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(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
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(&nsi->refcnt, 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(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(nsinfo__refcnt(nsi));
232
233	return result;
234}
235
236void 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
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
269pid_t nsinfo__in_pidns(const struct nsinfo  *nsi)
270{
271	return RC_CHK_ACCESS(nsi)->in_pidns;
272}
273
274void 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
314errout:
315	free(oldcwd);
316	if (oldns > -1)
317		close(oldns);
318	if (newns > -1)
319		close(newns);
320}
321
322void 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
345char *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
357int 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
369bool 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