fuse: allow umask processing in userspace

This patch lets filesystems handle masking the file mode on creation.
This is needed if filesystem is using ACLs.

 - The CREATE, MKDIR and MKNOD requests are extended with a "umask"
   parameter.

 - A new FUSE_DONT_MASK flag is added to the INIT request/reply.  With
   this the filesystem may request that the create mode is not masked.

CC: Jean-Pierre André <jean-pierre.andre@wanadoo.fr>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>

3 files changed, 28 insertions, 4 deletions

diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index b3089a083d30..6b700734e519 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -375,7 +375,7 @@ static int fuse_create_open(struct inode *dir, struct dentry *entry, int mode,
         struct fuse_conn *fc = get_fuse_conn(dir);
         struct fuse_req *req;
         struct fuse_req *forget_req;
-        struct fuse_open_in inarg;
+        struct fuse_create_in inarg;
         struct fuse_open_out outopen;
         struct fuse_entry_out outentry;
         struct fuse_file *ff;
@@ -399,15 +399,20 @@ static int fuse_create_open(struct inode *dir, struct dentry *entry, int mode,
         if (!ff)
                 goto out_put_request;
 
+        if (!fc->dont_mask)
+                mode &= ~current_umask();
+
         flags &= ~O_NOCTTY;
         memset(&inarg, 0, sizeof(inarg));
         memset(&outentry, 0, sizeof(outentry));
         inarg.flags = flags;
         inarg.mode = mode;
+        inarg.umask = current_umask();
         req->in.h.opcode = FUSE_CREATE;
         req->in.h.nodeid = get_node_id(dir);
         req->in.numargs = 2;
-        req->in.args[0].size = sizeof(inarg);
+        req->in.args[0].size = fc->minor < 12 ? sizeof(struct fuse_open_in) :
+                                                sizeof(inarg);
         req->in.args[0].value = &inarg;
         req->in.args[1].size = entry->d_name.len + 1;
         req->in.args[1].value = entry->d_name.name;
@@ -546,12 +551,17 @@ static int fuse_mknod(struct inode *dir, struct dentry *entry, int mode,
         if (IS_ERR(req))
                 return PTR_ERR(req);
 
+        if (!fc->dont_mask)
+                mode &= ~current_umask();
+
         memset(&inarg, 0, sizeof(inarg));
         inarg.mode = mode;
         inarg.rdev = new_encode_dev(rdev);
+        inarg.umask = current_umask();
         req->in.h.opcode = FUSE_MKNOD;
         req->in.numargs = 2;
-        req->in.args[0].size = sizeof(inarg);
+        req->in.args[0].size = fc->minor < 12 ? FUSE_COMPAT_MKNOD_IN_SIZE :
+                                                sizeof(inarg);
         req->in.args[0].value = &inarg;
         req->in.args[1].size = entry->d_name.len + 1;
         req->in.args[1].value = entry->d_name.name;
@@ -578,8 +588,12 @@ static int fuse_mkdir(struct inode *dir, struct dentry *entry, int mode)
         if (IS_ERR(req))
                 return PTR_ERR(req);
 
+        if (!fc->dont_mask)
+                mode &= ~current_umask();
+
         memset(&inarg, 0, sizeof(inarg));
         inarg.mode = mode;
+        inarg.umask = current_umask();
         req->in.h.opcode = FUSE_MKDIR;
         req->in.numargs = 2;
         req->in.args[0].size = sizeof(inarg);
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index aaf2f9ff970e..ede4f77b2d6c 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -446,6 +446,9 @@ struct fuse_conn {
         /** Do multi-page cached writes */
         unsigned big_writes:1;
 
+        /** Don't apply umask to creation modes */
+        unsigned dont_mask:1;
+
         /** The number of requests waiting for completion */
         atomic_t num_waiting;
 
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index d8673ccf90b7..6cc501bd0187 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -725,6 +725,8 @@ static void process_init_reply(struct fuse_conn *fc, struct fuse_req *req)
                         }
                         if (arg->flags & FUSE_BIG_WRITES)
                                 fc->big_writes = 1;
+                        if (arg->flags & FUSE_DONT_MASK)
+                                fc->dont_mask = 1;
                 } else {
                         ra_pages = fc->max_read / PAGE_CACHE_SIZE;
                         fc->no_lock = 1;
@@ -748,7 +750,7 @@ static void fuse_send_init(struct fuse_conn *fc, struct fuse_req *req)
         arg->minor = FUSE_KERNEL_MINOR_VERSION;
         arg->max_readahead = fc->bdi.ra_pages * PAGE_CACHE_SIZE;
         arg->flags |= FUSE_ASYNC_READ | FUSE_POSIX_LOCKS | FUSE_ATOMIC_O_TRUNC |
-                FUSE_EXPORT_SUPPORT | FUSE_BIG_WRITES;
+                FUSE_EXPORT_SUPPORT | FUSE_BIG_WRITES | FUSE_DONT_MASK;
         req->in.h.opcode = FUSE_INIT;
         req->in.numargs = 1;
         req->in.args[0].size = sizeof(*arg);
@@ -864,6 +866,11 @@ static int fuse_fill_super(struct super_block *sb, void *data, int silent)
         if (err)
                 goto err_put_conn;
 
+        /* Handle umasking inside the fuse code */
+        if (sb->s_flags & MS_POSIXACL)
+                fc->dont_mask = 1;
+        sb->s_flags |= MS_POSIXACL;
+
         fc->release = fuse_free_conn;
         fc->flags = d.flags;
         fc->user_id = d.user_id;