src/import/import-common.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2 /***
   3   This file is part of systemd.
   4
   5   Copyright 2015 Lennart Poettering
   6
   7   systemd is free software; you can redistribute it and/or modify it
   8   under the terms of the GNU Lesser General Public License as published by
   9   the Free Software Foundation; either version 2.1 of the License, or
  10   (at your option) any later version.
  11
  12   systemd is distributed in the hope that it will be useful, but
  13   WITHOUT ANY WARRANTY; without even the implied warranty of
  14   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  15   Lesser General Public License for more details.
  16
  17   You should have received a copy of the GNU Lesser General Public License
  18   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  19 ***/
  20
  21 #include <sched.h>
  22 #include <sys/prctl.h>
  23 #include <sys/stat.h>
  24 #include <unistd.h>
  25
  26 #include "btrfs-util.h"
  27 #include "capability-util.h"
  28 #include "fd-util.h"
  29 #include "import-common.h"
  30 #include "signal-util.h"
  31 #include "util.h"
  32
  33 int import_make_read_only_fd(int fd) {
  34         int r;
  35
  36         assert(fd >= 0);
  37
  38         /* First, let's make this a read-only subvolume if it refers
  39          * to a subvolume */
  40         r = btrfs_subvol_set_read_only_fd(fd, true);
  41         if (IN_SET(r, -ENOTTY, -ENOTDIR, -EINVAL)) {
  42                 struct stat st;
  43
  44                 /* This doesn't refer to a subvolume, or the file
  45                  * system isn't even btrfs. In that, case fall back to
  46                  * chmod()ing */
  47
  48                 r = fstat(fd, &st);
  49                 if (r < 0)
  50                         return log_error_errno(errno, "Failed to stat temporary image: %m");
  51
  52                 /* Drop "w" flag */
  53                 if (fchmod(fd, st.st_mode & 07555) < 0)
  54                         return log_error_errno(errno, "Failed to chmod() final image: %m");
  55
  56                 return 0;
  57
  58         } else if (r < 0)
  59                 return log_error_errno(r, "Failed to make subvolume read-only: %m");
  60
  61         return 0;
  62 }
  63
  64 int import_make_read_only(const char *path) {
  65         _cleanup_close_ int fd = 1;
  66
  67         fd = open(path, O_RDONLY|O_NOCTTY|O_CLOEXEC);
  68         if (fd < 0)
  69                 return log_error_errno(errno, "Failed to open %s: %m", path);
  70
  71         return import_make_read_only_fd(fd);
  72 }
  73
  74 int import_fork_tar_x(const char *path, pid_t *ret) {
  75         _cleanup_close_pair_ int pipefd[2] = { -1, -1 };
  76         pid_t pid;
  77         int r;
  78
  79         assert(path);
  80         assert(ret);
  81
  82         if (pipe2(pipefd, O_CLOEXEC) < 0)
  83                 return log_error_errno(errno, "Failed to create pipe for tar: %m");
  84
  85         pid = fork();
  86         if (pid < 0)
  87                 return log_error_errno(errno, "Failed to fork off tar: %m");
  88
  89         if (pid == 0) {
  90                 int null_fd;
  91                 uint64_t retain =
  92                         (1ULL << CAP_CHOWN) |
  93                         (1ULL << CAP_FOWNER) |
  94                         (1ULL << CAP_FSETID) |
  95                         (1ULL << CAP_MKNOD) |
  96                         (1ULL << CAP_SETFCAP) |
  97                         (1ULL << CAP_DAC_OVERRIDE);
  98
  99                 /* Child */
 100
 101                 (void) reset_all_signal_handlers();
 102                 (void) reset_signal_mask();
 103                 assert_se(prctl(PR_SET_PDEATHSIG, SIGTERM) == 0);
 104
 105                 pipefd[1] = safe_close(pipefd[1]);
 106
 107                 if (dup2(pipefd[0], STDIN_FILENO) != STDIN_FILENO) {
 108                         log_error_errno(errno, "Failed to dup2() fd: %m");
 109                         _exit(EXIT_FAILURE);
 110                 }
 111
 112                 if (pipefd[0] != STDIN_FILENO)
 113                         pipefd[0] = safe_close(pipefd[0]);
 114
 115                 null_fd = open("/dev/null", O_WRONLY|O_NOCTTY);
 116                 if (null_fd < 0) {
 117                         log_error_errno(errno, "Failed to open /dev/null: %m");
 118                         _exit(EXIT_FAILURE);
 119                 }
 120
 121                 if (dup2(null_fd, STDOUT_FILENO) != STDOUT_FILENO) {
 122                         log_error_errno(errno, "Failed to dup2() fd: %m");
 123                         _exit(EXIT_FAILURE);
 124                 }
 125
 126                 if (null_fd != STDOUT_FILENO)
 127                         null_fd = safe_close(null_fd);
 128
 129                 stdio_unset_cloexec();
 130
 131                 if (unshare(CLONE_NEWNET) < 0)
 132                         log_error_errno(errno, "Failed to lock tar into network namespace, ignoring: %m");
 133
 134                 r = capability_bounding_set_drop(retain, true);
 135                 if (r < 0)
 136                         log_error_errno(r, "Failed to drop capabilities, ignoring: %m");
 137
 138                 execlp("tar", "tar", "--numeric-owner", "-C", path, "-px", "--xattrs", "--xattrs-include=*", NULL);
 139                 log_error_errno(errno, "Failed to execute tar: %m");
 140                 _exit(EXIT_FAILURE);
 141         }
 142
 143         pipefd[0] = safe_close(pipefd[0]);
 144         r = pipefd[1];
 145         pipefd[1] = -1;
 146
 147         *ret = pid;
 148
 149         return r;
 150 }
 151
 152 int import_fork_tar_c(const char *path, pid_t *ret) {
 153         _cleanup_close_pair_ int pipefd[2] = { -1, -1 };
 154         pid_t pid;
 155         int r;
 156
 157         assert(path);
 158         assert(ret);
 159
 160         if (pipe2(pipefd, O_CLOEXEC) < 0)
 161                 return log_error_errno(errno, "Failed to create pipe for tar: %m");
 162
 163         pid = fork();
 164         if (pid < 0)
 165                 return log_error_errno(errno, "Failed to fork off tar: %m");
 166
 167         if (pid == 0) {
 168                 int null_fd;
 169                 uint64_t retain = (1ULL << CAP_DAC_OVERRIDE);
 170
 171                 /* Child */
 172
 173                 (void) reset_all_signal_handlers();
 174                 (void) reset_signal_mask();
 175                 assert_se(prctl(PR_SET_PDEATHSIG, SIGTERM) == 0);
 176
 177                 pipefd[0] = safe_close(pipefd[0]);
 178
 179                 if (dup2(pipefd[1], STDOUT_FILENO) != STDOUT_FILENO) {
 180                         log_error_errno(errno, "Failed to dup2() fd: %m");
 181                         _exit(EXIT_FAILURE);
 182                 }
 183
 184                 if (pipefd[1] != STDOUT_FILENO)
 185                         pipefd[1] = safe_close(pipefd[1]);
 186
 187                 null_fd = open("/dev/null", O_RDONLY|O_NOCTTY);
 188                 if (null_fd < 0) {
 189                         log_error_errno(errno, "Failed to open /dev/null: %m");
 190                         _exit(EXIT_FAILURE);
 191                 }
 192
 193                 if (dup2(null_fd, STDIN_FILENO) != STDIN_FILENO) {
 194                         log_error_errno(errno, "Failed to dup2() fd: %m");
 195                         _exit(EXIT_FAILURE);
 196                 }
 197
 198                 if (null_fd != STDIN_FILENO)
 199                         null_fd = safe_close(null_fd);
 200
 201                 stdio_unset_cloexec();
 202
 203                 if (unshare(CLONE_NEWNET) < 0)
 204                         log_error_errno(errno, "Failed to lock tar into network namespace, ignoring: %m");
 205
 206                 r = capability_bounding_set_drop(retain, true);
 207                 if (r < 0)
 208                         log_error_errno(r, "Failed to drop capabilities, ignoring: %m");
 209
 210                 execlp("tar", "tar", "-C", path, "-c", "--xattrs", "--xattrs-include=*", ".", NULL);
 211                 log_error_errno(errno, "Failed to execute tar: %m");
 212                 _exit(EXIT_FAILURE);
 213         }
 214
 215         pipefd[1] = safe_close(pipefd[1]);
 216         r = pipefd[0];
 217         pipefd[0] = -1;
 218
 219         *ret = pid;
 220
 221         return r;
 222 }