Merge tag 'fs.openat2.unknown_flags.v5.14' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux

Pull openat2 fixes from Christian Brauner:

 - Remove the unused VALID_UPGRADE_FLAGS define we carried from an
   extension to openat2() that we haven't merged. Aleksa might be
   getting back to it at some point but just not right now.

 - openat2() used to accidently ignore unknown flag values in the upper
   32 bits.

   The new openat2() syscall verifies that no unknown O-flag values are
   set and returns an error to userspace if they are while the older
   open syscalls like open() and openat() simply ignore unknown flag
   values:

      #define O_FLAG_CURRENTLY_INVALID (1 << 31)
      struct open_how how = {
            .flags = O_RDONLY | O_FLAG_CURRENTLY_INVALID,
            .resolve = 0,
      };

      /* fails */
      fd = openat2(-EBADF, "/dev/null", &how, sizeof(how));

      /* succeeds */
      fd = openat(-EBADF, "/dev/null", O_RDONLY | O_FLAG_CURRENTLY_INVALID);

   However, openat2() silently truncates the upper 32 bits meaning:

      #define O_FLAG_CURRENTLY_INVALID_LOWER32 (1 << 31)
      #define O_FLAG_CURRENTLY_INVALID_UPPER32 (1 << 40)

      struct open_how how_lowe32 = {
            .flags = O_RDONLY | O_FLAG_CURRENTLY_INVALID_LOWER32,
      };

      struct open_how how_upper32 = {
            .flags = O_RDONLY | O_FLAG_CURRENTLY_INVALID_UPPER32,
      };

      /* fails */
      fd = openat2(-EBADF, "/dev/null", &how_lower32, sizeof(how_lower32));

      /* succeeds */
      fd = openat2(-EBADF, "/dev/null", &how_upper32, sizeof(how_upper32));

   Fix this by preventing the immediate truncation in build_open_flags()
   and add a compile-time check to catch when we add flags in the upper
   32 bit range.

* tag 'fs.openat2.unknown_flags.v5.14' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux:
  test: add openat2() test for invalid upper 32 bit flag value
  open: don't silently ignore unknown O-flags in openat2()
  fcntl: remove unused VALID_UPGRADE_FLAGS

1 files changed, 0 insertions, 4 deletions

diff --git a/include/linux/fcntl.h b/include/linux/fcntl.h
index 766fcd973beb..a332e79b3207 100644
--- a/include/linux/fcntl.h
+++ b/include/linux/fcntl.h
@@ -12,10 +12,6 @@
 	 FASYNC	| O_DIRECT | O_LARGEFILE | O_DIRECTORY | O_NOFOLLOW | \
 	 O_NOATIME | O_CLOEXEC | O_PATH | __O_TMPFILE)
 
-/* List of all valid flags for the how->upgrade_mask argument: */
-#define VALID_UPGRADE_FLAGS \
-	(UPGRADE_NOWRITE | UPGRADE_NOREAD)
-
 /* List of all valid flags for the how->resolve argument: */
 #define VALID_RESOLVE_FLAGS \
 	(RESOLVE_NO_XDEV | RESOLVE_NO_MAGICLINKS | RESOLVE_NO_SYMLINKS | \