From 5aca284210ce827f780ea2f4f9c6ab8d6e2d6648 Mon Sep 17 00:00:00 2001 From: "Darrick J. Wong" Date: Mon, 1 Jul 2019 08:25:34 -0700 Subject: vfs: create a generic checking and prep function for FS_IOC_SETFLAGS Create a generic function to check incoming FS_IOC_SETFLAGS flag values and later prepare the inode for updates so that we can standardize the implementations that follow ext4's flag values. Note that the efivarfs implementation no longer fails a no-op SETFLAGS without CAP_LINUX_IMMUTABLE since that's the behavior in ext*. Signed-off-by: Darrick J. Wong Reviewed-by: Jan Kara Reviewed-by: Christoph Hellwig Acked-by: David Sterba Reviewed-by: Bob Peterson --- fs/inode.c | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) (limited to 'fs/inode.c') diff --git a/fs/inode.c b/fs/inode.c index df6542ec3b88..8072a09fd0b9 100644 --- a/fs/inode.c +++ b/fs/inode.c @@ -2170,3 +2170,27 @@ struct timespec64 current_time(struct inode *inode) return timespec64_trunc(now, inode->i_sb->s_time_gran); } EXPORT_SYMBOL(current_time); + +/* + * Generic function to check FS_IOC_SETFLAGS 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_setflags_prepare(struct inode *inode, unsigned int oldflags, + unsigned int flags) +{ + /* + * The IMMUTABLE and APPEND_ONLY flags can only be changed by + * the relevant capability. + * + * This test looks nicer. Thanks to Pauline Middelink + */ + if ((flags ^ oldflags) & (FS_APPEND_FL | FS_IMMUTABLE_FL) && + !capable(CAP_LINUX_IMMUTABLE)) + return -EPERM; + + return 0; +} +EXPORT_SYMBOL(vfs_ioc_setflags_prepare); -- cgit v1.2.3-70-g09d2