1. 05 Aug, 2023 1 commit
  2. 28 Jul, 2023 1 commit
    • Aleksa Sarai's avatar
      fchmodat2: add support for AT_EMPTY_PATH · 5daeb41a
      Aleksa Sarai authored
      This allows userspace to avoid going through /proc/self/fd when dealing
      with all types of file descriptors for chmod(), and makes fchmodat2() a
      proper superset of all other chmod syscalls.
      
      The primary difference between fchmodat2(AT_EMPTY_PATH) and fchmod() is
      that fchmod() doesn't operate on O_PATH file descriptors by design. To
      quote open(2):
      
      > O_PATH (since Linux 2.6.39)
      > [...]
      > The file itself is not opened, and other file operations (e.g.,
      > read(2), write(2), fchmod(2), fchown(2), fgetxattr(2), ioctl(2),
      > mmap(2)) fail with the error EBADF.
      
      However, procfs has allowed userspace to do this operation ever since
      the introduction of O_PATH through magic-links, so adding this feature
      is only an improvement for programs that have to mess around with
      /proc/self/fd/$n today to get this behaviour. In addition,
      fchownat(AT_EMPTY_PATH) has existed since the introduction of O_PATH and
      allows chown() operations directly on O_PATH descriptors.
      Signed-off-by: default avatarAleksa Sarai <cyphar@cyphar.com>
      Acked-by: default avatarAlexey Gladkov <legion@kernel.org>
      Message-Id: <20230728-fchmodat2-at_empty_path-v1-1-f3add31d3516@cyphar.com>
      Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
      5daeb41a
  3. 27 Jul, 2023 3 commits
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