From ad5cd4f4ee4d5fcdb1bfb7a0c073072961e70783 Mon Sep 17 00:00:00 2001 From: "Darrick J. Wong" Date: Tue, 8 Mar 2022 10:50:43 -0800 Subject: ext4: fix fallocate to use file_modified to update permissions consistently Since the initial introduction of (posix) fallocate back at the turn of the century, it has been possible to use this syscall to change the user-visible contents of files. This can happen by extending the file size during a preallocation, or through any of the newer modes (punch, zero, collapse, insert range). Because the call can be used to change file contents, we should treat it like we do any other modification to a file -- update the mtime, and drop set[ug]id privileges/capabilities. The VFS function file_modified() does all this for us if pass it a locked inode, so let's make fallocate drop permissions correctly. Signed-off-by: Darrick J. Wong Link: https://lore.kernel.org/r/20220308185043.GA117678@magnolia Signed-off-by: Theodore Ts'o Cc: stable@kernel.org --- fs/ext4/inode.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) (limited to 'fs/ext4/inode.c') diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 26218088f63b..955dd978dccf 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -3946,8 +3946,9 @@ int ext4_break_layouts(struct inode *inode) * Returns: 0 on success or negative on failure */ -int ext4_punch_hole(struct inode *inode, loff_t offset, loff_t length) +int ext4_punch_hole(struct file *file, loff_t offset, loff_t length) { + struct inode *inode = file_inode(file); struct super_block *sb = inode->i_sb; ext4_lblk_t first_block, stop_block; struct address_space *mapping = inode->i_mapping; @@ -4009,6 +4010,10 @@ int ext4_punch_hole(struct inode *inode, loff_t offset, loff_t length) /* Wait all existing dio workers, newcomers will block on i_rwsem */ inode_dio_wait(inode); + ret = file_modified(file); + if (ret) + goto out_mutex; + /* * Prevent page faults from reinstantiating pages we have released from * page cache. -- cgit v1.2.3