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
23 static 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
perf_ns__name(unsigned int id)33 const 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
namespaces__new(struct perf_record_namespaces * event)40 struct 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
namespaces__free(struct namespaces * namespaces)58 void namespaces__free(struct namespaces *namespaces)
59 {
60 free(namespaces);
61 }
62
nsinfo__get_nspid(pid_t * tgid,pid_t * nstgid,bool * in_pidns,const char * path)63 static 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
nsinfo__init(struct nsinfo * nsi)98 int 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(oldns, PATH_MAX, "/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(spath, PATH_MAX, "/proc/%d/status", nsinfo__pid(nsi)) >= PATH_MAX)
132 goto out;
133
134 rv = nsinfo__get_nspid(&RC_CHK_ACCESS(nsi)->tgid, &RC_CHK_ACCESS(nsi)->nstgid,
135 &RC_CHK_ACCESS(nsi)->in_pidns, spath);
136
137 out:
138 free(newns);
139 return rv;
140 }
141
nsinfo__alloc(void)142 static 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(&nsi->refcnt, 1);
150
151 return res;
152 }
153
nsinfo__new(pid_t pid)154 struct 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
nsinfo__mntns_path(const struct nsinfo * nsi)180 static const char *nsinfo__mntns_path(const struct nsinfo *nsi)
181 {
182 return RC_CHK_ACCESS(nsi)->mntns_path;
183 }
184
nsinfo__copy(const struct nsinfo * nsi)185 struct 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(nnsi);
205 return NULL;
206 }
207 }
208
209 return nnsi;
210 }
211
nsinfo__refcnt(struct nsinfo * nsi)212 static refcount_t *nsinfo__refcnt(struct nsinfo *nsi)
213 {
214 return &RC_CHK_ACCESS(nsi)->refcnt;
215 }
216
nsinfo__delete(struct nsinfo * nsi)217 static 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
nsinfo__get(struct nsinfo * nsi)226 struct nsinfo *nsinfo__get(struct nsinfo *nsi)
227 {
228 struct nsinfo *result;
229
230 if (RC_CHK_GET(result, nsi))
231 refcount_inc(nsinfo__refcnt(nsi));
232
233 return result;
234 }
235
nsinfo__put(struct nsinfo * nsi)236 void nsinfo__put(struct nsinfo *nsi)
237 {
238 if (nsi && refcount_dec_and_test(nsinfo__refcnt(nsi)))
239 nsinfo__delete(nsi);
240 else
241 RC_CHK_PUT(nsi);
242 }
243
nsinfo__need_setns(const struct nsinfo * nsi)244 bool nsinfo__need_setns(const struct nsinfo *nsi)
245 {
246 return RC_CHK_ACCESS(nsi)->need_setns;
247 }
248
nsinfo__clear_need_setns(struct nsinfo * nsi)249 void nsinfo__clear_need_setns(struct nsinfo *nsi)
250 {
251 RC_CHK_ACCESS(nsi)->need_setns = false;
252 }
253
nsinfo__tgid(const struct nsinfo * nsi)254 pid_t nsinfo__tgid(const struct nsinfo *nsi)
255 {
256 return RC_CHK_ACCESS(nsi)->tgid;
257 }
258
nsinfo__nstgid(const struct nsinfo * nsi)259 pid_t nsinfo__nstgid(const struct nsinfo *nsi)
260 {
261 return RC_CHK_ACCESS(nsi)->nstgid;
262 }
263
nsinfo__pid(const struct nsinfo * nsi)264 pid_t nsinfo__pid(const struct nsinfo *nsi)
265 {
266 return RC_CHK_ACCESS(nsi)->pid;
267 }
268
nsinfo__in_pidns(const struct nsinfo * nsi)269 pid_t nsinfo__in_pidns(const struct nsinfo *nsi)
270 {
271 return RC_CHK_ACCESS(nsi)->in_pidns;
272 }
273
nsinfo__mountns_enter(struct nsinfo * nsi,struct nscookie * nc)274 void nsinfo__mountns_enter(struct nsinfo *nsi,
275 struct nscookie *nc)
276 {
277 char curpath[PATH_MAX];
278 int oldns = -1;
279 int newns = -1;
280 char *oldcwd = NULL;
281
282 if (nc == NULL)
283 return;
284
285 nc->oldns = -1;
286 nc->newns = -1;
287
288 if (!nsi || !nsinfo__need_setns(nsi))
289 return;
290
291 if (snprintf(curpath, PATH_MAX, "/proc/self/ns/mnt") >= PATH_MAX)
292 return;
293
294 oldcwd = get_current_dir_name();
295 if (!oldcwd)
296 return;
297
298 oldns = open(curpath, O_RDONLY);
299 if (oldns < 0)
300 goto errout;
301
302 newns = open(nsinfo__mntns_path(nsi), O_RDONLY);
303 if (newns < 0)
304 goto errout;
305
306 if (setns(newns, CLONE_NEWNS) < 0)
307 goto errout;
308
309 nc->oldcwd = oldcwd;
310 nc->oldns = oldns;
311 nc->newns = newns;
312 return;
313
314 errout:
315 free(oldcwd);
316 if (oldns > -1)
317 close(oldns);
318 if (newns > -1)
319 close(newns);
320 }
321
nsinfo__mountns_exit(struct nscookie * nc)322 void nsinfo__mountns_exit(struct nscookie *nc)
323 {
324 if (nc == NULL || nc->oldns == -1 || nc->newns == -1 || !nc->oldcwd)
325 return;
326
327 setns(nc->oldns, CLONE_NEWNS);
328
329 if (nc->oldcwd) {
330 WARN_ON_ONCE(chdir(nc->oldcwd));
331 zfree(&nc->oldcwd);
332 }
333
334 if (nc->oldns > -1) {
335 close(nc->oldns);
336 nc->oldns = -1;
337 }
338
339 if (nc->newns > -1) {
340 close(nc->newns);
341 nc->newns = -1;
342 }
343 }
344
nsinfo__realpath(const char * path,struct nsinfo * nsi)345 char *nsinfo__realpath(const char *path, struct nsinfo *nsi)
346 {
347 char *rpath;
348 struct nscookie nsc;
349
350 nsinfo__mountns_enter(nsi, &nsc);
351 rpath = realpath(path, NULL);
352 nsinfo__mountns_exit(&nsc);
353
354 return rpath;
355 }
356
nsinfo__stat(const char * filename,struct stat * st,struct nsinfo * nsi)357 int nsinfo__stat(const char *filename, struct stat *st, struct nsinfo *nsi)
358 {
359 int ret;
360 struct nscookie nsc;
361
362 nsinfo__mountns_enter(nsi, &nsc);
363 ret = stat(filename, st);
364 nsinfo__mountns_exit(&nsc);
365
366 return ret;
367 }
368
nsinfo__is_in_root_namespace(void)369 bool nsinfo__is_in_root_namespace(void)
370 {
371 pid_t tgid = 0, nstgid = 0;
372 bool in_pidns = false;
373
374 nsinfo__get_nspid(&tgid, &nstgid, &in_pidns, "/proc/self/status");
375 return !in_pidns;
376 }
377