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-rw-r--r--debian/patches/user-group-modes.patch210
1 files changed, 210 insertions, 0 deletions
diff --git a/debian/patches/user-group-modes.patch b/debian/patches/user-group-modes.patch
new file mode 100644
index 0000000..bc2390e
--- /dev/null
+++ b/debian/patches/user-group-modes.patch
@@ -0,0 +1,210 @@
+From 7b931d36ad36a93d2b1811858ca29408ec44ecae Mon Sep 17 00:00:00 2001
+From: Colin Watson <cjwatson@debian.org>
+Date: Sun, 9 Feb 2014 16:09:58 +0000
+Subject: Allow harmless group-writability
+
+Allow secure files (~/.ssh/config, ~/.ssh/authorized_keys, etc.) to be
+group-writable, provided that the group in question contains only the file's
+owner. Rejected upstream for IMO incorrect reasons (e.g. a misunderstanding
+about the contents of gr->gr_mem). Given that per-user groups and umask 002
+are the default setup in Debian (for good reasons - this makes operating in
+setgid directories with other groups much easier), we need to permit this by
+default.
+
+Bug: https://bugzilla.mindrot.org/show_bug.cgi?id=1060
+Bug-Debian: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=314347
+Last-Update: 2017-10-04
+
+Patch-Name: user-group-modes.patch
+---
+ auth-rhosts.c | 6 ++----
+ auth.c | 3 +--
+ misc.c | 58 ++++++++++++++++++++++++++++++++++++++++++++++-----
+ misc.h | 2 ++
+ readconf.c | 3 +--
+ ssh.1 | 2 ++
+ ssh_config.5 | 2 ++
+ 7 files changed, 63 insertions(+), 13 deletions(-)
+
+diff --git a/auth-rhosts.c b/auth-rhosts.c
+index 57296e1f6..546aa0495 100644
+--- a/auth-rhosts.c
++++ b/auth-rhosts.c
+@@ -261,8 +261,7 @@ auth_rhosts2(struct passwd *pw, const char *client_user, const char *hostname,
+ return 0;
+ }
+ if (options.strict_modes &&
+- ((st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
+- (st.st_mode & 022) != 0)) {
++ !secure_permissions(&st, pw->pw_uid)) {
+ logit("Rhosts authentication refused for %.100s: "
+ "bad ownership or modes for home directory.", pw->pw_name);
+ auth_debug_add("Rhosts authentication refused for %.100s: "
+@@ -288,8 +287,7 @@ auth_rhosts2(struct passwd *pw, const char *client_user, const char *hostname,
+ * allowing access to their account by anyone.
+ */
+ if (options.strict_modes &&
+- ((st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
+- (st.st_mode & 022) != 0)) {
++ !secure_permissions(&st, pw->pw_uid)) {
+ logit("Rhosts authentication refused for %.100s: bad modes for %.200s",
+ pw->pw_name, buf);
+ auth_debug_add("Bad file modes for %.200s", buf);
+diff --git a/auth.c b/auth.c
+index d8e6b4a3d..9d1d453f1 100644
+--- a/auth.c
++++ b/auth.c
+@@ -473,8 +473,7 @@ check_key_in_hostfiles(struct passwd *pw, struct sshkey *key, const char *host,
+ user_hostfile = tilde_expand_filename(userfile, pw->pw_uid);
+ if (options.strict_modes &&
+ (stat(user_hostfile, &st) == 0) &&
+- ((st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
+- (st.st_mode & 022) != 0)) {
++ !secure_permissions(&st, pw->pw_uid)) {
+ logit("Authentication refused for %.100s: "
+ "bad owner or modes for %.200s",
+ pw->pw_name, user_hostfile);
+diff --git a/misc.c b/misc.c
+index bdc06fdb3..5159e6692 100644
+--- a/misc.c
++++ b/misc.c
+@@ -58,8 +58,9 @@
+ #include <netdb.h>
+ #ifdef HAVE_PATHS_H
+ # include <paths.h>
+-#include <pwd.h>
+ #endif
++#include <pwd.h>
++#include <grp.h>
+ #ifdef SSH_TUN_OPENBSD
+ #include <net/if.h>
+ #endif
+@@ -1028,6 +1029,55 @@ percent_expand(const char *string, ...)
+ #undef EXPAND_MAX_KEYS
+ }
+
++int
++secure_permissions(struct stat *st, uid_t uid)
++{
++ if (!platform_sys_dir_uid(st->st_uid) && st->st_uid != uid)
++ return 0;
++ if ((st->st_mode & 002) != 0)
++ return 0;
++ if ((st->st_mode & 020) != 0) {
++ /* If the file is group-writable, the group in question must
++ * have exactly one member, namely the file's owner.
++ * (Zero-member groups are typically used by setgid
++ * binaries, and are unlikely to be suitable.)
++ */
++ struct passwd *pw;
++ struct group *gr;
++ int members = 0;
++
++ gr = getgrgid(st->st_gid);
++ if (!gr)
++ return 0;
++
++ /* Check primary group memberships. */
++ while ((pw = getpwent()) != NULL) {
++ if (pw->pw_gid == gr->gr_gid) {
++ ++members;
++ if (pw->pw_uid != uid)
++ return 0;
++ }
++ }
++ endpwent();
++
++ pw = getpwuid(st->st_uid);
++ if (!pw)
++ return 0;
++
++ /* Check supplementary group memberships. */
++ if (gr->gr_mem[0]) {
++ ++members;
++ if (strcmp(pw->pw_name, gr->gr_mem[0]) ||
++ gr->gr_mem[1])
++ return 0;
++ }
++
++ if (!members)
++ return 0;
++ }
++ return 1;
++}
++
+ int
+ tun_open(int tun, int mode, char **ifname)
+ {
+@@ -1786,8 +1836,7 @@ safe_path(const char *name, struct stat *stp, const char *pw_dir,
+ snprintf(err, errlen, "%s is not a regular file", buf);
+ return -1;
+ }
+- if ((!platform_sys_dir_uid(stp->st_uid) && stp->st_uid != uid) ||
+- (stp->st_mode & 022) != 0) {
++ if (!secure_permissions(stp, uid)) {
+ snprintf(err, errlen, "bad ownership or modes for file %s",
+ buf);
+ return -1;
+@@ -1802,8 +1851,7 @@ safe_path(const char *name, struct stat *stp, const char *pw_dir,
+ strlcpy(buf, cp, sizeof(buf));
+
+ if (stat(buf, &st) < 0 ||
+- (!platform_sys_dir_uid(st.st_uid) && st.st_uid != uid) ||
+- (st.st_mode & 022) != 0) {
++ !secure_permissions(&st, uid)) {
+ snprintf(err, errlen,
+ "bad ownership or modes for directory %s", buf);
+ return -1;
+diff --git a/misc.h b/misc.h
+index 31b207a8d..aaf966e65 100644
+--- a/misc.h
++++ b/misc.h
+@@ -168,6 +168,8 @@ int safe_path_fd(int, const char *, struct passwd *,
+ char *read_passphrase(const char *, int);
+ int ask_permission(const char *, ...) __attribute__((format(printf, 1, 2)));
+
++int secure_permissions(struct stat *st, uid_t uid);
++
+ #define MINIMUM(a, b) (((a) < (b)) ? (a) : (b))
+ #define MAXIMUM(a, b) (((a) > (b)) ? (a) : (b))
+ #define ROUNDUP(x, y) ((((x)+((y)-1))/(y))*(y))
+diff --git a/readconf.c b/readconf.c
+index 052d4b1ac..6b01f20d2 100644
+--- a/readconf.c
++++ b/readconf.c
+@@ -1820,8 +1820,7 @@ read_config_file_depth(const char *filename, struct passwd *pw,
+
+ if (fstat(fileno(f), &sb) == -1)
+ fatal("fstat %s: %s", filename, strerror(errno));
+- if (((sb.st_uid != 0 && sb.st_uid != getuid()) ||
+- (sb.st_mode & 022) != 0))
++ if (!secure_permissions(&sb, getuid()))
+ fatal("Bad owner or permissions on %s", filename);
+ }
+
+diff --git a/ssh.1 b/ssh.1
+index 7760c3075..81f29af43 100644
+--- a/ssh.1
++++ b/ssh.1
+@@ -1485,6 +1485,8 @@ The file format and configuration options are described in
+ .Xr ssh_config 5 .
+ Because of the potential for abuse, this file must have strict permissions:
+ read/write for the user, and not writable by others.
++It may be group-writable provided that the group in question contains only
++the user.
+ .Pp
+ .It Pa ~/.ssh/environment
+ Contains additional definitions for environment variables; see
+diff --git a/ssh_config.5 b/ssh_config.5
+index 54e143c93..7d55fa820 100644
+--- a/ssh_config.5
++++ b/ssh_config.5
+@@ -1835,6 +1835,8 @@ The format of this file is described above.
+ This file is used by the SSH client.
+ Because of the potential for abuse, this file must have strict permissions:
+ read/write for the user, and not accessible by others.
++It may be group-writable provided that the group in question contains only
++the user.
+ .It Pa /etc/ssh/ssh_config
+ Systemwide configuration file.
+ This file provides defaults for those