It isn't possible to execute anoymous inodes because they cannot be opened in any way after they have been created. This includes execution: execveat(fd_anon_inode, "", NULL, NULL, AT_EMPTY_PATH) Anonymous inodes have inode->f_op set to no_open_fops which sets no_open() which returns ENXIO. That means any call to do_dentry_open() which is the endpoint of the do_open_execat() will fail. There's no chance to execute an anonymous inode. Unless a given subsystem overrides it ofc. Howerver, we should still harden this and raise SB_I_NODEV and SB_I_NOEXEC on the superblock itself so that no one gets any creative ideas. Cc: <stable@xxxxxxxxxxxxxxx> # all LTS kernels Signed-off-by: Christian Brauner <brauner@xxxxxxxxxx> --- fs/anon_inodes.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/anon_inodes.c b/fs/anon_inodes.c index cb51a90bece0..e51e7d88980a 100644 --- a/fs/anon_inodes.c +++ b/fs/anon_inodes.c @@ -86,6 +86,8 @@ static int anon_inodefs_init_fs_context(struct fs_context *fc) struct pseudo_fs_context *ctx = init_pseudo(fc, ANON_INODE_FS_MAGIC); if (!ctx) return -ENOMEM; + fc->s_iflags |= SB_I_NOEXEC; + fc->s_iflags |= SB_I_NODEV; ctx->dops = &anon_inodefs_dentry_operations; return 0; } -- 2.47.2
