- (djm) [groupaccess.c uidswap.c] Bug #787: Size group arrays at runtime

   using sysconf() if available Based on patches from
   holger AT van-lengerich.de and openssh_bugzilla AT hockin.org

1 files changed, 24 insertions, 3 deletions

diff --git a/uidswap.c b/uidswap.c
index 4cabaa444..e652161af 100644
--- a/uidswap.c
+++ b/uidswap.c
@@ -16,6 +16,7 @@ RCSID("$OpenBSD: uidswap.c,v 1.24 2003/05/29 16:58:45 deraadt Exp $");
 
 #include "log.h"
 #include "uidswap.h"
+#include "xmalloc.h"
 
 /*
  * Note: all these functions must work in all of the following cases:
@@ -38,7 +39,7 @@ static gid_t	saved_egid = 0;
 /* Saved effective uid. */
 static int      privileged = 0;
 static int      temporarily_use_uid_effective = 0;
-static gid_t    saved_egroups[NGROUPS_MAX], user_groups[NGROUPS_MAX];
+static gid_t    *saved_egroups = NULL, *user_groups = NULL;
 static int      saved_egroupslen = -1, user_groupslen = -1;
 
 /*
@@ -68,18 +69,38 @@ temporarily_use_uid(struct passwd *pw)
 
         privileged = 1;
         temporarily_use_uid_effective = 1;
-        saved_egroupslen = getgroups(NGROUPS_MAX, saved_egroups);
+
+        saved_egroupslen = getgroups(0, NULL);
         if (saved_egroupslen < 0)
                 fatal("getgroups: %.100s", strerror(errno));
+        if (saved_egroupslen > 0) {
+                saved_egroups = xrealloc(saved_egroups,
+                    saved_egroupslen * sizeof(gid_t));
+                if (getgroups(saved_egroupslen, saved_egroups) < 0)
+                        fatal("getgroups: %.100s", strerror(errno));
+        } else { /* saved_egroupslen == 0 */
+                if (saved_egroups)
+                        xfree(saved_egroups);
+        }
 
         /* set and save the user's groups */
         if (user_groupslen == -1) {
                 if (initgroups(pw->pw_name, pw->pw_gid) < 0)
                         fatal("initgroups: %s: %.100s", pw->pw_name,
                             strerror(errno));
-                user_groupslen = getgroups(NGROUPS_MAX, user_groups);
+
+                user_groupslen = getgroups(0, NULL);
                 if (user_groupslen < 0)
                         fatal("getgroups: %.100s", strerror(errno));
+                if (user_groupslen > 0) {
+                        user_groups = xrealloc(user_groups,
+                            user_groupslen * sizeof(gid_t));
+                        if (getgroups(user_groupslen, user_groups) < 0)
+                                fatal("getgroups: %.100s", strerror(errno));
+                } else { /* user_groupslen == 0 */
+                        if (user_groups)
+                                xfree(user_groups);
+                }
         }
         /* Set the effective uid to the given (unprivileged) uid. */
         if (setgroups(user_groupslen, user_groups) < 0)