1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * 4 * Copyright (C) 2017 Hari Bathini, IBM Corporation 5 */ 6 7 #include "namespaces.h" 8 #include "util.h" 9 #include "event.h" 10 #include <sys/types.h> 11 #include <sys/stat.h> 12 #include <fcntl.h> 13 #include <limits.h> 14 #include <sched.h> 15 #include <stdlib.h> 16 #include <stdio.h> 17 #include <string.h> 18 #include <unistd.h> 19 #include <asm/bug.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 if (nsi == NULL) 142 return NULL; 143 144 nnsi = calloc(1, sizeof(*nnsi)); 145 if (nnsi != NULL) { 146 nnsi->pid = nsi->pid; 147 nnsi->tgid = nsi->tgid; 148 nnsi->nstgid = nsi->nstgid; 149 nnsi->need_setns = nsi->need_setns; 150 if (nsi->mntns_path) { 151 nnsi->mntns_path = strdup(nsi->mntns_path); 152 if (!nnsi->mntns_path) { 153 free(nnsi); 154 return NULL; 155 } 156 } 157 refcount_set(&nnsi->refcnt, 1); 158 } 159 160 return nnsi; 161 } 162 163 void nsinfo__delete(struct nsinfo *nsi) 164 { 165 zfree(&nsi->mntns_path); 166 free(nsi); 167 } 168 169 struct nsinfo *nsinfo__get(struct nsinfo *nsi) 170 { 171 if (nsi) 172 refcount_inc(&nsi->refcnt); 173 return nsi; 174 } 175 176 void nsinfo__put(struct nsinfo *nsi) 177 { 178 if (nsi && refcount_dec_and_test(&nsi->refcnt)) 179 nsinfo__delete(nsi); 180 } 181 182 void nsinfo__mountns_enter(struct nsinfo *nsi, 183 struct nscookie *nc) 184 { 185 char curpath[PATH_MAX]; 186 int oldns = -1; 187 int newns = -1; 188 char *oldcwd = NULL; 189 190 if (nc == NULL) 191 return; 192 193 nc->oldns = -1; 194 nc->newns = -1; 195 196 if (!nsi || !nsi->need_setns) 197 return; 198 199 if (snprintf(curpath, PATH_MAX, "/proc/self/ns/mnt") >= PATH_MAX) 200 return; 201 202 oldcwd = get_current_dir_name(); 203 if (!oldcwd) 204 return; 205 206 oldns = open(curpath, O_RDONLY); 207 if (oldns < 0) 208 goto errout; 209 210 newns = open(nsi->mntns_path, O_RDONLY); 211 if (newns < 0) 212 goto errout; 213 214 if (setns(newns, CLONE_NEWNS) < 0) 215 goto errout; 216 217 nc->oldcwd = oldcwd; 218 nc->oldns = oldns; 219 nc->newns = newns; 220 return; 221 222 errout: 223 free(oldcwd); 224 if (oldns > -1) 225 close(oldns); 226 if (newns > -1) 227 close(newns); 228 } 229 230 void nsinfo__mountns_exit(struct nscookie *nc) 231 { 232 if (nc == NULL || nc->oldns == -1 || nc->newns == -1 || !nc->oldcwd) 233 return; 234 235 setns(nc->oldns, CLONE_NEWNS); 236 237 if (nc->oldcwd) { 238 WARN_ON_ONCE(chdir(nc->oldcwd)); 239 zfree(&nc->oldcwd); 240 } 241 242 if (nc->oldns > -1) { 243 close(nc->oldns); 244 nc->oldns = -1; 245 } 246 247 if (nc->newns > -1) { 248 close(nc->newns); 249 nc->newns = -1; 250 } 251 } 252 253 char *nsinfo__realpath(const char *path, struct nsinfo *nsi) 254 { 255 char *rpath; 256 struct nscookie nsc; 257 258 nsinfo__mountns_enter(nsi, &nsc); 259 rpath = realpath(path, NULL); 260 nsinfo__mountns_exit(&nsc); 261 262 return rpath; 263 } 264