import-common.c revision 430f0182b72373145c839dbfe99d2382855cb8f8
/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
/***
This file is part of systemd.
Copyright 2015 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 <sched.h>
#include <sys/prctl.h>
#include <sys/stat.h>
#include <unistd.h>
#include "btrfs-util.h"
#include "capability-util.h"
#include "fd-util.h"
#include "import-common.h"
#include "signal-util.h"
#include "util.h"
int import_make_read_only_fd(int fd) {
int r;
assert(fd >= 0);
/* First, let's make this a read-only subvolume if it refers
* to a subvolume */
r = btrfs_subvol_set_read_only_fd(fd, true);
if (r == -ENOTTY || r == -ENOTDIR || r == -EINVAL) {
struct stat st;
/* This doesn't refer to a subvolume, or the file
* system isn't even btrfs. In that, case fall back to
* chmod()ing */
r = fstat(fd, &st);
if (r < 0)
return log_error_errno(errno, "Failed to stat temporary image: %m");
/* Drop "w" flag */
if (fchmod(fd, st.st_mode & 07555) < 0)
return log_error_errno(errno, "Failed to chmod() final image: %m");
return 0;
} else if (r < 0)
return log_error_errno(r, "Failed to make subvolume read-only: %m");
return 0;
}
int import_make_read_only(const char *path) {
_cleanup_close_ int fd = 1;
fd = open(path, O_RDONLY|O_NOCTTY|O_CLOEXEC);
if (fd < 0)
return log_error_errno(errno, "Failed to open %s: %m", path);
return import_make_read_only_fd(fd);
}
int import_fork_tar_x(const char *path, pid_t *ret) {
_cleanup_close_pair_ int pipefd[2] = { -1, -1 };
pid_t pid;
int r;
assert(path);
assert(ret);
if (pipe2(pipefd, O_CLOEXEC) < 0)
return log_error_errno(errno, "Failed to create pipe for tar: %m");
pid = fork();
if (pid < 0)
return log_error_errno(errno, "Failed to fork off tar: %m");
if (pid == 0) {
int null_fd;
uint64_t retain =
(1ULL << CAP_CHOWN) |
(1ULL << CAP_FOWNER) |
(1ULL << CAP_FSETID) |
(1ULL << CAP_MKNOD) |
(1ULL << CAP_SETFCAP) |
(1ULL << CAP_DAC_OVERRIDE);
/* Child */
(void) reset_all_signal_handlers();
(void) reset_signal_mask();
assert_se(prctl(PR_SET_PDEATHSIG, SIGTERM) == 0);
pipefd[1] = safe_close(pipefd[1]);
if (dup2(pipefd[0], STDIN_FILENO) != STDIN_FILENO) {
log_error_errno(errno, "Failed to dup2() fd: %m");
_exit(EXIT_FAILURE);
}
if (pipefd[0] != STDIN_FILENO)
pipefd[0] = safe_close(pipefd[0]);
null_fd = open("/dev/null", O_WRONLY|O_NOCTTY);
if (null_fd < 0) {
log_error_errno(errno, "Failed to open /dev/null: %m");
_exit(EXIT_FAILURE);
}
if (dup2(null_fd, STDOUT_FILENO) != STDOUT_FILENO) {
log_error_errno(errno, "Failed to dup2() fd: %m");
_exit(EXIT_FAILURE);
}
if (null_fd != STDOUT_FILENO)
null_fd = safe_close(null_fd);
fd_cloexec(STDIN_FILENO, false);
fd_cloexec(STDOUT_FILENO, false);
fd_cloexec(STDERR_FILENO, false);
if (unshare(CLONE_NEWNET) < 0)
log_error_errno(errno, "Failed to lock tar into network namespace, ignoring: %m");
r = capability_bounding_set_drop(~retain, true);
if (r < 0)
log_error_errno(r, "Failed to drop capabilities, ignoring: %m");
execlp("tar", "tar", "--numeric-owner", "-C", path, "-px", NULL);
log_error_errno(errno, "Failed to execute tar: %m");
_exit(EXIT_FAILURE);
}
pipefd[0] = safe_close(pipefd[0]);
r = pipefd[1];
pipefd[1] = -1;
*ret = pid;
return r;
}
int import_fork_tar_c(const char *path, pid_t *ret) {
_cleanup_close_pair_ int pipefd[2] = { -1, -1 };
pid_t pid;
int r;
assert(path);
assert(ret);
if (pipe2(pipefd, O_CLOEXEC) < 0)
return log_error_errno(errno, "Failed to create pipe for tar: %m");
pid = fork();
if (pid < 0)
return log_error_errno(errno, "Failed to fork off tar: %m");
if (pid == 0) {
int null_fd;
uint64_t retain = (1ULL << CAP_DAC_OVERRIDE);
/* Child */
(void) reset_all_signal_handlers();
(void) reset_signal_mask();
assert_se(prctl(PR_SET_PDEATHSIG, SIGTERM) == 0);
pipefd[0] = safe_close(pipefd[0]);
if (dup2(pipefd[1], STDOUT_FILENO) != STDOUT_FILENO) {
log_error_errno(errno, "Failed to dup2() fd: %m");
_exit(EXIT_FAILURE);
}
if (pipefd[1] != STDOUT_FILENO)
pipefd[1] = safe_close(pipefd[1]);
null_fd = open("/dev/null", O_RDONLY|O_NOCTTY);
if (null_fd < 0) {
log_error_errno(errno, "Failed to open /dev/null: %m");
_exit(EXIT_FAILURE);
}
if (dup2(null_fd, STDIN_FILENO) != STDIN_FILENO) {
log_error_errno(errno, "Failed to dup2() fd: %m");
_exit(EXIT_FAILURE);
}
if (null_fd != STDIN_FILENO)
null_fd = safe_close(null_fd);
fd_cloexec(STDIN_FILENO, false);
fd_cloexec(STDOUT_FILENO, false);
fd_cloexec(STDERR_FILENO, false);
if (unshare(CLONE_NEWNET) < 0)
log_error_errno(errno, "Failed to lock tar into network namespace, ignoring: %m");
r = capability_bounding_set_drop(~retain, true);
if (r < 0)
log_error_errno(r, "Failed to drop capabilities, ignoring: %m");
execlp("tar", "tar", "-C", path, "-c", ".", NULL);
log_error_errno(errno, "Failed to execute tar: %m");
_exit(EXIT_FAILURE);
}
pipefd[1] = safe_close(pipefd[1]);
r = pipefd[0];
pipefd[0] = -1;
*ret = pid;
return r;
}