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
 63int nsinfo__init(struct nsinfo *nsi)
 64{
 65	char oldns[PATH_MAX];
 66	char spath[PATH_MAX];
 67	char *newns = NULL;
 68	char *statln = NULL;
 69	char *nspid;
 70	struct stat old_stat;
 71	struct stat new_stat;
 72	FILE *f = NULL;
 73	size_t linesz = 0;
 74	int rv = -1;
 75
 76	if (snprintf(oldns, PATH_MAX, "/proc/self/ns/mnt") >= PATH_MAX)
 77		return rv;
 78
 79	if (asprintf(&newns, "/proc/%d/ns/mnt", nsi->pid) == -1)
 80		return rv;
 81
 82	if (stat(oldns, &old_stat) < 0)
 83		goto out;
 84
 85	if (stat(newns, &new_stat) < 0)
 86		goto out;
 87
 88	/* Check if the mount namespaces differ, if so then indicate that we
 89	 * want to switch as part of looking up dso/map data.
 90	 */
 91	if (old_stat.st_ino != new_stat.st_ino) {
 92		nsi->need_setns = true;
 93		nsi->mntns_path = newns;
 94		newns = NULL;
 95	}
 96
 97	/* If we're dealing with a process that is in a different PID namespace,
 98	 * attempt to work out the innermost tgid for the process.
 99	 */
100	if (snprintf(spath, PATH_MAX, "/proc/%d/status", nsi->pid) >= PATH_MAX)
101		goto out;
102
103	f = fopen(spath, "r");
104	if (f == NULL)
105		goto out;
106
107	while (getline(&statln, &linesz, f) != -1) {
108		/* Use tgid if CONFIG_PID_NS is not defined. */
109		if (strstr(statln, "Tgid:") != NULL) {
110			nsi->tgid = (pid_t)strtol(strrchr(statln, '\t'),
111						     NULL, 10);
112			nsi->nstgid = nsi->tgid;
113		}
114
115		if (strstr(statln, "NStgid:") != NULL) {
116			nspid = strrchr(statln, '\t');
117			nsi->nstgid = (pid_t)strtol(nspid, NULL, 10);
118			/* If innermost tgid is not the first, process is in a different
119			 * PID namespace.
120			 */
121			nsi->in_pidns = (statln + sizeof("NStgid:") - 1) != nspid;
122			break;
123		}
124	}
125	rv = 0;
126
127out:
128	if (f != NULL)
129		(void) fclose(f);
130	free(statln);
131	free(newns);
132	return rv;
133}
134
135struct nsinfo *nsinfo__new(pid_t pid)
136{
137	struct nsinfo *nsi;
138
139	if (pid == 0)
140		return NULL;
141
142	nsi = calloc(1, sizeof(*nsi));
143	if (nsi != NULL) {
144		nsi->pid = pid;
145		nsi->tgid = pid;
146		nsi->nstgid = pid;
147		nsi->need_setns = false;
148		nsi->in_pidns = false;
149		/* Init may fail if the process exits while we're trying to look
150		 * at its proc information.  In that case, save the pid but
151		 * don't try to enter the namespace.
152		 */
153		if (nsinfo__init(nsi) == -1)
154			nsi->need_setns = false;
155
156		refcount_set(&nsi->refcnt, 1);
157	}
158
159	return nsi;
160}
161
162struct nsinfo *nsinfo__copy(struct nsinfo *nsi)
163{
164	struct nsinfo *nnsi;
165
166	if (nsi == NULL)
167		return NULL;
168
169	nnsi = calloc(1, sizeof(*nnsi));
170	if (nnsi != NULL) {
171		nnsi->pid = nsi->pid;
172		nnsi->tgid = nsi->tgid;
173		nnsi->nstgid = nsi->nstgid;
174		nnsi->need_setns = nsi->need_setns;
175		nnsi->in_pidns = nsi->in_pidns;
176		if (nsi->mntns_path) {
177			nnsi->mntns_path = strdup(nsi->mntns_path);
178			if (!nnsi->mntns_path) {
179				free(nnsi);
180				return NULL;
181			}
182		}
183		refcount_set(&nnsi->refcnt, 1);
184	}
185
186	return nnsi;
187}
188
189void nsinfo__delete(struct nsinfo *nsi)
190{
191	zfree(&nsi->mntns_path);
192	free(nsi);
193}
194
195struct nsinfo *nsinfo__get(struct nsinfo *nsi)
196{
197	if (nsi)
198		refcount_inc(&nsi->refcnt);
199	return nsi;
200}
201
202void nsinfo__put(struct nsinfo *nsi)
203{
204	if (nsi && refcount_dec_and_test(&nsi->refcnt))
205		nsinfo__delete(nsi);
206}
207
208void nsinfo__mountns_enter(struct nsinfo *nsi,
209				  struct nscookie *nc)
210{
211	char curpath[PATH_MAX];
212	int oldns = -1;
213	int newns = -1;
214	char *oldcwd = NULL;
215
216	if (nc == NULL)
217		return;
218
219	nc->oldns = -1;
220	nc->newns = -1;
221
222	if (!nsi || !nsi->need_setns)
223		return;
224
225	if (snprintf(curpath, PATH_MAX, "/proc/self/ns/mnt") >= PATH_MAX)
226		return;
227
228	oldcwd = get_current_dir_name();
229	if (!oldcwd)
230		return;
231
232	oldns = open(curpath, O_RDONLY);
233	if (oldns < 0)
234		goto errout;
235
236	newns = open(nsi->mntns_path, O_RDONLY);
237	if (newns < 0)
238		goto errout;
239
240	if (setns(newns, CLONE_NEWNS) < 0)
241		goto errout;
242
243	nc->oldcwd = oldcwd;
244	nc->oldns = oldns;
245	nc->newns = newns;
246	return;
247
248errout:
249	free(oldcwd);
250	if (oldns > -1)
251		close(oldns);
252	if (newns > -1)
253		close(newns);
254}
255
256void nsinfo__mountns_exit(struct nscookie *nc)
257{
258	if (nc == NULL || nc->oldns == -1 || nc->newns == -1 || !nc->oldcwd)
259		return;
260
261	setns(nc->oldns, CLONE_NEWNS);
262
263	if (nc->oldcwd) {
264		WARN_ON_ONCE(chdir(nc->oldcwd));
265		zfree(&nc->oldcwd);
266	}
267
268	if (nc->oldns > -1) {
269		close(nc->oldns);
270		nc->oldns = -1;
271	}
272
273	if (nc->newns > -1) {
274		close(nc->newns);
275		nc->newns = -1;
276	}
277}
278
279char *nsinfo__realpath(const char *path, struct nsinfo *nsi)
280{
281	char *rpath;
282	struct nscookie nsc;
283
284	nsinfo__mountns_enter(nsi, &nsc);
285	rpath = realpath(path, NULL);
286	nsinfo__mountns_exit(&nsc);
287
288	return rpath;
289}
290
291int nsinfo__stat(const char *filename, struct stat *st, struct nsinfo *nsi)
292{
293	int ret;
294	struct nscookie nsc;
295
296	nsinfo__mountns_enter(nsi, &nsc);
297	ret = stat(filename, st);
298	nsinfo__mountns_exit(&nsc);
299
300	return ret;
301}