Re: [PATCH v3 0/4] uaccess: Add unsafe accessors for arm64

Julien Thierry
2019-01-30T16:17:07Z

Hi,

Gentle ping for patches 3 and 4.

Thanks,

Julien

On 15/01/2019 13:58, Julien Thierry wrote:
> Hi,
>
> First version of this series[1] was briefly in linux-next but had to be
> reverted due to a bug where schedule would end up being called while
> user_access was active[2].
>
> After clarifications[3], rescheduling while in a user_access region is not
> allowed.
>
> * Patches 1 and 2 implement the unsafe accessors for arm64
> * Patches 3 and 4 clarify this restriction in the API and attempts to
> check against violations of the restriction.
>
> Changes since v2[4]:
> - Rebase on v5.0-rc2
> - access_ok() is now done in user_access_begin(), so rework accessors
> so access_ok() is not called in unsafe_get/put_user()
> - Split addition of unsafe accessors and the user_access_region check
> into separate patches
> - Avoid reading SCTLR_EL1 in user_access_region check
> - Add build option for user_access_region checking
> - Reword clarifications on unsafe accessors API
>
> Changes since v1[1]:
> - Add a way to detect code calling schedule within a user_access region
> - Make sure put_user/get_user arguments are evaluated before disabling PAN
>
> [1] https://www.spinics.net/lists/arm-kernel/msg674925.html
> [2] https://patchwork.kernel.org/patch/10634783/
> [3] https://lkml.org/lkml/2018/11/28/50
> [4] http://lists.infradead.org/pipermail/linux-arm-kernel/2018-December/617080.html
>
> Cheers,
>
> Julien
>
> -->
>
> Julien Thierry (4):
> arm64: uaccess: Cleanup get/put_user()
> arm64: uaccess: Implement unsafe accessors
> uaccess: Check no rescheduling function is called in unsafe region
> arm64: uaccess: Implement user_access_region_active
>
> arch/arm64/include/asm/sysreg.h | 2 +
> arch/arm64/include/asm/uaccess.h | 123 ++++++++++++++++++++++++++-------------
> include/linux/kernel.h | 11 +++-
> include/linux/uaccess.h | 13 +++++
> kernel/sched/core.c | 22 +++++++
> lib/Kconfig.debug | 8 +++
> 6 files changed, 135 insertions(+), 44 deletions(-)
>
> --
> 1.9.1
>

--
Julien Thierry