bus-container.c revision 2b7d6d33dc04d9ef370b51afe88d28be8a4f9f84
/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
/***
This file is part of systemd.
Copyright 2013 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 <unistd.h>
#include <fcntl.h>
#include "util.h"
#include "process-util.h"
#include "bus-internal.h"
#include "bus-socket.h"
#include "bus-container.h"
int bus_container_connect_socket(sd_bus *b) {
_cleanup_close_pair_ int pair[2] = { -1, -1 };
_cleanup_close_ int pidnsfd = -1, mntnsfd = -1, usernsfd = -1, rootfd = -1;
pid_t child;
siginfo_t si;
int r, error_buf = 0;
ssize_t n;
assert(b);
assert(b->input_fd < 0);
assert(b->output_fd < 0);
assert(b->nspid > 0 || b->machine);
if (b->nspid <= 0) {
r = container_get_leader(b->machine, &b->nspid);
if (r < 0)
return r;
}
r = namespace_open(b->nspid, &pidnsfd, &mntnsfd, NULL, &usernsfd, &rootfd);
if (r < 0)
return r;
b->input_fd = socket(b->sockaddr.sa.sa_family, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
if (b->input_fd < 0)
return -errno;
b->output_fd = b->input_fd;
bus_socket_setup(b);
if (socketpair(AF_UNIX, SOCK_SEQPACKET, 0, pair) < 0)
return -errno;
child = fork();
if (child < 0)
return -errno;
if (child == 0) {
pid_t grandchild;
pair[0] = safe_close(pair[0]);
r = namespace_enter(pidnsfd, mntnsfd, -1, usernsfd, rootfd);
if (r < 0)
_exit(EXIT_FAILURE);
/* We just changed PID namespace, however it will only
* take effect on the children we now fork. Hence,
* let's fork another time, and connect from this
* grandchild, so that SO_PEERCRED of our connection
* comes from a process from within the container, and
* not outside of it */
grandchild = fork();
if (grandchild < 0)
_exit(EXIT_FAILURE);
if (grandchild == 0) {
r = connect(b->input_fd, &b->sockaddr.sa, b->sockaddr_size);
if (r < 0) {
/* Try to send error up */
error_buf = errno;
(void) write(pair[1], &error_buf, sizeof(error_buf));
_exit(EXIT_FAILURE);
}
_exit(EXIT_SUCCESS);
}
r = wait_for_terminate(grandchild, &si);
if (r < 0)
_exit(EXIT_FAILURE);
if (si.si_code != CLD_EXITED)
_exit(EXIT_FAILURE);
_exit(si.si_status);
}
pair[1] = safe_close(pair[1]);
r = wait_for_terminate(child, &si);
if (r < 0)
return r;
n = read(pair[0], &error_buf, sizeof(error_buf));
if (n < 0)
return -errno;
if (n > 0) {
if (n != sizeof(error_buf))
return -EIO;
if (error_buf < 0)
return -EIO;
if (error_buf == EINPROGRESS)
return 1;
if (error_buf > 0)
return -error_buf;
}
if (si.si_code != CLD_EXITED)
return -EIO;
if (si.si_status != EXIT_SUCCESS)
return -EIO;
return bus_socket_start_auth(b);
}
int bus_container_connect_kernel(sd_bus *b) {
_cleanup_close_pair_ int pair[2] = { -1, -1 };
_cleanup_close_ int pidnsfd = -1, mntnsfd = -1, usernsfd = -1, rootfd = -1;
union {
struct cmsghdr cmsghdr;
uint8_t buf[CMSG_SPACE(sizeof(int))];
} control = {};
int error_buf = 0;
struct iovec iov = {
.iov_base = &error_buf,
.iov_len = sizeof(error_buf),
};
struct msghdr mh = {
.msg_control = &control,
.msg_controllen = sizeof(control),
.msg_iov = &iov,
.msg_iovlen = 1,
};
struct cmsghdr *cmsg;
pid_t child;
siginfo_t si;
int r, fd = -1;
ssize_t n;
assert(b);
assert(b->input_fd < 0);
assert(b->output_fd < 0);
assert(b->nspid > 0 || b->machine);
if (b->nspid <= 0) {
r = container_get_leader(b->machine, &b->nspid);
if (r < 0)
return r;
}
r = namespace_open(b->nspid, &pidnsfd, &mntnsfd, NULL, &usernsfd, &rootfd);
if (r < 0)
return r;
if (socketpair(AF_UNIX, SOCK_SEQPACKET, 0, pair) < 0)
return -errno;
child = fork();
if (child < 0)
return -errno;
if (child == 0) {
pid_t grandchild;
pair[0] = safe_close(pair[0]);
r = namespace_enter(pidnsfd, mntnsfd, -1, usernsfd, rootfd);
if (r < 0)
_exit(EXIT_FAILURE);
/* We just changed PID namespace, however it will only
* take effect on the children we now fork. Hence,
* let's fork another time, and connect from this
* grandchild, so that kdbus only sees the credentials
* of this process which comes from within the
* container, and not outside of it */
grandchild = fork();
if (grandchild < 0)
_exit(EXIT_FAILURE);
if (grandchild == 0) {
fd = open(b->kernel, O_RDWR|O_NOCTTY|O_CLOEXEC);
if (fd < 0) {
/* Try to send error up */
error_buf = errno;
(void) write(pair[1], &error_buf, sizeof(error_buf));
_exit(EXIT_FAILURE);
}
cmsg = CMSG_FIRSTHDR(&mh);
cmsg->cmsg_level = SOL_SOCKET;
cmsg->cmsg_type = SCM_RIGHTS;
cmsg->cmsg_len = CMSG_LEN(sizeof(int));
memcpy(CMSG_DATA(cmsg), &fd, sizeof(int));
mh.msg_controllen = cmsg->cmsg_len;
if (sendmsg(pair[1], &mh, MSG_NOSIGNAL) < 0)
_exit(EXIT_FAILURE);
_exit(EXIT_SUCCESS);
}
r = wait_for_terminate(grandchild, &si);
if (r < 0)
_exit(EXIT_FAILURE);
if (si.si_code != CLD_EXITED)
_exit(EXIT_FAILURE);
_exit(si.si_status);
}
pair[1] = safe_close(pair[1]);
r = wait_for_terminate(child, &si);
if (r < 0)
return r;
n = recvmsg(pair[0], &mh, MSG_NOSIGNAL|MSG_CMSG_CLOEXEC);
if (n < 0)
return -errno;
CMSG_FOREACH(cmsg, &mh) {
if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == SCM_RIGHTS) {
int *fds;
unsigned n_fds;
assert(fd < 0);
fds = (int*) CMSG_DATA(cmsg);
n_fds = (cmsg->cmsg_len - CMSG_LEN(0)) / sizeof(int);
if (n_fds != 1) {
close_many(fds, n_fds);
return -EIO;
}
fd = fds[0];
}
}
/* If there's an fd passed, we are good. */
if (fd >= 0) {
b->input_fd = b->output_fd = fd;
return bus_kernel_take_fd(b);
}
/* If there's an error passed, use it */
if (n == sizeof(error_buf) && error_buf > 0)
return -error_buf;
/* Otherwise, we have no clue */
return -EIO;
}