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: 2013-09-14

Patch-Name: user-group-modes.patch

1 files changed, 3 insertions, 2 deletions

diff --git a/readconf.c b/readconf.c
index 2dcbf3187..389de7d60 100644
--- a/readconf.c
+++ b/readconf.c
@@ -30,6 +30,8 @@
 #include <stdio.h>
 #include <string.h>
 #include <unistd.h>
+#include <pwd.h>
+#include <grp.h>
 #ifdef HAVE_UTIL_H
 #include <util.h>
 #endif
@@ -1160,8 +1162,7 @@ read_config_file(const char *filename, const char *host, Options *options,
 
                 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);
         }