This patch-set implements the OA2_INHERIT_CRED flag for openat2() syscall. It is needed to perform an open operation with the creds that were in effect when the dir_fd was opened. This allows the process to pre-open some dirs and switch eUID (and other UIDs/GIDs) to the less-privileged user, while still retaining the possibility to open/create files within the pre-opened directory set. Changes in v2: - capture full struct cred instead of just fsuid/fsgid. Suggested by Stefan Metzmacher <metze@xxxxxxxxx> CC: Stefan Metzmacher <metze@xxxxxxxxx> CC: Eric Biederman <ebiederm@xxxxxxxxxxxx> CC: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx> CC: Andy Lutomirski <luto@xxxxxxxxxx> CC: Christian Brauner <brauner@xxxxxxxxxx> CC: Jan Kara <jack@xxxxxxx> CC: Jeff Layton <jlayton@xxxxxxxxxx> CC: Chuck Lever <chuck.lever@xxxxxxxxxx> CC: Alexander Aring <alex.aring@xxxxxxxxx> CC: linux-fsdevel@xxxxxxxxxxxxxxx CC: linux-kernel@xxxxxxxxxxxxxxx CC: linux-api@xxxxxxxxxxxxxxx CC: Paolo Bonzini <pbonzini@xxxxxxxxxx> CC: Christian Göttsche <cgzones@xxxxxxxxxxxxxx> Stas Sergeev (2): fs: reorganize path_openat() openat2: add OA2_INHERIT_CRED flag fs/internal.h | 2 +- fs/namei.c | 52 +++++++++++++++++++++++++++++------- fs/open.c | 2 +- include/linux/fcntl.h | 2 ++ include/uapi/linux/openat2.h | 3 +++ 5 files changed, 50 insertions(+), 11 deletions(-) -- 2.44.0
