kernel/linux.git/fs/internal.h, branch v5.10.257

fs: Establish locking order for unrelated directories

2023-07-27T06:44:13+00:00

commit f23ce757185319886ca80c4864ce5f81ac6cc9e9 upstream. Currently the locking order of inode locks for directories that are not in ancestor relationship is not defined because all operations that needed to lock two directories like this were serialized by sb->s_vfs_rename_mutex. However some filesystems need to lock two subdirectories for RENAME_EXCHANGE operations and for this we need the locking order established even for two tree-unrelated directories. Provide a helper function lock_two_inodes() that establishes lock ordering for any two inodes and use it in lock_two_directories(). CC: stable@vger.kernel.org Signed-off-by: Jan Kara Message-Id: <20230601105830.13168-4-jack@suse.cz> Signed-off-by: Christian Brauner Signed-off-by: Greg Kroah-Hartman

attr: add setattr_should_drop_sgid()

2023-03-22T12:30:07+00:00

commit 72ae017c5451860443a16fb2a8c243bff3e396b8 upstream. [backported to 5.10.y, prior to idmapped mounts] The current setgid stripping logic during write and ownership change operations is inconsistent and strewn over multiple places. In order to consolidate it and make more consistent we'll add a new helper setattr_should_drop_sgid(). The function retains the old behavior where we remove the S_ISGID bit unconditionally when S_IXGRP is set but also when it isn't set and the caller is neither in the group of the inode nor privileged over the inode. We will use this helper both in write operation permission removal such as file_remove_privs() as well as in ownership change operations. Reviewed-by: Amir Goldstein Signed-off-by: Christian Brauner (Microsoft) Signed-off-by: Amir Goldstein Signed-off-by: Greg Kroah-Hartman

attr: add in_group_or_capable()

2023-03-22T12:30:07+00:00

commit 11c2a8700cdcabf9b639b7204a1e38e2a0b6798e upstream. [backported to 5.10.y, prior to idmapped mounts] In setattr_{copy,prepare}() we need to perform the same permission checks to determine whether we need to drop the setgid bit or not. Instead of open-coding it twice add a simple helper the encapsulates the logic. We will reuse this helpers to make dropping the setgid bit during write operations more consistent in a follow up patch. Reviewed-by: Amir Goldstein Signed-off-by: Christian Brauner (Microsoft) Signed-off-by: Amir Goldstein Signed-off-by: Greg Kroah-Hartman

fs: provide locked helper variant of close_fd_get_file()

2023-01-04T10:39:18+00:00

[ Upstream commit 53dec2ea74f2ef360e8455439be96a780baa6097 ] Assumes current->files->file_lock is already held on invocation. Helps the caller check the file before removing the fd, if it needs to. Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

fs: make do_renameat2() take struct filename

2023-01-04T10:39:18+00:00

[ Upstream commit e886663cfd029b64a1d8da7efae7014526d884e9 ] Pass in the struct filename pointers instead of the user string, and update the three callers to do the same. This behaves like do_unlinkat(), which also takes a filename struct and puts it when it is done. Converting callers is then trivial. Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

cgroup1: fix leaked context root causing sporadic NULL deref in LTP

2021-07-31T06:16:11+00:00

commit 1e7107c5ef44431bc1ebbd4c353f1d7c22e5f2ec upstream. Richard reported sporadic (roughly one in 10 or so) null dereferences and other strange behaviour for a set of automated LTP tests. Things like: BUG: kernel NULL pointer dereference, address: 0000000000000008 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops: 0000 [#1] PREEMPT SMP PTI CPU: 0 PID: 1516 Comm: umount Not tainted 5.10.0-yocto-standard #1 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-48-gd9c812dda519-prebuilt.qemu.org 04/01/2014 RIP: 0010:kernfs_sop_show_path+0x1b/0x60 ...or these others: RIP: 0010:do_mkdirat+0x6a/0xf0 RIP: 0010:d_alloc_parallel+0x98/0x510 RIP: 0010:do_readlinkat+0x86/0x120 There were other less common instances of some kind of a general scribble but the common theme was mount and cgroup and a dubious dentry triggering the NULL dereference. I was only able to reproduce it under qemu by replicating Richard's setup as closely as possible - I never did get it to happen on bare metal, even while keeping everything else the same. In commit 71d883c37e8d ("cgroup_do_mount(): massage calling conventions") we see this as a part of the overall change: -------------- struct cgroup_subsys *ss; - struct dentry *dentry; [...] - dentry = cgroup_do_mount(&cgroup_fs_type, fc->sb_flags, root, - CGROUP_SUPER_MAGIC, ns); [...] - if (percpu_ref_is_dying(&root->cgrp.self.refcnt)) { - struct super_block *sb = dentry->d_sb; - dput(dentry); + ret = cgroup_do_mount(fc, CGROUP_SUPER_MAGIC, ns); + if (!ret && percpu_ref_is_dying(&root->cgrp.self.refcnt)) { + struct super_block *sb = fc->root->d_sb; + dput(fc->root); deactivate_locked_super(sb); msleep(10); return restart_syscall(); } -------------- In changing from the local "*dentry" variable to using fc->root, we now export/leave that dentry pointer in the file context after doing the dput() in the unlikely "is_dying" case. With LTP doing a crazy amount of back to back mount/unmount [testcases/bin/cgroup_regression_5_1.sh] the unlikely becomes slightly likely and then bad things happen. A fix would be to not leave the stale reference in fc->root as follows: -------------- dput(fc->root); + fc->root = NULL; deactivate_locked_super(sb); -------------- ...but then we are just open-coding a duplicate of fc_drop_locked() so we simply use that instead. Cc: Al Viro Cc: Tejun Heo Cc: Zefan Li Cc: Johannes Weiner Cc: stable@vger.kernel.org # v5.1+ Reported-by: Richard Purdie Fixes: 71d883c37e8d ("cgroup_do_mount(): massage calling conventions") Signed-off-by: Paul Gortmaker Signed-off-by: Tejun Heo Signed-off-by: Greg Kroah-Hartman

fs: remove compat_sys_mount

2020-09-23T03:45:57+00:00

compat_sys_mount is identical to the regular sys_mount now, so remove it and use the native version everywhere. Signed-off-by: Christoph Hellwig Signed-off-by: Al Viro

Merge branch 'hch.init_path' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2020-08-07T16:40:34+00:00

Pull init and set_fs() cleanups from Al Viro: "Christoph's 'getting rid of ksys_...() uses under KERNEL_DS' series" * 'hch.init_path' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (50 commits) init: add an init_dup helper init: add an init_utimes helper init: add an init_stat helper init: add an init_mknod helper init: add an init_mkdir helper init: add an init_symlink helper init: add an init_link helper init: add an init_eaccess helper init: add an init_chmod helper init: add an init_chown helper init: add an init_chroot helper init: add an init_chdir helper init: add an init_rmdir helper init: add an init_unlink helper init: add an init_umount helper init: add an init_mount helper init: mark create_dev as __init init: mark console_on_rootfs as __init init: initialize ramdisk_execute_command at compile time devtmpfs: refactor devtmpfsd() ...

init: add an init_mknod helper

2020-07-31T06:17:54+00:00

Add a simple helper to mknod with a kernel space file name and switch the early init code over to it. Remove the now unused ksys_mknod. Signed-off-by: Christoph Hellwig

init: add an init_mkdir helper

2020-07-31T06:17:53+00:00

Add a simple helper to mkdir with a kernel space file name and switch the early init code over to it. Remove the now unused ksys_mkdir. Signed-off-by: Christoph Hellwig