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-rw-r--r--debian/patches/ssh-vulnkey.patch1382
1 files changed, 1382 insertions, 0 deletions
diff --git a/debian/patches/ssh-vulnkey.patch b/debian/patches/ssh-vulnkey.patch
new file mode 100644
index 000000000..a56911290
--- /dev/null
+++ b/debian/patches/ssh-vulnkey.patch
@@ -0,0 +1,1382 @@
1Description: Reject vulnerable keys to mitigate Debian OpenSSL flaw
2 In 2008, Debian (and derived distributions such as Ubuntu) shipped an
3 OpenSSL package with a flawed random number generator, causing OpenSSH to
4 generate only a very limited set of keys which were subject to private half
5 precomputation. To mitigate this, this patch checks key authentications
6 against a blacklist of known-vulnerable keys, and adds a new ssh-vulnkey
7 program which can be used to explicitly check keys against that blacklist.
8 See CVE-2008-0166.
9Author: Colin Watson <cjwatson@ubuntu.com>
10Bug: https://bugzilla.mindrot.org/show_bug.cgi?id=1469
11Last-Update: 2013-09-14
12
13Index: b/Makefile.in
14===================================================================
15--- a/Makefile.in
16+++ b/Makefile.in
17@@ -26,6 +26,7 @@
18 SFTP_SERVER=$(libexecdir)/sftp-server
19 SSH_KEYSIGN=$(libexecdir)/ssh-keysign
20 SSH_PKCS11_HELPER=$(libexecdir)/ssh-pkcs11-helper
21+SSH_DATADIR=$(datadir)/ssh
22 PRIVSEP_PATH=@PRIVSEP_PATH@
23 SSH_PRIVSEP_USER=@SSH_PRIVSEP_USER@
24 STRIP_OPT=@STRIP_OPT@
25@@ -37,7 +38,8 @@
26 -D_PATH_SSH_KEY_SIGN=\"$(SSH_KEYSIGN)\" \
27 -D_PATH_SSH_PKCS11_HELPER=\"$(SSH_PKCS11_HELPER)\" \
28 -D_PATH_SSH_PIDDIR=\"$(piddir)\" \
29- -D_PATH_PRIVSEP_CHROOT_DIR=\"$(PRIVSEP_PATH)\"
30+ -D_PATH_PRIVSEP_CHROOT_DIR=\"$(PRIVSEP_PATH)\" \
31+ -D_PATH_SSH_DATADIR=\"$(SSH_DATADIR)\"
32
33 CC=@CC@
34 LD=@LD@
35@@ -61,7 +63,7 @@
36 EXEEXT=@EXEEXT@
37 MANFMT=@MANFMT@
38
39-TARGETS=ssh$(EXEEXT) sshd$(EXEEXT) ssh-add$(EXEEXT) ssh-keygen$(EXEEXT) ssh-keyscan${EXEEXT} ssh-keysign${EXEEXT} ssh-pkcs11-helper$(EXEEXT) ssh-agent$(EXEEXT) scp$(EXEEXT) sftp-server$(EXEEXT) sftp$(EXEEXT)
40+TARGETS=ssh$(EXEEXT) sshd$(EXEEXT) ssh-add$(EXEEXT) ssh-keygen$(EXEEXT) ssh-keyscan${EXEEXT} ssh-keysign${EXEEXT} ssh-pkcs11-helper$(EXEEXT) ssh-agent$(EXEEXT) scp$(EXEEXT) sftp-server$(EXEEXT) sftp$(EXEEXT) ssh-vulnkey$(EXEEXT)
41
42 LIBSSH_OBJS=authfd.o authfile.o bufaux.o bufbn.o buffer.o \
43 canohost.o channels.o cipher.o cipher-aes.o \
44@@ -96,8 +98,8 @@
45 sandbox-null.o sandbox-rlimit.o sandbox-systrace.o sandbox-darwin.o \
46 sandbox-seccomp-filter.o
47
48-MANPAGES = moduli.5.out scp.1.out ssh-add.1.out ssh-agent.1.out ssh-keygen.1.out ssh-keyscan.1.out ssh.1.out sshd.8.out sftp-server.8.out sftp.1.out ssh-keysign.8.out ssh-pkcs11-helper.8.out sshd_config.5.out ssh_config.5.out
49-MANPAGES_IN = moduli.5 scp.1 ssh-add.1 ssh-agent.1 ssh-keygen.1 ssh-keyscan.1 ssh.1 sshd.8 sftp-server.8 sftp.1 ssh-keysign.8 ssh-pkcs11-helper.8 sshd_config.5 ssh_config.5
50+MANPAGES = moduli.5.out scp.1.out ssh-add.1.out ssh-agent.1.out ssh-keygen.1.out ssh-keyscan.1.out ssh.1.out sshd.8.out sftp-server.8.out sftp.1.out ssh-keysign.8.out ssh-pkcs11-helper.8.out ssh-vulnkey.1.out sshd_config.5.out ssh_config.5.out
51+MANPAGES_IN = moduli.5 scp.1 ssh-add.1 ssh-agent.1 ssh-keygen.1 ssh-keyscan.1 ssh.1 sshd.8 sftp-server.8 sftp.1 ssh-keysign.8 ssh-pkcs11-helper.8 ssh-vulnkey.1 sshd_config.5 ssh_config.5
52 MANTYPE = @MANTYPE@
53
54 CONFIGFILES=sshd_config.out ssh_config.out moduli.out
55@@ -176,6 +178,9 @@
56 sftp$(EXEEXT): $(LIBCOMPAT) libssh.a sftp.o sftp-client.o sftp-common.o sftp-glob.o progressmeter.o
57 $(LD) -o $@ progressmeter.o sftp.o sftp-client.o sftp-common.o sftp-glob.o $(LDFLAGS) -lssh -lopenbsd-compat $(LIBS) $(LIBEDIT)
58
59+ssh-vulnkey$(EXEEXT): $(LIBCOMPAT) libssh.a ssh-vulnkey.o
60+ $(LD) -o $@ ssh-vulnkey.o $(LDFLAGS) -lssh -lopenbsd-compat $(LIBS)
61+
62 # test driver for the loginrec code - not built by default
63 logintest: logintest.o $(LIBCOMPAT) libssh.a loginrec.o
64 $(LD) -o $@ logintest.o $(LDFLAGS) loginrec.o -lopenbsd-compat -lssh $(LIBS)
65@@ -272,6 +277,7 @@
66 $(INSTALL) -m 0755 $(STRIP_OPT) ssh-pkcs11-helper$(EXEEXT) $(DESTDIR)$(SSH_PKCS11_HELPER)$(EXEEXT)
67 $(INSTALL) -m 0755 $(STRIP_OPT) sftp$(EXEEXT) $(DESTDIR)$(bindir)/sftp$(EXEEXT)
68 $(INSTALL) -m 0755 $(STRIP_OPT) sftp-server$(EXEEXT) $(DESTDIR)$(SFTP_SERVER)$(EXEEXT)
69+ $(INSTALL) -m 0755 $(STRIP_OPT) ssh-vulnkey$(EXEEXT) $(DESTDIR)$(bindir)/ssh-vulnkey$(EXEEXT)
70 $(INSTALL) -m 644 ssh.1.out $(DESTDIR)$(mandir)/$(mansubdir)1/ssh.1
71 $(INSTALL) -m 644 scp.1.out $(DESTDIR)$(mandir)/$(mansubdir)1/scp.1
72 $(INSTALL) -m 644 ssh-add.1.out $(DESTDIR)$(mandir)/$(mansubdir)1/ssh-add.1
73@@ -286,6 +292,7 @@
74 $(INSTALL) -m 644 sftp-server.8.out $(DESTDIR)$(mandir)/$(mansubdir)8/sftp-server.8
75 $(INSTALL) -m 644 ssh-keysign.8.out $(DESTDIR)$(mandir)/$(mansubdir)8/ssh-keysign.8
76 $(INSTALL) -m 644 ssh-pkcs11-helper.8.out $(DESTDIR)$(mandir)/$(mansubdir)8/ssh-pkcs11-helper.8
77+ $(INSTALL) -m 644 ssh-vulnkey.1.out $(DESTDIR)$(mandir)/$(mansubdir)1/ssh-vulnkey.1
78 -rm -f $(DESTDIR)$(bindir)/slogin
79 ln -s ./ssh$(EXEEXT) $(DESTDIR)$(bindir)/slogin
80 -rm -f $(DESTDIR)$(mandir)/$(mansubdir)1/slogin.1
81@@ -367,6 +374,7 @@
82 -rm -f $(DESTDIR)$(bindir)/ssh-agent$(EXEEXT)
83 -rm -f $(DESTDIR)$(bindir)/ssh-keygen$(EXEEXT)
84 -rm -f $(DESTDIR)$(bindir)/ssh-keyscan$(EXEEXT)
85+ -rm -f $(DESTDIR)$(bindir)/ssh-vulnkey$(EXEEXT)
86 -rm -f $(DESTDIR)$(bindir)/sftp$(EXEEXT)
87 -rm -f $(DESTDIR)$(sbindir)/sshd$(EXEEXT)
88 -rm -r $(DESTDIR)$(SFTP_SERVER)$(EXEEXT)
89@@ -379,6 +387,7 @@
90 -rm -f $(DESTDIR)$(mandir)/$(mansubdir)1/ssh-keygen.1
91 -rm -f $(DESTDIR)$(mandir)/$(mansubdir)1/sftp.1
92 -rm -f $(DESTDIR)$(mandir)/$(mansubdir)1/ssh-keyscan.1
93+ -rm -f $(DESTDIR)$(mandir)/$(mansubdir)1/ssh-vulnkey.1
94 -rm -f $(DESTDIR)$(mandir)/$(mansubdir)8/sshd.8
95 -rm -f $(DESTDIR)$(mandir)/$(mansubdir)8/sftp-server.8
96 -rm -f $(DESTDIR)$(mandir)/$(mansubdir)8/ssh-keysign.8
97Index: b/auth-rh-rsa.c
98===================================================================
99--- a/auth-rh-rsa.c
100+++ b/auth-rh-rsa.c
101@@ -44,7 +44,7 @@
102 {
103 HostStatus host_status;
104
105- if (auth_key_is_revoked(client_host_key))
106+ if (auth_key_is_revoked(client_host_key, 0))
107 return 0;
108
109 /* Check if we would accept it using rhosts authentication. */
110Index: b/auth-rsa.c
111===================================================================
112--- a/auth-rsa.c
113+++ b/auth-rsa.c
114@@ -237,7 +237,7 @@
115 free(fp);
116
117 /* Never accept a revoked key */
118- if (auth_key_is_revoked(key))
119+ if (auth_key_is_revoked(key, 0))
120 break;
121
122 /* We have found the desired key. */
123Index: b/auth.c
124===================================================================
125--- a/auth.c
126+++ b/auth.c
127@@ -59,6 +59,7 @@
128 #include "servconf.h"
129 #include "key.h"
130 #include "hostfile.h"
131+#include "authfile.h"
132 #include "auth.h"
133 #include "auth-options.h"
134 #include "canohost.h"
135@@ -657,10 +658,34 @@
136
137 /* Returns 1 if key is revoked by revoked_keys_file, 0 otherwise */
138 int
139-auth_key_is_revoked(Key *key)
140+auth_key_is_revoked(Key *key, int hostkey)
141 {
142 char *key_fp;
143
144+ if (blacklisted_key(key, &key_fp) == 1) {
145+ if (options.permit_blacklisted_keys) {
146+ if (hostkey)
147+ error("Host key %s blacklisted (see "
148+ "ssh-vulnkey(1)); continuing anyway",
149+ key_fp);
150+ else
151+ logit("Public key %s from %s blacklisted (see "
152+ "ssh-vulnkey(1)); continuing anyway",
153+ key_fp, get_remote_ipaddr());
154+ free(key_fp);
155+ } else {
156+ if (hostkey)
157+ error("Host key %s blacklisted (see "
158+ "ssh-vulnkey(1))", key_fp);
159+ else
160+ logit("Public key %s from %s blacklisted (see "
161+ "ssh-vulnkey(1))",
162+ key_fp, get_remote_ipaddr());
163+ free(key_fp);
164+ return 1;
165+ }
166+ }
167+
168 if (options.revoked_keys_file == NULL)
169 return 0;
170 switch (ssh_krl_file_contains_key(options.revoked_keys_file, key)) {
171Index: b/auth.h
172===================================================================
173--- a/auth.h
174+++ b/auth.h
175@@ -191,7 +191,7 @@
176
177 FILE *auth_openkeyfile(const char *, struct passwd *, int);
178 FILE *auth_openprincipals(const char *, struct passwd *, int);
179-int auth_key_is_revoked(Key *);
180+int auth_key_is_revoked(Key *, int);
181
182 HostStatus
183 check_key_in_hostfiles(struct passwd *, Key *, const char *,
184Index: b/auth2-hostbased.c
185===================================================================
186--- a/auth2-hostbased.c
187+++ b/auth2-hostbased.c
188@@ -150,7 +150,7 @@
189 int len;
190 char *fp;
191
192- if (auth_key_is_revoked(key))
193+ if (auth_key_is_revoked(key, 0))
194 return 0;
195
196 resolvedname = get_canonical_hostname(options.use_dns);
197Index: b/auth2-pubkey.c
198===================================================================
199--- a/auth2-pubkey.c
200+++ b/auth2-pubkey.c
201@@ -647,9 +647,10 @@
202 u_int success, i;
203 char *file;
204
205- if (auth_key_is_revoked(key))
206+ if (auth_key_is_revoked(key, 0))
207 return 0;
208- if (key_is_cert(key) && auth_key_is_revoked(key->cert->signature_key))
209+ if (key_is_cert(key) &&
210+ auth_key_is_revoked(key->cert->signature_key, 0))
211 return 0;
212
213 success = user_cert_trusted_ca(pw, key);
214Index: b/authfile.c
215===================================================================
216--- a/authfile.c
217+++ b/authfile.c
218@@ -68,6 +68,7 @@
219 #include "rsa.h"
220 #include "misc.h"
221 #include "atomicio.h"
222+#include "pathnames.h"
223
224 #define MAX_KEY_FILE_SIZE (1024 * 1024)
225
226@@ -944,3 +945,139 @@
227 return ret;
228 }
229
230+/* Scan a blacklist of known-vulnerable keys in blacklist_file. */
231+static int
232+blacklisted_key_in_file(Key *key, const char *blacklist_file, char **fp)
233+{
234+ int fd = -1;
235+ char *dgst_hex = NULL;
236+ char *dgst_packed = NULL, *p;
237+ int i;
238+ size_t line_len;
239+ struct stat st;
240+ char buf[256];
241+ off_t start, lower, upper;
242+ int ret = 0;
243+
244+ debug("Checking blacklist file %s", blacklist_file);
245+ fd = open(blacklist_file, O_RDONLY);
246+ if (fd < 0) {
247+ ret = -1;
248+ goto out;
249+ }
250+
251+ dgst_hex = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
252+ /* Remove all colons */
253+ dgst_packed = xcalloc(1, strlen(dgst_hex) + 1);
254+ for (i = 0, p = dgst_packed; dgst_hex[i]; i++)
255+ if (dgst_hex[i] != ':')
256+ *p++ = dgst_hex[i];
257+ /* Only compare least-significant 80 bits (to keep the blacklist
258+ * size down)
259+ */
260+ line_len = strlen(dgst_packed + 12);
261+ if (line_len > 32)
262+ goto out;
263+
264+ /* Skip leading comments */
265+ start = 0;
266+ for (;;) {
267+ ssize_t r;
268+ char *newline;
269+
270+ r = atomicio(read, fd, buf, sizeof(buf));
271+ if (r <= 0)
272+ goto out;
273+ if (buf[0] != '#')
274+ break;
275+
276+ newline = memchr(buf, '\n', sizeof(buf));
277+ if (!newline)
278+ goto out;
279+ start += newline + 1 - buf;
280+ if (lseek(fd, start, SEEK_SET) < 0)
281+ goto out;
282+ }
283+
284+ /* Initialise binary search record numbers */
285+ if (fstat(fd, &st) < 0)
286+ goto out;
287+ lower = 0;
288+ upper = (st.st_size - start) / (line_len + 1);
289+
290+ while (lower != upper) {
291+ off_t cur;
292+ int cmp;
293+
294+ cur = lower + (upper - lower) / 2;
295+
296+ /* Read this line and compare to digest; this is
297+ * overflow-safe since cur < max(off_t) / (line_len + 1) */
298+ if (lseek(fd, start + cur * (line_len + 1), SEEK_SET) < 0)
299+ break;
300+ if (atomicio(read, fd, buf, line_len) != line_len)
301+ break;
302+ cmp = memcmp(buf, dgst_packed + 12, line_len);
303+ if (cmp < 0) {
304+ if (cur == lower)
305+ break;
306+ lower = cur;
307+ } else if (cmp > 0) {
308+ if (cur == upper)
309+ break;
310+ upper = cur;
311+ } else {
312+ debug("Found %s in blacklist", dgst_hex);
313+ ret = 1;
314+ break;
315+ }
316+ }
317+
318+out:
319+ free(dgst_packed);
320+ if (ret != 1 && dgst_hex) {
321+ free(dgst_hex);
322+ dgst_hex = NULL;
323+ }
324+ if (fp)
325+ *fp = dgst_hex;
326+ if (fd >= 0)
327+ close(fd);
328+ return ret;
329+}
330+
331+/*
332+ * Scan blacklists of known-vulnerable keys. If a vulnerable key is found,
333+ * its fingerprint is returned in *fp, unless fp is NULL.
334+ */
335+int
336+blacklisted_key(Key *key, char **fp)
337+{
338+ Key *public;
339+ char *blacklist_file;
340+ int ret, ret2;
341+
342+ public = key_demote(key);
343+ if (public->type == KEY_RSA1)
344+ public->type = KEY_RSA;
345+
346+ xasprintf(&blacklist_file, "%s.%s-%u",
347+ _PATH_BLACKLIST, key_type(public), key_size(public));
348+ ret = blacklisted_key_in_file(public, blacklist_file, fp);
349+ free(blacklist_file);
350+ if (ret > 0) {
351+ key_free(public);
352+ return ret;
353+ }
354+
355+ xasprintf(&blacklist_file, "%s.%s-%u",
356+ _PATH_BLACKLIST_CONFIG, key_type(public), key_size(public));
357+ ret2 = blacklisted_key_in_file(public, blacklist_file, fp);
358+ free(blacklist_file);
359+ if (ret2 > ret)
360+ ret = ret2;
361+
362+ key_free(public);
363+ return ret;
364+}
365+
366Index: b/authfile.h
367===================================================================
368--- a/authfile.h
369+++ b/authfile.h
370@@ -28,4 +28,6 @@
371 int key_perm_ok(int, const char *);
372 int key_in_file(Key *, const char *, int);
373
374+int blacklisted_key(Key *key, char **fp);
375+
376 #endif
377Index: b/pathnames.h
378===================================================================
379--- a/pathnames.h
380+++ b/pathnames.h
381@@ -18,6 +18,10 @@
382 #define SSHDIR ETCDIR "/ssh"
383 #endif
384
385+#ifndef _PATH_SSH_DATADIR
386+#define _PATH_SSH_DATADIR "/usr/share/ssh"
387+#endif
388+
389 #ifndef _PATH_SSH_PIDDIR
390 #define _PATH_SSH_PIDDIR "/var/run"
391 #endif
392@@ -44,6 +48,9 @@
393 /* Backwards compatibility */
394 #define _PATH_DH_PRIMES SSHDIR "/primes"
395
396+#define _PATH_BLACKLIST _PATH_SSH_DATADIR "/blacklist"
397+#define _PATH_BLACKLIST_CONFIG SSHDIR "/blacklist"
398+
399 #ifndef _PATH_SSH_PROGRAM
400 #define _PATH_SSH_PROGRAM "/usr/bin/ssh"
401 #endif
402Index: b/readconf.c
403===================================================================
404--- a/readconf.c
405+++ b/readconf.c
406@@ -128,6 +128,7 @@
407 oGlobalKnownHostsFile2, oUserKnownHostsFile2, oPubkeyAuthentication,
408 oKbdInteractiveAuthentication, oKbdInteractiveDevices, oHostKeyAlias,
409 oDynamicForward, oPreferredAuthentications, oHostbasedAuthentication,
410+ oUseBlacklistedKeys,
411 oHostKeyAlgorithms, oBindAddress, oPKCS11Provider,
412 oClearAllForwardings, oNoHostAuthenticationForLocalhost,
413 oEnableSSHKeysign, oRekeyLimit, oVerifyHostKeyDNS, oConnectTimeout,
414@@ -161,6 +162,7 @@
415 { "passwordauthentication", oPasswordAuthentication },
416 { "kbdinteractiveauthentication", oKbdInteractiveAuthentication },
417 { "kbdinteractivedevices", oKbdInteractiveDevices },
418+ { "useblacklistedkeys", oUseBlacklistedKeys },
419 { "rsaauthentication", oRSAAuthentication },
420 { "pubkeyauthentication", oPubkeyAuthentication },
421 { "dsaauthentication", oPubkeyAuthentication }, /* alias */
422@@ -523,6 +525,10 @@
423 intptr = &options->challenge_response_authentication;
424 goto parse_flag;
425
426+ case oUseBlacklistedKeys:
427+ intptr = &options->use_blacklisted_keys;
428+ goto parse_flag;
429+
430 case oGssAuthentication:
431 intptr = &options->gss_authentication;
432 goto parse_flag;
433@@ -1210,6 +1216,7 @@
434 options->kbd_interactive_devices = NULL;
435 options->rhosts_rsa_authentication = -1;
436 options->hostbased_authentication = -1;
437+ options->use_blacklisted_keys = -1;
438 options->batch_mode = -1;
439 options->check_host_ip = -1;
440 options->strict_host_key_checking = -1;
441@@ -1320,6 +1327,8 @@
442 options->rhosts_rsa_authentication = 0;
443 if (options->hostbased_authentication == -1)
444 options->hostbased_authentication = 0;
445+ if (options->use_blacklisted_keys == -1)
446+ options->use_blacklisted_keys = 0;
447 if (options->batch_mode == -1)
448 options->batch_mode = 0;
449 if (options->check_host_ip == -1)
450Index: b/readconf.h
451===================================================================
452--- a/readconf.h
453+++ b/readconf.h
454@@ -59,6 +59,7 @@
455 int kbd_interactive_authentication; /* Try keyboard-interactive auth. */
456 char *kbd_interactive_devices; /* Keyboard-interactive auth devices. */
457 int zero_knowledge_password_authentication; /* Try jpake */
458+ int use_blacklisted_keys; /* If true, send */
459 int batch_mode; /* Batch mode: do not ask for passwords. */
460 int check_host_ip; /* Also keep track of keys for IP address */
461 int strict_host_key_checking; /* Strict host key checking. */
462Index: b/servconf.c
463===================================================================
464--- a/servconf.c
465+++ b/servconf.c
466@@ -114,6 +114,7 @@
467 options->password_authentication = -1;
468 options->kbd_interactive_authentication = -1;
469 options->challenge_response_authentication = -1;
470+ options->permit_blacklisted_keys = -1;
471 options->permit_empty_passwd = -1;
472 options->permit_user_env = -1;
473 options->use_login = -1;
474@@ -257,6 +258,8 @@
475 options->kbd_interactive_authentication = 0;
476 if (options->challenge_response_authentication == -1)
477 options->challenge_response_authentication = 1;
478+ if (options->permit_blacklisted_keys == -1)
479+ options->permit_blacklisted_keys = 0;
480 if (options->permit_empty_passwd == -1)
481 options->permit_empty_passwd = 0;
482 if (options->permit_user_env == -1)
483@@ -338,7 +341,7 @@
484 sListenAddress, sAddressFamily,
485 sPrintMotd, sPrintLastLog, sIgnoreRhosts,
486 sX11Forwarding, sX11DisplayOffset, sX11UseLocalhost,
487- sStrictModes, sEmptyPasswd, sTCPKeepAlive,
488+ sStrictModes, sPermitBlacklistedKeys, sEmptyPasswd, sTCPKeepAlive,
489 sPermitUserEnvironment, sUseLogin, sAllowTcpForwarding, sCompression,
490 sRekeyLimit, sAllowUsers, sDenyUsers, sAllowGroups, sDenyGroups,
491 sIgnoreUserKnownHosts, sCiphers, sMacs, sProtocol, sPidFile,
492@@ -451,6 +454,7 @@
493 { "x11uselocalhost", sX11UseLocalhost, SSHCFG_ALL },
494 { "xauthlocation", sXAuthLocation, SSHCFG_GLOBAL },
495 { "strictmodes", sStrictModes, SSHCFG_GLOBAL },
496+ { "permitblacklistedkeys", sPermitBlacklistedKeys, SSHCFG_GLOBAL },
497 { "permitemptypasswords", sEmptyPasswd, SSHCFG_ALL },
498 { "permituserenvironment", sPermitUserEnvironment, SSHCFG_GLOBAL },
499 { "uselogin", sUseLogin, SSHCFG_GLOBAL },
500@@ -1158,6 +1162,10 @@
501 intptr = &options->tcp_keep_alive;
502 goto parse_flag;
503
504+ case sPermitBlacklistedKeys:
505+ intptr = &options->permit_blacklisted_keys;
506+ goto parse_flag;
507+
508 case sEmptyPasswd:
509 intptr = &options->permit_empty_passwd;
510 goto parse_flag;
511@@ -2036,6 +2044,7 @@
512 dump_cfg_fmtint(sX11UseLocalhost, o->x11_use_localhost);
513 dump_cfg_fmtint(sStrictModes, o->strict_modes);
514 dump_cfg_fmtint(sTCPKeepAlive, o->tcp_keep_alive);
515+ dump_cfg_fmtint(sPermitBlacklistedKeys, o->permit_blacklisted_keys);
516 dump_cfg_fmtint(sEmptyPasswd, o->permit_empty_passwd);
517 dump_cfg_fmtint(sPermitUserEnvironment, o->permit_user_env);
518 dump_cfg_fmtint(sUseLogin, o->use_login);
519Index: b/servconf.h
520===================================================================
521--- a/servconf.h
522+++ b/servconf.h
523@@ -121,6 +121,7 @@
524 int challenge_response_authentication;
525 int zero_knowledge_password_authentication;
526 /* If true, permit jpake auth */
527+ int permit_blacklisted_keys; /* If true, permit */
528 int permit_empty_passwd; /* If false, do not permit empty
529 * passwords. */
530 int permit_user_env; /* If true, read ~/.ssh/environment */
531Index: b/ssh-add.1
532===================================================================
533--- a/ssh-add.1
534+++ b/ssh-add.1
535@@ -81,6 +81,10 @@
536 .Nm
537 to work.
538 .Pp
539+Any keys recorded in the blacklist of known-compromised keys (see
540+.Xr ssh-vulnkey 1 )
541+will be refused.
542+.Pp
543 The options are as follows:
544 .Bl -tag -width Ds
545 .It Fl c
546@@ -186,6 +190,7 @@
547 .Xr ssh 1 ,
548 .Xr ssh-agent 1 ,
549 .Xr ssh-keygen 1 ,
550+.Xr ssh-vulnkey 1 ,
551 .Xr sshd 8
552 .Sh AUTHORS
553 OpenSSH is a derivative of the original and free
554Index: b/ssh-add.c
555===================================================================
556--- a/ssh-add.c
557+++ b/ssh-add.c
558@@ -167,7 +167,7 @@
559 add_file(AuthenticationConnection *ac, const char *filename, int key_only)
560 {
561 Key *private, *cert;
562- char *comment = NULL;
563+ char *comment = NULL, *fp;
564 char msg[1024], *certpath = NULL;
565 int fd, perms_ok, ret = -1;
566 Buffer keyblob;
567@@ -243,6 +243,14 @@
568 } else {
569 fprintf(stderr, "Could not add identity: %s\n", filename);
570 }
571+ if (blacklisted_key(private, &fp) == 1) {
572+ fprintf(stderr, "Public key %s blacklisted (see "
573+ "ssh-vulnkey(1)); refusing to add it\n", fp);
574+ free(fp);
575+ key_free(private);
576+ free(comment);
577+ return -1;
578+ }
579
580 /* Skip trying to load the cert if requested */
581 if (key_only)
582Index: b/ssh-keygen.1
583===================================================================
584--- a/ssh-keygen.1
585+++ b/ssh-keygen.1
586@@ -809,6 +809,7 @@
587 .Xr ssh 1 ,
588 .Xr ssh-add 1 ,
589 .Xr ssh-agent 1 ,
590+.Xr ssh-vulnkey 1 ,
591 .Xr moduli 5 ,
592 .Xr sshd 8
593 .Rs
594Index: b/ssh-vulnkey.1
595===================================================================
596--- /dev/null
597+++ b/ssh-vulnkey.1
598@@ -0,0 +1,242 @@
599+.\" Copyright (c) 2008 Canonical Ltd. All rights reserved.
600+.\"
601+.\" Redistribution and use in source and binary forms, with or without
602+.\" modification, are permitted provided that the following conditions
603+.\" are met:
604+.\" 1. Redistributions of source code must retain the above copyright
605+.\" notice, this list of conditions and the following disclaimer.
606+.\" 2. Redistributions in binary form must reproduce the above copyright
607+.\" notice, this list of conditions and the following disclaimer in the
608+.\" documentation and/or other materials provided with the distribution.
609+.\"
610+.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
611+.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
612+.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
613+.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
614+.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
615+.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
616+.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
617+.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
618+.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
619+.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
620+.\"
621+.Dd $Mdocdate: May 12 2008 $
622+.Dt SSH-VULNKEY 1
623+.Os
624+.Sh NAME
625+.Nm ssh-vulnkey
626+.Nd check blacklist of compromised keys
627+.Sh SYNOPSIS
628+.Nm
629+.Op Fl q | Fl v
630+.Ar file ...
631+.Nm
632+.Fl a
633+.Sh DESCRIPTION
634+.Nm
635+checks a key against a blacklist of compromised keys.
636+.Pp
637+A substantial number of keys are known to have been generated using a broken
638+version of OpenSSL distributed by Debian which failed to seed its random
639+number generator correctly.
640+Keys generated using these OpenSSL versions should be assumed to be
641+compromised.
642+This tool may be useful in checking for such keys.
643+.Pp
644+Keys that are compromised cannot be repaired; replacements must be generated
645+using
646+.Xr ssh-keygen 1 .
647+Make sure to update
648+.Pa authorized_keys
649+files on all systems where compromised keys were permitted to authenticate.
650+.Pp
651+The argument list will be interpreted as a list of paths to public key files
652+or
653+.Pa authorized_keys
654+files.
655+If no suitable file is found at a given path,
656+.Nm
657+will append
658+.Pa .pub
659+and retry, in case it was given a private key file.
660+If no files are given as arguments,
661+.Nm
662+will check
663+.Pa ~/.ssh/id_rsa ,
664+.Pa ~/.ssh/id_dsa ,
665+.Pa ~/.ssh/identity ,
666+.Pa ~/.ssh/authorized_keys
667+and
668+.Pa ~/.ssh/authorized_keys2 ,
669+as well as the system's host keys if readable.
670+.Pp
671+If
672+.Dq -
673+is given as an argument,
674+.Nm
675+will read from standard input.
676+This can be used to process output from
677+.Xr ssh-keyscan 1 ,
678+for example:
679+.Pp
680+.Dl $ ssh-keyscan -t rsa remote.example.org | ssh-vulnkey -
681+.Pp
682+Unless the
683+.Cm PermitBlacklistedKeys
684+option is used,
685+.Xr sshd 8
686+will reject attempts to authenticate with keys in the compromised list.
687+.Pp
688+The output from
689+.Nm
690+looks like this:
691+.Pp
692+.Bd -literal -offset indent
693+/etc/ssh/ssh_host_key:1: COMPROMISED: RSA1 2048 xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx root@host
694+/home/user/.ssh/id_dsa:1: Not blacklisted: DSA 1024 xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx /home/user/.ssh/id_dsa.pub
695+/home/user/.ssh/authorized_keys:3: Unknown (blacklist file not installed): RSA 1024 xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx user@host
696+.Ed
697+.Pp
698+Each line is of the following format (any lines beginning with
699+.Dq #
700+should be ignored by scripts):
701+.Pp
702+.Dl Ar filename : Ns Ar line : Ar status : Ar type Ar size Ar fingerprint Ar comment
703+.Pp
704+It is important to distinguish between the possible values of
705+.Ar status :
706+.Pp
707+.Bl -tag -width Ds
708+.It COMPROMISED
709+These keys are listed in a blacklist file, normally because their
710+corresponding private keys are well-known.
711+Replacements must be generated using
712+.Xr ssh-keygen 1 .
713+.It Not blacklisted
714+A blacklist file exists for this key type and size, but this key is not
715+listed in it.
716+Unless there is some particular reason to believe otherwise, this key
717+may be used safely.
718+(Note that DSA keys used with the broken version of OpenSSL distributed
719+by Debian may be compromised in the event that anyone captured a network
720+trace, even if they were generated with a secure version of OpenSSL.)
721+.It Unknown (blacklist file not installed)
722+No blacklist file exists for this key type and size.
723+You should find a suitable published blacklist and install it before
724+deciding whether this key is safe to use.
725+.El
726+.Pp
727+The options are as follows:
728+.Bl -tag -width Ds
729+.It Fl a
730+Check keys of all users on the system.
731+You will typically need to run
732+.Nm
733+as root to use this option.
734+For each user,
735+.Nm
736+will check
737+.Pa ~/.ssh/id_rsa ,
738+.Pa ~/.ssh/id_dsa ,
739+.Pa ~/.ssh/identity ,
740+.Pa ~/.ssh/authorized_keys
741+and
742+.Pa ~/.ssh/authorized_keys2 .
743+It will also check the system's host keys.
744+.It Fl q
745+Quiet mode.
746+Normally,
747+.Nm
748+outputs the fingerprint of each key scanned, with a description of its
749+status.
750+This option suppresses that output.
751+.It Fl v
752+Verbose mode.
753+Normally,
754+.Nm
755+does not output anything for keys that are not listed in their corresponding
756+blacklist file (although it still produces output for keys for which there
757+is no blacklist file, since their status is unknown).
758+This option causes
759+.Nm
760+to produce output for all keys.
761+.El
762+.Sh EXIT STATUS
763+.Nm
764+will exit zero if any of the given keys were in the compromised list,
765+otherwise non-zero.
766+.Sh BLACKLIST FILE FORMAT
767+The blacklist file may start with comments, on lines starting with
768+.Dq # .
769+After these initial comments, it must follow a strict format:
770+.Pp
771+.Bl -bullet -offset indent -compact
772+.It
773+All the lines must be exactly the same length (20 characters followed by a
774+newline) and must be in sorted order.
775+.It
776+Each line must consist of the lower-case hexadecimal MD5 key fingerprint,
777+without colons, and with the first 12 characters removed (that is, the least
778+significant 80 bits of the fingerprint).
779+.El
780+.Pp
781+The key fingerprint may be generated using
782+.Xr ssh-keygen 1 :
783+.Pp
784+.Dl $ ssh-keygen -l -f /path/to/key
785+.Pp
786+This strict format is necessary to allow the blacklist file to be checked
787+quickly, using a binary-search algorithm.
788+.Sh FILES
789+.Bl -tag -width Ds
790+.It Pa ~/.ssh/id_rsa
791+If present, contains the protocol version 2 RSA authentication identity of
792+the user.
793+.It Pa ~/.ssh/id_dsa
794+If present, contains the protocol version 2 DSA authentication identity of
795+the user.
796+.It Pa ~/.ssh/identity
797+If present, contains the protocol version 1 RSA authentication identity of
798+the user.
799+.It Pa ~/.ssh/authorized_keys
800+If present, lists the public keys (RSA/DSA) that can be used for logging in
801+as this user.
802+.It Pa ~/.ssh/authorized_keys2
803+Obsolete name for
804+.Pa ~/.ssh/authorized_keys .
805+This file may still be present on some old systems, but should not be
806+created if it is missing.
807+.It Pa /etc/ssh/ssh_host_rsa_key
808+If present, contains the protocol version 2 RSA identity of the system.
809+.It Pa /etc/ssh/ssh_host_dsa_key
810+If present, contains the protocol version 2 DSA identity of the system.
811+.It Pa /etc/ssh/ssh_host_key
812+If present, contains the protocol version 1 RSA identity of the system.
813+.It Pa /usr/share/ssh/blacklist. Ns Ar TYPE Ns Pa - Ns Ar LENGTH
814+If present, lists the blacklisted keys of type
815+.Ar TYPE
816+.Pf ( Dq RSA
817+or
818+.Dq DSA )
819+and bit length
820+.Ar LENGTH .
821+The format of this file is described above.
822+RSA1 keys are converted to RSA before being checked in the blacklist.
823+Note that the fingerprints of RSA1 keys are computed differently, so you
824+will not be able to find them in the blacklist by hand.
825+.It Pa /etc/ssh/blacklist. Ns Ar TYPE Ns Pa - Ns Ar LENGTH
826+Same as
827+.Pa /usr/share/ssh/blacklist. Ns Ar TYPE Ns Pa - Ns Ar LENGTH ,
828+but may be edited by the system administrator to add new blacklist entries.
829+.El
830+.Sh SEE ALSO
831+.Xr ssh-keygen 1 ,
832+.Xr sshd 8
833+.Sh AUTHORS
834+.An -nosplit
835+.An Colin Watson Aq cjwatson@ubuntu.com
836+.Pp
837+Florian Weimer suggested the option to check keys of all users, and the idea
838+of processing
839+.Xr ssh-keyscan 1
840+output.
841Index: b/ssh-vulnkey.c
842===================================================================
843--- /dev/null
844+++ b/ssh-vulnkey.c
845@@ -0,0 +1,386 @@
846+/*
847+ * Copyright (c) 2008 Canonical Ltd. All rights reserved.
848+ *
849+ * Redistribution and use in source and binary forms, with or without
850+ * modification, are permitted provided that the following conditions
851+ * are met:
852+ * 1. Redistributions of source code must retain the above copyright
853+ * notice, this list of conditions and the following disclaimer.
854+ * 2. Redistributions in binary form must reproduce the above copyright
855+ * notice, this list of conditions and the following disclaimer in the
856+ * documentation and/or other materials provided with the distribution.
857+ *
858+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
859+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
860+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
861+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
862+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
863+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
864+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
865+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
866+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
867+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
868+ */
869+
870+#include "includes.h"
871+
872+#include <sys/types.h>
873+#include <sys/stat.h>
874+
875+#include <errno.h>
876+#include <string.h>
877+#include <stdio.h>
878+#include <fcntl.h>
879+#include <unistd.h>
880+
881+#include <openssl/evp.h>
882+
883+#include "xmalloc.h"
884+#include "ssh.h"
885+#include "log.h"
886+#include "key.h"
887+#include "authfile.h"
888+#include "pathnames.h"
889+#include "uidswap.h"
890+#include "misc.h"
891+
892+extern char *__progname;
893+
894+/* Default files to check */
895+static char *default_host_files[] = {
896+ _PATH_HOST_RSA_KEY_FILE,
897+ _PATH_HOST_DSA_KEY_FILE,
898+ _PATH_HOST_KEY_FILE,
899+ NULL
900+};
901+static char *default_files[] = {
902+ _PATH_SSH_CLIENT_ID_RSA,
903+ _PATH_SSH_CLIENT_ID_DSA,
904+ _PATH_SSH_CLIENT_IDENTITY,
905+ _PATH_SSH_USER_PERMITTED_KEYS,
906+ _PATH_SSH_USER_PERMITTED_KEYS2,
907+ NULL
908+};
909+
910+static int verbosity = 0;
911+
912+static int some_keys = 0;
913+static int some_unknown = 0;
914+static int some_compromised = 0;
915+
916+static void
917+usage(void)
918+{
919+ fprintf(stderr, "usage: %s [-aqv] [file ...]\n", __progname);
920+ fprintf(stderr, "Options:\n");
921+ fprintf(stderr, " -a Check keys of all users.\n");
922+ fprintf(stderr, " -q Quiet mode.\n");
923+ fprintf(stderr, " -v Verbose mode.\n");
924+ exit(1);
925+}
926+
927+static void
928+describe_key(const char *filename, u_long linenum, const char *msg,
929+ Key *key, const char *comment, int min_verbosity)
930+{
931+ char *fp;
932+
933+ fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
934+ if (verbosity >= min_verbosity) {
935+ if (strchr(filename, ':'))
936+ printf("\"%s\"", filename);
937+ else
938+ printf("%s", filename);
939+ printf(":%lu: %s: %s %u %s %s\n", linenum, msg,
940+ key_type(key), key_size(key), fp, comment);
941+ }
942+ free(fp);
943+}
944+
945+static int
946+do_key(const char *filename, u_long linenum,
947+ Key *key, const char *comment)
948+{
949+ Key *public;
950+ int blacklist_status;
951+ int ret = 1;
952+
953+ some_keys = 1;
954+
955+ public = key_demote(key);
956+ if (public->type == KEY_RSA1)
957+ public->type = KEY_RSA;
958+
959+ blacklist_status = blacklisted_key(public, NULL);
960+ if (blacklist_status == -1) {
961+ describe_key(filename, linenum,
962+ "Unknown (blacklist file not installed)", key, comment, 0);
963+ some_unknown = 1;
964+ } else if (blacklist_status == 1) {
965+ describe_key(filename, linenum,
966+ "COMPROMISED", key, comment, 0);
967+ some_compromised = 1;
968+ ret = 0;
969+ } else
970+ describe_key(filename, linenum,
971+ "Not blacklisted", key, comment, 1);
972+
973+ key_free(public);
974+
975+ return ret;
976+}
977+
978+static int
979+do_filename(const char *filename, int quiet_open)
980+{
981+ FILE *f;
982+ char line[SSH_MAX_PUBKEY_BYTES];
983+ char *cp;
984+ u_long linenum = 0;
985+ Key *key;
986+ char *comment = NULL;
987+ int found = 0, ret = 1;
988+
989+ /* Copy much of key_load_public's logic here so that we can read
990+ * several keys from a single file (e.g. authorized_keys).
991+ */
992+
993+ if (strcmp(filename, "-") != 0) {
994+ int save_errno;
995+ f = fopen(filename, "r");
996+ save_errno = errno;
997+ if (!f) {
998+ char pubfile[MAXPATHLEN];
999+ if (strlcpy(pubfile, filename, sizeof pubfile) <
1000+ sizeof(pubfile) &&
1001+ strlcat(pubfile, ".pub", sizeof pubfile) <
1002+ sizeof(pubfile))
1003+ f = fopen(pubfile, "r");
1004+ }
1005+ errno = save_errno; /* earlier errno is more useful */
1006+ if (!f) {
1007+ if (!quiet_open)
1008+ perror(filename);
1009+ return -1;
1010+ }
1011+ if (verbosity > 0)
1012+ printf("# %s\n", filename);
1013+ } else
1014+ f = stdin;
1015+ while (read_keyfile_line(f, filename, line, sizeof(line),
1016+ &linenum) != -1) {
1017+ int i;
1018+ char *space;
1019+ int type;
1020+ char *end;
1021+
1022+ /* Chop trailing newline. */
1023+ i = strlen(line) - 1;
1024+ if (line[i] == '\n')
1025+ line[i] = '\0';
1026+
1027+ /* Skip leading whitespace, empty and comment lines. */
1028+ for (cp = line; *cp == ' ' || *cp == '\t'; cp++)
1029+ ;
1030+ if (!*cp || *cp == '\n' || *cp == '#')
1031+ continue;
1032+
1033+ /* Cope with ssh-keyscan output and options in
1034+ * authorized_keys files.
1035+ */
1036+ space = strchr(cp, ' ');
1037+ if (!space)
1038+ continue;
1039+ *space = '\0';
1040+ type = key_type_from_name(cp);
1041+ *space = ' ';
1042+ /* Leading number (RSA1) or valid type (RSA/DSA) indicates
1043+ * that we have no host name or options to skip.
1044+ */
1045+ if ((strtol(cp, &end, 10) == 0 || *end != ' ') &&
1046+ type == KEY_UNSPEC) {
1047+ int quoted = 0;
1048+
1049+ for (; *cp && (quoted || (*cp != ' ' && *cp != '\t')); cp++) {
1050+ if (*cp == '\\' && cp[1] == '"')
1051+ cp++; /* Skip both */
1052+ else if (*cp == '"')
1053+ quoted = !quoted;
1054+ }
1055+ /* Skip remaining whitespace. */
1056+ for (; *cp == ' ' || *cp == '\t'; cp++)
1057+ ;
1058+ if (!*cp)
1059+ continue;
1060+ }
1061+
1062+ /* Read and process the key itself. */
1063+ key = key_new(KEY_RSA1);
1064+ if (key_read(key, &cp) == 1) {
1065+ while (*cp == ' ' || *cp == '\t')
1066+ cp++;
1067+ if (!do_key(filename, linenum,
1068+ key, *cp ? cp : filename))
1069+ ret = 0;
1070+ found = 1;
1071+ } else {
1072+ key_free(key);
1073+ key = key_new(KEY_UNSPEC);
1074+ if (key_read(key, &cp) == 1) {
1075+ while (*cp == ' ' || *cp == '\t')
1076+ cp++;
1077+ if (!do_key(filename, linenum,
1078+ key, *cp ? cp : filename))
1079+ ret = 0;
1080+ found = 1;
1081+ }
1082+ }
1083+ key_free(key);
1084+ }
1085+ if (f != stdin)
1086+ fclose(f);
1087+
1088+ if (!found && filename) {
1089+ key = key_load_public(filename, &comment);
1090+ if (key) {
1091+ if (!do_key(filename, 1, key, comment))
1092+ ret = 0;
1093+ found = 1;
1094+ }
1095+ free(comment);
1096+ }
1097+
1098+ return ret;
1099+}
1100+
1101+static int
1102+do_host(int quiet_open)
1103+{
1104+ int i;
1105+ struct stat st;
1106+ int ret = 1;
1107+
1108+ for (i = 0; default_host_files[i]; i++) {
1109+ if (stat(default_host_files[i], &st) < 0 && errno == ENOENT)
1110+ continue;
1111+ if (!do_filename(default_host_files[i], quiet_open))
1112+ ret = 0;
1113+ }
1114+
1115+ return ret;
1116+}
1117+
1118+static int
1119+do_user(const char *dir)
1120+{
1121+ int i;
1122+ char *file;
1123+ struct stat st;
1124+ int ret = 1;
1125+
1126+ for (i = 0; default_files[i]; i++) {
1127+ xasprintf(&file, "%s/%s", dir, default_files[i]);
1128+ if (stat(file, &st) < 0 && errno == ENOENT) {
1129+ free(file);
1130+ continue;
1131+ }
1132+ if (!do_filename(file, 0))
1133+ ret = 0;
1134+ free(file);
1135+ }
1136+
1137+ return ret;
1138+}
1139+
1140+int
1141+main(int argc, char **argv)
1142+{
1143+ int opt, all_users = 0;
1144+ int ret = 1;
1145+ extern int optind;
1146+
1147+ /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1148+ sanitise_stdfd();
1149+
1150+ __progname = ssh_get_progname(argv[0]);
1151+
1152+ SSLeay_add_all_algorithms();
1153+ log_init(argv[0], SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_USER, 1);
1154+
1155+ /* We don't need the RNG ourselves, but symbol references here allow
1156+ * ld to link us properly.
1157+ */
1158+ seed_rng();
1159+
1160+ while ((opt = getopt(argc, argv, "ahqv")) != -1) {
1161+ switch (opt) {
1162+ case 'a':
1163+ all_users = 1;
1164+ break;
1165+ case 'q':
1166+ verbosity--;
1167+ break;
1168+ case 'v':
1169+ verbosity++;
1170+ break;
1171+ case 'h':
1172+ default:
1173+ usage();
1174+ }
1175+ }
1176+
1177+ if (all_users) {
1178+ struct passwd *pw;
1179+
1180+ if (!do_host(0))
1181+ ret = 0;
1182+
1183+ while ((pw = getpwent()) != NULL) {
1184+ if (pw->pw_dir) {
1185+ temporarily_use_uid(pw);
1186+ if (!do_user(pw->pw_dir))
1187+ ret = 0;
1188+ restore_uid();
1189+ }
1190+ }
1191+ } else if (optind == argc) {
1192+ struct passwd *pw;
1193+
1194+ if (!do_host(1))
1195+ ret = 0;
1196+
1197+ if ((pw = getpwuid(geteuid())) == NULL)
1198+ fprintf(stderr, "No user found with uid %u\n",
1199+ (u_int)geteuid());
1200+ else {
1201+ if (!do_user(pw->pw_dir))
1202+ ret = 0;
1203+ }
1204+ } else {
1205+ while (optind < argc)
1206+ if (!do_filename(argv[optind++], 0))
1207+ ret = 0;
1208+ }
1209+
1210+ if (verbosity >= 0) {
1211+ if (some_unknown) {
1212+ printf("#\n");
1213+ printf("# The status of some keys on your system is unknown.\n");
1214+ printf("# You may need to install additional blacklist files.\n");
1215+ }
1216+ if (some_compromised) {
1217+ printf("#\n");
1218+ printf("# Some keys on your system have been compromised!\n");
1219+ printf("# You must replace them using ssh-keygen(1).\n");
1220+ }
1221+ if (some_unknown || some_compromised) {
1222+ printf("#\n");
1223+ printf("# See the ssh-vulnkey(1) manual page for further advice.\n");
1224+ } else if (some_keys && verbosity > 0) {
1225+ printf("#\n");
1226+ printf("# No blacklisted keys!\n");
1227+ }
1228+ }
1229+
1230+ return ret;
1231+}
1232Index: b/ssh.1
1233===================================================================
1234--- a/ssh.1
1235+++ b/ssh.1
1236@@ -1447,6 +1447,7 @@
1237 .Xr ssh-agent 1 ,
1238 .Xr ssh-keygen 1 ,
1239 .Xr ssh-keyscan 1 ,
1240+.Xr ssh-vulnkey 1 ,
1241 .Xr tun 4 ,
1242 .Xr hosts.equiv 5 ,
1243 .Xr ssh_config 5 ,
1244Index: b/ssh.c
1245===================================================================
1246--- a/ssh.c
1247+++ b/ssh.c
1248@@ -1525,7 +1525,7 @@
1249 static void
1250 load_public_identity_files(void)
1251 {
1252- char *filename, *cp, thishost[NI_MAXHOST];
1253+ char *filename, *cp, thishost[NI_MAXHOST], *fp;
1254 char *pwdir = NULL, *pwname = NULL;
1255 int i = 0;
1256 Key *public;
1257@@ -1583,6 +1583,22 @@
1258 public = key_load_public(filename, NULL);
1259 debug("identity file %s type %d", filename,
1260 public ? public->type : -1);
1261+ if (public && blacklisted_key(public, &fp) == 1) {
1262+ if (options.use_blacklisted_keys)
1263+ logit("Public key %s blacklisted (see "
1264+ "ssh-vulnkey(1)); continuing anyway", fp);
1265+ else
1266+ logit("Public key %s blacklisted (see "
1267+ "ssh-vulnkey(1)); refusing to send it",
1268+ fp);
1269+ free(fp);
1270+ if (!options.use_blacklisted_keys) {
1271+ key_free(public);
1272+ free(filename);
1273+ filename = NULL;
1274+ public = NULL;
1275+ }
1276+ }
1277 free(options.identity_files[i]);
1278 identity_files[n_ids] = filename;
1279 identity_keys[n_ids] = public;
1280Index: b/ssh_config.5
1281===================================================================
1282--- a/ssh_config.5
1283+++ b/ssh_config.5
1284@@ -1229,6 +1229,23 @@
1285 .Dq any .
1286 The default is
1287 .Dq any:any .
1288+.It Cm UseBlacklistedKeys
1289+Specifies whether
1290+.Xr ssh 1
1291+should use keys recorded in its blacklist of known-compromised keys (see
1292+.Xr ssh-vulnkey 1 )
1293+for authentication.
1294+If
1295+.Dq yes ,
1296+then attempts to use compromised keys for authentication will be logged but
1297+accepted.
1298+It is strongly recommended that this be used only to install new authorized
1299+keys on the remote system, and even then only with the utmost care.
1300+If
1301+.Dq no ,
1302+then attempts to use compromised keys for authentication will be prevented.
1303+The default is
1304+.Dq no .
1305 .It Cm UsePrivilegedPort
1306 Specifies whether to use a privileged port for outgoing connections.
1307 The argument must be
1308Index: b/sshconnect2.c
1309===================================================================
1310--- a/sshconnect2.c
1311+++ b/sshconnect2.c
1312@@ -1491,6 +1491,8 @@
1313
1314 /* list of keys stored in the filesystem and PKCS#11 */
1315 for (i = 0; i < options.num_identity_files; i++) {
1316+ if (options.identity_files[i] == NULL)
1317+ continue;
1318 key = options.identity_keys[i];
1319 if (key && key->type == KEY_RSA1)
1320 continue;
1321@@ -1608,7 +1610,7 @@
1322 debug("Offering %s public key: %s", key_type(id->key),
1323 id->filename);
1324 sent = send_pubkey_test(authctxt, id);
1325- } else if (id->key == NULL) {
1326+ } else if (id->key == NULL && id->filename) {
1327 debug("Trying private key: %s", id->filename);
1328 id->key = load_identity_file(id->filename,
1329 id->userprovided);
1330Index: b/sshd.8
1331===================================================================
1332--- a/sshd.8
1333+++ b/sshd.8
1334@@ -954,6 +954,7 @@
1335 .Xr ssh-agent 1 ,
1336 .Xr ssh-keygen 1 ,
1337 .Xr ssh-keyscan 1 ,
1338+.Xr ssh-vulnkey 1 ,
1339 .Xr chroot 2 ,
1340 .Xr hosts_access 5 ,
1341 .Xr login.conf 5 ,
1342Index: b/sshd.c
1343===================================================================
1344--- a/sshd.c
1345+++ b/sshd.c
1346@@ -1688,6 +1688,11 @@
1347 sensitive_data.host_pubkeys[i] = NULL;
1348 continue;
1349 }
1350+ if (auth_key_is_revoked(key != NULL ? key : pubkey, 1)) {
1351+ sensitive_data.host_keys[i] = NULL;
1352+ sensitive_data.host_pubkeys[i] = NULL;
1353+ continue;
1354+ }
1355
1356 switch (keytype) {
1357 case KEY_RSA1:
1358Index: b/sshd_config.5
1359===================================================================
1360--- a/sshd_config.5
1361+++ b/sshd_config.5
1362@@ -885,6 +885,20 @@
1363 Specifies whether password authentication is allowed.
1364 The default is
1365 .Dq yes .
1366+.It Cm PermitBlacklistedKeys
1367+Specifies whether
1368+.Xr sshd 8
1369+should allow keys recorded in its blacklist of known-compromised keys (see
1370+.Xr ssh-vulnkey 1 ) .
1371+If
1372+.Dq yes ,
1373+then attempts to authenticate with compromised keys will be logged but
1374+accepted.
1375+If
1376+.Dq no ,
1377+then attempts to authenticate with compromised keys will be rejected.
1378+The default is
1379+.Dq no .
1380 .It Cm PermitEmptyPasswords
1381 When password authentication is allowed, it specifies whether the
1382 server allows login to accounts with empty password strings.
generated by cgit v1.2.3 (git 2.39.1) at 2024-07-19 00:02:59 +0000