| /* SPDX-License-Identifier: LGPL-2.1-or-later */ |
| |
| #include <fcntl.h> |
| #include <sys/types.h> |
| #include <unistd.h> |
| |
| #include "alloc-util.h" |
| #include "constants.h" |
| #include "errno.h" |
| #include "fd-util.h" |
| #include "fileio.h" |
| #include "mkdir.h" |
| #include "nspawn-setuid.h" |
| #include "process-util.h" |
| #include "signal-util.h" |
| #include "string-util.h" |
| #include "strv.h" |
| #include "user-util.h" |
| |
| static int spawn_getent(const char *database, const char *key, pid_t *rpid) { |
| int pipe_fds[2], r; |
| pid_t pid; |
| |
| assert(database); |
| assert(key); |
| assert(rpid); |
| |
| if (pipe2(pipe_fds, O_CLOEXEC) < 0) |
| return log_error_errno(errno, "Failed to allocate pipe: %m"); |
| |
| r = safe_fork("(getent)", FORK_RESET_SIGNALS|FORK_DEATHSIG|FORK_LOG|FORK_RLIMIT_NOFILE_SAFE, &pid); |
| if (r < 0) { |
| safe_close_pair(pipe_fds); |
| return r; |
| } |
| if (r == 0) { |
| char *empty_env = NULL; |
| |
| pipe_fds[0] = safe_close(pipe_fds[0]); |
| |
| if (rearrange_stdio(-EBADF, TAKE_FD(pipe_fds[1]), -EBADF) < 0) |
| _exit(EXIT_FAILURE); |
| |
| (void) close_all_fds(NULL, 0); |
| |
| execle("/usr/bin/getent", "getent", database, key, NULL, &empty_env); |
| execle("/bin/getent", "getent", database, key, NULL, &empty_env); |
| _exit(EXIT_FAILURE); |
| } |
| |
| pipe_fds[1] = safe_close(pipe_fds[1]); |
| |
| *rpid = pid; |
| |
| return pipe_fds[0]; |
| } |
| |
| int change_uid_gid_raw( |
| uid_t uid, |
| gid_t gid, |
| const gid_t *supplementary_gids, |
| size_t n_supplementary_gids, |
| bool chown_stdio) { |
| |
| if (!uid_is_valid(uid)) |
| uid = 0; |
| if (!gid_is_valid(gid)) |
| gid = 0; |
| |
| if (chown_stdio) { |
| (void) fchown(STDIN_FILENO, uid, gid); |
| (void) fchown(STDOUT_FILENO, uid, gid); |
| (void) fchown(STDERR_FILENO, uid, gid); |
| } |
| |
| if (setgroups(n_supplementary_gids, supplementary_gids) < 0) |
| return log_error_errno(errno, "Failed to set auxiliary groups: %m"); |
| |
| if (setresgid(gid, gid, gid) < 0) |
| return log_error_errno(errno, "setresgid() failed: %m"); |
| |
| if (setresuid(uid, uid, uid) < 0) |
| return log_error_errno(errno, "setresuid() failed: %m"); |
| |
| return 0; |
| } |
| |
| int change_uid_gid(const char *user, bool chown_stdio, char **ret_home) { |
| char *x, *u, *g, *h; |
| _cleanup_free_ gid_t *gids = NULL; |
| _cleanup_free_ char *home = NULL, *line = NULL; |
| _cleanup_fclose_ FILE *f = NULL; |
| _cleanup_close_ int fd = -EBADF; |
| unsigned n_gids = 0; |
| uid_t uid; |
| gid_t gid; |
| pid_t pid; |
| int r; |
| |
| assert(ret_home); |
| |
| if (!user || STR_IN_SET(user, "root", "0")) { |
| /* Reset everything fully to 0, just in case */ |
| |
| r = reset_uid_gid(); |
| if (r < 0) |
| return log_error_errno(r, "Failed to become root: %m"); |
| |
| *ret_home = NULL; |
| return 0; |
| } |
| |
| /* First, get user credentials */ |
| fd = spawn_getent("passwd", user, &pid); |
| if (fd < 0) |
| return fd; |
| |
| f = take_fdopen(&fd, "r"); |
| if (!f) |
| return log_oom(); |
| |
| r = read_line(f, LONG_LINE_MAX, &line); |
| if (r == 0) |
| return log_error_errno(SYNTHETIC_ERRNO(ESRCH), |
| "Failed to resolve user %s.", user); |
| if (r < 0) |
| return log_error_errno(r, "Failed to read from getent: %m"); |
| |
| (void) wait_for_terminate_and_check("getent passwd", pid, WAIT_LOG); |
| |
| x = strchr(line, ':'); |
| if (!x) |
| return log_error_errno(SYNTHETIC_ERRNO(EIO), |
| "/etc/passwd entry has invalid user field."); |
| |
| u = strchr(x+1, ':'); |
| if (!u) |
| return log_error_errno(SYNTHETIC_ERRNO(EIO), |
| "/etc/passwd entry has invalid password field."); |
| |
| u++; |
| g = strchr(u, ':'); |
| if (!g) |
| return log_error_errno(SYNTHETIC_ERRNO(EIO), |
| "/etc/passwd entry has invalid UID field."); |
| |
| *g = 0; |
| g++; |
| x = strchr(g, ':'); |
| if (!x) |
| return log_error_errno(SYNTHETIC_ERRNO(EIO), |
| "/etc/passwd entry has invalid GID field."); |
| |
| *x = 0; |
| h = strchr(x+1, ':'); |
| if (!h) |
| return log_error_errno(SYNTHETIC_ERRNO(EIO), |
| "/etc/passwd entry has invalid GECOS field."); |
| |
| h++; |
| x = strchr(h, ':'); |
| if (!x) |
| return log_error_errno(SYNTHETIC_ERRNO(EIO), |
| "/etc/passwd entry has invalid home directory field."); |
| |
| *x = 0; |
| |
| r = parse_uid(u, &uid); |
| if (r < 0) |
| return log_error_errno(SYNTHETIC_ERRNO(EIO), |
| "Failed to parse UID of user."); |
| |
| r = parse_gid(g, &gid); |
| if (r < 0) |
| return log_error_errno(SYNTHETIC_ERRNO(EIO), |
| "Failed to parse GID of user."); |
| |
| home = strdup(h); |
| if (!home) |
| return log_oom(); |
| |
| f = safe_fclose(f); |
| line = mfree(line); |
| |
| /* Second, get group memberships */ |
| fd = spawn_getent("initgroups", user, &pid); |
| if (fd < 0) |
| return fd; |
| |
| f = take_fdopen(&fd, "r"); |
| if (!f) |
| return log_oom(); |
| |
| r = read_line(f, LONG_LINE_MAX, &line); |
| if (r == 0) |
| return log_error_errno(SYNTHETIC_ERRNO(ESRCH), |
| "Failed to resolve user %s.", user); |
| if (r < 0) |
| return log_error_errno(r, "Failed to read from getent: %m"); |
| |
| (void) wait_for_terminate_and_check("getent initgroups", pid, WAIT_LOG); |
| |
| /* Skip over the username and subsequent separator whitespace */ |
| x = line; |
| x += strcspn(x, WHITESPACE); |
| x += strspn(x, WHITESPACE); |
| |
| for (const char *p = x;;) { |
| _cleanup_free_ char *word = NULL; |
| |
| r = extract_first_word(&p, &word, NULL, 0); |
| if (r < 0) |
| return log_error_errno(r, "Failed to parse group data from getent: %m"); |
| if (r == 0) |
| break; |
| |
| if (!GREEDY_REALLOC(gids, n_gids+1)) |
| return log_oom(); |
| |
| r = parse_gid(word, &gids[n_gids++]); |
| if (r < 0) |
| return log_error_errno(r, "Failed to parse group data from getent: %m"); |
| } |
| |
| r = mkdir_parents(home, 0775); |
| if (r < 0) |
| return log_error_errno(r, "Failed to make home root directory: %m"); |
| |
| r = mkdir_safe(home, 0755, uid, gid, 0); |
| if (r < 0 && !IN_SET(r, -EEXIST, -ENOTDIR)) |
| return log_error_errno(r, "Failed to make home directory: %m"); |
| |
| r = change_uid_gid_raw(uid, gid, gids, n_gids, chown_stdio); |
| if (r < 0) |
| return r; |
| |
| if (ret_home) |
| *ret_home = TAKE_PTR(home); |
| |
| return 0; |
| } |
