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
  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
  40 void namespaces__free(struct namespaces *namespaces)
  41 {
  42         free(namespaces);
  43 }
  44
  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
 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
 138 struct nsinfo *nsinfo__copy(struct nsinfo *nsi)
 139 {
 140         struct nsinfo *nnsi;
 141
 142         nnsi = calloc(1, sizeof(*nnsi));
 143         if (nnsi != NULL) {
 144                 nnsi->pid = nsi->pid;
 145                 nnsi->tgid = nsi->tgid;
 146                 nnsi->nstgid = nsi->nstgid;
 147                 nnsi->need_setns = nsi->need_setns;
 148                 if (nsi->mntns_path) {
 149                         nnsi->mntns_path = strdup(nsi->mntns_path);
 150                         if (!nnsi->mntns_path) {
 151                                 free(nnsi);
 152                                 return NULL;
 153                         }
 154                 }
 155                 refcount_set(&nnsi->refcnt, 1);
 156         }
 157
 158         return nnsi;
 159 }
 160
 161 void nsinfo__delete(struct nsinfo *nsi)
 162 {
 163         zfree(&nsi->mntns_path);
 164         free(nsi);
 165 }
 166
 167 struct nsinfo *nsinfo__get(struct nsinfo *nsi)
 168 {
 169         if (nsi)
 170                 refcount_inc(&nsi->refcnt);
 171         return nsi;
 172 }
 173
 174 void nsinfo__put(struct nsinfo *nsi)
 175 {
 176         if (nsi && refcount_dec_and_test(&nsi->refcnt))
 177                 nsinfo__delete(nsi);
 178 }
 179
 180 void nsinfo__mountns_enter(struct nsinfo *nsi,
 181                                   struct nscookie *nc)
 182 {
 183         char curpath[PATH_MAX];
 184         int oldns = -1;
 185         int newns = -1;
 186
 187         if (nc == NULL)
 188                 return;
 189
 190         nc->oldns = -1;
 191         nc->newns = -1;
 192
 193         if (!nsi || !nsi->need_setns)
 194                 return;
 195
 196         if (snprintf(curpath, PATH_MAX, "/proc/self/ns/mnt") >= PATH_MAX)
 197                 return;
 198
 199         oldns = open(curpath, O_RDONLY);
 200         if (oldns < 0)
 201                 return;
 202
 203         newns = open(nsi->mntns_path, O_RDONLY);
 204         if (newns < 0)
 205                 goto errout;
 206
 207         if (setns(newns, CLONE_NEWNS) < 0)
 208                 goto errout;
 209
 210         nc->oldns = oldns;
 211         nc->newns = newns;
 212         return;
 213
 214 errout:
 215         if (oldns > -1)
 216                 close(oldns);
 217         if (newns > -1)
 218                 close(newns);
 219 }
 220
 221 void nsinfo__mountns_exit(struct nscookie *nc)
 222 {
 223         if (nc == NULL || nc->oldns == -1 || nc->newns == -1)
 224                 return;
 225
 226         setns(nc->oldns, CLONE_NEWNS);
 227
 228         if (nc->oldns > -1) {
 229                 close(nc->oldns);
 230                 nc->oldns = -1;
 231         }
 232
 233         if (nc->newns > -1) {
 234                 close(nc->newns);
 235                 nc->newns = -1;
 236         }
 237 }
 238
 239 char *nsinfo__realpath(const char *path, struct nsinfo *nsi)
 240 {
 241         char *rpath;
 242         struct nscookie nsc;
 243
 244         nsinfo__mountns_enter(nsi, &nsc);
 245         rpath = realpath(path, NULL);
 246         nsinfo__mountns_exit(&nsc);
 247
 248         return rpath;
 249 }