namespaces.c (6737B)
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(struct nsinfo *nsi, 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 nsi->tgid = (pid_t)strtol(strrchr(statln, '\t'), 78 NULL, 10); 79 nsi->nstgid = nsinfo__tgid(nsi); 80 } 81 82 if (strstr(statln, "NStgid:") != NULL) { 83 nspid = strrchr(statln, '\t'); 84 nsi->nstgid = (pid_t)strtol(nspid, NULL, 10); 85 /* 86 * If innermost tgid is not the first, process is in a different 87 * PID namespace. 88 */ 89 nsi->in_pidns = (statln + sizeof("NStgid:") - 1) != nspid; 90 break; 91 } 92 } 93 94 fclose(f); 95 free(statln); 96 return 0; 97} 98 99int nsinfo__init(struct nsinfo *nsi) 100{ 101 char oldns[PATH_MAX]; 102 char spath[PATH_MAX]; 103 char *newns = NULL; 104 struct stat old_stat; 105 struct stat new_stat; 106 int rv = -1; 107 108 if (snprintf(oldns, PATH_MAX, "/proc/self/ns/mnt") >= PATH_MAX) 109 return rv; 110 111 if (asprintf(&newns, "/proc/%d/ns/mnt", nsinfo__pid(nsi)) == -1) 112 return rv; 113 114 if (stat(oldns, &old_stat) < 0) 115 goto out; 116 117 if (stat(newns, &new_stat) < 0) 118 goto out; 119 120 /* Check if the mount namespaces differ, if so then indicate that we 121 * want to switch as part of looking up dso/map data. 122 */ 123 if (old_stat.st_ino != new_stat.st_ino) { 124 nsi->need_setns = true; 125 nsi->mntns_path = newns; 126 newns = NULL; 127 } 128 129 /* If we're dealing with a process that is in a different PID namespace, 130 * attempt to work out the innermost tgid for the process. 131 */ 132 if (snprintf(spath, PATH_MAX, "/proc/%d/status", nsinfo__pid(nsi)) >= PATH_MAX) 133 goto out; 134 135 rv = nsinfo__get_nspid(nsi, spath); 136 137out: 138 free(newns); 139 return rv; 140} 141 142struct nsinfo *nsinfo__new(pid_t pid) 143{ 144 struct nsinfo *nsi; 145 146 if (pid == 0) 147 return NULL; 148 149 nsi = calloc(1, sizeof(*nsi)); 150 if (nsi != NULL) { 151 nsi->pid = pid; 152 nsi->tgid = pid; 153 nsi->nstgid = pid; 154 nsi->need_setns = false; 155 nsi->in_pidns = false; 156 /* Init may fail if the process exits while we're trying to look 157 * at its proc information. In that case, save the pid but 158 * don't try to enter the namespace. 159 */ 160 if (nsinfo__init(nsi) == -1) 161 nsi->need_setns = false; 162 163 refcount_set(&nsi->refcnt, 1); 164 } 165 166 return nsi; 167} 168 169struct nsinfo *nsinfo__copy(const struct nsinfo *nsi) 170{ 171 struct nsinfo *nnsi; 172 173 if (nsi == NULL) 174 return NULL; 175 176 nnsi = calloc(1, sizeof(*nnsi)); 177 if (nnsi != NULL) { 178 nnsi->pid = nsinfo__pid(nsi); 179 nnsi->tgid = nsinfo__tgid(nsi); 180 nnsi->nstgid = nsinfo__nstgid(nsi); 181 nnsi->need_setns = nsinfo__need_setns(nsi); 182 nnsi->in_pidns = nsinfo__in_pidns(nsi); 183 if (nsi->mntns_path) { 184 nnsi->mntns_path = strdup(nsi->mntns_path); 185 if (!nnsi->mntns_path) { 186 free(nnsi); 187 return NULL; 188 } 189 } 190 refcount_set(&nnsi->refcnt, 1); 191 } 192 193 return nnsi; 194} 195 196static void nsinfo__delete(struct nsinfo *nsi) 197{ 198 zfree(&nsi->mntns_path); 199 free(nsi); 200} 201 202struct nsinfo *nsinfo__get(struct nsinfo *nsi) 203{ 204 if (nsi) 205 refcount_inc(&nsi->refcnt); 206 return nsi; 207} 208 209void nsinfo__put(struct nsinfo *nsi) 210{ 211 if (nsi && refcount_dec_and_test(&nsi->refcnt)) 212 nsinfo__delete(nsi); 213} 214 215bool nsinfo__need_setns(const struct nsinfo *nsi) 216{ 217 return nsi->need_setns; 218} 219 220void nsinfo__clear_need_setns(struct nsinfo *nsi) 221{ 222 nsi->need_setns = false; 223} 224 225pid_t nsinfo__tgid(const struct nsinfo *nsi) 226{ 227 return nsi->tgid; 228} 229 230pid_t nsinfo__nstgid(const struct nsinfo *nsi) 231{ 232 return nsi->nstgid; 233} 234 235pid_t nsinfo__pid(const struct nsinfo *nsi) 236{ 237 return nsi->pid; 238} 239 240pid_t nsinfo__in_pidns(const struct nsinfo *nsi) 241{ 242 return nsi->in_pidns; 243} 244 245void nsinfo__mountns_enter(struct nsinfo *nsi, 246 struct nscookie *nc) 247{ 248 char curpath[PATH_MAX]; 249 int oldns = -1; 250 int newns = -1; 251 char *oldcwd = NULL; 252 253 if (nc == NULL) 254 return; 255 256 nc->oldns = -1; 257 nc->newns = -1; 258 259 if (!nsi || !nsi->need_setns) 260 return; 261 262 if (snprintf(curpath, PATH_MAX, "/proc/self/ns/mnt") >= PATH_MAX) 263 return; 264 265 oldcwd = get_current_dir_name(); 266 if (!oldcwd) 267 return; 268 269 oldns = open(curpath, O_RDONLY); 270 if (oldns < 0) 271 goto errout; 272 273 newns = open(nsi->mntns_path, O_RDONLY); 274 if (newns < 0) 275 goto errout; 276 277 if (setns(newns, CLONE_NEWNS) < 0) 278 goto errout; 279 280 nc->oldcwd = oldcwd; 281 nc->oldns = oldns; 282 nc->newns = newns; 283 return; 284 285errout: 286 free(oldcwd); 287 if (oldns > -1) 288 close(oldns); 289 if (newns > -1) 290 close(newns); 291} 292 293void nsinfo__mountns_exit(struct nscookie *nc) 294{ 295 if (nc == NULL || nc->oldns == -1 || nc->newns == -1 || !nc->oldcwd) 296 return; 297 298 setns(nc->oldns, CLONE_NEWNS); 299 300 if (nc->oldcwd) { 301 WARN_ON_ONCE(chdir(nc->oldcwd)); 302 zfree(&nc->oldcwd); 303 } 304 305 if (nc->oldns > -1) { 306 close(nc->oldns); 307 nc->oldns = -1; 308 } 309 310 if (nc->newns > -1) { 311 close(nc->newns); 312 nc->newns = -1; 313 } 314} 315 316char *nsinfo__realpath(const char *path, struct nsinfo *nsi) 317{ 318 char *rpath; 319 struct nscookie nsc; 320 321 nsinfo__mountns_enter(nsi, &nsc); 322 rpath = realpath(path, NULL); 323 nsinfo__mountns_exit(&nsc); 324 325 return rpath; 326} 327 328int nsinfo__stat(const char *filename, struct stat *st, struct nsinfo *nsi) 329{ 330 int ret; 331 struct nscookie nsc; 332 333 nsinfo__mountns_enter(nsi, &nsc); 334 ret = stat(filename, st); 335 nsinfo__mountns_exit(&nsc); 336 337 return ret; 338} 339 340bool nsinfo__is_in_root_namespace(void) 341{ 342 struct nsinfo nsi; 343 344 memset(&nsi, 0x0, sizeof(nsi)); 345 nsinfo__get_nspid(&nsi, "/proc/self/status"); 346 return !nsi.in_pidns; 347}