ovl: Copy up underlying inode's ->i_mode to overlay inode

Right now when a new overlay inode is created, we initialize overlay
inode's ->i_mode from underlying inode ->i_mode but we retain only
file type bits (S_IFMT) and discard permission bits.

This patch changes it and retains permission bits too. This should allow
overlay to do permission checks on overlay inode itself in task context.

[SzM] It also fixes clearing suid/sgid bits on write.

Signed-off-by: Vivek Goyal <[email protected]>
Reported-by: Eryu Guan <[email protected]>
Signed-off-by: Miklos Szeredi <[email protected]>
Fixes: 4bacc9c9234c ("overlayfs: Make f_path always point to the overlay and f_inode to the underlay")
Cc: <[email protected]>

diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index 1233992a7c4714b756f183a506f8ffea2381a383..d1cdc60dd68fa25aa74e2474a09e07aab08b7e26 100644 (file)
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -413,12 +413,11 @@ struct inode *ovl_new_inode(struct super_block *sb, umode_t mode,
        if (!inode)
                return NULL;
 
-       mode &= S_IFMT;
-
        inode->i_ino = get_next_ino();
        inode->i_mode = mode;
        inode->i_flags |= S_NOATIME | S_NOCMTIME;
 
+       mode &= S_IFMT;
        switch (mode) {
        case S_IFDIR:
                inode->i_private = oe;

diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index 4bd9b5ba8f42008b7f72cf271fac89c67b7eca6d..cfbca53590d078b89ca613e65c3b10486763f656 100644 (file)
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -187,6 +187,7 @@ static inline void ovl_copyattr(struct inode *from, struct inode *to)
 {
        to->i_uid = from->i_uid;
        to->i_gid = from->i_gid;
+       to->i_mode = from->i_mode;
 }
 
 /* dir.c */