autofs4: track uid and gid of last mount requester

Track the uid and gid of the last process to request a mount for on an
autofs dentry.

[akpm@linux-foundation.org: fix tpyo in comment]
Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 39 insertions, 0 deletions

diff --git a/fs/autofs4/autofs_i.h b/fs/autofs4/autofs_i.h
index ea024d8e37ed..fa76d18be082 100644
--- a/fs/autofs4/autofs_i.h
+++ b/fs/autofs4/autofs_i.h
@@ -63,6 +63,9 @@ struct autofs_info {
         unsigned long last_used;
         atomic_t count;
 
+        uid_t uid;
+        gid_t gid;
+
         mode_t  mode;
         size_t  size;
 
diff --git a/fs/autofs4/inode.c b/fs/autofs4/inode.c
index 7303099fcc1a..c7e65bb30ba0 100644
--- a/fs/autofs4/inode.c
+++ b/fs/autofs4/inode.c
@@ -53,6 +53,8 @@ struct autofs_info *autofs4_init_ino(struct autofs_info *ino,
                 atomic_set(&ino->count, 0);
         }
 
+        ino->uid = 0;
+        ino->gid = 0;
         ino->mode = mode;
         ino->last_used = jiffies;
 
diff --git a/fs/autofs4/waitq.c b/fs/autofs4/waitq.c
index 6d87bb156326..4b67c2a2d77c 100644
--- a/fs/autofs4/waitq.c
+++ b/fs/autofs4/waitq.c
@@ -457,6 +457,40 @@ int autofs4_wait(struct autofs_sb_info *sbi, struct dentry *dentry,
 
         status = wq->status;
 
+        /*
+         * For direct and offset mounts we need to track the requester's
+         * uid and gid in the dentry info struct. This is so it can be
+         * supplied, on request, by the misc device ioctl interface.
+         * This is needed during daemon resatart when reconnecting
+         * to existing, active, autofs mounts. The uid and gid (and
+         * related string values) may be used for macro substitution
+         * in autofs mount maps.
+         */
+        if (!status) {
+                struct autofs_info *ino;
+                struct dentry *de = NULL;
+
+                /* direct mount or browsable map */
+                ino = autofs4_dentry_ino(dentry);
+                if (!ino) {
+                        /* If not lookup actual dentry used */
+                        de = d_lookup(dentry->d_parent, &dentry->d_name);
+                        if (de)
+                                ino = autofs4_dentry_ino(de);
+                }
+
+                /* Set mount requester */
+                if (ino) {
+                        spin_lock(&sbi->fs_lock);
+                        ino->uid = wq->uid;
+                        ino->gid = wq->gid;
+                        spin_unlock(&sbi->fs_lock);
+                }
+
+                if (de)
+                        dput(de);
+        }
+
         /* Are we the last process to need status? */
         mutex_lock(&sbi->wq_mutex);
         if (!--wq->wait_ctr)