| 1 | /* |
| 2 | * Copyright (C) 2011 - David Goulet <david.goulet@polymtl.ca> |
| 3 | * Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
| 4 | * |
| 5 | * This program is free software; you can redistribute it and/or modify it |
| 6 | * under the terms of the GNU General Public License as published by the Free |
| 7 | * Software Foundation; only version 2 of the License. |
| 8 | * |
| 9 | * This program is distributed in the hope that it will be useful, but WITHOUT |
| 10 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| 11 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for |
| 12 | * more details. |
| 13 | * |
| 14 | * You should have received a copy of the GNU General Public License along with |
| 15 | * this program; if not, write to the Free Software Foundation, Inc., 59 Temple |
| 16 | * Place - Suite 330, Boston, MA 02111-1307, USA. |
| 17 | */ |
| 18 | |
| 19 | #define _GNU_SOURCE |
| 20 | #include <errno.h> |
| 21 | #include <limits.h> |
| 22 | #include <stdio.h> |
| 23 | #include <stdlib.h> |
| 24 | #include <string.h> |
| 25 | #include <sys/wait.h> |
| 26 | #include <sys/types.h> |
| 27 | #include <sys/stat.h> |
| 28 | #include <unistd.h> |
| 29 | |
| 30 | #include <lttngerr.h> |
| 31 | |
| 32 | #include "utils.h" |
| 33 | |
| 34 | /* |
| 35 | * Write to writable pipe used to notify a thread. |
| 36 | */ |
| 37 | int notify_thread_pipe(int wpipe) |
| 38 | { |
| 39 | int ret; |
| 40 | |
| 41 | ret = write(wpipe, "!", 1); |
| 42 | if (ret < 0) { |
| 43 | PERROR("write poll pipe"); |
| 44 | } |
| 45 | |
| 46 | return ret; |
| 47 | } |
| 48 | |
| 49 | /* |
| 50 | * Return pointer to home directory path using the env variable HOME. |
| 51 | * |
| 52 | * No home, NULL is returned. |
| 53 | */ |
| 54 | const char *get_home_dir(void) |
| 55 | { |
| 56 | return ((const char *) getenv("HOME")); |
| 57 | } |
| 58 | |
| 59 | /* |
| 60 | * Create recursively directory using the FULL path. |
| 61 | */ |
| 62 | static |
| 63 | int _mkdir_recursive(const char *path, mode_t mode, uid_t uid, gid_t gid) |
| 64 | { |
| 65 | int ret; |
| 66 | char *p, tmp[PATH_MAX]; |
| 67 | size_t len; |
| 68 | mode_t old_umask; |
| 69 | |
| 70 | ret = snprintf(tmp, sizeof(tmp), "%s", path); |
| 71 | if (ret < 0) { |
| 72 | PERROR("snprintf mkdir"); |
| 73 | goto error; |
| 74 | } |
| 75 | |
| 76 | len = ret; |
| 77 | if (tmp[len - 1] == '/') { |
| 78 | tmp[len - 1] = 0; |
| 79 | } |
| 80 | |
| 81 | old_umask = umask(0); |
| 82 | for (p = tmp + 1; *p; p++) { |
| 83 | if (*p == '/') { |
| 84 | *p = 0; |
| 85 | ret = mkdir(tmp, mode); |
| 86 | if (ret < 0) { |
| 87 | if (!(errno == EEXIST)) { |
| 88 | PERROR("mkdir recursive"); |
| 89 | ret = -errno; |
| 90 | goto umask_error; |
| 91 | } |
| 92 | } |
| 93 | *p = '/'; |
| 94 | } |
| 95 | } |
| 96 | |
| 97 | ret = mkdir(tmp, mode); |
| 98 | if (ret < 0) { |
| 99 | if (!(errno == EEXIST)) { |
| 100 | PERROR("mkdir recursive last piece"); |
| 101 | ret = -errno; |
| 102 | } else { |
| 103 | ret = 0; |
| 104 | } |
| 105 | } |
| 106 | |
| 107 | umask_error: |
| 108 | umask(old_umask); |
| 109 | error: |
| 110 | return ret; |
| 111 | } |
| 112 | |
| 113 | static |
| 114 | int run_as(int (*cmd)(const char *path, mode_t mode, uid_t uid, gid_t gid), |
| 115 | const char *path, mode_t mode, uid_t uid, gid_t gid) |
| 116 | { |
| 117 | int ret = 0; |
| 118 | pid_t pid; |
| 119 | |
| 120 | /* |
| 121 | * If we are non-root, we can only deal with our own uid. |
| 122 | */ |
| 123 | if (geteuid() != 0) { |
| 124 | if (uid != geteuid()) { |
| 125 | ERR("Client (%d)/Server (%d) UID mismatch (and sessiond is not root)", |
| 126 | uid, geteuid()); |
| 127 | return -EPERM; |
| 128 | } |
| 129 | return (*cmd)(path, mode, uid, gid); |
| 130 | } |
| 131 | |
| 132 | pid = fork(); |
| 133 | if (pid > 0) { |
| 134 | int status; |
| 135 | |
| 136 | /* |
| 137 | * Parent: wait for child to return, in which case the |
| 138 | * shared memory map will have been created. |
| 139 | */ |
| 140 | pid = wait(&status); |
| 141 | if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) { |
| 142 | ret = -1; |
| 143 | goto end; |
| 144 | } |
| 145 | goto end; |
| 146 | } else if (pid == 0) { |
| 147 | /* Child */ |
| 148 | setegid(gid); |
| 149 | if (ret < 0) { |
| 150 | perror("setegid"); |
| 151 | exit(EXIT_FAILURE); |
| 152 | } |
| 153 | ret = seteuid(uid); |
| 154 | if (ret < 0) { |
| 155 | perror("seteuid"); |
| 156 | exit(EXIT_FAILURE); |
| 157 | } |
| 158 | ret = (*cmd)(path, mode, uid, gid); |
| 159 | if (!ret) |
| 160 | exit(EXIT_SUCCESS); |
| 161 | else |
| 162 | exit(EXIT_FAILURE); |
| 163 | } else { |
| 164 | return -1; |
| 165 | } |
| 166 | end: |
| 167 | return ret; |
| 168 | } |
| 169 | |
| 170 | int mkdir_recursive(const char *path, mode_t mode, uid_t uid, gid_t gid) |
| 171 | { |
| 172 | DBG3("mkdir() recursive %s with mode %d for uid %d and gid %d", |
| 173 | path, mode, uid, gid); |
| 174 | return run_as(_mkdir_recursive, path, mode, uid, gid); |
| 175 | } |