]> git.proxmox.com Git - mirror_qemu.git/commitdiff
linux-user: Emulate CLONE_PIDFD flag in clone()
authorHelge Deller <deller@gmx.de>
Tue, 29 Nov 2022 11:08:20 +0000 (12:08 +0100)
committerLaurent Vivier <laurent@vivier.eu>
Fri, 10 Mar 2023 19:45:47 +0000 (20:45 +0100)
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
linux-user/syscall.c

index e08bd53afb482d65689c55739da51adcf3d1511d..aad2b62ca41632734893c869f1e67d5c773850db 100644 (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),
index dad2c3312032011b32913c8c2e913f669a768962..24cea6fb6a63b80cc4f908a7b51e0bf3e3455173 100644 (file)
 #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));