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linux-user: Emulate CLONE_PIDFD flag in clone() 

Add emulation for the CLONE_PIDFD flag of the clone() syscall.
This flag was added in Linux kernel 5.2.

Successfully tested on a x86-64 Linux host with hppa-linux target.
Can be verified by running the testsuite of the qcoro debian package,
which breaks hard and kills the currently logged-in user without this
patch.

Signed-off-by: Helge Deller <deller@gmx.de>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>

Message-Id: <Y4XoJCpvUA1JD7Sj@p100>
[lv: define CLONE_PIDFD if it is not]
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
master
Helge Deller 2022-11-29 12:08:20 +01:00 committed by Laurent Vivier
parent fe080593dd
commit 895ce8bb53
2 changed files with 35 additions and 1 deletions
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5
linux-user/strace.c
View File

@ -1111,11 +1111,16 @@ UNUSED static const struct flags mmap_flags[] = {
FLAG_END,
};
#ifndef CLONE_PIDFD
# define CLONE_PIDFD 0x00001000
#endif
UNUSED static const struct flags clone_flags[] = {
FLAG_GENERIC(CLONE_VM),
FLAG_GENERIC(CLONE_FS),
FLAG_GENERIC(CLONE_FILES),
FLAG_GENERIC(CLONE_SIGHAND),
FLAG_GENERIC(CLONE_PIDFD),
FLAG_GENERIC(CLONE_PTRACE),
FLAG_GENERIC(CLONE_VFORK),
FLAG_GENERIC(CLONE_PARENT),

31
linux-user/syscall.c
View File

@ -169,9 +169,13 @@
#define CLONE_IGNORED_FLAGS \
(CLONE_DETACHED | CLONE_IO)
#ifndef CLONE_PIDFD
# define CLONE_PIDFD 0x00001000
#endif
/* Flags for fork which we can implement within QEMU itself */
#define CLONE_OPTIONAL_FORK_FLAGS \
(CLONE_SETTLS | CLONE_PARENT_SETTID | \
(CLONE_SETTLS | CLONE_PARENT_SETTID | CLONE_PIDFD | \
CLONE_CHILD_CLEARTID | CLONE_CHILD_SETTID)
/* Flags for thread creation which we can implement within QEMU itself */
@ -6730,6 +6734,17 @@ static int do_fork(CPUArchState *env, unsigned int flags, abi_ulong newsp,
return -TARGET_EINVAL;
}
#if !defined(__NR_pidfd_open) || !defined(TARGET_NR_pidfd_open)
if (flags & CLONE_PIDFD) {
return -TARGET_EINVAL;
}
#endif
/* Can not allow CLONE_PIDFD with CLONE_PARENT_SETTID */
if ((flags & CLONE_PIDFD) && (flags & CLONE_PARENT_SETTID)) {
return -TARGET_EINVAL;
}
if (block_signals()) {
return -QEMU_ERESTARTSYS;
}
@ -6757,6 +6772,20 @@ static int do_fork(CPUArchState *env, unsigned int flags, abi_ulong newsp,
ts->child_tidptr = child_tidptr;
} else {
cpu_clone_regs_parent(env, flags);
if (flags & CLONE_PIDFD) {
int pid_fd = 0;
#if defined(__NR_pidfd_open) && defined(TARGET_NR_pidfd_open)
int pid_child = ret;
pid_fd = pidfd_open(pid_child, 0);
if (pid_fd >= 0) {
fcntl(pid_fd, F_SETFD, fcntl(pid_fd, F_GETFL)
| FD_CLOEXEC);
} else {
pid_fd = 0;
}
#endif
put_user_u32(pid_fd, parent_tidptr);
}
fork_end(0);
}
g_assert(!cpu_in_exclusive_context(cpu));