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>

4 files changed, 25 insertions, 4 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;
diff --git a/libglusterfs/src/gidcache.h b/libglusterfs/src/gidcache.h
index 9379f8e8b01..886721e719f 100644
--- a/libglusterfs/src/gidcache.h
+++ b/libglusterfs/src/gidcache.h
@@ -32,6 +32,8 @@
 
 typedef struct {
 	uint64_t	gl_id;
+	uint64_t        gl_uid;
+	uint64_t        gl_gid;
 	int		gl_count;
 	gid_t		*gl_list;
 	time_t		gl_deadline;
@@ -46,7 +48,7 @@ typedef struct {
 
 int gid_cache_init(gid_cache_t *, uint32_t);
 int gid_cache_reconf(gid_cache_t *, uint32_t);
-const gid_list_t *gid_cache_lookup(gid_cache_t *, uint64_t);
+const gid_list_t *gid_cache_lookup(gid_cache_t *, uint64_t, uint64_t, uint64_t);
 void gid_cache_release(gid_cache_t *, const gid_list_t *);
 int gid_cache_add(gid_cache_t *, gid_list_t *);
 
diff --git a/xlators/mount/fuse/src/fuse-helpers.c b/xlators/mount/fuse/src/fuse-helpers.c
index 4d478b919f2..6c54cb88200 100644
--- a/xlators/mount/fuse/src/fuse-helpers.c
+++ b/xlators/mount/fuse/src/fuse-helpers.c
@@ -266,7 +266,8 @@ static void get_groups(fuse_private_t *priv, call_frame_t *frame)
 		return;
 	}
 
-	gl = gid_cache_lookup(&priv->gid_cache, frame->root->pid);
+	gl = gid_cache_lookup(&priv->gid_cache, frame->root->pid,
+			      frame->root->uid, frame->root->gid);
 	if (gl) {
 		if (call_stack_alloc_groups (frame->root, gl->gl_count) != 0)
 			return;
@@ -280,6 +281,8 @@ static void get_groups(fuse_private_t *priv, call_frame_t *frame)
 	frame_fill_groups (frame);
 
 	agl.gl_id = frame->root->pid;
+	agl.gl_uid = frame->root->uid;
+	agl.gl_gid = frame->root->gid;
 	agl.gl_count = frame->root->ngrps;
 	agl.gl_list = GF_CALLOC(frame->root->ngrps, sizeof(gid_t),
 			gf_fuse_mt_gids_t);
diff --git a/xlators/nfs/server/src/nfs-fops.c b/xlators/nfs/server/src/nfs-fops.c
index 236b80c7620..60a5a9a843c 100644
--- a/xlators/nfs/server/src/nfs-fops.c
+++ b/xlators/nfs/server/src/nfs-fops.c
@@ -47,7 +47,7 @@ nfs_fix_groups (xlator_t *this, call_stack_t *root)
                 return;
         }
 
-	agl = gid_cache_lookup(&priv->gid_cache, root->uid);
+	agl = gid_cache_lookup(&priv->gid_cache, root->uid, 0, 0);
 	if (agl) {
 		for (ngroups = 0; ngroups < agl->gl_count; ngroups++) 
 			root->groups[ngroups] = agl->gl_list[ngroups];
@@ -84,6 +84,8 @@ nfs_fix_groups (xlator_t *this, call_stack_t *root)
 	if (gl.gl_list) {
 		/* It's not fatal if the alloc failed. */
 		gl.gl_id = root->uid;
+		gl.gl_uid = 0;
+		gl.gl_gid = 0;
 		gl.gl_count = ngroups;
 		memcpy(gl.gl_list, mygroups, sizeof(gid_t) * ngroups);
 		if (gid_cache_add(&priv->gid_cache, &gl) != 1)