nspawn: split out --uid= logic into nspawn-setuid.[ch]

3 files changed, 299 insertions, 242 deletions

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;