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