New subject: [PATCH v2] btrfs: add missing check for nocow and compression inode flags

10 Jul 2020

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
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: David Sterba dsterba@suse.com
---
 fs/btrfs/ioctl.c | 30 ++++++++++++++++++++++--------
 1 file changed, 22 insertions(+), 8 deletions(-)

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 3a566cf71fc6..0c13bb38425b 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -164,8 +164,11 @@ static int btrfs_ioctl_getflags(struct file *file, void __user *arg)
    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 flags)
    	      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 file *file, void __user *arg)
    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 file *file, void __user *arg)
    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
-- 
2.25.0


    

[PATCH] btrfs: add missing check for nocow and compression inode flags