This patch tightens the read-only access checks in btrfs_permission to
match the constraints in inode_permission. Currently, even though the
device node itself will be unmodified, read-write access to device nodes
is denied to when the device node resides on a read-only subvolume or a
is a file that has been marked read-only by the btrfs conversion utility.
With this patch applied, the check only affects regular files,
directories, and symlinks. It also restructures the code a bit so that
we don't duplicate the MAY_WRITE check for both tests.
Signed-off-by: Jeff Mahoney <jeffm@xxxxxxxx>
---
fs/btrfs/inode.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -7354,11 +7354,15 @@ static int btrfs_set_page_dirty(struct p
static int btrfs_permission(struct inode *inode, int mask)
{
struct btrfs_root *root = BTRFS_I(inode)->root;
+ umode_t mode = inode->i_mode;
- if (btrfs_root_readonly(root) && (mask & MAY_WRITE))
- return -EROFS;
- if ((BTRFS_I(inode)->flags & BTRFS_INODE_READONLY) && (mask & MAY_WRITE))
- return -EACCES;
+ if (mask & MAY_WRITE &&
+ (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) {
+ if (btrfs_root_readonly(root))
+ return -EROFS;
+ if (BTRFS_I(inode)->flags & BTRFS_INODE_READONLY)
+ return -EACCES;
+ }
return generic_permission(inode, mask);
}
Jeff Mahoney
SUSE Labs
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