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-rw-r--r--debian/patches/user-group-modes.patch266
1 files changed, 266 insertions, 0 deletions
diff --git a/debian/patches/user-group-modes.patch b/debian/patches/user-group-modes.patch
new file mode 100644
index 000000000..98d37d36c
--- /dev/null
+++ b/debian/patches/user-group-modes.patch
@@ -0,0 +1,266 @@
1From aae427a0c7d5702bf294191533ab1f33437a8a56 Mon Sep 17 00:00:00 2001
2From: Colin Watson <cjwatson@debian.org>
3Date: Sun, 9 Feb 2014 16:09:58 +0000
4Subject: Allow harmless group-writability
5
6Allow secure files (~/.ssh/config, ~/.ssh/authorized_keys, etc.) to be
7group-writable, provided that the group in question contains only the file's
8owner. Rejected upstream for IMO incorrect reasons (e.g. a misunderstanding
9about the contents of gr->gr_mem). Given that per-user groups and umask 002
10are the default setup in Debian (for good reasons - this makes operating in
11setgid directories with other groups much easier), we need to permit this by
12default.
13
14Bug: https://bugzilla.mindrot.org/show_bug.cgi?id=1060
15Bug-Debian: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=314347
16Last-Update: 2013-09-14
17
18Patch-Name: user-group-modes.patch
19---
20 auth-rhosts.c | 6 ++----
21 auth.c | 9 +++-----
22 misc.c | 69 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
23 misc.h | 2 ++
24 platform.c | 16 --------------
25 readconf.c | 5 +++--
26 ssh.1 | 2 ++
27 ssh_config.5 | 2 ++
28 8 files changed, 82 insertions(+), 29 deletions(-)
29
30diff --git a/auth-rhosts.c b/auth-rhosts.c
31index ee9e827..2ff2cff 100644
32--- a/auth-rhosts.c
33+++ b/auth-rhosts.c
34@@ -271,8 +271,7 @@ auth_rhosts2_raw(struct passwd *pw, const char *client_user, const char *hostnam
35 return 0;
36 }
37 if (options.strict_modes &&
38- ((st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
39- (st.st_mode & 022) != 0)) {
40+ !secure_permissions(&st, pw->pw_uid)) {
41 logit("Rhosts authentication refused for %.100s: "
42 "bad ownership or modes for home directory.", pw->pw_name);
43 auth_debug_add("Rhosts authentication refused for %.100s: "
44@@ -298,8 +297,7 @@ auth_rhosts2_raw(struct passwd *pw, const char *client_user, const char *hostnam
45 * allowing access to their account by anyone.
46 */
47 if (options.strict_modes &&
48- ((st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
49- (st.st_mode & 022) != 0)) {
50+ !secure_permissions(&st, pw->pw_uid)) {
51 logit("Rhosts authentication refused for %.100s: bad modes for %.200s",
52 pw->pw_name, buf);
53 auth_debug_add("Bad file modes for %.200s", buf);
54diff --git a/auth.c b/auth.c
55index 214c2c7..25be632 100644
56--- a/auth.c
57+++ b/auth.c
58@@ -424,8 +424,7 @@ check_key_in_hostfiles(struct passwd *pw, Key *key, const char *host,
59 user_hostfile = tilde_expand_filename(userfile, pw->pw_uid);
60 if (options.strict_modes &&
61 (stat(user_hostfile, &st) == 0) &&
62- ((st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
63- (st.st_mode & 022) != 0)) {
64+ !secure_permissions(&st, pw->pw_uid)) {
65 logit("Authentication refused for %.100s: "
66 "bad owner or modes for %.200s",
67 pw->pw_name, user_hostfile);
68@@ -487,8 +486,7 @@ auth_secure_path(const char *name, struct stat *stp, const char *pw_dir,
69 snprintf(err, errlen, "%s is not a regular file", buf);
70 return -1;
71 }
72- if ((!platform_sys_dir_uid(stp->st_uid) && stp->st_uid != uid) ||
73- (stp->st_mode & 022) != 0) {
74+ if (!secure_permissions(stp, uid)) {
75 snprintf(err, errlen, "bad ownership or modes for file %s",
76 buf);
77 return -1;
78@@ -503,8 +501,7 @@ auth_secure_path(const char *name, struct stat *stp, const char *pw_dir,
79 strlcpy(buf, cp, sizeof(buf));
80
81 if (stat(buf, &st) < 0 ||
82- (!platform_sys_dir_uid(st.st_uid) && st.st_uid != uid) ||
83- (st.st_mode & 022) != 0) {
84+ !secure_permissions(&st, uid)) {
85 snprintf(err, errlen,
86 "bad ownership or modes for directory %s", buf);
87 return -1;
88diff --git a/misc.c b/misc.c
89index ddd2b2d..1c063ea 100644
90--- a/misc.c
91+++ b/misc.c
92@@ -50,8 +50,9 @@
93 #include <netdb.h>
94 #ifdef HAVE_PATHS_H
95 # include <paths.h>
96-#include <pwd.h>
97 #endif
98+#include <pwd.h>
99+#include <grp.h>
100 #ifdef SSH_TUN_OPENBSD
101 #include <net/if.h>
102 #endif
103@@ -60,6 +61,7 @@
104 #include "misc.h"
105 #include "log.h"
106 #include "ssh.h"
107+#include "platform.h"
108
109 /* remove newline at end of string */
110 char *
111@@ -644,6 +646,71 @@ read_keyfile_line(FILE *f, const char *filename, char *buf, size_t bufsz,
112 return -1;
113 }
114
115+/*
116+ * return 1 if the specified uid is a uid that may own a system directory
117+ * otherwise 0.
118+ */
119+int
120+platform_sys_dir_uid(uid_t uid)
121+{
122+ if (uid == 0)
123+ return 1;
124+#ifdef PLATFORM_SYS_DIR_UID
125+ if (uid == PLATFORM_SYS_DIR_UID)
126+ return 1;
127+#endif
128+ return 0;
129+}
130+
131+int
132+secure_permissions(struct stat *st, uid_t uid)
133+{
134+ if (!platform_sys_dir_uid(st->st_uid) && st->st_uid != uid)
135+ return 0;
136+ if ((st->st_mode & 002) != 0)
137+ return 0;
138+ if ((st->st_mode & 020) != 0) {
139+ /* If the file is group-writable, the group in question must
140+ * have exactly one member, namely the file's owner.
141+ * (Zero-member groups are typically used by setgid
142+ * binaries, and are unlikely to be suitable.)
143+ */
144+ struct passwd *pw;
145+ struct group *gr;
146+ int members = 0;
147+
148+ gr = getgrgid(st->st_gid);
149+ if (!gr)
150+ return 0;
151+
152+ /* Check primary group memberships. */
153+ while ((pw = getpwent()) != NULL) {
154+ if (pw->pw_gid == gr->gr_gid) {
155+ ++members;
156+ if (pw->pw_uid != uid)
157+ return 0;
158+ }
159+ }
160+ endpwent();
161+
162+ pw = getpwuid(st->st_uid);
163+ if (!pw)
164+ return 0;
165+
166+ /* Check supplementary group memberships. */
167+ if (gr->gr_mem[0]) {
168+ ++members;
169+ if (strcmp(pw->pw_name, gr->gr_mem[0]) ||
170+ gr->gr_mem[1])
171+ return 0;
172+ }
173+
174+ if (!members)
175+ return 0;
176+ }
177+ return 1;
178+}
179+
180 int
181 tun_open(int tun, int mode)
182 {
183diff --git a/misc.h b/misc.h
184index 374c33c..89e1f75 100644
185--- a/misc.h
186+++ b/misc.h
187@@ -135,4 +135,6 @@ char *read_passphrase(const char *, int);
188 int ask_permission(const char *, ...) __attribute__((format(printf, 1, 2)));
189 int read_keyfile_line(FILE *, const char *, char *, size_t, u_long *);
190
191+int secure_permissions(struct stat *st, uid_t uid);
192+
193 #endif /* _MISC_H */
194diff --git a/platform.c b/platform.c
195index f35ec39..9a23e6e 100644
196--- a/platform.c
197+++ b/platform.c
198@@ -197,19 +197,3 @@ platform_krb5_get_principal_name(const char *pw_name)
199 return NULL;
200 #endif
201 }
202-
203-/*
204- * return 1 if the specified uid is a uid that may own a system directory
205- * otherwise 0.
206- */
207-int
208-platform_sys_dir_uid(uid_t uid)
209-{
210- if (uid == 0)
211- return 1;
212-#ifdef PLATFORM_SYS_DIR_UID
213- if (uid == PLATFORM_SYS_DIR_UID)
214- return 1;
215-#endif
216- return 0;
217-}
218diff --git a/readconf.c b/readconf.c
219index 46c343f..c0ba5a7 100644
220--- a/readconf.c
221+++ b/readconf.c
222@@ -39,6 +39,8 @@
223 #include <stdio.h>
224 #include <string.h>
225 #include <unistd.h>
226+#include <pwd.h>
227+#include <grp.h>
228 #ifdef HAVE_UTIL_H
229 #include <util.h>
230 #endif
231@@ -1579,8 +1581,7 @@ read_config_file(const char *filename, struct passwd *pw, const char *host,
232
233 if (fstat(fileno(f), &sb) == -1)
234 fatal("fstat %s: %s", filename, strerror(errno));
235- if (((sb.st_uid != 0 && sb.st_uid != getuid()) ||
236- (sb.st_mode & 022) != 0))
237+ if (!secure_permissions(&sb, getuid()))
238 fatal("Bad owner or permissions on %s", filename);
239 }
240
241diff --git a/ssh.1 b/ssh.1
242index 2ea0a20..ff80022 100644
243--- a/ssh.1
244+++ b/ssh.1
245@@ -1458,6 +1458,8 @@ The file format and configuration options are described in
246 .Xr ssh_config 5 .
247 Because of the potential for abuse, this file must have strict permissions:
248 read/write for the user, and not writable by others.
249+It may be group-writable provided that the group in question contains only
250+the user.
251 .Pp
252 .It Pa ~/.ssh/environment
253 Contains additional definitions for environment variables; see
254diff --git a/ssh_config.5 b/ssh_config.5
255index 78e918a..1e9c058 100644
256--- a/ssh_config.5
257+++ b/ssh_config.5
258@@ -1757,6 +1757,8 @@ The format of this file is described above.
259 This file is used by the SSH client.
260 Because of the potential for abuse, this file must have strict permissions:
261 read/write for the user, and not accessible by others.
262+It may be group-writable provided that the group in question contains only
263+the user.
264 .It Pa /etc/ssh/ssh_config
265 Systemwide configuration file.
266 This file provides defaults for those
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-06 19:26:18 +0000