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 } 266