diff options
Diffstat (limited to 'lib/util/secure_path.c')
-rw-r--r-- | lib/util/secure_path.c | 203 |
1 files changed, 203 insertions, 0 deletions
diff --git a/lib/util/secure_path.c b/lib/util/secure_path.c new file mode 100644 index 0000000..aaceb57 --- /dev/null +++ b/lib/util/secure_path.c @@ -0,0 +1,203 @@ +/* + * SPDX-License-Identifier: ISC + * + * Copyright (c) 2012, 2014-2022 Todd C. Miller <Todd.Miller@sudo.ws> + * + * Permission to use, copy, modify, and distribute this software for any + * purpose with or without fee is hereby granted, provided that the above + * copyright notice and this permission notice appear in all copies. + * + * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES + * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF + * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR + * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES + * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN + * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF + * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. + */ + +/* + * This is an open source non-commercial project. Dear PVS-Studio, please check it. + * PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com + */ + +#include <config.h> + +#include <sys/stat.h> +#include <errno.h> +#include <fcntl.h> +#include <string.h> +#include <unistd.h> + +#include <sudo_compat.h> +#include <sudo_util.h> +#include <sudo_debug.h> + +/* + * Verify that path is the right type and not writable by other users. + */ +static int +sudo_check_secure(struct stat *sb, unsigned int type, uid_t uid, gid_t gid) +{ + int ret = SUDO_PATH_SECURE; + debug_decl(sudo_check_secure, SUDO_DEBUG_UTIL); + + if ((sb->st_mode & S_IFMT) != type) { + ret = SUDO_PATH_BAD_TYPE; + } else if (uid != (uid_t)-1 && sb->st_uid != uid) { + ret = SUDO_PATH_WRONG_OWNER; + } else if (sb->st_mode & S_IWOTH) { + ret = SUDO_PATH_WORLD_WRITABLE; + } else if (ISSET(sb->st_mode, S_IWGRP) && + (gid == (gid_t)-1 || sb->st_gid != gid)) { + ret = SUDO_PATH_GROUP_WRITABLE; + } + + debug_return_int(ret); +} + +/* + * Verify that path is the right type and not writable by other users. + */ +static int +sudo_secure_path(const char *path, unsigned int type, uid_t uid, gid_t gid, + struct stat *sb) +{ + int ret = SUDO_PATH_MISSING; + struct stat stat_buf; + debug_decl(sudo_secure_path, SUDO_DEBUG_UTIL); + + if (sb == NULL) + sb = &stat_buf; + + if (path != NULL && stat(path, sb) == 0) + ret = sudo_check_secure(sb, type, uid, gid); + + debug_return_int(ret); +} + +/* + * Verify that path is a regular file and not writable by other users. + * Not currently used. + */ +int +sudo_secure_file_v1(const char *path, uid_t uid, gid_t gid, struct stat *sb) +{ + return sudo_secure_path(path, S_IFREG, uid, gid, sb); +} + +/* + * Verify that path is a directory and not writable by other users. + */ +int +sudo_secure_dir_v1(const char *path, uid_t uid, gid_t gid, struct stat *sb) +{ + return sudo_secure_path(path, S_IFDIR, uid, gid, sb); +} + +/* + * Verify that fd matches type and not writable by other users. + */ +int +sudo_secure_fd_v1(int fd, unsigned int type, uid_t uid, gid_t gid, + struct stat *sb) +{ + int ret = SUDO_PATH_MISSING; + debug_decl(sudo_secure_fd, SUDO_DEBUG_UTIL); + + if (fd != -1 && fstat(fd, sb) == 0) + ret = sudo_check_secure(sb, type, uid, gid); + debug_return_int(ret); +} + +/* + * Open path read-only as long as it is not writable by other users. + * Returns an open file descriptor on success, else -1. + * Sets error to SUDO_PATH_SECURE on success, and a value < 0 on failure. + */ +static int +sudo_secure_open(const char *path, unsigned int type, uid_t uid, gid_t gid, + struct stat *sb, int *error) +{ + struct stat stat_buf; + int fd; + debug_decl(sudo_secure_open, SUDO_DEBUG_UTIL); + + if (sb == NULL) + sb = &stat_buf; + + fd = open(path, O_RDONLY|O_NONBLOCK); + if (fd == -1 || fstat(fd, sb) != 0) { + if (fd != -1) + close(fd); + *error = SUDO_PATH_MISSING; + debug_return_int(-1); + } + + *error = sudo_check_secure(sb, type, uid, gid); + if (*error == SUDO_PATH_SECURE) { + (void)fcntl(fd, F_SETFL, fcntl(fd, F_GETFL, 0) & ~O_NONBLOCK); + } else { + /* Not secure, caller can check error flag. */ + close(fd); + fd = -1; + } + + debug_return_int(fd); +} + +int +sudo_secure_open_file_v1(const char *path, uid_t uid, gid_t gid, + struct stat *sb, int *error) +{ + return sudo_secure_open(path, S_IFREG, uid, gid, sb, error); +} + +int +sudo_secure_open_dir_v1(const char *path, uid_t uid, gid_t gid, + struct stat *sb, int *error) +{ + return sudo_secure_open(path, S_IFDIR, uid, gid, sb, error); +} + +/* + * Open the first file found in a colon-separated list of paths. + * Subsequent files in the path are only attempted if the + * previous file does not exist. Errors other than ENOENT are + * considered fatal and will stop processing the path. + * Sets name based on the last file it tried to open, even on error. + */ +int +sudo_open_conf_path_v1(const char *path, char *name, size_t namesize, + int (*fn)(const char *, int)) +{ + const char *cp, *ep, *path_end; + int fd = -1; + debug_decl(sudo_open_conf_path, SUDO_DEBUG_UTIL); + + path_end = path + strlen(path); + for (cp = sudo_strsplit(path, path_end, ":", &ep); + cp != NULL; cp = sudo_strsplit(NULL, path_end, ":", &ep)) { + + const size_t len = (size_t)(ep - cp); + if (len >= namesize) { + /* We always set name, even on error. */ + memcpy(name, cp, namesize - 1); + name[namesize - 1] = '\0'; + errno = ENAMETOOLONG; + break; + } + memcpy(name, cp, len); + name[len] = '\0'; + + fd = fn ? + fn(name, O_RDONLY|O_NONBLOCK) : open(name, O_RDONLY|O_NONBLOCK); + if (fd != -1) { + (void)fcntl(fd, F_SETFL, fcntl(fd, F_GETFL, 0) & ~O_NONBLOCK); + break; + } + if (errno != ENOENT) + break; + } + debug_return_int(fd); +} |