From: Helge Deller <deller@gmx.de>
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>
---
linux-user/strace.c | 5 +++++
linux-user/syscall.c | 31 ++++++++++++++++++++++++++++++-
2 files changed, 35 insertions(+), 1 deletion(-)
diff --git a/linux-user/strace.c b/linux-user/strace.c
index e08bd53afb48..aad2b62ca416 100644
--- a/linux-user/strace.c
+++ b/linux-user/strace.c
@@ -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),
diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index dad2c3312032..24cea6fb6a63 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -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));
--
2.39.2