tools/perf/util/namespaces.c

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