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380 lines · 7.5 KiB

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