From 7b0e492e6b80d51db4156996b248522c7b50d467 Mon Sep 17 00:00:00 2001 From: Darrick J. Wong Date: Mon, 1 Jul 2019 08:25:35 -0700 Subject: vfs: create a generic checking function for FS_IOC_FSSETXATTR Create a generic checking function for the incoming FS_IOC_FSSETXATTR fsxattr values so that we can standardize some of the implementation behaviors. Signed-off-by: Darrick J. Wong Reviewed-by: Jan Kara --- fs/inode.c | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) (limited to 'fs/inode.c') diff --git a/fs/inode.c b/fs/inode.c index 8072a09fd0b9..ba2bafa22885 100644 --- a/fs/inode.c +++ b/fs/inode.c @@ -2194,3 +2194,26 @@ int vfs_ioc_setflags_prepare(struct inode *inode, unsigned int oldflags, return 0; } EXPORT_SYMBOL(vfs_ioc_setflags_prepare); + +/* + * Generic function to check FS_IOC_FSSETXATTR values and reject any invalid + * configurations. + * + * Note: the caller should be holding i_mutex, or else be sure that they have + * exclusive access to the inode structure. + */ +int vfs_ioc_fssetxattr_check(struct inode *inode, const struct fsxattr *old_fa, + struct fsxattr *fa) +{ + /* + * Can't modify an immutable/append-only file unless we have + * appropriate permission. + */ + if ((old_fa->fsx_xflags ^ fa->fsx_xflags) & + (FS_XFLAG_IMMUTABLE | FS_XFLAG_APPEND) && + !capable(CAP_LINUX_IMMUTABLE)) + return -EPERM; + + return 0; +} +EXPORT_SYMBOL(vfs_ioc_fssetxattr_check); -- cgit v1.2.3-55-g7522