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https://github.com/checkpoint-restore/criu.git
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42058dc7ce
Here is a race when someone umounted something and this operation
isn't propagated into our namespace.
CRIU | Another process
-----------------------------------------------------------------
pivot_root(".", put_root) |
mount(put_root, MS_REC|MS_PRIVATE) |
| umount /xxx/yyy
| umount /xxx -> EBUSY
umount(put_root)
We do this to not affect mounts in put_root, but we can mask
these mounts as slave and this will work for us and for external
users.
Reported-by: Mr Travis
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>
67 lines
1.6 KiB
C
67 lines
1.6 KiB
C
#include <sched.h>
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#include <sys/types.h>
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#include <sys/wait.h>
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#include <stdlib.h>
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#include <stdio.h>
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#include <sys/mount.h>
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#include <unistd.h>
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int main(int argc, char **argv)
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{
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pid_t pid;
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int status;
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/*
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* pidns is used to avoid conflicts
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* mntns is used to mount /proc
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* net is used to avoid conflicts of parasite sockets
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*/
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if (unshare(CLONE_NEWNS | CLONE_NEWPID | CLONE_NEWNET | CLONE_NEWIPC))
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return 1;
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pid = fork();
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if (pid == 0) {
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if (mount(NULL, "/", NULL, MS_REC | MS_SLAVE, NULL)) {
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fprintf(stderr, "mount(/, S_REC | MS_SLAVE)): %m");
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return 1;
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}
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umount2("/proc", MNT_DETACH);
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umount2("/dev/pts", MNT_DETACH);
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if (mount("zdtm_proc", "/proc", "proc", 0, NULL)) {
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fprintf(stderr, "mount(/proc): %m");
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return 1;
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}
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if (mount("zdtm_devpts", "/dev/pts", "devpts", 0,
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"newinstance,ptmxmode=0666")) {
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fprintf(stderr, "mount(pts): %m");
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return 1;
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}
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if (mount("zdtm_binfmt", "/proc/sys/fs/binfmt_misc", "binfmt_misc", 0,
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NULL)) {
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fprintf(stderr, "mount(binfmt_misc): %m");
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return 1;
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}
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if (mount("/dev/pts/ptmx", "/dev/ptmx", NULL, MS_BIND, NULL)) {
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fprintf(stderr, "mount(ptmx): %m");
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return 1;
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}
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if (system("ip link set up dev lo"))
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return 1;
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execv(argv[1], argv + 1);
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fprintf(stderr, "execve: %m");
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return 1;
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}
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if (waitpid(pid, &status, 0) != pid) {
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fprintf(stderr, "waitpid: %m");
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return 1;
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}
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if (WIFEXITED(status))
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return WEXITSTATUS(status);
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else if (WIFSIGNALED(status))
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kill(getpid(), WTERMSIG(status));
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else
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fprintf(stderr, "Unexpected exit status: %x\n", status);
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return 1;
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}
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