/*** 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 <fcntl.h> #include <unistd.h> #include "bus-container.h" #include "bus-internal.h" #include "bus-socket.h" #include "fd-util.h" #include "process-util.h" #include "util.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); } r = send_one_fd(pair[1], fd, 0); if (r < 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; }