• Home
  • Line#
  • Scopes#
  • Navigate#
  • Raw
  • Download
1 /*
2  * This program is free software; you can redistribute it and/or modify
3  * it under the terms of the GNU General Public License, version 2, as
4  * published by the Free Software Foundation.
5  *
6  * Copyright (C) 2017 Hari Bathini, IBM Corporation
7  */
8 
9 #include "namespaces.h"
10 #include "util.h"
11 #include "event.h"
12 #include <sys/types.h>
13 #include <sys/stat.h>
14 #include <limits.h>
15 #include <sched.h>
16 #include <stdlib.h>
17 #include <stdio.h>
18 #include <string.h>
19 #include <unistd.h>
20 #include <asm/bug.h>
21 
namespaces__new(struct namespaces_event * event)22 struct namespaces *namespaces__new(struct namespaces_event *event)
23 {
24 	struct namespaces *namespaces;
25 	u64 link_info_size = ((event ? event->nr_namespaces : NR_NAMESPACES) *
26 			      sizeof(struct perf_ns_link_info));
27 
28 	namespaces = zalloc(sizeof(struct namespaces) + link_info_size);
29 	if (!namespaces)
30 		return NULL;
31 
32 	namespaces->end_time = -1;
33 
34 	if (event)
35 		memcpy(namespaces->link_info, event->link_info, link_info_size);
36 
37 	return namespaces;
38 }
39 
namespaces__free(struct namespaces * namespaces)40 void namespaces__free(struct namespaces *namespaces)
41 {
42 	free(namespaces);
43 }
44 
nsinfo__init(struct nsinfo * nsi)45 int nsinfo__init(struct nsinfo *nsi)
46 {
47 	char oldns[PATH_MAX];
48 	char spath[PATH_MAX];
49 	char *newns = NULL;
50 	char *statln = NULL;
51 	struct stat old_stat;
52 	struct stat new_stat;
53 	FILE *f = NULL;
54 	size_t linesz = 0;
55 	int rv = -1;
56 
57 	if (snprintf(oldns, PATH_MAX, "/proc/self/ns/mnt") >= PATH_MAX)
58 		return rv;
59 
60 	if (asprintf(&newns, "/proc/%d/ns/mnt", nsi->pid) == -1)
61 		return rv;
62 
63 	if (stat(oldns, &old_stat) < 0)
64 		goto out;
65 
66 	if (stat(newns, &new_stat) < 0)
67 		goto out;
68 
69 	/* Check if the mount namespaces differ, if so then indicate that we
70 	 * want to switch as part of looking up dso/map data.
71 	 */
72 	if (old_stat.st_ino != new_stat.st_ino) {
73 		nsi->need_setns = true;
74 		nsi->mntns_path = newns;
75 		newns = NULL;
76 	}
77 
78 	/* If we're dealing with a process that is in a different PID namespace,
79 	 * attempt to work out the innermost tgid for the process.
80 	 */
81 	if (snprintf(spath, PATH_MAX, "/proc/%d/status", nsi->pid) >= PATH_MAX)
82 		goto out;
83 
84 	f = fopen(spath, "r");
85 	if (f == NULL)
86 		goto out;
87 
88 	while (getline(&statln, &linesz, f) != -1) {
89 		/* Use tgid if CONFIG_PID_NS is not defined. */
90 		if (strstr(statln, "Tgid:") != NULL) {
91 			nsi->tgid = (pid_t)strtol(strrchr(statln, '\t'),
92 						     NULL, 10);
93 			nsi->nstgid = nsi->tgid;
94 		}
95 
96 		if (strstr(statln, "NStgid:") != NULL) {
97 			nsi->nstgid = (pid_t)strtol(strrchr(statln, '\t'),
98 						     NULL, 10);
99 			break;
100 		}
101 	}
102 	rv = 0;
103 
104 out:
105 	if (f != NULL)
106 		(void) fclose(f);
107 	free(statln);
108 	free(newns);
109 	return rv;
110 }
111 
nsinfo__new(pid_t pid)112 struct nsinfo *nsinfo__new(pid_t pid)
113 {
114 	struct nsinfo *nsi;
115 
116 	if (pid == 0)
117 		return NULL;
118 
119 	nsi = calloc(1, sizeof(*nsi));
120 	if (nsi != NULL) {
121 		nsi->pid = pid;
122 		nsi->tgid = pid;
123 		nsi->nstgid = pid;
124 		nsi->need_setns = false;
125 		/* Init may fail if the process exits while we're trying to look
126 		 * at its proc information.  In that case, save the pid but
127 		 * don't try to enter the namespace.
128 		 */
129 		if (nsinfo__init(nsi) == -1)
130 			nsi->need_setns = false;
131 
132 		refcount_set(&nsi->refcnt, 1);
133 	}
134 
135 	return nsi;
136 }
137 
nsinfo__copy(struct nsinfo * nsi)138 struct nsinfo *nsinfo__copy(struct nsinfo *nsi)
139 {
140 	struct nsinfo *nnsi;
141 
142 	if (nsi == NULL)
143 		return NULL;
144 
145 	nnsi = calloc(1, sizeof(*nnsi));
146 	if (nnsi != NULL) {
147 		nnsi->pid = nsi->pid;
148 		nnsi->tgid = nsi->tgid;
149 		nnsi->nstgid = nsi->nstgid;
150 		nnsi->need_setns = nsi->need_setns;
151 		if (nsi->mntns_path) {
152 			nnsi->mntns_path = strdup(nsi->mntns_path);
153 			if (!nnsi->mntns_path) {
154 				free(nnsi);
155 				return NULL;
156 			}
157 		}
158 		refcount_set(&nnsi->refcnt, 1);
159 	}
160 
161 	return nnsi;
162 }
163 
nsinfo__delete(struct nsinfo * nsi)164 void nsinfo__delete(struct nsinfo *nsi)
165 {
166 	zfree(&nsi->mntns_path);
167 	free(nsi);
168 }
169 
nsinfo__get(struct nsinfo * nsi)170 struct nsinfo *nsinfo__get(struct nsinfo *nsi)
171 {
172 	if (nsi)
173 		refcount_inc(&nsi->refcnt);
174 	return nsi;
175 }
176 
nsinfo__put(struct nsinfo * nsi)177 void nsinfo__put(struct nsinfo *nsi)
178 {
179 	if (nsi && refcount_dec_and_test(&nsi->refcnt))
180 		nsinfo__delete(nsi);
181 }
182 
nsinfo__mountns_enter(struct nsinfo * nsi,struct nscookie * nc)183 void nsinfo__mountns_enter(struct nsinfo *nsi,
184 				  struct nscookie *nc)
185 {
186 	char curpath[PATH_MAX];
187 	int oldns = -1;
188 	int newns = -1;
189 	char *oldcwd = NULL;
190 
191 	if (nc == NULL)
192 		return;
193 
194 	nc->oldns = -1;
195 	nc->newns = -1;
196 
197 	if (!nsi || !nsi->need_setns)
198 		return;
199 
200 	if (snprintf(curpath, PATH_MAX, "/proc/self/ns/mnt") >= PATH_MAX)
201 		return;
202 
203 	oldcwd = get_current_dir_name();
204 	if (!oldcwd)
205 		return;
206 
207 	oldns = open(curpath, O_RDONLY);
208 	if (oldns < 0)
209 		goto errout;
210 
211 	newns = open(nsi->mntns_path, O_RDONLY);
212 	if (newns < 0)
213 		goto errout;
214 
215 	if (setns(newns, CLONE_NEWNS) < 0)
216 		goto errout;
217 
218 	nc->oldcwd = oldcwd;
219 	nc->oldns = oldns;
220 	nc->newns = newns;
221 	return;
222 
223 errout:
224 	free(oldcwd);
225 	if (oldns > -1)
226 		close(oldns);
227 	if (newns > -1)
228 		close(newns);
229 }
230 
nsinfo__mountns_exit(struct nscookie * nc)231 void nsinfo__mountns_exit(struct nscookie *nc)
232 {
233 	if (nc == NULL || nc->oldns == -1 || nc->newns == -1 || !nc->oldcwd)
234 		return;
235 
236 	setns(nc->oldns, CLONE_NEWNS);
237 
238 	if (nc->oldcwd) {
239 		WARN_ON_ONCE(chdir(nc->oldcwd));
240 		zfree(&nc->oldcwd);
241 	}
242 
243 	if (nc->oldns > -1) {
244 		close(nc->oldns);
245 		nc->oldns = -1;
246 	}
247 
248 	if (nc->newns > -1) {
249 		close(nc->newns);
250 		nc->newns = -1;
251 	}
252 }
253 
nsinfo__realpath(const char * path,struct nsinfo * nsi)254 char *nsinfo__realpath(const char *path, struct nsinfo *nsi)
255 {
256 	char *rpath;
257 	struct nscookie nsc;
258 
259 	nsinfo__mountns_enter(nsi, &nsc);
260 	rpath = realpath(path, NULL);
261 	nsinfo__mountns_exit(&nsc);
262 
263 	return rpath;
264 }
265