* Mitigate OpenSSL security vulnerability:

  - Add key blacklisting support. Keys listed in
    /etc/ssh/blacklist.TYPE-LENGTH will be rejected for authentication by
    sshd, unless "PermitBlacklistedKeys yes" is set in
    /etc/ssh/sshd_config.
  - Add a new program, ssh-vulnkey, which can be used to check keys
    against these blacklists.
  - Depend on openssh-blacklist.
  - Force dependencies on libssl0.9.8 / libcrypto0.9.8-udeb to at least
    0.9.8g-9.
  - Automatically regenerate known-compromised host keys, with a
    critical-priority debconf note. (I regret that there was no time to
    gather translations.)

1 files changed, 311 insertions, 0 deletions

diff --git a/ssh-vulnkey.c b/ssh-vulnkey.c
new file mode 100644
index 000000000..ba87cbd28
--- /dev/null
+++ b/ssh-vulnkey.c
@@ -0,0 +1,311 @@
+/*
+ * Copyright (c) 2008 Canonical Ltd.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * 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.
+ */
+
+#include "includes.h"
+
+#include <sys/types.h>
+#include <sys/stat.h>
+
+#include <string.h>
+#include <stdio.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+#include <openssl/evp.h>
+
+#include "xmalloc.h"
+#include "ssh.h"
+#include "log.h"
+#include "key.h"
+#include "authfile.h"
+#include "pathnames.h"
+#include "misc.h"
+
+extern char *__progname;
+
+/* Default files to check */
+static char *default_host_files[] = {
+        _PATH_HOST_RSA_KEY_FILE,
+        _PATH_HOST_DSA_KEY_FILE,
+        _PATH_HOST_KEY_FILE,
+        NULL
+};
+static char *default_files[] = {
+        _PATH_SSH_CLIENT_ID_RSA,
+        _PATH_SSH_CLIENT_ID_DSA,
+        _PATH_SSH_CLIENT_IDENTITY,
+        _PATH_SSH_USER_PERMITTED_KEYS,
+        _PATH_SSH_USER_PERMITTED_KEYS2,
+        NULL
+};
+
+static int quiet = 0;
+
+static void
+usage(void)
+{
+        fprintf(stderr, "usage: %s [-aq] [file ...]\n", __progname);
+        fprintf(stderr, "Options:\n");
+        fprintf(stderr, "  -a          Check keys of all users.\n");
+        fprintf(stderr, "  -q          Quiet mode.\n");
+        exit(1);
+}
+
+void
+describe_key(const char *msg, const Key *key, const char *comment)
+{
+        char *fp;
+
+        fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
+        if (!quiet)
+                printf("%s: %u %s %s\n", msg, key_size(key), fp, comment);
+        xfree(fp);
+}
+
+int
+do_key(const Key *key, const char *comment)
+{
+        char *blacklist_file;
+        struct stat st;
+        int ret = 1;
+
+        blacklist_file = blacklist_filename(key);
+        if (stat(blacklist_file, &st) < 0)
+                describe_key("Unknown (no blacklist information)",
+                    key, comment);
+        else if (blacklisted_key(key)) {
+                describe_key("COMPROMISED", key, comment);
+                ret = 0;
+        } else
+                describe_key("Not blacklisted", key, comment);
+        xfree(blacklist_file);
+
+        return ret;
+}
+
+int
+do_filename(const char *filename, int quiet_open)
+{
+        FILE *f;
+        char line[SSH_MAX_PUBKEY_BYTES];
+        char *cp;
+        u_long linenum = 0;
+        Key *key;
+        char *comment = NULL;
+        int found = 0, ret = 1;
+
+        /* Copy much of key_load_public's logic here so that we can read
+         * several keys from a single file (e.g. authorized_keys).
+         */
+
+        if (strcmp(filename, "-") != 0) {
+                f = fopen(filename, "r");
+                if (!f) {
+                        char pubfile[MAXPATHLEN];
+                        if (strlcpy(pubfile, filename, sizeof pubfile) <
+                            sizeof(pubfile) &&
+                            strlcat(pubfile, ".pub", sizeof pubfile) <
+                            sizeof(pubfile))
+                                f = fopen(pubfile, "r");
+                }
+                if (!f) {
+                        if (!quiet_open)
+                                perror(filename);
+                        return -1;
+                }
+        } else
+                f = stdin;
+        while (read_keyfile_line(f, filename, line, sizeof(line),
+                    &linenum) != -1) {
+                cp = line;
+                switch (*cp) {
+                case '#':
+                case '\n':
+                case '\0':
+                        continue;
+                }
+                /* Skip leading whitespace. */
+                for (; *cp && (*cp == ' ' || *cp == '\t'); cp++)
+                        ;
+                /* Cope with ssh-keyscan output. */
+                comment = NULL;
+                if (*cp) {
+                        char *space;
+                        int type;
+
+                        space = strchr(cp, ' ');
+                        if (!space)
+                                continue;
+                        *space = '\0';
+                        type = key_type_from_name(cp);
+                        if (type == KEY_UNSPEC) {
+                                comment = xstrdup(cp);
+                                cp = space + 1;
+                        }
+                        *space = ' ';
+                }
+                if (!comment)
+                        comment = xstrdup(filename);
+                if (*cp) {
+                        key = key_new(KEY_RSA1);
+                        if (key_read(key, &cp) == 1) {
+                                if (!do_key(key, comment))
+                                        ret = 0;
+                                key_free(key);
+                                found = 1;
+                        } else {
+                                key_free(key);
+                                key = key_new(KEY_UNSPEC);
+                                if (key_read(key, &cp) == 1) {
+                                        if (!do_key(key, comment))
+                                                ret = 0;
+                                        key_free(key);
+                                        found = 1;
+                                }
+                        }
+                }
+                xfree(comment);
+                comment = NULL;
+        }
+        if (f != stdin)
+                fclose(f);
+
+        if (!found && filename) {
+                key = key_load_public(filename, &comment);
+                if (key) {
+                        if (!do_key(key, comment))
+                                ret = 0;
+                        found = 1;
+                }
+                if (comment)
+                        xfree(comment);
+        }
+
+        return ret;
+}
+
+int
+do_host(void)
+{
+        int i;
+        struct stat st;
+        int ret = 1;
+
+        for (i = 0; default_host_files[i]; i++) {
+                if (stat(default_host_files[i], &st) < 0)
+                        continue;
+                if (!do_filename(default_host_files[i], 1))
+                        ret = 0;
+        }
+
+        return ret;
+}
+
+int
+do_user(const char *dir)
+{
+        int i;
+        char buf[MAXPATHLEN];
+        struct stat st;
+        int ret = 1;
+
+        for (i = 0; default_files[i]; i++) {
+                snprintf(buf, sizeof(buf), "%s/%s", dir, default_files[i]);
+                if (stat(buf, &st) < 0)
+                        continue;
+                if (!do_filename(buf, 0))
+                        ret = 0;
+        }
+
+        return ret;
+}
+
+int
+main(int argc, char **argv)
+{
+        int opt, all_users = 0;
+        int ret = 1;
+        extern int optind;
+
+        /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
+        sanitise_stdfd();
+
+        __progname = ssh_get_progname(argv[0]);
+
+        SSLeay_add_all_algorithms();
+        log_init(argv[0], SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_USER, 1);
+
+        /* We don't need the RNG ourselves, but symbol references here allow
+         * ld to link us properly.
+         */
+        init_rng();
+        seed_rng();
+
+        while ((opt = getopt(argc, argv, "ahq")) != -1) {
+                switch (opt) {
+                case 'a':
+                        all_users = 1;
+                        break;
+                case 'q':
+                        quiet = 1;
+                        break;
+                case 'h':
+                default:
+                        usage();
+                }
+        }
+
+        if (all_users) {
+                struct passwd *pw;
+
+                if (!do_host())
+                        ret = 0;
+
+                while ((pw = getpwent()) != NULL) {
+                        if (pw->pw_dir) {
+                                if (!do_user(pw->pw_dir))
+                                        ret = 0;
+                        }
+                }
+        } else if (optind == argc) {
+                struct passwd *pw;
+
+                if (!do_host())
+                        ret = 0;
+
+                if ((pw = getpwuid(getuid())) == NULL)
+                        fprintf(stderr, "No user found with uid %u\n",
+                            (u_int)getuid());
+                else {
+                        if (!do_user(pw->pw_dir))
+                                ret = 0;
+                }
+        } else {
+                while (optind < argc)
+                        if (!do_filename(argv[optind++], 0))
+                                ret = 0;
+        }
+
+        return ret;
+}