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arm64: Introduce prctl() options to control the tagged user addresses ABI

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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>
This commit is contained in:
Catalin Marinas
2019-07-23 19:58:39 +02:00
committed by Will Deacon
parent 2b835e24b5
commit 63f0c60379
7 changed files with 111 additions and 1 deletions
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8
arch/arm64/include/asm/processor.h
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@@ -306,6 +306,14 @@ extern void __init minsigstksz_setup(void);
/* PR_PAC_RESET_KEYS prctl */
#define PAC_RESET_KEYS(tsk, arg) ptrauth_prctl_reset_keys(tsk, arg)
#ifdef CONFIG_ARM64_TAGGED_ADDR_ABI
/* PR_{SET,GET}_TAGGED_ADDR_CTRL prctl */
long set_tagged_addr_ctrl(unsigned long arg);
long get_tagged_addr_ctrl(void);
#define SET_TAGGED_ADDR_CTRL(arg) set_tagged_addr_ctrl(arg)
#define GET_TAGGED_ADDR_CTRL() get_tagged_addr_ctrl()
#endif
/*
* For CONFIG_GCC_PLUGIN_STACKLEAK
*