Merge tag 'vfs-6.19-rc1.coredump' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull pidfd and coredump updates from Christian Brauner:
 "Features:

   - Expose coredump signal via pidfd

     Expose the signal that caused the coredump through the pidfd
     interface. The recent changes to rework coredump handling to rely
     on unix sockets are in the process of being used in systemd. The
     previous systemd coredump container interface requires the coredump
     file descriptor and basic information including the signal number
     to be sent to the container. This means the signal number needs to
     be available before sending the coredump to the container.

   - Add supported_mask field to pidfd

     Add a new supported_mask field to struct pidfd_info that indicates
     which information fields are supported by the running kernel. This
     allows userspace to detect feature availability without relying on
     error codes or kernel version checks.

  Cleanups:

   - Drop struct pidfs_exit_info and prepare to drop exit_info pointer,
     simplifying the internal publication mechanism for exit and
     coredump information retrievable via the pidfd ioctl

   - Use guard() for task_lock in pidfs

   - Reduce wait_pidfd lock scope

   - Add missing PIDFD_INFO_SIZE_VER1 constant

   - Add missing BUILD_BUG_ON() assert on struct pidfd_info

  Fixes:

   - Fix PIDFD_INFO_COREDUMP handling

  Selftests:

   - Split out coredump socket tests and common helpers into separate
     files for better organization

   - Fix userspace coredump client detection issues

   - Handle edge-triggered epoll correctly

   - Ignore ENOSPC errors in tests

   - Add debug logging to coredump socket tests, socket protocol tests,
     and test helpers

   - Add tests for PIDFD_INFO_COREDUMP_SIGNAL

   - Add tests for supported_mask field

   - Update pidfd header for selftests"

* tag 'vfs-6.19-rc1.coredump' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (23 commits)
  pidfs: reduce wait_pidfd lock scope
  selftests/coredump: add second PIDFD_INFO_COREDUMP_SIGNAL test
  selftests/coredump: add first PIDFD_INFO_COREDUMP_SIGNAL test
  selftests/coredump: ignore ENOSPC errors
  selftests/coredump: add debug logging to coredump socket protocol tests
  selftests/coredump: add debug logging to coredump socket tests
  selftests/coredump: add debug logging to test helpers
  selftests/coredump: handle edge-triggered epoll correctly
  selftests/coredump: fix userspace coredump client detection
  selftests/coredump: fix userspace client detection
  selftests/coredump: split out coredump socket tests
  selftests/coredump: split out common helpers
  selftests/pidfd: add second supported_mask test
  selftests/pidfd: add first supported_mask test
  selftests/pidfd: update pidfd header
  pidfs: expose coredump signal
  pidfs: drop struct pidfs_exit_info
  pidfs: prepare to drop exit_info pointer
  pidfd: add a new supported_mask field
  pidfs: add missing BUILD_BUG_ON() assert on struct pidfd_info
  ...

1 files changed, 9 insertions, 2 deletions

diff --git a/include/uapi/linux/pidfd.h b/include/uapi/linux/pidfd.h
index 957db425d459..ea9a6811fc76 100644
--- a/include/uapi/linux/pidfd.h
+++ b/include/uapi/linux/pidfd.h
@@ -26,8 +26,12 @@
 #define PIDFD_INFO_CGROUPID		(1UL << 2) /* Always returned if available, even if not requested */
 #define PIDFD_INFO_EXIT			(1UL << 3) /* Only returned if requested. */
 #define PIDFD_INFO_COREDUMP		(1UL << 4) /* Only returned if requested. */
+#define PIDFD_INFO_SUPPORTED_MASK	(1UL << 5) /* Want/got supported mask flags */
+#define PIDFD_INFO_COREDUMP_SIGNAL	(1UL << 6) /* Always returned if PIDFD_INFO_COREDUMP is requested. */
 
 #define PIDFD_INFO_SIZE_VER0		64 /* sizeof first published struct */
+#define PIDFD_INFO_SIZE_VER1		72 /* sizeof second published struct */
+#define PIDFD_INFO_SIZE_VER2		80 /* sizeof third published struct */
 
 /*
  * Values for @coredump_mask in pidfd_info.
@@ -91,8 +95,11 @@ struct pidfd_info {
 	__u32 fsuid;
 	__u32 fsgid;
 	__s32 exit_code;
-	__u32 coredump_mask;
-	__u32 __spare1;
+	struct /* coredump info */ {
+		__u32 coredump_mask;
+		__u32 coredump_signal;
+	};
+	__u64 supported_mask;	/* Mask flags that this kernel supports */
 };
 
 #define PIDFS_IOCTL_MAGIC 0xFF