151 lines
4.8 KiB
C
151 lines
4.8 KiB
C
/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
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/***
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This file is part of systemd.
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Copyright 2015 Lennart Poettering
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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***/
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#include <sys/prctl.h>
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#include <sys/stat.h>
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#include <unistd.h>
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#include "util.h"
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#include "btrfs-util.h"
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#include "capability.h"
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#include "import-common.h"
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int import_make_read_only_fd(int fd) {
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int r;
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assert(fd >= 0);
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/* First, let's make this a read-only subvolume if it refers
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* to a subvolume */
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r = btrfs_subvol_set_read_only_fd(fd, true);
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if (r == -ENOTTY || r == -ENOTDIR || r == -EINVAL) {
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struct stat st;
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/* This doesn't refer to a subvolume, or the file
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* system isn't even btrfs. In that, case fall back to
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* chmod()ing */
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r = fstat(fd, &st);
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if (r < 0)
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return log_error_errno(errno, "Failed to stat temporary image: %m");
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/* Drop "w" flag */
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if (fchmod(fd, st.st_mode & 07555) < 0)
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return log_error_errno(errno, "Failed to chmod() final image: %m");
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return 0;
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} else if (r < 0)
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return log_error_errno(r, "Failed to make subvolume read-only: %m");
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return 0;
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}
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int import_make_read_only(const char *path) {
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_cleanup_close_ int fd = 1;
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fd = open(path, O_RDONLY|O_NOCTTY|O_CLOEXEC);
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if (fd < 0)
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return log_error_errno(errno, "Failed to open %s: %m", path);
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return import_make_read_only_fd(fd);
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}
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int import_fork_tar(const char *path, pid_t *ret) {
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_cleanup_close_pair_ int pipefd[2] = { -1, -1 };
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pid_t pid;
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int r;
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assert(path);
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assert(ret);
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if (pipe2(pipefd, O_CLOEXEC) < 0)
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return log_error_errno(errno, "Failed to create pipe for tar: %m");
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pid = fork();
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if (pid < 0)
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return log_error_errno(errno, "Failed to fork off tar: %m");
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if (pid == 0) {
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int null_fd;
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uint64_t retain =
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(1ULL << CAP_CHOWN) |
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(1ULL << CAP_FOWNER) |
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(1ULL << CAP_FSETID) |
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(1ULL << CAP_MKNOD) |
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(1ULL << CAP_SETFCAP) |
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(1ULL << CAP_DAC_OVERRIDE);
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/* Child */
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reset_all_signal_handlers();
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reset_signal_mask();
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assert_se(prctl(PR_SET_PDEATHSIG, SIGTERM) == 0);
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pipefd[1] = safe_close(pipefd[1]);
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if (dup2(pipefd[0], STDIN_FILENO) != STDIN_FILENO) {
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log_error_errno(errno, "Failed to dup2() fd: %m");
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_exit(EXIT_FAILURE);
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}
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if (pipefd[0] != STDIN_FILENO)
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pipefd[0] = safe_close(pipefd[0]);
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null_fd = open("/dev/null", O_WRONLY|O_NOCTTY);
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if (null_fd < 0) {
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log_error_errno(errno, "Failed to open /dev/null: %m");
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_exit(EXIT_FAILURE);
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}
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if (dup2(null_fd, STDOUT_FILENO) != STDOUT_FILENO) {
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log_error_errno(errno, "Failed to dup2() fd: %m");
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_exit(EXIT_FAILURE);
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}
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if (null_fd != STDOUT_FILENO)
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null_fd = safe_close(null_fd);
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fd_cloexec(STDIN_FILENO, false);
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fd_cloexec(STDOUT_FILENO, false);
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fd_cloexec(STDERR_FILENO, false);
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if (unshare(CLONE_NEWNET) < 0)
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log_error_errno(errno, "Failed to lock tar into network namespace, ignoring: %m");
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r = capability_bounding_set_drop(~retain, true);
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if (r < 0)
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log_error_errno(r, "Failed to drop capabilities, ignoring: %m");
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execlp("tar", "tar", "--numeric-owner", "-C", path, "-px", NULL);
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log_error_errno(errno, "Failed to execute tar: %m");
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_exit(EXIT_FAILURE);
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}
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pipefd[0] = safe_close(pipefd[0]);
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r = pipefd[1];
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pipefd[1] = -1;
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*ret = pid;
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return r;
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}
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