This is the second attempt at this patch. The main changes are that this
one doesn't set a floor value for the size of the group list. There are
also a few minor cleanups and comments added.
If authunix_create_default() is called by a user with more than 16
supplimental groups, it'll abort(), which causes the program to crash
and coredump.
Fix it to handle this situation gracefully. Get the number of groups
that the user has first, and then allocate a big enough buffer to hold
them. Then, just don't let the lower function use more than the NGRPS
groups.
Also fix up the error handling in this function so that it just returns
a NULL pointer on error and logs a message via warnx() instead of
calling abort().
Reported-by: Peter Engel <peter.engel@xxxxxxx>
Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
---
src/auth_unix.c | 62 +++++++++++++++++++++++++++++++++++++++++++++++++-----
1 files changed, 56 insertions(+), 6 deletions(-)
diff --git a/src/auth_unix.c b/src/auth_unix.c
index 71ca15d..a295e71 100644
--- a/src/auth_unix.c
+++ b/src/auth_unix.c
@@ -49,6 +49,7 @@
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
+#include <errno.h>
#include <rpc/types.h>
#include <rpc/xdr.h>
@@ -175,20 +176,69 @@ AUTH *
authunix_create_default()
{
int len;
+ size_t bufsize = 0;
char machname[MAXHOSTNAMELEN + 1];
uid_t uid;
gid_t gid;
- gid_t gids[NGRPS];
+ gid_t *gids = NULL;
+ AUTH *auth;
+
+ if (gethostname(machname, sizeof machname) == -1) {
+ warnx("%s: gethostname() failed: %s", __func__,
+ strerror(errno));
+ return NULL;
+ }
- if (gethostname(machname, sizeof machname) == -1)
- abort();
machname[sizeof(machname) - 1] = 0;
uid = geteuid();
gid = getegid();
- if ((len = getgroups(NGRPS, gids)) < 0)
- abort();
+
+retry:
+ len = getgroups(0, NULL);
+ if (len < 0) {
+ warnx("%s: failed to get number of groups: %s", __func__,
+ strerror(errno));
+ return NULL;
+ }
+
+ if (len == 0)
+ goto no_groups;
+
+ bufsize = len * sizeof(gid_t);
+ gids = mem_alloc(bufsize);
+ if (gids == NULL) {
+ warnx("%s: memory allocation failed: %s", __func__,
+ strerror(ENOMEM));
+ return NULL;
+ }
+
+ len = getgroups(len, gids);
+ if (len < 0) {
+ mem_free(gids, bufsize);
+ /*
+ * glibc equivalent routines mention that it's possible for
+ * the number of groups to change between two getgroups calls.
+ * If that happens, retry the whole thing again.
+ */
+ if (len == -EINVAL) {
+ gids = NULL;
+ bufsize = 0;
+ goto retry;
+ }
+ warnx("%s: failed to get group list: %s", __func__,
+ strerror(errno));
+ return NULL;
+ }
+
+ /* AUTH_UNIX has a hard limit of NGRPS supplemental groups */
+ if (len > NGRPS)
+ len = NGRPS;
+
+no_groups:
/* XXX: interface problem; those should all have been unsigned */
- return (authunix_create(machname, uid, gid, len, gids));
+ auth = authunix_create(machname, uid, gid, len, gids);
+ mem_free(gids, bufsize);
+ return auth;
}
/*
--
1.6.6
--
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