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

   1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
   2
   3 #include <fcntl.h>
   4 #include <unistd.h>
   5
   6 #include "bus-container.h"
   7 #include "bus-internal.h"
   8 #include "bus-socket.h"
   9 #include "fd-util.h"
  10 #include "namespace-util.h"
  11 #include "process-util.h"
  12 #include "string-util.h"
  13
  14 int bus_container_connect_socket(sd_bus *b) {
  15         _cleanup_close_pair_ int pair[2] = { -EBADF, -EBADF };
  16         _cleanup_close_ int pidnsfd = -EBADF, mntnsfd = -EBADF, usernsfd = -EBADF, rootfd = -EBADF;
  17         int r, error_buf = 0;
  18         pid_t child;
  19         ssize_t n;
  20
  21         assert(b);
  22         assert(b->input_fd < 0);
  23         assert(b->output_fd < 0);
  24         assert(b->nspid > 0 || b->machine);
  25
  26         if (b->nspid <= 0) {
  27                 log_debug("sd-bus: connecting bus%s%s to machine %s...",
  28                           b->description ? " " : "", strempty(b->description), b->machine);
  29
  30                 r = container_get_leader(b->machine, &b->nspid);
  31                 if (r < 0)
  32                         return r;
  33         } else
  34                 log_debug("sd-bus: connecting bus%s%s to namespace of PID "PID_FMT"...",
  35                           b->description ? " " : "", strempty(b->description), b->nspid);
  36
  37         r = namespace_open(b->nspid, &pidnsfd, &mntnsfd, NULL, &usernsfd, &rootfd);
  38         if (r < 0)
  39                 return log_debug_errno(r, "Failed to open namespace of PID "PID_FMT": %m", b->nspid);
  40
  41         b->input_fd = socket(b->sockaddr.sa.sa_family, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
  42         if (b->input_fd < 0)
  43                 return log_debug_errno(errno, "Failed to create a socket: %m");
  44
  45         b->input_fd = fd_move_above_stdio(b->input_fd);
  46
  47         b->output_fd = b->input_fd;
  48
  49         bus_socket_setup(b);
  50
  51         if (socketpair(AF_UNIX, SOCK_SEQPACKET|SOCK_CLOEXEC, 0, pair) < 0)
  52                 return log_debug_errno(errno, "Failed to create a socket pair: %m");
  53
  54         r = namespace_fork("(sd-buscntrns)", "(sd-buscntr)", NULL, 0, FORK_RESET_SIGNALS|FORK_DEATHSIG,
  55                            pidnsfd, mntnsfd, -1, usernsfd, rootfd, &child);
  56         if (r < 0)
  57                 return log_debug_errno(r, "Failed to create namespace for (sd-buscntr): %m");
  58         if (r == 0) {
  59                 pair[0] = safe_close(pair[0]);
  60
  61                 r = connect(b->input_fd, &b->sockaddr.sa, b->sockaddr_size);
  62                 if (r < 0) {
  63                         /* Try to send error up */
  64                         error_buf = errno;
  65                         (void) write(pair[1], &error_buf, sizeof(error_buf));
  66                         _exit(EXIT_FAILURE);
  67                 }
  68
  69                 _exit(EXIT_SUCCESS);
  70         }
  71
  72         pair[1] = safe_close(pair[1]);
  73
  74         r = wait_for_terminate_and_check("(sd-buscntrns)", child, 0);
  75         if (r < 0)
  76                 return r;
  77         bool nonzero_exit_status = r != EXIT_SUCCESS;
  78
  79         n = read(pair[0], &error_buf, sizeof(error_buf));
  80         if (n < 0)
  81                 return log_debug_errno(errno, "Failed to read error status from (sd-buscntr): %m");
  82
  83         if (n > 0) {
  84                 if (n != sizeof(error_buf))
  85                         return log_debug_errno(SYNTHETIC_ERRNO(EIO),
  86                                                "Read error status of unexpected length %zd from (sd-buscntr): %m", n);
  87
  88                 if (error_buf < 0)
  89                         return log_debug_errno(SYNTHETIC_ERRNO(EBADMSG),
  90                                                "Got unexpected error status from (sd-buscntr): %m");
  91
  92                 if (error_buf == EINPROGRESS)
  93                         return 1;
  94
  95                 if (error_buf > 0)
  96                         return log_debug_errno(error_buf, "(sd-buscntr) failed to connect to D-Bus socket: %m");
  97         }
  98
  99         if (nonzero_exit_status)
 100                 return -EPROTO;
 101
 102         return bus_socket_start_auth(b);
 103 }