1// SPDX-License-Identifier: GPL-2.0-or-later
2// Copyright (c) 2024 Christian Brauner <brauner@kernel.org>
3
4#define _GNU_SOURCE
5#include <errno.h>
6#include <limits.h>
7#include <linux/types.h>
8#include <inttypes.h>
9#include <stdio.h>
10
11#include "../../tools/testing/selftests/pidfd/pidfd.h"
12#include "samples-vfs.h"
13
14static int __statmount(__u64 mnt_id, __u64 mnt_ns_id, __u64 mask,
15 struct statmount *stmnt, size_t bufsize,
16 unsigned int flags)
17{
18 struct mnt_id_req req = {
19 .size = MNT_ID_REQ_SIZE_VER1,
20 .mnt_id = mnt_id,
21 .param = mask,
22 .mnt_ns_id = mnt_ns_id,
23 };
24
25 return syscall(__NR_statmount, &req, stmnt, bufsize, flags);
26}
27
28static struct statmount *sys_statmount(__u64 mnt_id, __u64 mnt_ns_id,
29 __u64 mask, unsigned int flags)
30{
31 size_t bufsize = 1 << 15;
32 struct statmount *stmnt = NULL, *tmp = NULL;
33 int ret;
34
35 for (;;) {
36 tmp = realloc(stmnt, bufsize);
37 if (!tmp)
38 goto out;
39
40 stmnt = tmp;
41 ret = __statmount(mnt_id, mnt_ns_id, mask, stmnt, bufsize, flags);
42 if (!ret)
43 return stmnt;
44
45 if (errno != EOVERFLOW)
46 goto out;
47
48 bufsize <<= 1;
49 if (bufsize >= UINT_MAX / 2)
50 goto out;
51 }
52
53out:
54 free(stmnt);
55 return NULL;
56}
57
58static ssize_t sys_listmount(__u64 mnt_id, __u64 last_mnt_id, __u64 mnt_ns_id,
59 __u64 list[], size_t num, unsigned int flags)
60{
61 struct mnt_id_req req = {
62 .size = MNT_ID_REQ_SIZE_VER1,
63 .mnt_id = mnt_id,
64 .param = last_mnt_id,
65 .mnt_ns_id = mnt_ns_id,
66 };
67
68 return syscall(__NR_listmount, &req, list, num, flags);
69}
70
71int main(int argc, char *argv[])
72{
73#define LISTMNT_BUFFER 10
74 __u64 list[LISTMNT_BUFFER], last_mnt_id = 0;
75 int ret, pidfd, fd_mntns;
76 struct mnt_ns_info info = {};
77
78 pidfd = sys_pidfd_open(pid: getpid(), flags: 0);
79 if (pidfd < 0)
80 die_errno("pidfd_open failed");
81
82 fd_mntns = ioctl(pidfd, PIDFD_GET_MNT_NAMESPACE, 0);
83 if (fd_mntns < 0)
84 die_errno("ioctl(PIDFD_GET_MNT_NAMESPACE) failed");
85
86 ret = ioctl(fd_mntns, NS_MNT_GET_INFO, &info);
87 if (ret < 0)
88 die_errno("ioctl(NS_GET_MNTNS_ID) failed");
89
90 printf("Listing %u mounts for mount namespace %" PRIu64 "\n",
91 info.nr_mounts, (uint64_t)info.mnt_ns_id);
92 for (;;) {
93 ssize_t nr_mounts;
94next:
95 nr_mounts = sys_listmount(LSMT_ROOT, last_mnt_id,
96 mnt_ns_id: info.mnt_ns_id, list, LISTMNT_BUFFER,
97 flags: 0);
98 if (nr_mounts <= 0) {
99 int fd_mntns_next;
100
101 printf("Finished listing %u mounts for mount namespace %" PRIu64 "\n\n",
102 info.nr_mounts, (uint64_t)info.mnt_ns_id);
103 fd_mntns_next = ioctl(fd_mntns, NS_MNT_GET_NEXT, &info);
104 if (fd_mntns_next < 0) {
105 if (errno == ENOENT) {
106 printf("Finished listing all mount namespaces\n");
107 exit(0);
108 }
109 die_errno("ioctl(NS_MNT_GET_NEXT) failed");
110 }
111 close(fd_mntns);
112 fd_mntns = fd_mntns_next;
113 last_mnt_id = 0;
114 printf("Listing %u mounts for mount namespace %" PRIu64 "\n",
115 info.nr_mounts, (uint64_t)info.mnt_ns_id);
116 goto next;
117 }
118
119 for (size_t cur = 0; cur < nr_mounts; cur++) {
120 struct statmount *stmnt;
121
122 last_mnt_id = list[cur];
123
124 stmnt = sys_statmount(mnt_id: last_mnt_id, mnt_ns_id: info.mnt_ns_id,
125 STATMOUNT_SB_BASIC |
126 STATMOUNT_MNT_BASIC |
127 STATMOUNT_MNT_ROOT |
128 STATMOUNT_MNT_POINT |
129 STATMOUNT_MNT_NS_ID |
130 STATMOUNT_MNT_OPTS |
131 STATMOUNT_FS_TYPE |
132 STATMOUNT_MNT_UIDMAP |
133 STATMOUNT_MNT_GIDMAP, flags: 0);
134 if (!stmnt) {
135 printf("Failed to statmount(%" PRIu64 ") in mount namespace(%" PRIu64 ")\n",
136 (uint64_t)last_mnt_id, (uint64_t)info.mnt_ns_id);
137 continue;
138 }
139
140 printf("mnt_id:\t\t%" PRIu64 "\nmnt_parent_id:\t%" PRIu64 "\nfs_type:\t%s\nmnt_root:\t%s\nmnt_point:\t%s\nmnt_opts:\t%s\n",
141 (uint64_t)stmnt->mnt_id,
142 (uint64_t)stmnt->mnt_parent_id,
143 (stmnt->mask & STATMOUNT_FS_TYPE) ? stmnt->str + stmnt->fs_type : "",
144 (stmnt->mask & STATMOUNT_MNT_ROOT) ? stmnt->str + stmnt->mnt_root : "",
145 (stmnt->mask & STATMOUNT_MNT_POINT) ? stmnt->str + stmnt->mnt_point : "",
146 (stmnt->mask & STATMOUNT_MNT_OPTS) ? stmnt->str + stmnt->mnt_opts : "");
147
148 if (stmnt->mask & STATMOUNT_MNT_UIDMAP) {
149 const char *idmap = stmnt->str + stmnt->mnt_uidmap;
150
151 for (size_t idx = 0; idx < stmnt->mnt_uidmap_num; idx++) {
152 printf("mnt_uidmap[%zu]:\t%s\n", idx, idmap);
153 idmap += strlen(idmap) + 1;
154 }
155 }
156
157 if (stmnt->mask & STATMOUNT_MNT_GIDMAP) {
158 const char *idmap = stmnt->str + stmnt->mnt_gidmap;
159
160 for (size_t idx = 0; idx < stmnt->mnt_gidmap_num; idx++) {
161 printf("mnt_gidmap[%zu]:\t%s\n", idx, idmap);
162 idmap += strlen(idmap) + 1;
163 }
164 }
165
166 printf("\n");
167
168 free(stmnt);
169 }
170 }
171
172 exit(0);
173}
174

source code of linux/samples/vfs/test-list-all-mounts.c