Catalin Marinas f077ee2609 BACKPORT: arm64: Introduce prctl() options to control the tagged user addresses ABI ...

(Upstream commit 63f0c60379650d82250f22e4cf4137ef3dc4f43d).

It is not desirable to relax the ABI to allow tagged user addresses into
the kernel indiscriminately. This patch introduces a prctl() interface
for enabling or disabling the tagged ABI with a global sysctl control
for preventing applications from enabling the relaxed ABI (meant for
testing user-space prctl() return error checking without reconfiguring
the kernel). The ABI properties are inherited by threads of the same
application and fork()'ed children but cleared on execve(). A Kconfig
option allows the overall disabling of the relaxed ABI.

The PR_SET_TAGGED_ADDR_CTRL will be expanded in the future to handle
MTE-specific settings like imprecise vs precise exceptions.

Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Will Deacon <will@kernel.org>
Change-Id: I2d52c5589b05415faab315c116245f1058d64750
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Bug: 135692346

2019-10-07 15:27:39 -04:00

7.6 KiB

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