diff options
| -rw-r--r-- | Makefile.am | 2 | ||||
| -rw-r--r-- | src/nspawn/nspawn-setuid.c | 273 | ||||
| -rw-r--r-- | src/nspawn/nspawn-setuid.h | 24 | ||||
| -rw-r--r-- | src/nspawn/nspawn.c | 244 |
4 files changed, 301 insertions, 242 deletions
diff --git a/Makefile.am b/Makefile.am index 6852a3ab5c..3e4000819c 100644 --- a/Makefile.am +++ b/Makefile.am @@ -2791,6 +2791,8 @@ systemd_nspawn_SOURCES = \ src/nspawn/nspawn-cgroup.h \ src/nspawn/nspawn-register.c \ src/nspawn/nspawn-register.h \ + src/nspawn/nspawn-setuid.c \ + src/nspawn/nspawn-setuid.h \ src/core/mount-setup.c \ src/core/mount-setup.h \ src/core/loopback-setup.c \ diff --git a/src/nspawn/nspawn-setuid.c b/src/nspawn/nspawn-setuid.c new file mode 100644 index 0000000000..3da54c8dd2 --- /dev/null +++ b/src/nspawn/nspawn-setuid.c @@ -0,0 +1,273 @@ +/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/ + +/*** + This file is part of systemd. + + Copyright 2015 Lennart Poettering + + systemd is free software; you can redistribute it and/or modify it + under the terms of the GNU Lesser General Public License as published by + the Free Software Foundation; either version 2.1 of the License, or + (at your option) any later version. + + systemd is distributed in the hope that it will be useful, but + WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public License + along with systemd; If not, see <http://www.gnu.org/licenses/>. +***/ + +#include <sys/types.h> +#include <unistd.h> +#include <grp.h> + +#include "util.h" +#include "signal-util.h" +#include "mkdir.h" +#include "process-util.h" + +#include "nspawn.h" +#include "nspawn-setuid.h" + +static int spawn_getent(const char *database, const char *key, pid_t *rpid) { + int pipe_fds[2]; + 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"); + + pid = fork(); + if (pid < 0) + return log_error_errno(errno, "Failed to fork getent child: %m"); + else if (pid == 0) { + int nullfd; + char *empty_env = NULL; + + if (dup3(pipe_fds[1], STDOUT_FILENO, 0) < 0) + _exit(EXIT_FAILURE); + + if (pipe_fds[0] > 2) + safe_close(pipe_fds[0]); + if (pipe_fds[1] > 2) + safe_close(pipe_fds[1]); + + nullfd = open("/dev/null", O_RDWR); + if (nullfd < 0) + _exit(EXIT_FAILURE); + + if (dup3(nullfd, STDIN_FILENO, 0) < 0) + _exit(EXIT_FAILURE); + + if (dup3(nullfd, STDERR_FILENO, 0) < 0) + _exit(EXIT_FAILURE); + + if (nullfd > 2) + safe_close(nullfd); + + (void) reset_all_signal_handlers(); + (void) reset_signal_mask(); + 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(const char *user, char **_home) { + char line[LINE_MAX], *x, *u, *g, *h; + const char *word, *state; + _cleanup_free_ uid_t *uids = NULL; + _cleanup_free_ char *home = NULL; + _cleanup_fclose_ FILE *f = NULL; + _cleanup_close_ int fd = -1; + unsigned n_uids = 0; + size_t sz = 0, l; + uid_t uid; + gid_t gid; + pid_t pid; + int r; + + assert(_home); + + if (!user || streq(user, "root") || streq(user, "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"); + + *_home = NULL; + return 0; + } + + /* First, get user credentials */ + fd = spawn_getent("passwd", user, &pid); + if (fd < 0) + return fd; + + f = fdopen(fd, "r"); + if (!f) + return log_oom(); + fd = -1; + + if (!fgets(line, sizeof(line), f)) { + + if (!ferror(f)) { + log_error("Failed to resolve user %s.", user); + return -ESRCH; + } + + log_error_errno(errno, "Failed to read from getent: %m"); + return -errno; + } + + truncate_nl(line); + + wait_for_terminate_and_warn("getent passwd", pid, true); + + x = strchr(line, ':'); + if (!x) { + log_error("/etc/passwd entry has invalid user field."); + return -EIO; + } + + u = strchr(x+1, ':'); + if (!u) { + log_error("/etc/passwd entry has invalid password field."); + return -EIO; + } + + u++; + g = strchr(u, ':'); + if (!g) { + log_error("/etc/passwd entry has invalid UID field."); + return -EIO; + } + + *g = 0; + g++; + x = strchr(g, ':'); + if (!x) { + log_error("/etc/passwd entry has invalid GID field."); + return -EIO; + } + + *x = 0; + h = strchr(x+1, ':'); + if (!h) { + log_error("/etc/passwd entry has invalid GECOS field."); + return -EIO; + } + + h++; + x = strchr(h, ':'); + if (!x) { + log_error("/etc/passwd entry has invalid home directory field."); + return -EIO; + } + + *x = 0; + + r = parse_uid(u, &uid); + if (r < 0) { + log_error("Failed to parse UID of user."); + return -EIO; + } + + r = parse_gid(g, &gid); + if (r < 0) { + log_error("Failed to parse GID of user."); + return -EIO; + } + + home = strdup(h); + if (!home) + return log_oom(); + + /* Second, get group memberships */ + fd = spawn_getent("initgroups", user, &pid); + if (fd < 0) + return fd; + + fclose(f); + f = fdopen(fd, "r"); + if (!f) + return log_oom(); + fd = -1; + + if (!fgets(line, sizeof(line), f)) { + if (!ferror(f)) { + log_error("Failed to resolve user %s.", user); + return -ESRCH; + } + + log_error_errno(errno, "Failed to read from getent: %m"); + return -errno; + } + + truncate_nl(line); + + wait_for_terminate_and_warn("getent initgroups", pid, true); + + /* Skip over the username and subsequent separator whitespace */ + x = line; + x += strcspn(x, WHITESPACE); + x += strspn(x, WHITESPACE); + + FOREACH_WORD(word, l, x, state) { + char c[l+1]; + + memcpy(c, word, l); + c[l] = 0; + + if (!GREEDY_REALLOC(uids, sz, n_uids+1)) + return log_oom(); + + r = parse_uid(c, &uids[n_uids++]); + if (r < 0) { + log_error("Failed to parse group data from getent."); + return -EIO; + } + } + + 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); + if (r < 0 && r != -EEXIST) + return log_error_errno(r, "Failed to make home directory: %m"); + + (void) fchown(STDIN_FILENO, uid, gid); + (void) fchown(STDOUT_FILENO, uid, gid); + (void) fchown(STDERR_FILENO, uid, gid); + + if (setgroups(n_uids, uids) < 0) + return log_error_errno(errno, "Failed to set auxiliary groups: %m"); + + if (setresgid(gid, gid, gid) < 0) + return log_error_errno(errno, "setregid() failed: %m"); + + if (setresuid(uid, uid, uid) < 0) + return log_error_errno(errno, "setreuid() failed: %m"); + + if (_home) { + *_home = home; + home = NULL; + } + + return 0; +} diff --git a/src/nspawn/nspawn-setuid.h b/src/nspawn/nspawn-setuid.h new file mode 100644 index 0000000000..33be44a946 --- /dev/null +++ b/src/nspawn/nspawn-setuid.h @@ -0,0 +1,24 @@ +/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/ + +#pragma once + +/*** + This file is part of systemd. + + Copyright 2015 Lennart Poettering + + systemd is free software; you can redistribute it and/or modify it + under the terms of the GNU Lesser General Public License as published by + the Free Software Foundation; either version 2.1 of the License, or + (at your option) any later version. + + systemd is distributed in the hope that it will be useful, but + WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public License + along with systemd; If not, see <http://www.gnu.org/licenses/>. +***/ + +int change_uid_gid(const char *user, char **ret); diff --git a/src/nspawn/nspawn.c b/src/nspawn/nspawn.c index fcabe24601..cdb699eaaa 100644 --- a/src/nspawn/nspawn.c +++ b/src/nspawn/nspawn.c @@ -103,6 +103,7 @@ #include "nspawn-expose-ports.h" #include "nspawn-cgroup.h" #include "nspawn-register.h" +#include "nspawn-setuid.h" typedef enum ContainerStatus { CONTAINER_TERMINATED, @@ -2246,247 +2247,6 @@ static void loop_remove(int nr, int *image_fd) { log_debug_errno(errno, "Failed to remove loop %d: %m", nr); } -static int spawn_getent(const char *database, const char *key, pid_t *rpid) { - int pipe_fds[2]; - 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"); - - pid = fork(); - if (pid < 0) - return log_error_errno(errno, "Failed to fork getent child: %m"); - else if (pid == 0) { - int nullfd; - char *empty_env = NULL; - - if (dup3(pipe_fds[1], STDOUT_FILENO, 0) < 0) - _exit(EXIT_FAILURE); - - if (pipe_fds[0] > 2) - safe_close(pipe_fds[0]); - if (pipe_fds[1] > 2) - safe_close(pipe_fds[1]); - - nullfd = open("/dev/null", O_RDWR); - if (nullfd < 0) - _exit(EXIT_FAILURE); - - if (dup3(nullfd, STDIN_FILENO, 0) < 0) - _exit(EXIT_FAILURE); - - if (dup3(nullfd, STDERR_FILENO, 0) < 0) - _exit(EXIT_FAILURE); - - if (nullfd > 2) - safe_close(nullfd); - - (void) reset_all_signal_handlers(); - (void) reset_signal_mask(); - 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]; -} - -static int change_uid_gid(char **_home) { - char line[LINE_MAX], *x, *u, *g, *h; - const char *word, *state; - _cleanup_free_ uid_t *uids = NULL; - _cleanup_free_ char *home = NULL; - _cleanup_fclose_ FILE *f = NULL; - _cleanup_close_ int fd = -1; - unsigned n_uids = 0; - size_t sz = 0, l; - uid_t uid; - gid_t gid; - pid_t pid; - int r; - - assert(_home); - - if (!arg_user || streq(arg_user, "root") || streq(arg_user, "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"); - - *_home = NULL; - return 0; - } - - /* First, get user credentials */ - fd = spawn_getent("passwd", arg_user, &pid); - if (fd < 0) - return fd; - - f = fdopen(fd, "r"); - if (!f) - return log_oom(); - fd = -1; - - if (!fgets(line, sizeof(line), f)) { - - if (!ferror(f)) { - log_error("Failed to resolve user %s.", arg_user); - return -ESRCH; - } - - log_error_errno(errno, "Failed to read from getent: %m"); - return -errno; - } - - truncate_nl(line); - - wait_for_terminate_and_warn("getent passwd", pid, true); - - x = strchr(line, ':'); - if (!x) { - log_error("/etc/passwd entry has invalid user field."); - return -EIO; - } - - u = strchr(x+1, ':'); - if (!u) { - log_error("/etc/passwd entry has invalid password field."); - return -EIO; - } - - u++; - g = strchr(u, ':'); - if (!g) { - log_error("/etc/passwd entry has invalid UID field."); - return -EIO; - } - - *g = 0; - g++; - x = strchr(g, ':'); - if (!x) { - log_error("/etc/passwd entry has invalid GID field."); - return -EIO; - } - - *x = 0; - h = strchr(x+1, ':'); - if (!h) { - log_error("/etc/passwd entry has invalid GECOS field."); - return -EIO; - } - - h++; - x = strchr(h, ':'); - if (!x) { - log_error("/etc/passwd entry has invalid home directory field."); - return -EIO; - } - - *x = 0; - - r = parse_uid(u, &uid); - if (r < 0) { - log_error("Failed to parse UID of user."); - return -EIO; - } - - r = parse_gid(g, &gid); - if (r < 0) { - log_error("Failed to parse GID of user."); - return -EIO; - } - - home = strdup(h); - if (!home) - return log_oom(); - - /* Second, get group memberships */ - fd = spawn_getent("initgroups", arg_user, &pid); - if (fd < 0) - return fd; - - fclose(f); - f = fdopen(fd, "r"); - if (!f) - return log_oom(); - fd = -1; - - if (!fgets(line, sizeof(line), f)) { - if (!ferror(f)) { - log_error("Failed to resolve user %s.", arg_user); - return -ESRCH; - } - - log_error_errno(errno, "Failed to read from getent: %m"); - return -errno; - } - - truncate_nl(line); - - wait_for_terminate_and_warn("getent initgroups", pid, true); - - /* Skip over the username and subsequent separator whitespace */ - x = line; - x += strcspn(x, WHITESPACE); - x += strspn(x, WHITESPACE); - - FOREACH_WORD(word, l, x, state) { - char c[l+1]; - - memcpy(c, word, l); - c[l] = 0; - - if (!GREEDY_REALLOC(uids, sz, n_uids+1)) - return log_oom(); - - r = parse_uid(c, &uids[n_uids++]); - if (r < 0) { - log_error("Failed to parse group data from getent."); - return -EIO; - } - } - - 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); - if (r < 0 && r != -EEXIST) - return log_error_errno(r, "Failed to make home directory: %m"); - - (void) fchown(STDIN_FILENO, uid, gid); - (void) fchown(STDOUT_FILENO, uid, gid); - (void) fchown(STDERR_FILENO, uid, gid); - - if (setgroups(n_uids, uids) < 0) - return log_error_errno(errno, "Failed to set auxiliary groups: %m"); - - if (setresgid(gid, gid, gid) < 0) - return log_error_errno(errno, "setregid() failed: %m"); - - if (setresuid(uid, uid, uid) < 0) - return log_error_errno(errno, "setreuid() failed: %m"); - - if (_home) { - *_home = home; - home = NULL; - } - - return 0; -} - /* * Return values: * < 0 : wait_for_terminate() failed to get the state of the @@ -2787,7 +2547,7 @@ static int inner_child( return log_error_errno(errno, "setexeccon(\"%s\") failed: %m", arg_selinux_context); #endif - r = change_uid_gid(&home); + r = change_uid_gid(arg_user, &home); if (r < 0) return r; |