuf *m)
+recv_msg(int fd, struct sshbuf *m)
{
u_int l, len;
u_char c, buf[1024];
int r;
+ sshbuf_reset(m);
+ if (fd == -1)
+ return 0; /* XXX */
if ((len = atomicio(read, fd, buf, 4)) != 4) {
error("read from helper failed: %u", len);
return (0); /* XXX */
@@ -83,7 +207,6 @@ recv_msg(struct sshbuf *m)
if (len > 256 * 1024)
fatal("response too long: %u", len);
/* read len bytes into m */
- sshbuf_reset(m);
while (len > 0) {
l = len;
if (l > sizeof(buf))
@@ -104,14 +227,17 @@ recv_msg(struct sshbuf *m)
int
pkcs11_init(int interactive)
{
- return (0);
+ return 0;
}
void
pkcs11_terminate(void)
{
- if (fd >= 0)
- close(fd);
+ size_t i;
+
+ debug3_f("terminating %zu helpers", nhelpers);
+ for (i = 0; i < nhelpers; i++)
+ helper_terminate(helpers[i]);
}
static int
@@ -122,7 +248,11 @@ rsa_encrypt(int flen, const u_char *from, u_char *to, RSA *rsa, int padding)
u_char *blob = NULL, *signature = NULL;
size_t blen, slen = 0;
int r, ret = -1;
+ struct helper *helper;
+ if ((helper = helper_by_rsa(rsa)) == NULL || helper->fd == -1)
+ fatal_f("no helper for PKCS11 key");
+ debug3_f("signing with PKCS11 provider %s", helper->path);
if (padding != RSA_PKCS1_PADDING)
goto fail;
key = sshkey_new(KEY_UNSPEC);
@@ -144,10 +274,10 @@ rsa_encrypt(int flen, const u_char *from, u_char *to, RSA *rsa, int padding)
(r = sshbuf_put_string(msg, from, flen)) != 0 ||
(r = sshbuf_put_u32(msg, 0)) != 0)
fatal_fr(r, "compose");
- send_msg(msg);
+ send_msg(helper->fd, msg);
sshbuf_reset(msg);
- if (recv_msg(msg) == SSH2_AGENT_SIGN_RESPONSE) {
+ if (recv_msg(helper->fd, msg) == SSH2_AGENT_SIGN_RESPONSE) {
if ((r = sshbuf_get_string(msg, &signature, &slen)) != 0)
fatal_fr(r, "parse");
if (slen <= (size_t)RSA_size(rsa)) {
@@ -163,7 +293,26 @@ rsa_encrypt(int flen, const u_char *from, u_char *to, RSA *rsa, int padding)
return (ret);
}
-#if defined(OPENSSL_HAS_ECC) && defined(HAVE_EC_KEY_METHOD_NEW)
+static int
+rsa_finish(RSA *rsa)
+{
+ struct helper *helper;
+
+ if ((helper = helper_by_rsa(rsa)) == NULL)
+ fatal_f("no helper for PKCS11 key");
+ debug3_f("free PKCS11 RSA key for provider %s", helper->path);
+ if (helper->rsa_finish != NULL)
+ helper->rsa_finish(rsa);
+ if (helper->nrsa == 0)
+ fatal_f("RSA refcount error");
+ helper->nrsa--;
+ debug3_f("provider %s remaining keys: %zu RSA %zu ECDSA",
+ helper->path, helper->nrsa, helper->nec);
+ if (helper->nrsa == 0 && helper->nec == 0)
+ helper_terminate(helper);
+ return 1;
+}
+
static ECDSA_SIG *
ecdsa_do_sign(const unsigned char *dgst, int dgst_len, const BIGNUM *inv,
const BIGNUM *rp, EC_KEY *ec)
@@ -175,7 +324,11 @@ ecdsa_do_sign(const unsigned char *dgst, int dgst_len, const BIGNUM *inv,
u_char *blob = NULL, *signature = NULL;
size_t blen, slen = 0;
int r, nid;
+ struct helper *helper;
+ if ((helper = helper_by_ec(ec)) == NULL || helper->fd == -1)
+ fatal_f("no helper for PKCS11 key");
+ debug3_f("signing with PKCS11 provider %s", helper->path);
nid = sshkey_ecdsa_key_to_nid(ec);
if (nid < 0) {
error_f("couldn't get curve nid");
@@ -203,10 +356,10 @@ ecdsa_do_sign(const unsigned char *dgst, int dgst_len, const BIGNUM *inv,
(r = sshbuf_put_string(msg, dgst, dgst_len)) != 0 ||
(r = sshbuf_put_u32(msg, 0)) != 0)
fatal_fr(r, "compose");
- send_msg(msg);
+ send_msg(helper->fd, msg);
sshbuf_reset(msg);
- if (recv_msg(msg) == SSH2_AGENT_SIGN_RESPONSE) {
+ if (recv_msg(helper->fd, msg) == SSH2_AGENT_SIGN_RESPONSE) {
if ((r = sshbuf_get_string(msg, &signature, &slen)) != 0)
fatal_fr(r, "parse");
cp = signature;
@@ -220,75 +373,110 @@ ecdsa_do_sign(const unsigned char *dgst, int dgst_len, const BIGNUM *inv,
sshbuf_free(msg);
return (ret);
}
-#endif /* OPENSSL_HAS_ECC && HAVE_EC_KEY_METHOD_NEW */
-static RSA_METHOD *helper_rsa;
-#if defined(OPENSSL_HAS_ECC) && defined(HAVE_EC_KEY_METHOD_NEW)
-static EC_KEY_METHOD *helper_ecdsa;
-#endif /* OPENSSL_HAS_ECC && HAVE_EC_KEY_METHOD_NEW */
+static void
+ecdsa_do_finish(EC_KEY *ec)
+{
+ struct helper *helper;
+
+ if ((helper = helper_by_ec(ec)) == NULL)
+ fatal_f("no helper for PKCS11 key");
+ debug3_f("free PKCS11 ECDSA key for provider %s", helper->path);
+ if (helper->ec_finish != NULL)
+ helper->ec_finish(ec);
+ if (helper->nec == 0)
+ fatal_f("ECDSA refcount error");
+ helper->nec--;
+ debug3_f("provider %s remaining keys: %zu RSA %zu ECDSA",
+ helper->path, helper->nrsa, helper->nec);
+ if (helper->nrsa == 0 && helper->nec == 0)
+ helper_terminate(helper);
+}
/* redirect private key crypto operations to the ssh-pkcs11-helper */
static void
-wrap_key(struct sshkey *k)
+wrap_key(struct helper *helper, struct sshkey *k)
{
- if (k->type == KEY_RSA)
- RSA_set_method(k->rsa, helper_rsa);
-#if defined(OPENSSL_HAS_ECC) && defined(HAVE_EC_KEY_METHOD_NEW)
- else if (k->type == KEY_ECDSA)
- EC_KEY_set_method(k->ecdsa, helper_ecdsa);
-#endif /* OPENSSL_HAS_ECC && HAVE_EC_KEY_METHOD_NEW */
- else
+ debug3_f("wrap %s for provider %s", sshkey_type(k), helper->path);
+ if (k->type == KEY_RSA) {
+ RSA_set_method(k->rsa, helper->rsa_meth);
+ if (helper->nrsa++ >= INT_MAX)
+ fatal_f("RSA refcount error");
+ } else if (k->type == KEY_ECDSA) {
+ EC_KEY_set_method(k->ecdsa, helper->ec_meth);
+ if (helper->nec++ >= INT_MAX)
+ fatal_f("EC refcount error");
+ } else
fatal_f("unknown key type");
+ k->flags |= SSHKEY_FLAG_EXT;
+ debug3_f("provider %s remaining keys: %zu RSA %zu ECDSA",
+ helper->path, helper->nrsa, helper->nec);
}
static int
-pkcs11_start_helper_methods(void)
+pkcs11_start_helper_methods(struct helper *helper)
{
- if (helper_rsa != NULL)
- return (0);
-
-#if defined(OPENSSL_HAS_ECC) && defined(HAVE_EC_KEY_METHOD_NEW)
- int (*orig_sign)(int, const unsigned char *, int, unsigned char *,
+ int (*ec_init)(EC_KEY *key);
+ int (*ec_copy)(EC_KEY *dest, const EC_KEY *src);
+ int (*ec_set_group)(EC_KEY *key, const EC_GROUP *grp);
+ int (*ec_set_private)(EC_KEY *key, const BIGNUM *priv_key);
+ int (*ec_set_public)(EC_KEY *key, const EC_POINT *pub_key);
+ int (*ec_sign)(int, const unsigned char *, int, unsigned char *,
unsigned int *, const BIGNUM *, const BIGNUM *, EC_KEY *) = NULL;
- if (helper_ecdsa != NULL)
- return (0);
- helper_ecdsa = EC_KEY_METHOD_new(EC_KEY_OpenSSL());
- if (helper_ecdsa == NULL)
- return (-1);
- EC_KEY_METHOD_get_sign(helper_ecdsa, &orig_sign, NULL, NULL);
- EC_KEY_METHOD_set_sign(helper_ecdsa, orig_sign, NULL, ecdsa_do_sign);
-#endif /* OPENSSL_HAS_ECC && HAVE_EC_KEY_METHOD_NEW */
-
- if ((helper_rsa = RSA_meth_dup(RSA_get_default_method())) == NULL)
+ RSA_METHOD *rsa_meth;
+ EC_KEY_METHOD *ec_meth;
+
+ if ((ec_meth = EC_KEY_METHOD_new(EC_KEY_OpenSSL())) == NULL)
+ return -1;
+ EC_KEY_METHOD_get_sign(ec_meth, &ec_sign, NULL, NULL);
+ EC_KEY_METHOD_set_sign(ec_meth, ec_sign, NULL, ecdsa_do_sign);
+ EC_KEY_METHOD_get_init(ec_meth, &ec_init, &helper->ec_finish,
+ &ec_copy, &ec_set_group, &ec_set_private, &ec_set_public);
+ EC_KEY_METHOD_set_init(ec_meth, ec_init, ecdsa_do_finish,
+ ec_copy, ec_set_group, ec_set_private, ec_set_public);
+
+ if ((rsa_meth = RSA_meth_dup(RSA_get_default_method())) == NULL)
fatal_f("RSA_meth_dup failed");
- if (!RSA_meth_set1_name(helper_rsa, "ssh-pkcs11-helper") ||
- !RSA_meth_set_priv_enc(helper_rsa, rsa_encrypt))
+ helper->rsa_finish = RSA_meth_get_finish(rsa_meth);
+ if (!RSA_meth_set1_name(rsa_meth, "ssh-pkcs11-helper") ||
+ !RSA_meth_set_priv_enc(rsa_meth, rsa_encrypt) ||
+ !RSA_meth_set_finish(rsa_meth, rsa_finish))
fatal_f("failed to prepare method");
- return (0);
+ helper->ec_meth = ec_meth;
+ helper->rsa_meth = rsa_meth;
+ return 0;
}
-static int
-pkcs11_start_helper(void)
+static struct helper *
+pkcs11_start_helper(const char *path)
{
int pair[2];
- char *helper, *verbosity = NULL;
-
- if (log_level_get() >= SYSLOG_LEVEL_DEBUG1)
- verbosity = "-vvv";
-
- if (pkcs11_start_helper_methods() == -1) {
- error("pkcs11_start_helper_methods failed");
- return (-1);
- }
+ char *prog, *verbosity = NULL;
+ struct helper *helper;
+ pid_t pid;
+ if (nhelpers >= INT_MAX)
+ fatal_f("too many helpers");
+ debug3_f("start helper for %s", path);
if (socketpair(AF_UNIX, SOCK_STREAM, 0, pair) == -1) {
- error("socketpair: %s", strerror(errno));
- return (-1);
+ error_f("socketpair: %s", strerror(errno));
+ return NULL;
+ }
+ helper = xcalloc(1, sizeof(*helper));
+ if (pkcs11_start_helper_methods(helper) == -1) {
+ error_f("pkcs11_start_helper_methods failed");
+ goto fail;
}
if ((pid = fork()) == -1) {
- error("fork: %s", strerror(errno));
- return (-1);
+ error_f("fork: %s", strerror(errno));
+ fail:
+ close(pair[0]);
+ close(pair[1]);
+ RSA_meth_free(helper->rsa_meth);
+ EC_KEY_METHOD_free(helper->ec_meth);
+ free(helper);
+ return NULL;
} else if (pid == 0) {
if ((dup2(pair[1], STDIN_FILENO) == -1) ||
(dup2(pair[1], STDOUT_FILENO) == -1)) {
@@ -297,18 +485,27 @@ pkcs11_start_helper(void)
}
close(pair[0]);
close(pair[1]);
- helper = getenv("SSH_PKCS11_HELPER");
- if (helper == NULL || strlen(helper) == 0)
- helper = _PATH_SSH_PKCS11_HELPER;
- debug_f("starting %s %s", helper,
+ prog = getenv("SSH_PKCS11_HELPER");
+ if (prog == NULL || strlen(prog) == 0)
+ prog = _PATH_SSH_PKCS11_HELPER;
+ if (log_level_get() >= SYSLOG_LEVEL_DEBUG1)
+ verbosity = "-vvv";
+ debug_f("starting %s %s", prog,
verbosity == NULL ? "" : verbosity);
- execlp(helper, helper, verbosity, (char *)NULL);
- fprintf(stderr, "exec: %s: %s\n", helper, strerror(errno));
+ execlp(prog, prog, verbosity, (char *)NULL);
+ fprintf(stderr, "exec: %s: %s\n", prog, strerror(errno));
_exit(1);
}
close(pair[1]);
- fd = pair[0];
- return (0);
+ helper->fd = pair[0];
+ helper->path = xstrdup(path);
+ helper->pid = pid;
+ debug3_f("helper %zu for \"%s\" on fd %d pid %ld", nhelpers,
+ helper->path, helper->fd, (long)helper->pid);
+ helpers = xrecallocarray(helpers, nhelpers,
+ nhelpers + 1, sizeof(*helpers));
+ helpers[nhelpers++] = helper;
+ return helper;
}
int
@@ -322,9 +519,11 @@ pkcs11_add_provider(char *name, char *pin, struct sshkey ***keysp,
size_t blen;
u_int nkeys, i;
struct sshbuf *msg;
+ struct helper *helper;
- if (fd < 0 && pkcs11_start_helper() < 0)
- return (-1);
+ if ((helper = helper_by_provider(name)) == NULL &&
+ (helper = pkcs11_start_helper(name)) == NULL)
+ return -1;
if ((msg = sshbuf_new()) == NULL)
fatal_f("sshbuf_new failed");
@@ -332,10 +531,10 @@ pkcs11_add_provider(char *name, char *pin, struct sshkey ***keysp,
(r = sshbuf_put_cstring(msg, name)) != 0 ||
(r = sshbuf_put_cstring(msg, pin)) != 0)
fatal_fr(r, "compose");
- send_msg(msg);
+ send_msg(helper->fd, msg);
sshbuf_reset(msg);
- type = recv_msg(msg);
+ type = recv_msg(helper->fd, msg);
if (type == SSH2_AGENT_IDENTITIES_ANSWER) {
if ((r = sshbuf_get_u32(msg, &nkeys)) != 0)
fatal_fr(r, "parse nkeys");
@@ -349,7 +548,7 @@ pkcs11_add_provider(char *name, char *pin, struct sshkey ***keysp,
fatal_fr(r, "parse key");
if ((r = sshkey_from_blob(blob, blen, &k)) != 0)
fatal_fr(r, "decode key");
- wrap_key(k);
+ wrap_key(helper, k);
(*keysp)[i] = k;
if (labelsp)
(*labelsp)[i] = label;
@@ -370,22 +569,15 @@ pkcs11_add_provider(char *name, char *pin, struct sshkey ***keysp,
int
pkcs11_del_provider(char *name)
{
- int r, ret = -1;
- struct sshbuf *msg;
-
- if ((msg = sshbuf_new()) == NULL)
- fatal_f("sshbuf_new failed");
- if ((r = sshbuf_put_u8(msg, SSH_AGENTC_REMOVE_SMARTCARD_KEY)) != 0 ||
- (r = sshbuf_put_cstring(msg, name)) != 0 ||
- (r = sshbuf_put_cstring(msg, "")) != 0)
- fatal_fr(r, "compose");
- send_msg(msg);
- sshbuf_reset(msg);
-
- if (recv_msg(msg) == SSH_AGENT_SUCCESS)
- ret = 0;
- sshbuf_free(msg);
- return (ret);
+ struct helper *helper;
+
+ /*
+ * ssh-agent deletes keys before calling this, so the helper entry
+ * should be gone before we get here.
+ */
+ debug3_f("delete %s", name);
+ if ((helper = helper_by_provider(name)) != NULL)
+ helper_terminate(helper);
+ return 0;
}
-
#endif /* ENABLE_PKCS11 */
--
2.40.0

173
meta/recipes-connectivity/openssh/openssh/CVE-2023-38408-0002.patch Normal file
View File

@@ -0,0 +1,173 @@
From 29ef8a04866ca14688d5b7fed7b8b9deab851f77 Mon Sep 17 00:00:00 2001
From: "djm@openbsd.org" <djm@openbsd.org>
Date: Wed, 19 Jul 2023 14:02:27 +0000
Subject: [PATCH 2/4] upstream: Ensure FIDO/PKCS11 libraries contain expected
symbols
This checks via nlist(3) that candidate provider libraries contain one
of the symbols that we will require prior to dlopen(), which can cause
a number of side effects, including execution of constructors.
Feedback deraadt; ok markus
OpenBSD-Commit-ID: 1508a5fbd74e329e69a55b56c453c292029aefbe
Upstream-Status: Backport [https://github.com/openssh/openssh-portable/commit/29ef8a04866ca14688d5b7fed7b8b9deab851f77]
CVE: CVE-2023-38408
Signed-off-by: Archana Polampalli <archana.polampalli@windriver.com>
---
misc.c | 77 ++++++++++++++++++++++++++++++++++++++++++++++++++++
misc.h | 1 +
ssh-pkcs11.c | 4 +++
ssh-sk.c | 6 ++--
4 files changed, 86 insertions(+), 2 deletions(-)
diff --git a/misc.c b/misc.c
index 417498d..d0270e7 100644
--- a/misc.c
+++ b/misc.c
@@ -22,6 +22,7 @@
#include <sys/types.h>
#include <sys/ioctl.h>
+#include <sys/mman.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/time.h>
@@ -35,6 +36,9 @@
#ifdef HAVE_POLL_H
#include <poll.h>
#endif
+#ifdef HAVE_NLIST_H
+#include <nlist.h>
+#endif
#include <signal.h>
#include <stdarg.h>
#include <stdio.h>
@@ -2784,3 +2788,76 @@ lookup_env_in_list(const char *env, char * const *envs, size_t nenvs)
}
return NULL;
}
+
+
+/*
+ * Returns zero if the library at 'path' contains symbol 's', nonzero
+ * otherwise.
+ */
+int
+lib_contains_symbol(const char *path, const char *s)
+{
+#ifdef HAVE_NLIST_H
+ struct nlist nl[2];
+ int ret = -1, r;
+
+ memset(nl, 0, sizeof(nl));
+ nl[0].n_name = xstrdup(s);
+ nl[1].n_name = NULL;
+ if ((r = nlist(path, nl)) == -1) {
+ error_f("nlist failed for %s", path);
+ goto out;
+ }
+ if (r != 0 || nl[0].n_value == 0 || nl[0].n_type == 0) {
+ error_f("library %s does not contain symbol %s", path, s);
+ goto out;
+ }
+ /* success */
+ ret = 0;
+ out:
+ free(nl[0].n_name);
+ return ret;
+#else /* HAVE_NLIST_H */
+ int fd, ret = -1;
+ struct stat st;
+ void *m = NULL;
+ size_t sz = 0;
+
+ memset(&st, 0, sizeof(st));
+ if ((fd = open(path, O_RDONLY)) < 0) {
+ error_f("open %s: %s", path, strerror(errno));
+ return -1;
+ }
+ if (fstat(fd, &st) != 0) {
+ error_f("fstat %s: %s", path, strerror(errno));
+ goto out;
+ }
+ if (!S_ISREG(st.st_mode)) {
+ error_f("%s is not a regular file", path);
+ goto out;
+ }
+ if (st.st_size < 0 ||
+ (size_t)st.st_size < strlen(s) ||
+ st.st_size >= INT_MAX/2) {
+ error_f("%s bad size %lld", path, (long long)st.st_size);
+ goto out;
+ }
+ sz = (size_t)st.st_size;
+ if ((m = mmap(NULL, sz, PROT_READ, MAP_PRIVATE, fd, 0)) == MAP_FAILED ||
+ m == NULL) {
+ error_f("mmap %s: %s", path, strerror(errno));
+ goto out;
+ }
+ if (memmem(m, sz, s, strlen(s)) == NULL) {
+ error_f("%s does not contain expected string %s", path, s);
+ goto out;
+ }
+ /* success */
+ ret = 0;
+ out:
+ if (m != NULL && m != MAP_FAILED)
+ munmap(m, sz);
+ close(fd);
+ return ret;
+#endif /* HAVE_NLIST_H */
+}
diff --git a/misc.h b/misc.h
index 2e1b5fe..3f48315 100644
--- a/misc.h
+++ b/misc.h
@@ -96,6 +96,7 @@ int parse_absolute_time(const char *, uint64_t *);
void format_absolute_time(uint64_t, char *, size_t);
int path_absolute(const char *);
int stdfd_devnull(int, int, int);
+int lib_contains_symbol(const char *, const char *);
void sock_set_v6only(int);
diff --git a/ssh-pkcs11.c b/ssh-pkcs11.c
index b2e2b32..5eb28e9 100644
--- a/ssh-pkcs11.c
+++ b/ssh-pkcs11.c
@@ -1532,6 +1532,10 @@ pkcs11_register_provider(char *provider_id, char *pin,
debug_f("provider already registered: %s", provider_id);
goto fail;
}
+ if (lib_contains_symbol(provider_id, "C_GetFunctionList") != 0) {
+ error("provider %s is not a PKCS11 library", provider_id);
+ goto fail;
+ }
/* open shared pkcs11-library */
if ((handle = dlopen(provider_id, RTLD_NOW)) == NULL) {
error("dlopen %s failed: %s", provider_id, dlerror());
diff --git a/ssh-sk.c b/ssh-sk.c
index a1ff5cc..1042bf6 100644
--- a/ssh-sk.c
+++ b/ssh-sk.c
@@ -132,10 +132,12 @@ sshsk_open(const char *path)
#endif
return ret;
}
- if ((ret->dlhandle = dlopen(path, RTLD_NOW)) == NULL) {
- error("Provider \"%s\" dlopen failed: %s", path, dlerror());
+ if (lib_contains_symbol(path, "sk_api_version") != 0) {
+ error("provider %s is not an OpenSSH FIDO library", path);
goto fail;
}
+ if ((ret->dlhandle = dlopen(path, RTLD_NOW)) == NULL)
+ fatal("Provider \"%s\" dlopen failed: %s", path, dlerror());
if ((ret->sk_api_version = dlsym(ret->dlhandle,
"sk_api_version")) == NULL) {
error("Provider \"%s\" dlsym(sk_api_version) failed: %s",
--
2.40.0

36
meta/recipes-connectivity/openssh/openssh/CVE-2023-38408-0003.patch Normal file
View File

@@ -0,0 +1,36 @@
From 892506b13654301f69f9545f48213fc210e5c5cc Mon Sep 17 00:00:00 2001
From: "djm@openbsd.org" <djm@openbsd.org>
Date: Wed, 19 Jul 2023 13:55:53 +0000
Subject: [PATCH 3/4] upstream: terminate process if requested to load a
PKCS#11 provider that isn't a PKCS#11 provider; from / ok markus@
OpenBSD-Commit-ID: 39532cf18b115881bb4cfaee32084497aadfa05c
Upstream-Status: Backport [https://github.com/openssh/openssh-portable/commit/892506b13654301f69f9545f48213fc210e5c5cc]
CVE: CVE-2023-38408
Signed-off-by: Archana Polampalli <archana.polampalli@windriver.com>
---
ssh-pkcs11.c | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)
diff --git a/ssh-pkcs11.c b/ssh-pkcs11.c
index 5eb28e9..0aef379 100644
--- a/ssh-pkcs11.c
+++ b/ssh-pkcs11.c
@@ -1541,10 +1541,8 @@ pkcs11_register_provider(char *provider_id, char *pin,
error("dlopen %s failed: %s", provider_id, dlerror());
goto fail;
}
- if ((getfunctionlist = dlsym(handle, "C_GetFunctionList")) == NULL) {
- error("dlsym(C_GetFunctionList) failed: %s", dlerror());
- goto fail;
- }
+ if ((getfunctionlist = dlsym(handle, "C_GetFunctionList")) == NULL)
+ fatal("dlsym(C_GetFunctionList) failed: %s", dlerror());
p = xcalloc(1, sizeof(*p));
p->name = xstrdup(provider_id);
p->handle = handle;
--
2.40.0

114
meta/recipes-connectivity/openssh/openssh/CVE-2023-38408-0004.patch Normal file
View File

@@ -0,0 +1,114 @@
From 1f2731f5d7a8f8a8385c6031667ed29072c0d92a Mon Sep 17 00:00:00 2001
From: "djm@openbsd.org" <djm@openbsd.org>
Date: Wed, 19 Jul 2023 13:56:33 +0000
Subject: [PATCH 4/4] upstream: Disallow remote addition of FIDO/PKCS11
provider libraries to ssh-agent by default.
The old behaviour of allowing remote clients from loading providers
can be restored using `ssh-agent -O allow-remote-pkcs11`.
Detection of local/remote clients requires a ssh(1) that supports
the `session-bind@openssh.com` extension. Forwarding access to a
ssh-agent socket using non-OpenSSH tools may circumvent this control.
ok markus@
OpenBSD-Commit-ID: 4c2bdf79b214ae7e60cc8c39a45501344fa7bd7c
Upstream-Status: Backport [https://github.com/openssh/openssh-portable/commit/1f2731f5d7a8f8a8385c6031667ed29072c0d92a]
CVE: CVE-2023-38408
Signed-off-by: Archana Polampalli <archana.polampalli@windriver.com>
---
ssh-agent.1 | 21 +++++++++++++++++++++
ssh-agent.c | 21 ++++++++++++++++++++-
2 files changed, 41 insertions(+), 1 deletion(-)
diff --git a/ssh-agent.1 b/ssh-agent.1
index ed8c870..15d0a47 100644
--- a/ssh-agent.1
+++ b/ssh-agent.1
@@ -102,6 +102,27 @@ The default is
Kill the current agent (given by the
.Ev SSH_AGENT_PID
environment variable).
+Currently two options are supported:
+.Cm allow-remote-pkcs11
+and
+.Cm no-restrict-websafe .
+.Pp
+The
+.Cm allow-remote-pkcs11
+option allows clients of a forwarded
+.Nm
+to load PKCS#11 or FIDO provider libraries.
+By default only local clients may perform this operation.
+Note that signalling that a
+.Nm
+client remote is performed by
+.Xr ssh 1 ,
+and use of other tools to forward access to the agent socket may circumvent
+this restriction.
+.Pp
+The
+.Cm no-restrict-websafe ,
+instructs
.It Fl P Ar allowed_providers
Specify a pattern-list of acceptable paths for PKCS#11 provider and FIDO
authenticator middleware shared libraries that may be used with the
diff --git a/ssh-agent.c b/ssh-agent.c
index 03ae2b0..19eeaae 100644
--- a/ssh-agent.c
+++ b/ssh-agent.c
@@ -171,6 +171,12 @@ char socket_dir[PATH_MAX];
/* Pattern-list of allowed PKCS#11/Security key paths */
static char *allowed_providers;
+/*
+ * Allows PKCS11 providers or SK keys that use non-internal providers to
+ * be added over a remote connection (identified by session-bind@openssh.com).
+ */
+static int remote_add_provider;
+
/* locking */
#define LOCK_SIZE 32
#define LOCK_SALT_SIZE 16
@@ -1239,6 +1245,12 @@ process_add_identity(SocketEntry *e)
if (strcasecmp(sk_provider, "internal") == 0) {
debug_f("internal provider");
} else {
+ if (e->nsession_ids != 0 && !remote_add_provider) {
+ verbose("failed add of SK provider \"%.100s\": "
+ "remote addition of providers is disabled",
+ sk_provider);
+ goto out;
+ }
if (realpath(sk_provider, canonical_provider) == NULL) {
verbose("failed provider \"%.100s\": "
"realpath: %s", sk_provider,
@@ -1402,6 +1414,11 @@ process_add_smartcard_key(SocketEntry *e)
error_f("failed to parse constraints");
goto send;
}
+ if (e->nsession_ids != 0 && !remote_add_provider) {
+ verbose("failed PKCS#11 add of \"%.100s\": remote addition of "
+ "providers is disabled", provider);
+ goto send;
+ }
if (realpath(provider, canonical_provider) == NULL) {
verbose("failed PKCS#11 add of \"%.100s\": realpath: %s",
provider, strerror(errno));
@@ -2061,7 +2078,9 @@ main(int ac, char **av)
break;
case 'O':
if (strcmp(optarg, "no-restrict-websafe") == 0)
- restrict_websafe = 0;
+ restrict_websafe = 0;
+ else if (strcmp(optarg, "allow-remote-pkcs11") == 0)
+ remote_add_provider = 1;
else
fatal("Unknown -O option");
break;
--
2.40.0

4
meta/recipes-connectivity/openssh/openssh_8.9p1.bb
View File

@@ -28,6 +28,10 @@ SRC_URI = "http://ftp.openbsd.org/pub/OpenBSD/OpenSSH/portable/openssh-${PV}.tar
file://0001-Default-to-not-using-sandbox-when-cross-compiling.patch \
file://7280401bdd77ca54be6867a154cc01e0d72612e0.patch \
file://0001-upstream-include-destination-constraints-for-smartca.patch \
file://CVE-2023-38408-0001.patch \
file://CVE-2023-38408-0002.patch \
file://CVE-2023-38408-0003.patch \
file://CVE-2023-38408-0004.patch \
"
SRC_URI[sha256sum] = "fd497654b7ab1686dac672fb83dfb4ba4096e8b5ffcdaccd262380ae58bec5e7"