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shared/mount-util: use namespace_fork utils

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This commit is contained in:
Luca Boccassi 2020-08-13 14:47:01 +01:00
parent 724e689715
commit 2338a175fd
1 changed files with 24 additions and 16 deletions
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40
src/shared/mount-util.c
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@ -17,6 +17,7 @@
#include "mkdir.h"
#include "mount-util.h"
#include "mountpoint-util.h"
#include "namespace-util.h"
#include "parse-util.h"
#include "path-util.h"
#include "process-util.h"
@ -756,12 +757,13 @@ int bind_mount_in_namespace(
bool make_file_or_directory) {
_cleanup_close_pair_ int errno_pipe_fd[2] = { -1, -1 };
_cleanup_close_ int self_mntns_fd = -1, mntns_fd = -1, root_fd = -1;
char mount_slave[] = "/tmp/propagate.XXXXXX", *mount_tmp, *mount_outside, *p;
bool mount_slave_created = false, mount_slave_mounted = false,
mount_tmp_created = false, mount_tmp_mounted = false,
mount_outside_created = false, mount_outside_mounted = false;
_cleanup_free_ char *chased_src = NULL;
struct stat st;
struct stat st, self_mntns_st;
pid_t child;
int r;
@ -771,6 +773,24 @@ int bind_mount_in_namespace(
assert(src);
assert(dest);
r = namespace_open(target, NULL, &mntns_fd, NULL, NULL, &root_fd);
if (r < 0)
return log_debug_errno(r, "Failed to retrieve FDs of the target process' namespace: %m");
if (fstat(mntns_fd, &st) < 0)
return log_debug_errno(errno, "Failed to fstat mount namespace FD of target process: %m");
r = namespace_open(0, NULL, &self_mntns_fd, NULL, NULL, NULL);
if (r < 0)
return log_debug_errno(r, "Failed to retrieve FDs of systemd's namespace: %m");
if (fstat(self_mntns_fd, &self_mntns_st) < 0)
return log_debug_errno(errno, "Failed to fstat mount namespace FD of systemd: %m");
/* We can't add new mounts at runtime if the process wasn't started in a namespace */
if (st.st_ino == self_mntns_st.st_ino && st.st_dev == self_mntns_st.st_dev)
return log_debug_errno(SYNTHETIC_ERRNO(EINVAL), "Failed to activate bind mount in target, not running in a mount namespace");
/* One day, when bind mounting /proc/self/fd/n works across
* namespace boundaries we should rework this logic to make
* use of it... */
@ -877,27 +897,15 @@ int bind_mount_in_namespace(
goto finish;
}
r = safe_fork("(sd-bindmnt)", FORK_RESET_SIGNALS, &child);
r = namespace_fork("(sd-bindmnt)", "(sd-bindmnt-inner)", NULL, 0, FORK_RESET_SIGNALS|FORK_DEATHSIG,
-1, mntns_fd, -1, -1, root_fd, &child);
if (r < 0)
goto finish;
if (r == 0) {
const char *mount_inside, *q;
int mntfd;
const char *mount_inside;
errno_pipe_fd[0] = safe_close(errno_pipe_fd[0]);
q = procfs_file_alloca(target, "ns/mnt");
mntfd = open(q, O_RDONLY|O_NOCTTY|O_CLOEXEC);
if (mntfd < 0) {
r = log_error_errno(errno, "Failed to open mount namespace of leader: %m");
goto child_fail;
}
if (setns(mntfd, CLONE_NEWNS) < 0) {
r = log_error_errno(errno, "Failed to join namespace of leader: %m");
goto child_fail;
}
if (make_file_or_directory) {
(void) mkdir_parents(dest, 0755);
(void) make_mount_point_inode_from_stat(&st, dest, 0700);