[PATCH 5.7 023/204] btrfs: add missing check for nocow and compression inode flags

Greg Kroah-Hartman
2020-08-20T13:15:58Z

From: David Sterba <dsterba@suse.com>

commit f37c563bab4297024c300b05c8f48430e323809d upstream.

User Forza reported on IRC that some invalid combinations of file
attributes are accepted by chattr.

The NODATACOW and compression file flags/attributes are mutually
exclusive, but they could be set by 'chattr +c +C' on an empty file. The
nodatacow will be in effect because it's checked first in
btrfs_run_delalloc_range.

Extend the flag validation to catch the following cases:

- input flags are conflicting
- old and new flags are conflicting
- initialize the local variable with inode flags after inode ls locked

Inode attributes take precedence over mount options and are an
independent setting.

Nocompress would be a no-op with nodatacow, but we don't want to mix
any compression-related options with nodatacow.

CC: stable@vger.kernel.org # 4.4+
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/btrfs/ioctl.c | 30 ++++++++++++++++++++++--------
1 file changed, 22 insertions(+), 8 deletions(-)

--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -164,8 +164,11 @@ static int btrfs_ioctl_getflags(struct f
return 0;
}

-/* Check if @flags are a supported and valid set of FS_*_FL flags */
-static int check_fsflags(unsigned int flags)
+/*
+ * Check if @flags are a supported and valid set of FS_*_FL flags and that
+ * the old and new flags are not conflicting
+ */
+static int check_fsflags(unsigned int old_flags, unsigned int flags)
{
if (flags & ~(FS_IMMUTABLE_FL | FS_APPEND_FL | \
FS_NOATIME_FL | FS_NODUMP_FL | \
@@ -174,9 +177,19 @@ static int check_fsflags(unsigned int fl
FS_NOCOW_FL))
return -EOPNOTSUPP;

+ /* COMPR and NOCOMP on new/old are valid */
if ((flags & FS_NOCOMP_FL) && (flags & FS_COMPR_FL))
return -EINVAL;

+ if ((flags & FS_COMPR_FL) && (flags & FS_NOCOW_FL))
+ return -EINVAL;
+
+ /* NOCOW and compression options are mutually exclusive */
+ if ((old_flags & FS_NOCOW_FL) && (flags & (FS_COMPR_FL | FS_NOCOMP_FL)))
+ return -EINVAL;
+ if ((flags & FS_NOCOW_FL) && (old_flags & (FS_COMPR_FL | FS_NOCOMP_FL)))
+ return -EINVAL;
+
return 0;
}

@@ -190,7 +203,7 @@ static int btrfs_ioctl_setflags(struct f
unsigned int fsflags, old_fsflags;
int ret;
const char *comp = NULL;
- u32 binode_flags = binode->flags;
+ u32 binode_flags;

if (!inode_owner_or_capable(inode))
return -EPERM;
@@ -201,22 +214,23 @@ static int btrfs_ioctl_setflags(struct f
if (copy_from_user(&fsflags, arg, sizeof(fsflags)))
return -EFAULT;

- ret = check_fsflags(fsflags);
- if (ret)
- return ret;
-
ret = mnt_want_write_file(file);
if (ret)
return ret;

inode_lock(inode);
-
fsflags = btrfs_mask_fsflags_for_type(inode, fsflags);
old_fsflags = btrfs_inode_flags_to_fsflags(binode->flags);
+
ret = vfs_ioc_setflags_prepare(inode, old_fsflags, fsflags);
if (ret)
goto out_unlock;

+ ret = check_fsflags(old_fsflags, fsflags);
+ if (ret)
+ goto out_unlock;
+
+ binode_flags = binode->flags;
if (fsflags & FS_SYNC_FL)
binode_flags |= BTRFS_INODE_SYNC;
else