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

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