- (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

ChangeLog

@@ -16,6 +16,9 @@
  - (dtucker) [configure.ac gss-serv-krb5.c ssh-gss.h] Define GSSAPI when found
    with krb5-config, hunt down gssapi.h and friends.  Based partially on patch
    from deengert at anl.gov.  ok djm@
+ - (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
 
 20040223
  - (dtucker) [session.c] Bug #789: Only make setcred call for !privsep in the
@@ -1919,4 +1922,4 @@
  - Fix sshd BindAddress and -b options for systems using fake-getaddrinfo.
    Report from murple@murple.net, diagnosis from dtucker@zip.com.au
 
-$Id: ChangeLog,v 1.3249 2004/02/23 23:58:10 dtucker Exp $
+$Id: ChangeLog,v 1.3250 2004/02/24 02:05:11 djm Exp $

groupaccess.c

@@ -31,7 +31,7 @@ RCSID("$OpenBSD: groupaccess.c,v 1.6 2003/04/08 20:21:28 itojun Exp $");
 #include "log.h"
 
 static int ngroups;
-static char *groups_byname[NGROUPS_MAX + 1];	/* +1 for base/primary group */
+static char **groups_byname;
 
 /*
  * Initialize group access list for user with primary (base) and
@@ -40,19 +40,27 @@ static char *groups_byname[NGROUPS_MAX + 1];	/* +1 for base/primary group */
 int
 ga_init(const char *user, gid_t base)
 {
-	gid_t groups_bygid[NGROUPS_MAX + 1];
+	gid_t *groups_bygid;
 	int i, j;
 	struct group *gr;
 
 	if (ngroups > 0)
 		ga_free();
 
-	ngroups = sizeof(groups_bygid) / sizeof(gid_t);
+	ngroups = NGROUPS_MAX;
+#if defined(HAVE_SYSCONF) && defined(_SC_NGROUPS_MAX)
+	ngroups = MAX(NGROUPS_MAX, sysconf(_SC_NGROUPS_MAX));
+#endif
+
+	groups_bygid = xmalloc(ngroups * sizeof(*groups_bygid));
+	groups_byname = xmalloc(ngroups * sizeof(*groups_byname));
+
 	if (getgrouplist(user, base, groups_bygid, &ngroups) == -1)
 		logit("getgrouplist: groups list too small");
 	for (i = 0, j = 0; i < ngroups; i++)
 		if ((gr = getgrgid(groups_bygid[i])) != NULL)
 			groups_byname[j++] = xstrdup(gr->gr_name);
+	xfree(groups_bygid);
 	return (ngroups = j);
 }
 
@@ -84,5 +92,6 @@ ga_free(void)
 		for (i = 0; i < ngroups; i++)
 			xfree(groups_byname[i]);
 		ngroups = 0;
+		xfree(groups_byname);
 	}
 }

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)