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authorLinus Torvalds <torvalds@linux-foundation.org>2026-08-23 13:28:57 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2026-08-23 13:28:57 -0700
commit4352b8aee98005853aa63f57d6377282de17a33f (patch)
tree27614d7a9ef05c32d089004e104364ce42324837 /samples/vfs/mountinfo.c
downloadlinux-stable-4352b8aee98005853aa63f57d6377282de17a33f.tar.gz
linux-stable-4352b8aee98005853aa63f57d6377282de17a33f.zip
Merge tag 'i3c/for-7.3' of git://git.kernel.org/pub/scm/linux/kernel/git/i3c/linuxgrafted
Pull I3C updates from Alexandre Belloni: "A new driver this cycle, for the AMD AXI I3C controller. There are also new features such as IBI wakeup support, SETAASA device discovery and ACPI support for the the DAA methods, meaning we can now communicate with the SPD devices on DDR5 modules. New driver: - AMD AXI I3C master controller Subsystem: - I3C Common Command Code (CCC) handling improvements, especially around GET CCCs - SETAASA device discovery support - ACPI support for all existing DAA methods like SETDASA, SETNEWDA as well as I2C devices on I3C bus - IBI-based wakeup support Drivers: - dw: SETAASA support - mipi-i3c-hci: advertise IBI wakeup capability, AMD_PT I3C controller support, PIO queue management support for HCI v1.2 - renesas: improve suspend to RAM support, add runtime PM support" * tag 'i3c/for-7.3' of git://git.kernel.org/pub/scm/linux/kernel/git/i3c/linux: (70 commits) i3c: dw: reduce do_daa time if there's no client i3c: mipi-i3c-hci: Add support for AMD_PT I3C controller i3c: mipi-i3c-hci: Add PIO queue management support for HCI v1.2 i3c: mipi-i3c-hci: Fix missing STAT_IBI_STATUS_THLD in PIO mode i3c: dw: rename "pclk" to "apb" to match dt-binding i3c: dw: make struct dw_i3c_cmd smaller i3c: dw: use COMMAND_PORT_TRANSFER_ARG instead of hardcoding i3c: renesas: Don't register devices when ENTDAA times out i3c: master: dw-i3c-master: fix OD timing for first broadcast i3c: mipi-i3c-hci: Advertise IBI wakeup capability i3c: mipi-i3c-hci: Factor out i3c_hci_sysdev() i3c: mipi-i3c-hci-pci: Propagate I3C wakeup requirements to PCI i3c: master: Reject IBI requests from non-IBI-capable devices i3c: master: Add helper to query bus wakeup requirements i3c: master: Report wakeup events for IBIs i3c: master: Support IBI-based wakeup capability i3c: master: Fix potential UAF in i3c_device_match() i3c: master: Fix potential UAF in i3c_device_uevent() i3c: Make dev->desc locking assumptions explicit i3c: master: Fix use-after-free of master->this ...
Diffstat (limited to 'samples/vfs/mountinfo.c')
-rw-r--r--samples/vfs/mountinfo.c274
1 files changed, 274 insertions, 0 deletions
diff --git a/samples/vfs/mountinfo.c b/samples/vfs/mountinfo.c
new file mode 100644
index 000000000..bc78275ca
--- /dev/null
+++ b/samples/vfs/mountinfo.c
@@ -0,0 +1,274 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+/*
+ * Use pidfds, nsfds, listmount() and statmount() mimic the
+ * contents of /proc/self/mountinfo.
+ */
+#define _GNU_SOURCE
+#define __SANE_USERSPACE_TYPES__
+#include <stdio.h>
+#include <stdint.h>
+#include <unistd.h>
+#include <alloca.h>
+#include <getopt.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <errno.h>
+
+#include "samples-vfs.h"
+
+/* max mounts per listmount call */
+#define MAXMOUNTS 1024
+
+/* size of struct statmount (including trailing string buffer) */
+#define STATMOUNT_BUFSIZE 4096
+
+static bool ext_format;
+
+#ifndef __NR_pidfd_open
+#define __NR_pidfd_open -1
+#endif
+
+/*
+ * There are no bindings in glibc for listmount() and statmount() (yet),
+ * make our own here.
+ */
+static int statmount(__u64 mnt_id, __u64 mnt_ns_id, __u64 mask,
+ struct statmount *buf, size_t bufsize,
+ unsigned int flags)
+{
+ struct mnt_id_req req = {
+ .size = MNT_ID_REQ_SIZE_VER0,
+ .mnt_id = mnt_id,
+ .param = mask,
+ };
+
+ if (mnt_ns_id) {
+ req.size = MNT_ID_REQ_SIZE_VER1;
+ req.mnt_ns_id = mnt_ns_id;
+ }
+
+ return syscall(__NR_statmount, &req, buf, bufsize, flags);
+}
+
+static ssize_t listmount(__u64 mnt_id, __u64 mnt_ns_id, __u64 last_mnt_id,
+ __u64 list[], size_t num, unsigned int flags)
+{
+ struct mnt_id_req req = {
+ .size = MNT_ID_REQ_SIZE_VER0,
+ .mnt_id = mnt_id,
+ .param = last_mnt_id,
+ };
+
+ if (mnt_ns_id) {
+ req.size = MNT_ID_REQ_SIZE_VER1;
+ req.mnt_ns_id = mnt_ns_id;
+ }
+
+ return syscall(__NR_listmount, &req, list, num, flags);
+}
+
+static void show_mnt_attrs(__u64 flags)
+{
+ printf("%s", flags & MOUNT_ATTR_RDONLY ? "ro" : "rw");
+
+ if (flags & MOUNT_ATTR_NOSUID)
+ printf(",nosuid");
+ if (flags & MOUNT_ATTR_NODEV)
+ printf(",nodev");
+ if (flags & MOUNT_ATTR_NOEXEC)
+ printf(",noexec");
+
+ switch (flags & MOUNT_ATTR__ATIME) {
+ case MOUNT_ATTR_RELATIME:
+ printf(",relatime");
+ break;
+ case MOUNT_ATTR_NOATIME:
+ printf(",noatime");
+ break;
+ case MOUNT_ATTR_STRICTATIME:
+ /* print nothing */
+ break;
+ }
+
+ if (flags & MOUNT_ATTR_NODIRATIME)
+ printf(",nodiratime");
+ if (flags & MOUNT_ATTR_NOSYMFOLLOW)
+ printf(",nosymfollow");
+ if (flags & MOUNT_ATTR_IDMAP)
+ printf(",idmapped");
+}
+
+static void show_propagation(struct statmount *sm)
+{
+ if (sm->mnt_propagation & MS_SHARED)
+ printf(" shared:%llu", sm->mnt_peer_group);
+ if (sm->mnt_propagation & MS_SLAVE) {
+ printf(" master:%llu", sm->mnt_master);
+ if (sm->propagate_from && sm->propagate_from != sm->mnt_master)
+ printf(" propagate_from:%llu", sm->propagate_from);
+ }
+ if (sm->mnt_propagation & MS_UNBINDABLE)
+ printf(" unbindable");
+}
+
+static void show_sb_flags(__u64 flags)
+{
+ printf("%s", flags & MS_RDONLY ? "ro" : "rw");
+ if (flags & MS_SYNCHRONOUS)
+ printf(",sync");
+ if (flags & MS_DIRSYNC)
+ printf(",dirsync");
+ if (flags & MS_MANDLOCK)
+ printf(",mand");
+ if (flags & MS_LAZYTIME)
+ printf(",lazytime");
+}
+
+static int dump_mountinfo(__u64 mnt_id, __u64 mnt_ns_id)
+{
+ int ret;
+ struct statmount *buf = alloca(STATMOUNT_BUFSIZE);
+ const __u64 mask = STATMOUNT_SB_BASIC | STATMOUNT_MNT_BASIC |
+ STATMOUNT_PROPAGATE_FROM | STATMOUNT_FS_TYPE |
+ STATMOUNT_MNT_ROOT | STATMOUNT_MNT_POINT |
+ STATMOUNT_MNT_OPTS | STATMOUNT_FS_SUBTYPE |
+ STATMOUNT_SB_SOURCE;
+
+ ret = statmount(mnt_id, mnt_ns_id, mask, buf, STATMOUNT_BUFSIZE, 0);
+ if (ret < 0) {
+ perror("statmount");
+ return 1;
+ }
+
+ if (ext_format)
+ printf("0x%llx 0x%llx 0x%llx ", mnt_ns_id, mnt_id, buf->mnt_parent_id);
+
+ printf("%u %u %u:%u %s %s ", buf->mnt_id_old, buf->mnt_parent_id_old,
+ buf->sb_dev_major, buf->sb_dev_minor,
+ &buf->str[buf->mnt_root],
+ &buf->str[buf->mnt_point]);
+ show_mnt_attrs(buf->mnt_attr);
+ show_propagation(buf);
+
+ printf(" - %s", &buf->str[buf->fs_type]);
+ if (buf->mask & STATMOUNT_FS_SUBTYPE)
+ printf(".%s", &buf->str[buf->fs_subtype]);
+ if (buf->mask & STATMOUNT_SB_SOURCE)
+ printf(" %s ", &buf->str[buf->sb_source]);
+ else
+ printf(" :none ");
+
+ show_sb_flags(buf->sb_flags);
+ if (buf->mask & STATMOUNT_MNT_OPTS)
+ printf(",%s", &buf->str[buf->mnt_opts]);
+ printf("\n");
+ return 0;
+}
+
+static int dump_mounts(__u64 mnt_ns_id)
+{
+ __u64 mntid[MAXMOUNTS];
+ __u64 last_mnt_id = 0;
+ ssize_t count;
+ int i;
+
+ /*
+ * Get a list of all mntids in mnt_ns_id. If it returns MAXMOUNTS
+ * mounts, then go again until we get everything.
+ */
+ do {
+ count = listmount(LSMT_ROOT, mnt_ns_id, last_mnt_id, mntid, MAXMOUNTS, 0);
+ if (count < 0 || count > MAXMOUNTS) {
+ errno = count < 0 ? errno : count;
+ perror("listmount");
+ return 1;
+ }
+
+ /* Walk the returned mntids and print info about each */
+ for (i = 0; i < count; ++i) {
+ int ret = dump_mountinfo(mntid[i], mnt_ns_id);
+
+ if (ret != 0)
+ return ret;
+ }
+ /* Set up last_mnt_id to pick up where we left off */
+ last_mnt_id = mntid[count - 1];
+ } while (count == MAXMOUNTS);
+ return 0;
+}
+
+static void usage(const char * const prog)
+{
+ printf("Usage:\n");
+ printf("%s [-e] [-p pid] [-r] [-h]\n", prog);
+ printf(" -e: extended format\n");
+ printf(" -h: print usage message\n");
+ printf(" -p: get mount namespace from given pid\n");
+ printf(" -r: recursively print all mounts in all child namespaces\n");
+}
+
+int main(int argc, char * const *argv)
+{
+ struct mnt_ns_info mni = { .size = MNT_NS_INFO_SIZE_VER0 };
+ int pidfd, mntns, ret, opt;
+ pid_t pid = getpid();
+ bool recursive = false;
+
+ while ((opt = getopt(argc, argv, "ehp:r")) != -1) {
+ switch (opt) {
+ case 'e':
+ ext_format = true;
+ break;
+ case 'h':
+ usage(argv[0]);
+ return 0;
+ case 'p':
+ pid = atoi(optarg);
+ break;
+ case 'r':
+ recursive = true;
+ break;
+ }
+ }
+
+ /* Get a pidfd for pid */
+ pidfd = syscall(__NR_pidfd_open, pid, 0);
+ if (pidfd < 0) {
+ perror("pidfd_open");
+ return 1;
+ }
+
+ /* Get the mnt namespace for pidfd */
+ mntns = ioctl(pidfd, PIDFD_GET_MNT_NAMESPACE, NULL);
+ if (mntns < 0) {
+ perror("PIDFD_GET_MNT_NAMESPACE");
+ return 1;
+ }
+ close(pidfd);
+
+ /* get info about mntns. In particular, the mnt_ns_id */
+ ret = ioctl(mntns, NS_MNT_GET_INFO, &mni);
+ if (ret < 0) {
+ perror("NS_MNT_GET_INFO");
+ return 1;
+ }
+
+ do {
+ int ret;
+
+ ret = dump_mounts(mni.mnt_ns_id);
+ if (ret)
+ return ret;
+
+ if (!recursive)
+ break;
+
+ /* get the next mntns (and overwrite the old mount ns info) */
+ ret = ioctl(mntns, NS_MNT_GET_NEXT, &mni);
+ close(mntns);
+ mntns = ret;
+ } while (mntns >= 0);
+
+ return 0;
+}