src/libsystemd/sd-bus/bus-container.c

   1 /***
   2   This file is part of systemd.
   3
   4   Copyright 2013 Lennart Poettering
   5
   6   systemd is free software; you can redistribute it and/or modify it
   7   under the terms of the GNU Lesser General Public License as published by
   8   the Free Software Foundation; either version 2.1 of the License, or
   9   (at your option) any later version.
  10
  11   systemd is distributed in the hope that it will be useful, but
  12   WITHOUT ANY WARRANTY; without even the implied warranty of
  13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  14   Lesser General Public License for more details.
  15
  16   You should have received a copy of the GNU Lesser General Public License
  17   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  18 ***/
  19
  20 #include <fcntl.h>
  21 #include <unistd.h>
  22
  23 #include "bus-container.h"
  24 #include "bus-internal.h"
  25 #include "bus-socket.h"
  26 #include "fd-util.h"
  27 #include "process-util.h"
  28 #include "util.h"
  29
  30 int bus_container_connect_socket(sd_bus *b) {
  31         _cleanup_close_pair_ int pair[2] = { -1, -1 };
  32         _cleanup_close_ int pidnsfd = -1, mntnsfd = -1, usernsfd = -1, rootfd = -1;
  33         pid_t child;
  34         siginfo_t si;
  35         int r, error_buf = 0;
  36         ssize_t n;
  37
  38         assert(b);
  39         assert(b->input_fd < 0);
  40         assert(b->output_fd < 0);
  41         assert(b->nspid > 0 || b->machine);
  42
  43         if (b->nspid <= 0) {
  44                 r = container_get_leader(b->machine, &b->nspid);
  45                 if (r < 0)
  46                         return r;
  47         }
  48
  49         r = namespace_open(b->nspid, &pidnsfd, &mntnsfd, NULL, &usernsfd, &rootfd);
  50         if (r < 0)
  51                 return r;
  52
  53         b->input_fd = socket(b->sockaddr.sa.sa_family, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
  54         if (b->input_fd < 0)
  55                 return -errno;
  56
  57         b->output_fd = b->input_fd;
  58
  59         bus_socket_setup(b);
  60
  61         if (socketpair(AF_UNIX, SOCK_SEQPACKET, 0, pair) < 0)
  62                 return -errno;
  63
  64         child = fork();
  65         if (child < 0)
  66                 return -errno;
  67
  68         if (child == 0) {
  69                 pid_t grandchild;
  70
  71                 pair[0] = safe_close(pair[0]);
  72
  73                 r = namespace_enter(pidnsfd, mntnsfd, -1, usernsfd, rootfd);
  74                 if (r < 0)
  75                         _exit(EXIT_FAILURE);
  76
  77                 /* We just changed PID namespace, however it will only
  78                  * take effect on the children we now fork. Hence,
  79                  * let's fork another time, and connect from this
  80                  * grandchild, so that SO_PEERCRED of our connection
  81                  * comes from a process from within the container, and
  82                  * not outside of it */
  83
  84                 grandchild = fork();
  85                 if (grandchild < 0)
  86                         _exit(EXIT_FAILURE);
  87
  88                 if (grandchild == 0) {
  89
  90                         r = connect(b->input_fd, &b->sockaddr.sa, b->sockaddr_size);
  91                         if (r < 0) {
  92                                 /* Try to send error up */
  93                                 error_buf = errno;
  94                                 (void) write(pair[1], &error_buf, sizeof(error_buf));
  95                                 _exit(EXIT_FAILURE);
  96                         }
  97
  98                         _exit(EXIT_SUCCESS);
  99                 }
 100
 101                 r = wait_for_terminate(grandchild, &si);
 102                 if (r < 0)
 103                         _exit(EXIT_FAILURE);
 104
 105                 if (si.si_code != CLD_EXITED)
 106                         _exit(EXIT_FAILURE);
 107
 108                 _exit(si.si_status);
 109         }
 110
 111         pair[1] = safe_close(pair[1]);
 112
 113         r = wait_for_terminate(child, &si);
 114         if (r < 0)
 115                 return r;
 116
 117         n = read(pair[0], &error_buf, sizeof(error_buf));
 118         if (n < 0)
 119                 return -errno;
 120
 121         if (n > 0) {
 122                 if (n != sizeof(error_buf))
 123                         return -EIO;
 124
 125                 if (error_buf < 0)
 126                         return -EIO;
 127
 128                 if (error_buf == EINPROGRESS)
 129                         return 1;
 130
 131                 if (error_buf > 0)
 132                         return -error_buf;
 133         }
 134
 135         if (si.si_code != CLD_EXITED)
 136                 return -EIO;
 137
 138         if (si.si_status != EXIT_SUCCESS)
 139                 return -EIO;
 140
 141         return bus_socket_start_auth(b);
 142 }