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From: Aleksa Sarai <cyphar@cyphar.com>
To: Ingo Molnar <mingo@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
	Christian Brauner <christian@brauner.io>
Cc: Aleksa Sarai <cyphar@cyphar.com>,
	Rasmus Villemoes <linux@rasmusvillemoes.dk>,
	Al Viro <viro@zeniv.linux.org.uk>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	libc-alpha@sourceware.org, linux-api@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: [PATCH v1 0/4] lib: introduce copy_struct_from_user() helper
Date: Wed, 25 Sep 2019 18:59:11 +0200	[thread overview]
Message-ID: <20190925165915.8135-1-cyphar@cyphar.com> (raw)

This series was split off from the openat2(2) syscall discussion[1].
However, the copy_struct_to_user() helper has been dropped, because
after some discussion it appears that there is no really obvious
semantics for how copy_struct_to_user() should work on mixed-vintages
(for instance, whether [2] is the correct semantics for all syscalls).

A common pattern for syscall extensions is increasing the size of a
struct passed from userspace, such that the zero-value of the new fields
result in the old kernel behaviour (allowing for a mix of userspace and
kernel vintages to operate on one another in most cases).

Previously there was no common lib/ function that implemented
the necessary extension-checking semantics (and different syscalls
implemented them slightly differently or incompletely[3]). This series
implements the helper and ports several syscalls to use it.

[1]: https://lore.kernel.org/lkml/20190904201933.10736-1-cyphar@cyphar.com/

[2]: commit 1251201c0d34 ("sched/core: Fix uclamp ABI bug, clean up and
     robustify sched_read_attr() ABI logic and code")

[3]: For instance {sched_setattr,perf_event_open,clone3}(2) all do do
     similar checks to copy_struct_from_user() while rt_sigprocmask(2)
     always rejects differently-sized struct arguments.

Aleksa Sarai (4):
  lib: introduce copy_struct_from_user() helper
  clone3: switch to copy_struct_from_user()
  sched_setattr: switch to copy_struct_from_user()
  perf_event_open: switch to copy_struct_from_user()

 include/linux/uaccess.h    |  4 +++
 include/uapi/linux/sched.h |  2 ++
 kernel/events/core.c       | 47 +++++-------------------
 kernel/fork.c              | 34 ++++--------------
 kernel/sched/core.c        | 43 ++++------------------
 lib/Makefile               |  2 +-
 lib/strnlen_user.c         | 52 +++++++++++++++++++++++++++
 lib/struct_user.c          | 73 ++++++++++++++++++++++++++++++++++++++
 8 files changed, 155 insertions(+), 102 deletions(-)
 create mode 100644 lib/struct_user.c

-- 
2.23.0


             reply	other threads:[~2019-09-25 17:00 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-25 16:59 Aleksa Sarai [this message]
2019-09-25 16:59 ` [PATCH v1 1/4] lib: introduce copy_struct_from_user() helper Aleksa Sarai
2019-09-25 17:10   ` Linus Torvalds
2019-09-25 17:20     ` Aleksa Sarai
2019-09-25 17:48       ` Linus Torvalds
2019-09-25 18:04         ` Al Viro
2019-09-25 18:13           ` Linus Torvalds
2019-09-25 19:43             ` Al Viro
2019-09-25 20:23               ` Linus Torvalds
2019-09-25 17:18   ` Christian Brauner
2019-09-25 17:20     ` Christian Brauner
2019-09-25 19:16   ` kbuild test robot
2019-09-25 20:47   ` kbuild test robot
2019-09-25 16:59 ` [PATCH v1 2/4] clone3: switch to copy_struct_from_user() Aleksa Sarai
2019-09-25 17:22   ` Christian Brauner
2019-09-25 18:59   ` kbuild test robot
2019-09-25 19:08   ` kbuild test robot
2019-09-25 16:59 ` [PATCH v1 3/4] sched_setattr: " Aleksa Sarai
2019-09-25 16:59 ` [PATCH v1 4/4] perf_event_open: " Aleksa Sarai
2019-09-25 17:09 ` [PATCH v1 0/4] lib: introduce copy_struct_from_user() helper Christian Brauner

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