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 } 250