fuse: revalidate group id cache on uid/gid change detection

- Remember the uid and gid of the pid at the time of caching
  the group id list.

- Next time when referring to the cache confirm that uid and gid
  of that pid has not changed since. If it has, treat it like
  a timeout/cache miss.

- Solves group id caching issue caused when Samba runs on gluster
  FUSE mount and changes the uid/gid on a per syscall basis.

Change-Id: I3382b037ff0b6d5eaaa36d9c898232543475aeda
BUG: 1032438
Signed-off-by: Anand Avati <avati@redhat.com>
Reviewed-on: http://review.gluster.org/6320
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Amar Tumballi <amarts@redhat.com>

1 files changed, 15 insertions, 1 deletions

diff --git a/libglusterfs/src/gidcache.c b/libglusterfs/src/gidcache.c
index c5bdda92596..f2d98abefc3 100644
--- a/libglusterfs/src/gidcache.c
+++ b/libglusterfs/src/gidcache.c
@@ -54,7 +54,8 @@ int gid_cache_reconf(gid_cache_t *cache, uint32_t timeout)
  * an additional allocation and memory copy. The caller should copy the data and
  * release (unlock) the cache as soon as possible.
  */
-const gid_list_t *gid_cache_lookup(gid_cache_t *cache, uint64_t id)
+const gid_list_t *gid_cache_lookup(gid_cache_t *cache, uint64_t id,
+				   uint64_t uid, uint64_t gid)
 {
 	int bucket;
 	int i;
@@ -72,6 +73,17 @@ const gid_list_t *gid_cache_lookup(gid_cache_t *cache, uint64_t id)
 			continue;
 
 		/*
+		  @uid and @gid reflect the latest UID/GID of the
+		   process performing the syscall (taken from frame->root).
+
+		   If the UID and GID has changed for the PID since the
+		   time we cached it, we should treat the cache as having
+		   stale values and query them freshly.
+		*/
+		if (agl->gl_uid != uid || agl->gl_gid != gid)
+			break;
+
+		/*
 		 * We don't put new entries in the cache when expiration=0, but
 		 * there might be entries still in there if expiration was
 		 * changed very recently.  Writing the check this way ensures
@@ -182,6 +194,8 @@ int gid_cache_add(gid_cache_t *cache, gid_list_t *gl)
 	}
 
 	agl->gl_id = gl->gl_id;
+	agl->gl_uid = gl->gl_uid;
+	agl->gl_gid = gl->gl_gid;
 	agl->gl_count = gl->gl_count;
 	agl->gl_list = gl->gl_list;
 	agl->gl_deadline = now + cache->gc_max_age;