user/sven/linux.git/include/uapi/linux/mount.h, branch v6.13.1

statmount: retrieve security mount options

2024-11-14T16:03:25Z

Add the ability to retrieve security mount options. Keep them separate from filesystem specific mount options so it's easy to tell them apart. Also allow to retrieve them separate from other mount options as most of the time users won't be interested in security specific mount options. Link: https://lore.kernel.org/r/20241114-radtour-ofenrohr-ff34b567b40a@brauner Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner

statmount: add flag to retrieve unescaped options

2024-11-13T16:27:02Z

Filesystem options can be retrieved with STATMOUNT_MNT_OPTS, which returns a string of comma separated options, where some characters are escaped using the \OOO notation. Add a new flag, STATMOUNT_OPT_ARRAY, which instead returns the raw option values separated with '\0' charaters. Since escaped charaters are rare, this inteface is preferable for non-libmount users which likley don't want to deal with option de-escaping. Example code: if (st->mask & STATMOUNT_OPT_ARRAY) { const char *opt = st->str + st->opt_array; for (unsigned int i = 0; i < st->opt_num; i++) { printf("opt_array[%i]: <%s>\n", i, opt); opt += strlen(opt) + 1; } } Example ouput: (1) mnt_opts: (2) opt_array[0]: opt_array[1]: opt_array[2]: opt_array[3]: opt_array[4]: opt_array[5]: Signed-off-by: Miklos Szeredi Link: https://lore.kernel.org/r/20241112101006.30715-1-mszeredi@redhat.com Acked-by: Jeff Layton [brauner: tweak variable naming and parsing add example output] Signed-off-by: Christian Brauner

fs: add the ability for statmount() to report the sb_source

2024-11-13T13:08:17Z

/proc/self/mountinfo displays the source for the mount, but statmount() doesn't yet have a way to return it. Add a new STATMOUNT_SB_SOURCE flag, claim the 32-bit __spare1 field to hold the offset into the str[] array. Reviewed-by: Jan Kara Signed-off-by: Jeff Layton Link: https://lore.kernel.org/r/20241111-statmount-v4-3-2eaf35d07a80@kernel.org Acked-by: Miklos Szeredi Signed-off-by: Christian Brauner

fs: add the ability for statmount() to report the fs_subtype

2024-11-12T13:37:12Z

/proc/self/mountinfo prints out the sb->s_subtype after the type. This is particularly useful for disambiguating FUSE mounts (at least when the userland driver bothers to set it). Add STATMOUNT_FS_SUBTYPE and claim one of the __spare2 fields to point to the offset into the str[] array. Reviewed-by: Jan Kara Reviewed-by: Ian Kent Signed-off-by: Jeff Layton Link: https://lore.kernel.org/r/20241111-statmount-v4-2-2eaf35d07a80@kernel.org Acked-by: Miklos Szeredi Signed-off-by: Christian Brauner

fs: export mount options via statmount()

2024-06-28T12:36:43Z

statmount() can export arbitrary strings, so utilize the __spare1 slot for a mnt_opts string pointer, and then support asking for and setting the mount options during statmount(). This calls into the helper for showing mount options, which already uses a seq_file, so fits in nicely with our existing mechanism for exporting strings via statmount(). Signed-off-by: Josef Bacik Link: https://lore.kernel.org/r/3aa6bf8bd5d0a21df9ebd63813af8ab532c18276.1719257716.git.josef@toxicpanda.com Reviewed-by: Jeff Layton [brauner: only call sb->s_op->show_options()] Signed-off-by: Christian Brauner

fs: Allow listmount() in foreign mount namespace

2024-06-28T07:53:30Z

Expand struct mnt_id_req to add an optional mnt_ns_id field. When this field is populated, listmount() will be performed on the specified mount namespace, provided the currently application has CAP_SYS_ADMIN in its user namespace and the mount namespace is a child of the current namespace. Co-developed-by: Josef Bacik Signed-off-by: Josef Bacik Link: https://lore.kernel.org/r/49930bdce29a8367a213eb14c1e68e7e49284f86.1719243756.git.josef@toxicpanda.com Signed-off-by: Christian Brauner

fs: export the mount ns id via statmount

2024-06-28T07:53:30Z

In order to allow users to iterate through children mount namespaces via listmount we need a way for them to know what the ns id for the mount. Add a new field to statmount called mnt_ns_id which will carry the ns id for the given mount entry. Co-developed-by: Christian Brauner Signed-off-by: Josef Bacik Link: https://lore.kernel.org/r/6dabf437331fb7415d886f7c64b21cb2a50b1c66.1719243756.git.josef@toxicpanda.com Signed-off-by: Christian Brauner

listmount: allow listing in reverse order

2024-06-28T07:53:29Z

util-linux is about to implement listmount() and statmount() support. Karel requested the ability to scan the mount table in backwards order because that's what libmount currently does in order to get the latest mount first. We currently don't support this in listmount(). Add a new LISTMOUNT_REVERSE flag to allow listing mounts in reverse order. For example, listing all child mounts of /sys without LISTMOUNT_REVERSE gives: /sys/kernel/security @ mnt_id: 4294968369 /sys/fs/cgroup @ mnt_id: 4294968370 /sys/firmware/efi/efivars @ mnt_id: 4294968371 /sys/fs/bpf @ mnt_id: 4294968372 /sys/kernel/tracing @ mnt_id: 4294968373 /sys/kernel/debug @ mnt_id: 4294968374 /sys/fs/fuse/connections @ mnt_id: 4294968375 /sys/kernel/config @ mnt_id: 4294968376 whereas with LISTMOUNT_REVERSE it gives: /sys/kernel/config @ mnt_id: 4294968376 /sys/fs/fuse/connections @ mnt_id: 4294968375 /sys/kernel/debug @ mnt_id: 4294968374 /sys/kernel/tracing @ mnt_id: 4294968373 /sys/fs/bpf @ mnt_id: 4294968372 /sys/firmware/efi/efivars @ mnt_id: 4294968371 /sys/fs/cgroup @ mnt_id: 4294968370 /sys/kernel/security @ mnt_id: 4294968369 Link: https://lore.kernel.org/r/20240607-vfs-listmount-reverse-v1-4-7877a2bfa5e5@kernel.org Reviewed-by: Josef Bacik Signed-off-by: Christian Brauner

fs: keep struct mnt_id_req extensible

2023-12-14T10:49:17Z

Make it extensible so that we have the liberty to reuse it in future mount-id based apis. Treat zero size as the first published struct. Signed-off-by: Christian Brauner

add listmount(2) syscall

2023-12-14T10:49:17Z

Add way to query the children of a particular mount. This is a more flexible way to iterate the mount tree than having to parse /proc/self/mountinfo. Lookup the mount by the new 64bit mount ID. If a mount needs to be queried based on path, then statx(2) can be used to first query the mount ID belonging to the path. Return an array of new (64bit) mount ID's. Without privileges only mounts are listed which are reachable from the task's root. Folded into this patch are several later improvements. Keeping them separate would make the history pointlessly confusing: * Recursive listing of mounts is the default now (cf. [1]). * Remove explicit LISTMOUNT_UNREACHABLE flag (cf. [1]) and fail if mount is unreachable from current root. This also makes permission checking consistent with statmount() (cf. [3]). * Start listing mounts in unique mount ID order (cf. [2]) to allow continuing listmount() from a midpoint. * Allow to continue listmount(). The @request_mask parameter is renamed and to @param to be usable by both statmount() and listmount(). If @param is set to a mount id then listmount() will continue listing mounts from that id on. This allows listing mounts in multiple listmount invocations without having to resize the buffer. If @param is zero then the listing starts from the beginning (cf. [4]). * Don't return EOVERFLOW, instead return the buffer size which allows to detect a full buffer as well (cf. [4]). Signed-off-by: Miklos Szeredi Link: https://lore.kernel.org/r/20231025140205.3586473-6-mszeredi@redhat.com Reviewed-by: Ian Kent Link: https://lore.kernel.org/r/20231128160337.29094-2-mszeredi@redhat.com [1] (folded) Link: https://lore.kernel.org/r/20231128160337.29094-3-mszeredi@redhat.com [2] (folded) Link: https://lore.kernel.org/r/20231128160337.29094-4-mszeredi@redhat.com [3] (folded) Link: https://lore.kernel.org/r/20231128160337.29094-5-mszeredi@redhat.com [4] (folded) [Christian Brauner : various smaller fixes] Signed-off-by: Christian Brauner