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Merge pull request #2984 from brauner/2019-05-09/clone_pidfd

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clone: add infrastructure for CLONE_PIDFD
This commit is contained in:
Stéphane Graber 2019-05-09 09:37:51 -04:00 committed by GitHub
commit 1ab73d3800
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GPG Key ID: 4AEE18F83AFDEB23
7 changed files with 58 additions and 40 deletions
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2
src/lxc/attach.c
View File

@ -1426,7 +1426,7 @@ int lxc_attach(const char *name, const char *lxcpath,
payload.exec_function = exec_function;
payload.exec_payload = exec_payload;
pid = lxc_raw_clone(CLONE_PARENT);
pid = lxc_raw_clone(CLONE_PARENT, NULL);
if (pid < 0) {
SYSERROR("Failed to clone attached process");
shutdown(ipc_sockets[1], SHUT_RDWR);

2
src/lxc/conf.c
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@ -4337,7 +4337,7 @@ int userns_exec_1(struct lxc_conf *conf, int (*fn)(void *), void *data,
d.p[1] = p[1];
/* Clone child in new user namespace. */
pid = lxc_raw_clone_cb(run_userns_fn, &d, CLONE_NEWUSER);
pid = lxc_raw_clone_cb(run_userns_fn, &d, CLONE_NEWUSER, NULL);
if (pid < 0) {
ERROR("Failed to clone process in new user namespace");
goto on_error;

52
src/lxc/raw_syscalls.c
View File

@ -33,7 +33,7 @@ int lxc_raw_execveat(int dirfd, const char *pathname, char *const argv[],
* The nice thing about this is that we get fork() behavior. That is
* lxc_raw_clone() returns 0 in the child and the child pid in the parent.
*/
__returns_twice pid_t lxc_raw_clone(unsigned long flags)
__returns_twice pid_t lxc_raw_clone(unsigned long flags, int *pidfd)
{
/*
* These flags don't interest at all so we don't jump through any hoops
@ -48,7 +48,7 @@ __returns_twice pid_t lxc_raw_clone(unsigned long flags)
/* On s390/s390x and cris the order of the first and second arguments
* of the system call is reversed.
*/
return syscall(__NR_clone, NULL, flags | SIGCHLD);
return syscall(__NR_clone, NULL, flags | SIGCHLD, pidfd);
#elif defined(__sparc__) && defined(__arch64__)
{
/*
@ -56,46 +56,58 @@ __returns_twice pid_t lxc_raw_clone(unsigned long flags)
* boolean flag whether this is the child or the parent in %o1.
* Inline assembly is needed to get the flag returned in %o1.
*/
int child_pid, in_child, ret;
register long g1 asm("g1") = __NR_clone;
register long o0 asm("o0") = flags | SIGCHLD;
register long o1 asm("o1") = 0; /* is parent/child indicator */
register long o2 asm("o2") = (unsigned long)pidfd;
long is_error, retval, in_child;
pid_t child_pid;
asm volatile("mov %3, %%g1\n\t"
"mov %4, %%o0\n\t"
"mov 0 , %%o1\n\t"
asm volatile(
#if defined(__arch64__)
"t 0x6d\n\t"
"t 0x6d\n\t" /* 64-bit trap */
#else
"t 0x10\n\t"
"t 0x10\n\t" /* 32-bit trap */
#endif
"addx %%g0, 0, %2\n\t"
"mov %%o1, %0\n\t"
"mov %%o0, %1" :
"=r"(in_child), "=r"(child_pid), "=r"(ret) :
"i"(__NR_clone), "r"(flags | SIGCHLD) :
"%o1", "%o0", "%g1", "cc" );
/*
* catch errors: On sparc, the carry bit (csr) in the
* processor status register (psr) is used instead of a
* full register.
*/
"addx %%g0, 0, %g1"
: "=r"(g1), "=r"(o0), "=r"(o1), "=r"(o2) /* outputs */
: "r"(g1), "r"(o0), "r"(o1), "r"(o2) /* inputs */
: "%cc"); /* clobbers */
if (ret) {
errno = child_pid;
is_error = g1;
retval = o0;
in_child = o1;
if (is_error) {
errno = retval;
return -1;
}
if (in_child)
return 0;
child_pid = retval;
return child_pid;
}
#elif defined(__ia64__)
/* On ia64 the stack and stack size are passed as separate arguments. */
return syscall(__NR_clone, flags | SIGCHLD, NULL, prctl_arg(0));
return syscall(__NR_clone, flags | SIGCHLD, NULL, prctl_arg(0), pidfd);
#else
return syscall(__NR_clone, flags | SIGCHLD, NULL);
return syscall(__NR_clone, flags | SIGCHLD, NULL, pidfd);
#endif
}
pid_t lxc_raw_clone_cb(int (*fn)(void *), void *args, unsigned long flags)
pid_t lxc_raw_clone_cb(int (*fn)(void *), void *args, unsigned long flags,
int *pidfd)
{
pid_t pid;
pid = lxc_raw_clone(flags);
pid = lxc_raw_clone(flags, pidfd);
if (pid < 0)
return -1;

10
src/lxc/raw_syscalls.h
View File

@ -30,6 +30,11 @@
#include <sys/syscall.h>
#include <unistd.h>
/* clone */
#ifndef CLONE_PIDFD
#define CLONE_PIDFD 0x00001000
#endif
/*
* lxc_raw_clone() - create a new process
*
@ -57,7 +62,7 @@
* - must call lxc_raw_getpid():
* The child must use lxc_raw_getpid() to retrieve its pid.
*/
extern pid_t lxc_raw_clone(unsigned long flags);
extern pid_t lxc_raw_clone(unsigned long flags, int *pidfd);
/*
* lxc_raw_clone_cb() - create a new process
@ -70,7 +75,8 @@ extern pid_t lxc_raw_clone(unsigned long flags);
* All other comments that apply to lxc_raw_clone() apply to lxc_raw_clone_cb()
* as well.
*/
extern pid_t lxc_raw_clone_cb(int (*fn)(void *), void *args, unsigned long flags);
extern pid_t lxc_raw_clone_cb(int (*fn)(void *), void *args,
unsigned long flags, int *pidfd);
extern int lxc_raw_execveat(int dirfd, const char *pathname, char *const argv[],
char *const envp[], int flags);

4
src/lxc/start.c
View File

@ -1601,7 +1601,7 @@ static inline int do_share_ns(void *arg)
flags = handler->ns_on_clone_flags;
flags |= CLONE_PARENT;
handler->pid = lxc_raw_clone_cb(do_start, handler, flags);
handler->pid = lxc_raw_clone_cb(do_start, handler, flags, NULL);
if (handler->pid < 0)
return -1;
@ -1748,7 +1748,7 @@ static int lxc_spawn(struct lxc_handler *handler)
}
} else {
handler->pid = lxc_raw_clone_cb(do_start, handler,
handler->ns_on_clone_flags);
handler->ns_on_clone_flags, NULL);
}
if (handler->pid < 0) {
SYSERROR(LXC_CLONE_ERROR);

2
src/lxc/utils.c
View File

@ -1611,7 +1611,7 @@ int run_command_internal(char *buf, size_t buf_size, int (*child_fn)(void *), vo
return -1;
}
child = lxc_raw_clone(0);
child = lxc_raw_clone(0, NULL);
if (child < 0) {
close(pipefd[0]);
close(pipefd[1]);

26
src/tests/lxc_raw_clone.c
View File

@ -48,42 +48,42 @@ int main(int argc, char *argv[])
pid_t pid;
int flags = 0;
pid = lxc_raw_clone(CLONE_PARENT_SETTID);
pid = lxc_raw_clone(CLONE_PARENT_SETTID, NULL);
if (pid >= 0 || pid != -EINVAL) {
lxc_error("%s\n", "Calling lxc_raw_clone(CLONE_PARENT_SETTID) "
"should not be possible");
exit(EXIT_FAILURE);
}
pid = lxc_raw_clone(CLONE_CHILD_SETTID);
pid = lxc_raw_clone(CLONE_CHILD_SETTID, NULL);
if (pid >= 0 || pid != -EINVAL) {
lxc_error("%s\n", "Calling lxc_raw_clone(CLONE_CHILD_SETTID) "
"should not be possible");
exit(EXIT_FAILURE);
}
pid = lxc_raw_clone(CLONE_CHILD_CLEARTID);
pid = lxc_raw_clone(CLONE_CHILD_CLEARTID, NULL);
if (pid >= 0 || pid != -EINVAL) {
lxc_error("%s\n", "Calling lxc_raw_clone(CLONE_CHILD_CLEARTID) "
"should not be possible");
exit(EXIT_FAILURE);
}
pid = lxc_raw_clone(CLONE_SETTLS);
pid = lxc_raw_clone(CLONE_SETTLS, NULL);
if (pid >= 0 || pid != -EINVAL) {
lxc_error("%s\n", "Calling lxc_raw_clone(CLONE_SETTLS) should "
"not be possible");
exit(EXIT_FAILURE);
}
pid = lxc_raw_clone(CLONE_VM);
pid = lxc_raw_clone(CLONE_VM, NULL);
if (pid >= 0 || pid != -EINVAL) {
lxc_error("%s\n", "Calling lxc_raw_clone(CLONE_VM) should "
"not be possible");
exit(EXIT_FAILURE);
}
pid = lxc_raw_clone(0);
pid = lxc_raw_clone(0, NULL);
if (pid < 0) {
lxc_error("%s\n", "Failed to call lxc_raw_clone(0)");
exit(EXIT_FAILURE);
@ -100,7 +100,7 @@ int main(int argc, char *argv[])
exit(EXIT_FAILURE);
}
pid = lxc_raw_clone(0);
pid = lxc_raw_clone(0, NULL);
if (pid < 0) {
lxc_error("%s\n", "Failed to call lxc_raw_clone(0)");
exit(EXIT_FAILURE);
@ -127,7 +127,7 @@ int main(int argc, char *argv[])
flags |= CLONE_NEWPID;
flags |= CLONE_NEWUTS;
pid = lxc_raw_clone(flags);
pid = lxc_raw_clone(flags, NULL);
if (pid < 0) {
lxc_error("%s\n", "Failed to call lxc_raw_clone(CLONE_NEWUSER "
"| CLONE_NEWCGROUP | CLONE_NEWNS | "
@ -147,7 +147,7 @@ int main(int argc, char *argv[])
exit(EXIT_FAILURE);
}
pid = lxc_raw_clone(flags);
pid = lxc_raw_clone(flags, NULL);
if (pid < 0) {
lxc_error("%s\n", "Failed to call lxc_raw_clone(CLONE_NEWUSER "
"| CLONE_NEWCGROUP | CLONE_NEWNS | "
@ -168,7 +168,7 @@ int main(int argc, char *argv[])
exit(EXIT_FAILURE);
}
pid = lxc_raw_clone(CLONE_VFORK);
pid = lxc_raw_clone(CLONE_VFORK, NULL);
if (pid < 0) {
lxc_error("%s\n", "Failed to call lxc_raw_clone(CLONE_VFORK);");
exit(EXIT_FAILURE);
@ -185,7 +185,7 @@ int main(int argc, char *argv[])
exit(EXIT_FAILURE);
}
pid = lxc_raw_clone(CLONE_VFORK);
pid = lxc_raw_clone(CLONE_VFORK, NULL);
if (pid < 0) {
lxc_error("%s\n", "Failed to call lxc_raw_clone(CLONE_VFORK);");
exit(EXIT_FAILURE);
@ -202,7 +202,7 @@ int main(int argc, char *argv[])
exit(EXIT_FAILURE);
}
pid = lxc_raw_clone(CLONE_FILES);
pid = lxc_raw_clone(CLONE_FILES, NULL);
if (pid < 0) {
lxc_error("%s\n", "Failed to call lxc_raw_clone(CLONE_FILES);");
exit(EXIT_FAILURE);
@ -219,7 +219,7 @@ int main(int argc, char *argv[])
exit(EXIT_FAILURE);
}
pid = lxc_raw_clone(CLONE_FILES);
pid = lxc_raw_clone(CLONE_FILES, NULL);
if (pid < 0) {
lxc_error("%s\n", "Failed to call lxc_raw_clone(CLONE_FILES);");
exit(EXIT_FAILURE);