1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 *
4 * Copyright (C) 2017 Hari Bathini, IBM Corporation
5 */
6
7#include "namespaces.h"
8#include "event.h"
9#include "get_current_dir_name.h"
10#include <sys/types.h>
11#include <sys/stat.h>
12#include <fcntl.h>
13#include <limits.h>
14#include <sched.h>
15#include <stdlib.h>
16#include <stdio.h>
17#include <string.h>
18#include <unistd.h>
19#include <asm/bug.h>
20#include <linux/kernel.h>
21#include <linux/zalloc.h>
22
23static const char *perf_ns__names[] = {
24 [NET_NS_INDEX] = "net",
25 [UTS_NS_INDEX] = "uts",
26 [IPC_NS_INDEX] = "ipc",
27 [PID_NS_INDEX] = "pid",
28 [USER_NS_INDEX] = "user",
29 [MNT_NS_INDEX] = "mnt",
30 [CGROUP_NS_INDEX] = "cgroup",
31};
32
33const char *perf_ns__name(unsigned int id)
34{
35 if (id >= ARRAY_SIZE(perf_ns__names))
36 return "UNKNOWN";
37 return perf_ns__names[id];
38}
39
40struct namespaces *namespaces__new(struct perf_record_namespaces *event)
41{
42 struct namespaces *namespaces;
43 u64 link_info_size = ((event ? event->nr_namespaces : NR_NAMESPACES) *
44 sizeof(struct perf_ns_link_info));
45
46 namespaces = zalloc(sizeof(struct namespaces) + link_info_size);
47 if (!namespaces)
48 return NULL;
49
50 namespaces->end_time = -1;
51
52 if (event)
53 memcpy(namespaces->link_info, event->link_info, link_info_size);
54
55 return namespaces;
56}
57
58void namespaces__free(struct namespaces *namespaces)
59{
60 free(namespaces);
61}
62
63static int nsinfo__get_nspid(pid_t *tgid, pid_t *nstgid, bool *in_pidns, const char *path)
64{
65 FILE *f = NULL;
66 char *statln = NULL;
67 size_t linesz = 0;
68 char *nspid;
69
70 f = fopen(path, "r");
71 if (f == NULL)
72 return -1;
73
74 while (getline(&statln, &linesz, f) != -1) {
75 /* Use tgid if CONFIG_PID_NS is not defined. */
76 if (strstr(statln, "Tgid:") != NULL) {
77 *tgid = (pid_t)strtol(strrchr(statln, '\t'), NULL, 10);
78 *nstgid = *tgid;
79 }
80
81 if (strstr(statln, "NStgid:") != NULL) {
82 nspid = strrchr(statln, '\t');
83 *nstgid = (pid_t)strtol(nspid, NULL, 10);
84 /*
85 * If innermost tgid is not the first, process is in a different
86 * PID namespace.
87 */
88 *in_pidns = (statln + sizeof("NStgid:") - 1) != nspid;
89 break;
90 }
91 }
92
93 fclose(f);
94 free(statln);
95 return 0;
96}
97
98int nsinfo__init(struct nsinfo *nsi)
99{
100 char oldns[PATH_MAX];
101 char spath[PATH_MAX];
102 char *newns = NULL;
103 struct stat old_stat;
104 struct stat new_stat;
105 int rv = -1;
106
107 if (snprintf(buf: oldns, PATH_MAX, fmt: "/proc/self/ns/mnt") >= PATH_MAX)
108 return rv;
109
110 if (asprintf(&newns, "/proc/%d/ns/mnt", nsinfo__pid(nsi)) == -1)
111 return rv;
112
113 if (stat(oldns, &old_stat) < 0)
114 goto out;
115
116 if (stat(newns, &new_stat) < 0)
117 goto out;
118
119 /* Check if the mount namespaces differ, if so then indicate that we
120 * want to switch as part of looking up dso/map data.
121 */
122 if (old_stat.st_ino != new_stat.st_ino) {
123 RC_CHK_ACCESS(nsi)->need_setns = true;
124 RC_CHK_ACCESS(nsi)->mntns_path = newns;
125 newns = NULL;
126 }
127
128 /* If we're dealing with a process that is in a different PID namespace,
129 * attempt to work out the innermost tgid for the process.
130 */
131 if (snprintf(buf: spath, PATH_MAX, fmt: "/proc/%d/status", nsinfo__pid(nsi)) >= PATH_MAX)
132 goto out;
133
134 rv = nsinfo__get_nspid(tgid: &RC_CHK_ACCESS(nsi)->tgid, nstgid: &RC_CHK_ACCESS(nsi)->nstgid,
135 in_pidns: &RC_CHK_ACCESS(nsi)->in_pidns, path: spath);
136
137out:
138 free(newns);
139 return rv;
140}
141
142static struct nsinfo *nsinfo__alloc(void)
143{
144 struct nsinfo *res;
145 RC_STRUCT(nsinfo) *nsi;
146
147 nsi = calloc(1, sizeof(*nsi));
148 if (ADD_RC_CHK(res, nsi))
149 refcount_set(r: &nsi->refcnt, n: 1);
150
151 return res;
152}
153
154struct nsinfo *nsinfo__new(pid_t pid)
155{
156 struct nsinfo *nsi;
157
158 if (pid == 0)
159 return NULL;
160
161 nsi = nsinfo__alloc();
162 if (!nsi)
163 return NULL;
164
165 RC_CHK_ACCESS(nsi)->pid = pid;
166 RC_CHK_ACCESS(nsi)->tgid = pid;
167 RC_CHK_ACCESS(nsi)->nstgid = pid;
168 nsinfo__clear_need_setns(nsi);
169 RC_CHK_ACCESS(nsi)->in_pidns = false;
170 /* Init may fail if the process exits while we're trying to look at its
171 * proc information. In that case, save the pid but don't try to enter
172 * the namespace.
173 */
174 if (nsinfo__init(nsi) == -1)
175 nsinfo__clear_need_setns(nsi);
176
177 return nsi;
178}
179
180static const char *nsinfo__mntns_path(const struct nsinfo *nsi)
181{
182 return RC_CHK_ACCESS(nsi)->mntns_path;
183}
184
185struct nsinfo *nsinfo__copy(const struct nsinfo *nsi)
186{
187 struct nsinfo *nnsi;
188
189 if (nsi == NULL)
190 return NULL;
191
192 nnsi = nsinfo__alloc();
193 if (!nnsi)
194 return NULL;
195
196 RC_CHK_ACCESS(nnsi)->pid = nsinfo__pid(nsi);
197 RC_CHK_ACCESS(nnsi)->tgid = nsinfo__tgid(nsi);
198 RC_CHK_ACCESS(nnsi)->nstgid = nsinfo__nstgid(nsi);
199 RC_CHK_ACCESS(nnsi)->need_setns = nsinfo__need_setns(nsi);
200 RC_CHK_ACCESS(nnsi)->in_pidns = nsinfo__in_pidns(nsi);
201 if (nsinfo__mntns_path(nsi)) {
202 RC_CHK_ACCESS(nnsi)->mntns_path = strdup(nsinfo__mntns_path(nsi));
203 if (!RC_CHK_ACCESS(nnsi)->mntns_path) {
204 nsinfo__put(nsi: nnsi);
205 return NULL;
206 }
207 }
208
209 return nnsi;
210}
211
212static refcount_t *nsinfo__refcnt(struct nsinfo *nsi)
213{
214 return &RC_CHK_ACCESS(nsi)->refcnt;
215}
216
217static void nsinfo__delete(struct nsinfo *nsi)
218{
219 if (nsi) {
220 WARN_ONCE(refcount_read(nsinfo__refcnt(nsi)) != 0, "nsinfo refcnt unbalanced\n");
221 zfree(&RC_CHK_ACCESS(nsi)->mntns_path);
222 RC_CHK_FREE(nsi);
223 }
224}
225
226struct nsinfo *nsinfo__get(struct nsinfo *nsi)
227{
228 struct nsinfo *result;
229
230 if (RC_CHK_GET(result, nsi))
231 refcount_inc(r: nsinfo__refcnt(nsi));
232
233 return result;
234}
235
236void nsinfo__put(struct nsinfo *nsi)
237{
238 if (nsi && refcount_dec_and_test(r: nsinfo__refcnt(nsi)))
239 nsinfo__delete(nsi);
240 else
241 RC_CHK_PUT(nsi);
242}
243
244bool nsinfo__need_setns(const struct nsinfo *nsi)
245{
246 return RC_CHK_ACCESS(nsi)->need_setns;
247}
248
249void nsinfo__clear_need_setns(struct nsinfo *nsi)
250{
251 RC_CHK_ACCESS(nsi)->need_setns = false;
252}
253
254pid_t nsinfo__tgid(const struct nsinfo *nsi)
255{
256 return RC_CHK_ACCESS(nsi)->tgid;
257}
258
259pid_t nsinfo__nstgid(const struct nsinfo *nsi)
260{
261 return RC_CHK_ACCESS(nsi)->nstgid;
262}
263
264pid_t nsinfo__pid(const struct nsinfo *nsi)
265{
266 return RC_CHK_ACCESS(nsi)->pid;
267}
268
269bool nsinfo__in_pidns(const struct nsinfo *nsi)
270{
271 return RC_CHK_ACCESS(nsi)->in_pidns;
272}
273
274void nsinfo__set_in_pidns(struct nsinfo *nsi)
275{
276 RC_CHK_ACCESS(nsi)->in_pidns = true;
277}
278
279void nsinfo__mountns_enter(struct nsinfo *nsi,
280 struct nscookie *nc)
281{
282 char curpath[PATH_MAX];
283 int oldns = -1;
284 int newns = -1;
285 char *oldcwd = NULL;
286
287 if (nc == NULL)
288 return;
289
290 nc->oldns = -1;
291 nc->newns = -1;
292
293 if (!nsi || !nsinfo__need_setns(nsi))
294 return;
295
296 if (snprintf(buf: curpath, PATH_MAX, fmt: "/proc/self/ns/mnt") >= PATH_MAX)
297 return;
298
299 oldcwd = get_current_dir_name();
300 if (!oldcwd)
301 return;
302
303 oldns = open(curpath, O_RDONLY);
304 if (oldns < 0)
305 goto errout;
306
307 newns = open(nsinfo__mntns_path(nsi), O_RDONLY);
308 if (newns < 0)
309 goto errout;
310
311 if (setns(fd: newns, CLONE_NEWNS) < 0)
312 goto errout;
313
314 nc->oldcwd = oldcwd;
315 nc->oldns = oldns;
316 nc->newns = newns;
317 return;
318
319errout:
320 free(oldcwd);
321 if (oldns > -1)
322 close(oldns);
323 if (newns > -1)
324 close(newns);
325}
326
327void nsinfo__mountns_exit(struct nscookie *nc)
328{
329 if (nc == NULL || nc->oldns == -1 || nc->newns == -1 || !nc->oldcwd)
330 return;
331
332 setns(fd: nc->oldns, CLONE_NEWNS);
333
334 if (nc->oldcwd) {
335 WARN_ON_ONCE(chdir(nc->oldcwd));
336 zfree(&nc->oldcwd);
337 }
338
339 if (nc->oldns > -1) {
340 close(nc->oldns);
341 nc->oldns = -1;
342 }
343
344 if (nc->newns > -1) {
345 close(nc->newns);
346 nc->newns = -1;
347 }
348}
349
350char *nsinfo__realpath(const char *path, struct nsinfo *nsi)
351{
352 char *rpath;
353 struct nscookie nsc;
354
355 nsinfo__mountns_enter(nsi, nc: &nsc);
356 rpath = realpath(path, NULL);
357 nsinfo__mountns_exit(nc: &nsc);
358
359 return rpath;
360}
361
362int nsinfo__stat(const char *filename, struct stat *st, struct nsinfo *nsi)
363{
364 int ret;
365 struct nscookie nsc;
366
367 nsinfo__mountns_enter(nsi, nc: &nsc);
368 ret = stat(filename, st);
369 nsinfo__mountns_exit(nc: &nsc);
370
371 return ret;
372}
373
374bool nsinfo__is_in_root_namespace(void)
375{
376 pid_t tgid = 0, nstgid = 0;
377 bool in_pidns = false;
378
379 nsinfo__get_nspid(tgid: &tgid, nstgid: &nstgid, in_pidns: &in_pidns, path: "/proc/self/status");
380 return !in_pidns;
381}
382

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source code of linux/tools/perf/util/namespaces.c