leandrof/linux
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity
5b9fedb31e
linux/arch/arm64/include/asm/pointer_auth.h

146 lines
4.4 KiB
C
Raw Normal View History

arm64: Use the correct style for SPDX License Identifier This patch corrects the SPDX License Identifier style in the arm64 Hardware Architecture related files. Suggested-by: Joe Perches <joe@perches.com> Signed-off-by: Nishad Kamdar <nishadkamdar@gmail.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2019-04-16 15:19:35 +00:00
/* SPDX-License-Identifier: GPL-2.0 */
arm64: add basic pointer authentication support This patch adds basic support for pointer authentication, allowing userspace to make use of APIAKey, APIBKey, APDAKey, APDBKey, and APGAKey. The kernel maintains key values for each process (shared by all threads within), which are initialised to random values at exec() time. The ID_AA64ISAR1_EL1.{APA,API,GPA,GPI} fields are exposed to userspace, to describe that pointer authentication instructions are available and that the kernel is managing the keys. Two new hwcaps are added for the same reason: PACA (for address authentication) and PACG (for generic authentication). Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com> Tested-by: Adam Wallis <awallis@codeaurora.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Ramana Radhakrishnan <ramana.radhakrishnan@arm.com> Cc: Suzuki K Poulose <suzuki.poulose@arm.com> Cc: Will Deacon <will.deacon@arm.com> [will: Fix sizeof() usage and unroll address key initialisation] Signed-off-by: Will Deacon <will.deacon@arm.com>
2018-12-07 18:39:25 +00:00
#ifndef __ASM_POINTER_AUTH_H
#define __ASM_POINTER_AUTH_H
arm64: expose user PAC bit positions via ptrace When pointer authentication is in use, data/instruction pointers have a number of PAC bits inserted into them. The number and position of these bits depends on the configured TCR_ELx.TxSZ and whether tagging is enabled. ARMv8.3 allows tagging to differ for instruction and data pointers. For userspace debuggers to unwind the stack and/or to follow pointer chains, they need to be able to remove the PAC bits before attempting to use a pointer. This patch adds a new structure with masks describing the location of the PAC bits in userspace instruction and data pointers (i.e. those addressable via TTBR0), which userspace can query via PTRACE_GETREGSET. By clearing these bits from pointers (and replacing them with the value of bit 55), userspace can acquire the PAC-less versions. This new regset is exposed when the kernel is built with (user) pointer authentication support, and the address authentication feature is enabled. Otherwise, the regset is hidden. Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Ramana Radhakrishnan <ramana.radhakrishnan@arm.com> Cc: Will Deacon <will.deacon@arm.com> [will: Fix to use vabits_user instead of VA_BITS and rename macro] Signed-off-by: Will Deacon <will.deacon@arm.com>
2018-12-07 18:39:26 +00:00
#include <linux/bitops.h>
arm64: Introduce prctl(PR_PAC_{SET,GET}_ENABLED_KEYS) This change introduces a prctl that allows the user program to control which PAC keys are enabled in a particular task. The main reason why this is useful is to enable a userspace ABI that uses PAC to sign and authenticate function pointers and other pointers exposed outside of the function, while still allowing binaries conforming to the ABI to interoperate with legacy binaries that do not sign or authenticate pointers. The idea is that a dynamic loader or early startup code would issue this prctl very early after establishing that a process may load legacy binaries, but before executing any PAC instructions. This change adds a small amount of overhead to kernel entry and exit due to additional required instruction sequences. On a DragonBoard 845c (Cortex-A75) with the powersave governor, the overhead of similar instruction sequences was measured as 4.9ns when simulating the common case where IA is left enabled, or 43.7ns when simulating the uncommon case where IA is disabled. These numbers can be seen as the worst case scenario, since in more realistic scenarios a better performing governor would be used and a newer chip would be used that would support PAC unlike Cortex-A75 and would be expected to be faster than Cortex-A75. On an Apple M1 under a hypervisor, the overhead of the entry/exit instruction sequences introduced by this patch was measured as 0.3ns in the case where IA is left enabled, and 33.0ns in the case where IA is disabled. Signed-off-by: Peter Collingbourne <pcc@google.com> Reviewed-by: Dave Martin <Dave.Martin@arm.com> Link: https://linux-review.googlesource.com/id/Ibc41a5e6a76b275efbaa126b31119dc197b927a5 Link: https://lore.kernel.org/r/d6609065f8f40397a4124654eb68c9f490b4d477.1616123271.git.pcc@google.com Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2021-03-19 03:10:53 +00:00
#include <linux/prctl.h>
arm64: add basic pointer authentication support This patch adds basic support for pointer authentication, allowing userspace to make use of APIAKey, APIBKey, APDAKey, APDBKey, and APGAKey. The kernel maintains key values for each process (shared by all threads within), which are initialised to random values at exec() time. The ID_AA64ISAR1_EL1.{APA,API,GPA,GPI} fields are exposed to userspace, to describe that pointer authentication instructions are available and that the kernel is managing the keys. Two new hwcaps are added for the same reason: PACA (for address authentication) and PACG (for generic authentication). Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com> Tested-by: Adam Wallis <awallis@codeaurora.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Ramana Radhakrishnan <ramana.radhakrishnan@arm.com> Cc: Suzuki K Poulose <suzuki.poulose@arm.com> Cc: Will Deacon <will.deacon@arm.com> [will: Fix sizeof() usage and unroll address key initialisation] Signed-off-by: Will Deacon <will.deacon@arm.com>
2018-12-07 18:39:25 +00:00
#include <linux/random.h>
#include <asm/cpufeature.h>
arm64: expose user PAC bit positions via ptrace When pointer authentication is in use, data/instruction pointers have a number of PAC bits inserted into them. The number and position of these bits depends on the configured TCR_ELx.TxSZ and whether tagging is enabled. ARMv8.3 allows tagging to differ for instruction and data pointers. For userspace debuggers to unwind the stack and/or to follow pointer chains, they need to be able to remove the PAC bits before attempting to use a pointer. This patch adds a new structure with masks describing the location of the PAC bits in userspace instruction and data pointers (i.e. those addressable via TTBR0), which userspace can query via PTRACE_GETREGSET. By clearing these bits from pointers (and replacing them with the value of bit 55), userspace can acquire the PAC-less versions. This new regset is exposed when the kernel is built with (user) pointer authentication support, and the address authentication feature is enabled. Otherwise, the regset is hidden. Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Ramana Radhakrishnan <ramana.radhakrishnan@arm.com> Cc: Will Deacon <will.deacon@arm.com> [will: Fix to use vabits_user instead of VA_BITS and rename macro] Signed-off-by: Will Deacon <will.deacon@arm.com>
2018-12-07 18:39:26 +00:00
#include <asm/memory.h>
arm64: add basic pointer authentication support This patch adds basic support for pointer authentication, allowing userspace to make use of APIAKey, APIBKey, APDAKey, APDBKey, and APGAKey. The kernel maintains key values for each process (shared by all threads within), which are initialised to random values at exec() time. The ID_AA64ISAR1_EL1.{APA,API,GPA,GPI} fields are exposed to userspace, to describe that pointer authentication instructions are available and that the kernel is managing the keys. Two new hwcaps are added for the same reason: PACA (for address authentication) and PACG (for generic authentication). Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com> Tested-by: Adam Wallis <awallis@codeaurora.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Ramana Radhakrishnan <ramana.radhakrishnan@arm.com> Cc: Suzuki K Poulose <suzuki.poulose@arm.com> Cc: Will Deacon <will.deacon@arm.com> [will: Fix sizeof() usage and unroll address key initialisation] Signed-off-by: Will Deacon <will.deacon@arm.com>
2018-12-07 18:39:25 +00:00
#include <asm/sysreg.h>
#ifdef CONFIG_ARM64_PTR_AUTH
/*
* Each key is a 128-bit quantity which is split across a pair of 64-bit
* registers (Lo and Hi).
*/
struct ptrauth_key {
unsigned long lo, hi;
};
/*
* We give each process its own keys, which are shared by all threads. The keys
* are inherited upon fork(), and reinitialised upon exec*().
*/
arm64: rename ptrauth key structures to be user-specific We currently enable ptrauth for userspace, but do not use it within the kernel. We're going to enable it for the kernel, and will need to manage a separate set of ptrauth keys for the kernel. We currently keep all 5 keys in struct ptrauth_keys. However, as the kernel will only need to use 1 key, it is a bit wasteful to allocate a whole ptrauth_keys struct for every thread. Therefore, a subsequent patch will define a separate struct, with only 1 key, for the kernel. In preparation for that, rename the existing struct (and associated macros and functions) to reflect that they are specific to userspace. Acked-by: Catalin Marinas <catalin.marinas@arm.com> Reviewed-by: Vincenzo Frascino <Vincenzo.Frascino@arm.com> Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com> [Amit: Re-positioned the patch to reduce the diff] Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2020-03-13 09:04:50 +00:00
struct ptrauth_keys_user {
arm64: add basic pointer authentication support This patch adds basic support for pointer authentication, allowing userspace to make use of APIAKey, APIBKey, APDAKey, APDBKey, and APGAKey. The kernel maintains key values for each process (shared by all threads within), which are initialised to random values at exec() time. The ID_AA64ISAR1_EL1.{APA,API,GPA,GPI} fields are exposed to userspace, to describe that pointer authentication instructions are available and that the kernel is managing the keys. Two new hwcaps are added for the same reason: PACA (for address authentication) and PACG (for generic authentication). Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com> Tested-by: Adam Wallis <awallis@codeaurora.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Ramana Radhakrishnan <ramana.radhakrishnan@arm.com> Cc: Suzuki K Poulose <suzuki.poulose@arm.com> Cc: Will Deacon <will.deacon@arm.com> [will: Fix sizeof() usage and unroll address key initialisation] Signed-off-by: Will Deacon <will.deacon@arm.com>
2018-12-07 18:39:25 +00:00
struct ptrauth_key apia;
struct ptrauth_key apib;
struct ptrauth_key apda;
struct ptrauth_key apdb;
struct ptrauth_key apga;
};
arm64: initialize and switch ptrauth kernel keys Set up keys to use pointer authentication within the kernel. The kernel will be compiled with APIAKey instructions, the other keys are currently unused. Each task is given its own APIAKey, which is initialized during fork. The key is changed during context switch and on kernel entry from EL0. The keys for idle threads need to be set before calling any C functions, because it is not possible to enter and exit a function with different keys. Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Reviewed-by: Vincenzo Frascino <Vincenzo.Frascino@arm.com> Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com> [Amit: Modified secondary cores key structure, comments] Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2020-03-13 09:04:56 +00:00
struct ptrauth_keys_kernel {
struct ptrauth_key apia;
};
arm64: pac: Optimize kernel entry/exit key installation code paths The kernel does not use any keys besides IA so we don't need to install IB/DA/DB/GA on kernel exit if we arrange to install them on task switch instead, which we can expect to happen an order of magnitude less often. Furthermore we can avoid installing the user IA in the case where the user task has IA disabled and just leave the kernel IA installed. This also lets us avoid needing to install IA on kernel entry. On an Apple M1 under a hypervisor, the overhead of kernel entry/exit has been measured to be reduced by 15.6ns in the case where IA is enabled, and 31.9ns in the case where IA is disabled. Signed-off-by: Peter Collingbourne <pcc@google.com> Link: https://linux-review.googlesource.com/id/Ieddf6b580d23c9e0bed45a822dabe72d2ffc9a8e Link: https://lore.kernel.org/r/2d653d055f38f779937f2b92f8ddd5cf9e4af4f4.1616123271.git.pcc@google.com Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2021-03-19 03:10:54 +00:00
#define __ptrauth_key_install_nosync(k, v) \
do { \
struct ptrauth_key __pki_v = (v); \
write_sysreg_s(__pki_v.lo, SYS_ ## k ## KEYLO_EL1); \
write_sysreg_s(__pki_v.hi, SYS_ ## k ## KEYHI_EL1); \
} while (0)
static inline void ptrauth_keys_install_user(struct ptrauth_keys_user *keys)
{
if (system_supports_address_auth()) {
__ptrauth_key_install_nosync(APIB, keys->apib);
__ptrauth_key_install_nosync(APDA, keys->apda);
__ptrauth_key_install_nosync(APDB, keys->apdb);
}
if (system_supports_generic_auth())
__ptrauth_key_install_nosync(APGA, keys->apga);
}
arm64: rename ptrauth key structures to be user-specific We currently enable ptrauth for userspace, but do not use it within the kernel. We're going to enable it for the kernel, and will need to manage a separate set of ptrauth keys for the kernel. We currently keep all 5 keys in struct ptrauth_keys. However, as the kernel will only need to use 1 key, it is a bit wasteful to allocate a whole ptrauth_keys struct for every thread. Therefore, a subsequent patch will define a separate struct, with only 1 key, for the kernel. In preparation for that, rename the existing struct (and associated macros and functions) to reflect that they are specific to userspace. Acked-by: Catalin Marinas <catalin.marinas@arm.com> Reviewed-by: Vincenzo Frascino <Vincenzo.Frascino@arm.com> Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com> [Amit: Re-positioned the patch to reduce the diff] Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2020-03-13 09:04:50 +00:00
static inline void ptrauth_keys_init_user(struct ptrauth_keys_user *keys)
arm64: add basic pointer authentication support This patch adds basic support for pointer authentication, allowing userspace to make use of APIAKey, APIBKey, APDAKey, APDBKey, and APGAKey. The kernel maintains key values for each process (shared by all threads within), which are initialised to random values at exec() time. The ID_AA64ISAR1_EL1.{APA,API,GPA,GPI} fields are exposed to userspace, to describe that pointer authentication instructions are available and that the kernel is managing the keys. Two new hwcaps are added for the same reason: PACA (for address authentication) and PACG (for generic authentication). Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com> Tested-by: Adam Wallis <awallis@codeaurora.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Ramana Radhakrishnan <ramana.radhakrishnan@arm.com> Cc: Suzuki K Poulose <suzuki.poulose@arm.com> Cc: Will Deacon <will.deacon@arm.com> [will: Fix sizeof() usage and unroll address key initialisation] Signed-off-by: Will Deacon <will.deacon@arm.com>
2018-12-07 18:39:25 +00:00
{
if (system_supports_address_auth()) {
get_random_bytes(&keys->apia, sizeof(keys->apia));
get_random_bytes(&keys->apib, sizeof(keys->apib));
get_random_bytes(&keys->apda, sizeof(keys->apda));
get_random_bytes(&keys->apdb, sizeof(keys->apdb));
}
if (system_supports_generic_auth())
get_random_bytes(&keys->apga, sizeof(keys->apga));
arm64: pac: Optimize kernel entry/exit key installation code paths The kernel does not use any keys besides IA so we don't need to install IB/DA/DB/GA on kernel exit if we arrange to install them on task switch instead, which we can expect to happen an order of magnitude less often. Furthermore we can avoid installing the user IA in the case where the user task has IA disabled and just leave the kernel IA installed. This also lets us avoid needing to install IA on kernel entry. On an Apple M1 under a hypervisor, the overhead of kernel entry/exit has been measured to be reduced by 15.6ns in the case where IA is enabled, and 31.9ns in the case where IA is disabled. Signed-off-by: Peter Collingbourne <pcc@google.com> Link: https://linux-review.googlesource.com/id/Ieddf6b580d23c9e0bed45a822dabe72d2ffc9a8e Link: https://lore.kernel.org/r/2d653d055f38f779937f2b92f8ddd5cf9e4af4f4.1616123271.git.pcc@google.com Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2021-03-19 03:10:54 +00:00
ptrauth_keys_install_user(keys);
}
arm64: add basic pointer authentication support This patch adds basic support for pointer authentication, allowing userspace to make use of APIAKey, APIBKey, APDAKey, APDBKey, and APGAKey. The kernel maintains key values for each process (shared by all threads within), which are initialised to random values at exec() time. The ID_AA64ISAR1_EL1.{APA,API,GPA,GPI} fields are exposed to userspace, to describe that pointer authentication instructions are available and that the kernel is managing the keys. Two new hwcaps are added for the same reason: PACA (for address authentication) and PACG (for generic authentication). Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com> Tested-by: Adam Wallis <awallis@codeaurora.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Ramana Radhakrishnan <ramana.radhakrishnan@arm.com> Cc: Suzuki K Poulose <suzuki.poulose@arm.com> Cc: Will Deacon <will.deacon@arm.com> [will: Fix sizeof() usage and unroll address key initialisation] Signed-off-by: Will Deacon <will.deacon@arm.com>
2018-12-07 18:39:25 +00:00
arm64: initialize ptrauth keys for kernel booting task This patch uses the existing boot_init_stack_canary arch function to initialize the ptrauth keys for the booting task in the primary core. The requirement here is that it should be always inline and the caller must never return. As pointer authentication too detects a subset of stack corruption so it makes sense to place this code here. Both pointer authentication and stack canary codes are protected by their respective config option. Suggested-by: Ard Biesheuvel <ardb@kernel.org> Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com> Reviewed-by: Vincenzo Frascino <Vincenzo.Frascino@arm.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2020-03-13 09:04:57 +00:00
static __always_inline void ptrauth_keys_init_kernel(struct ptrauth_keys_kernel *keys)
arm64: initialize and switch ptrauth kernel keys Set up keys to use pointer authentication within the kernel. The kernel will be compiled with APIAKey instructions, the other keys are currently unused. Each task is given its own APIAKey, which is initialized during fork. The key is changed during context switch and on kernel entry from EL0. The keys for idle threads need to be set before calling any C functions, because it is not possible to enter and exit a function with different keys. Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Reviewed-by: Vincenzo Frascino <Vincenzo.Frascino@arm.com> Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com> [Amit: Modified secondary cores key structure, comments] Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2020-03-13 09:04:56 +00:00
{
if (system_supports_address_auth())
get_random_bytes(&keys->apia, sizeof(keys->apia));
}
arm64: initialize ptrauth keys for kernel booting task This patch uses the existing boot_init_stack_canary arch function to initialize the ptrauth keys for the booting task in the primary core. The requirement here is that it should be always inline and the caller must never return. As pointer authentication too detects a subset of stack corruption so it makes sense to place this code here. Both pointer authentication and stack canary codes are protected by their respective config option. Suggested-by: Ard Biesheuvel <ardb@kernel.org> Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com> Reviewed-by: Vincenzo Frascino <Vincenzo.Frascino@arm.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2020-03-13 09:04:57 +00:00
static __always_inline void ptrauth_keys_switch_kernel(struct ptrauth_keys_kernel *keys)
{
arm64: sync kernel APIAKey when installing A direct write to a APxxKey_EL1 register requires a context synchronization event to ensure that indirect reads made by subsequent instructions (e.g. AUTIASP, PACIASP) observe the new value. When we initialize the boot task's APIAKey in boot_init_stack_canary() via ptrauth_keys_switch_kernel() we miss the necessary ISB, and so there is a window where instructions are not guaranteed to use the new APIAKey value. This has been observed to result in boot-time crashes where PACIASP and AUTIASP within a function used a mixture of the old and new key values. Fix this by having ptrauth_keys_switch_kernel() synchronize the new key value with an ISB. At the same time, __ptrauth_key_install() is renamed to __ptrauth_key_install_nosync() so that it is obvious that this performs no synchronization itself. Fixes: 28321582334c261c ("arm64: initialize ptrauth keys for kernel booting task") Signed-off-by: Mark Rutland <mark.rutland@arm.com> Reported-by: Will Deacon <will@kernel.org> Cc: Amit Daniel Kachhap <amit.kachhap@arm.com> Cc: Marc Zyngier <maz@kernel.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Tested-by: Will Deacon <will@kernel.org>
2020-04-21 12:10:14 +00:00
if (!system_supports_address_auth())
return;
__ptrauth_key_install_nosync(APIA, keys->apia);
isb();
arm64: initialize ptrauth keys for kernel booting task This patch uses the existing boot_init_stack_canary arch function to initialize the ptrauth keys for the booting task in the primary core. The requirement here is that it should be always inline and the caller must never return. As pointer authentication too detects a subset of stack corruption so it makes sense to place this code here. Both pointer authentication and stack canary codes are protected by their respective config option. Suggested-by: Ard Biesheuvel <ardb@kernel.org> Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com> Reviewed-by: Vincenzo Frascino <Vincenzo.Frascino@arm.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2020-03-13 09:04:57 +00:00
}
arm64: add prctl control for resetting ptrauth keys Add an arm64-specific prctl to allow a thread to reinitialize its pointer authentication keys to random values. This can be useful when exec() is not used for starting new processes, to ensure that different processes still have different keys. Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2018-12-07 18:39:28 +00:00
extern int ptrauth_prctl_reset_keys(struct task_struct *tsk, unsigned long arg);
arm64: Introduce prctl(PR_PAC_{SET,GET}_ENABLED_KEYS) This change introduces a prctl that allows the user program to control which PAC keys are enabled in a particular task. The main reason why this is useful is to enable a userspace ABI that uses PAC to sign and authenticate function pointers and other pointers exposed outside of the function, while still allowing binaries conforming to the ABI to interoperate with legacy binaries that do not sign or authenticate pointers. The idea is that a dynamic loader or early startup code would issue this prctl very early after establishing that a process may load legacy binaries, but before executing any PAC instructions. This change adds a small amount of overhead to kernel entry and exit due to additional required instruction sequences. On a DragonBoard 845c (Cortex-A75) with the powersave governor, the overhead of similar instruction sequences was measured as 4.9ns when simulating the common case where IA is left enabled, or 43.7ns when simulating the uncommon case where IA is disabled. These numbers can be seen as the worst case scenario, since in more realistic scenarios a better performing governor would be used and a newer chip would be used that would support PAC unlike Cortex-A75 and would be expected to be faster than Cortex-A75. On an Apple M1 under a hypervisor, the overhead of the entry/exit instruction sequences introduced by this patch was measured as 0.3ns in the case where IA is left enabled, and 33.0ns in the case where IA is disabled. Signed-off-by: Peter Collingbourne <pcc@google.com> Reviewed-by: Dave Martin <Dave.Martin@arm.com> Link: https://linux-review.googlesource.com/id/Ibc41a5e6a76b275efbaa126b31119dc197b927a5 Link: https://lore.kernel.org/r/d6609065f8f40397a4124654eb68c9f490b4d477.1616123271.git.pcc@google.com Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2021-03-19 03:10:53 +00:00
extern int ptrauth_set_enabled_keys(struct task_struct *tsk, unsigned long keys,
unsigned long enabled);
extern int ptrauth_get_enabled_keys(struct task_struct *tsk);
arm64: perf: strip PAC when unwinding userspace When the kernel is unwinding userspace callchains, we can't expect that the userspace consumer of these callchains has the data necessary to strip the PAC from the stored LR. This patch has the kernel strip the PAC from user stackframes when the in-kernel unwinder is used. This only affects the LR value, and not the FP. This only affects the in-kernel unwinder. When userspace performs unwinding, it is up to userspace to strip PACs as necessary (which can be determined from DWARF information). Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Ramana Radhakrishnan <ramana.radhakrishnan@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2018-12-07 18:39:27 +00:00
static inline unsigned long ptrauth_strip_insn_pac(unsigned long ptr)
{
arm64: mask PAC bits of __builtin_return_address Functions like vmap() record how much memory has been allocated by their callers, and callers are identified using __builtin_return_address(). Once the kernel is using pointer-auth the return address will be signed. This means it will not match any kernel symbol, and will vary between threads even for the same caller. The output of /proc/vmallocinfo in this case may look like, 0x(____ptrval____)-0x(____ptrval____) 20480 0x86e28000100e7c60 pages=4 vmalloc N0=4 0x(____ptrval____)-0x(____ptrval____) 20480 0x86e28000100e7c60 pages=4 vmalloc N0=4 0x(____ptrval____)-0x(____ptrval____) 20480 0xc5c78000100e7c60 pages=4 vmalloc N0=4 The above three 64bit values should be the same symbol name and not different LR values. Use the pre-processor to add logic to clear the PAC to __builtin_return_address() callers. This patch adds a new file asm/compiler.h and is transitively included via include/compiler_types.h on the compiler command line so it is guaranteed to be loaded and the users of this macro will not find a wrong version. Helper macros ptrauth_kernel_pac_mask/ptrauth_clear_pac are created for this purpose and added in this file. Existing macro ptrauth_user_pac_mask moved from asm/pointer_auth.h. Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com> Reviewed-by: James Morse <james.morse@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2020-03-13 09:04:58 +00:00
return ptrauth_clear_pac(ptr);
arm64: perf: strip PAC when unwinding userspace When the kernel is unwinding userspace callchains, we can't expect that the userspace consumer of these callchains has the data necessary to strip the PAC from the stored LR. This patch has the kernel strip the PAC from user stackframes when the in-kernel unwinder is used. This only affects the LR value, and not the FP. This only affects the in-kernel unwinder. When userspace performs unwinding, it is up to userspace to strip PACs as necessary (which can be determined from DWARF information). Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Ramana Radhakrishnan <ramana.radhakrishnan@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2018-12-07 18:39:27 +00:00
}
arm64: Defer enabling pointer authentication on boot core Defer enabling pointer authentication on boot core until after its required to be enabled by cpufeature framework. This will help in controlling the feature dynamically with a boot parameter. Signed-off-by: Ajay Patil <pajay@qti.qualcomm.com> Signed-off-by: Prasad Sodagudi <psodagud@codeaurora.org> Signed-off-by: Srinivas Ramana <sramana@codeaurora.org> Signed-off-by: Marc Zyngier <maz@kernel.org> Link: https://lore.kernel.org/r/1610152163-16554-2-git-send-email-sramana@codeaurora.org Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: David Brazdil <dbrazdil@google.com> Link: https://lore.kernel.org/r/20210208095732.3267263-22-maz@kernel.org Signed-off-by: Will Deacon <will@kernel.org>
2021-02-08 09:57:30 +00:00
static __always_inline void ptrauth_enable(void)
{
if (!system_supports_address_auth())
return;
sysreg_clear_set(sctlr_el1, 0, (SCTLR_ELx_ENIA | SCTLR_ELx_ENIB |
SCTLR_ELx_ENDA | SCTLR_ELx_ENDB));
isb();
}
arm64: pac: Optimize kernel entry/exit key installation code paths The kernel does not use any keys besides IA so we don't need to install IB/DA/DB/GA on kernel exit if we arrange to install them on task switch instead, which we can expect to happen an order of magnitude less often. Furthermore we can avoid installing the user IA in the case where the user task has IA disabled and just leave the kernel IA installed. This also lets us avoid needing to install IA on kernel entry. On an Apple M1 under a hypervisor, the overhead of kernel entry/exit has been measured to be reduced by 15.6ns in the case where IA is enabled, and 31.9ns in the case where IA is disabled. Signed-off-by: Peter Collingbourne <pcc@google.com> Link: https://linux-review.googlesource.com/id/Ieddf6b580d23c9e0bed45a822dabe72d2ffc9a8e Link: https://lore.kernel.org/r/2d653d055f38f779937f2b92f8ddd5cf9e4af4f4.1616123271.git.pcc@google.com Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2021-03-19 03:10:54 +00:00
#define ptrauth_suspend_exit() \
ptrauth_keys_install_user(&current->thread.keys_user)
arm64: Introduce prctl(PR_PAC_{SET,GET}_ENABLED_KEYS) This change introduces a prctl that allows the user program to control which PAC keys are enabled in a particular task. The main reason why this is useful is to enable a userspace ABI that uses PAC to sign and authenticate function pointers and other pointers exposed outside of the function, while still allowing binaries conforming to the ABI to interoperate with legacy binaries that do not sign or authenticate pointers. The idea is that a dynamic loader or early startup code would issue this prctl very early after establishing that a process may load legacy binaries, but before executing any PAC instructions. This change adds a small amount of overhead to kernel entry and exit due to additional required instruction sequences. On a DragonBoard 845c (Cortex-A75) with the powersave governor, the overhead of similar instruction sequences was measured as 4.9ns when simulating the common case where IA is left enabled, or 43.7ns when simulating the uncommon case where IA is disabled. These numbers can be seen as the worst case scenario, since in more realistic scenarios a better performing governor would be used and a newer chip would be used that would support PAC unlike Cortex-A75 and would be expected to be faster than Cortex-A75. On an Apple M1 under a hypervisor, the overhead of the entry/exit instruction sequences introduced by this patch was measured as 0.3ns in the case where IA is left enabled, and 33.0ns in the case where IA is disabled. Signed-off-by: Peter Collingbourne <pcc@google.com> Reviewed-by: Dave Martin <Dave.Martin@arm.com> Link: https://linux-review.googlesource.com/id/Ibc41a5e6a76b275efbaa126b31119dc197b927a5 Link: https://lore.kernel.org/r/d6609065f8f40397a4124654eb68c9f490b4d477.1616123271.git.pcc@google.com Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2021-03-19 03:10:53 +00:00
#define ptrauth_thread_init_user() \
do { \
ptrauth_keys_init_user(&current->thread.keys_user); \
\
/* enable all keys */ \
if (system_supports_address_auth()) \
set_task_sctlr_el1(current->thread.sctlr_user | \
SCTLR_ELx_ENIA | SCTLR_ELx_ENIB | \
SCTLR_ELx_ENDA | SCTLR_ELx_ENDB); \
} while (0)
arm64: pac: Optimize kernel entry/exit key installation code paths The kernel does not use any keys besides IA so we don't need to install IB/DA/DB/GA on kernel exit if we arrange to install them on task switch instead, which we can expect to happen an order of magnitude less often. Furthermore we can avoid installing the user IA in the case where the user task has IA disabled and just leave the kernel IA installed. This also lets us avoid needing to install IA on kernel entry. On an Apple M1 under a hypervisor, the overhead of kernel entry/exit has been measured to be reduced by 15.6ns in the case where IA is enabled, and 31.9ns in the case where IA is disabled. Signed-off-by: Peter Collingbourne <pcc@google.com> Link: https://linux-review.googlesource.com/id/Ieddf6b580d23c9e0bed45a822dabe72d2ffc9a8e Link: https://lore.kernel.org/r/2d653d055f38f779937f2b92f8ddd5cf9e4af4f4.1616123271.git.pcc@google.com Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2021-03-19 03:10:54 +00:00
#define ptrauth_thread_switch_user(tsk) \
ptrauth_keys_install_user(&(tsk)->thread.keys_user)
arm64: initialize and switch ptrauth kernel keys Set up keys to use pointer authentication within the kernel. The kernel will be compiled with APIAKey instructions, the other keys are currently unused. Each task is given its own APIAKey, which is initialized during fork. The key is changed during context switch and on kernel entry from EL0. The keys for idle threads need to be set before calling any C functions, because it is not possible to enter and exit a function with different keys. Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Reviewed-by: Vincenzo Frascino <Vincenzo.Frascino@arm.com> Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com> [Amit: Modified secondary cores key structure, comments] Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2020-03-13 09:04:56 +00:00
#define ptrauth_thread_init_kernel(tsk) \
ptrauth_keys_init_kernel(&(tsk)->thread.keys_kernel)
arm64: initialize ptrauth keys for kernel booting task This patch uses the existing boot_init_stack_canary arch function to initialize the ptrauth keys for the booting task in the primary core. The requirement here is that it should be always inline and the caller must never return. As pointer authentication too detects a subset of stack corruption so it makes sense to place this code here. Both pointer authentication and stack canary codes are protected by their respective config option. Suggested-by: Ard Biesheuvel <ardb@kernel.org> Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com> Reviewed-by: Vincenzo Frascino <Vincenzo.Frascino@arm.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2020-03-13 09:04:57 +00:00
#define ptrauth_thread_switch_kernel(tsk) \
ptrauth_keys_switch_kernel(&(tsk)->thread.keys_kernel)
arm64: add basic pointer authentication support This patch adds basic support for pointer authentication, allowing userspace to make use of APIAKey, APIBKey, APDAKey, APDBKey, and APGAKey. The kernel maintains key values for each process (shared by all threads within), which are initialised to random values at exec() time. The ID_AA64ISAR1_EL1.{APA,API,GPA,GPI} fields are exposed to userspace, to describe that pointer authentication instructions are available and that the kernel is managing the keys. Two new hwcaps are added for the same reason: PACA (for address authentication) and PACG (for generic authentication). Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com> Tested-by: Adam Wallis <awallis@codeaurora.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Ramana Radhakrishnan <ramana.radhakrishnan@arm.com> Cc: Suzuki K Poulose <suzuki.poulose@arm.com> Cc: Will Deacon <will.deacon@arm.com> [will: Fix sizeof() usage and unroll address key initialisation] Signed-off-by: Will Deacon <will.deacon@arm.com>
2018-12-07 18:39:25 +00:00
#else /* CONFIG_ARM64_PTR_AUTH */
arm64: Defer enabling pointer authentication on boot core Defer enabling pointer authentication on boot core until after its required to be enabled by cpufeature framework. This will help in controlling the feature dynamically with a boot parameter. Signed-off-by: Ajay Patil <pajay@qti.qualcomm.com> Signed-off-by: Prasad Sodagudi <psodagud@codeaurora.org> Signed-off-by: Srinivas Ramana <sramana@codeaurora.org> Signed-off-by: Marc Zyngier <maz@kernel.org> Link: https://lore.kernel.org/r/1610152163-16554-2-git-send-email-sramana@codeaurora.org Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: David Brazdil <dbrazdil@google.com> Link: https://lore.kernel.org/r/20210208095732.3267263-22-maz@kernel.org Signed-off-by: Will Deacon <will@kernel.org>
2021-02-08 09:57:30 +00:00
#define ptrauth_enable()
arm64: add prctl control for resetting ptrauth keys Add an arm64-specific prctl to allow a thread to reinitialize its pointer authentication keys to random values. This can be useful when exec() is not used for starting new processes, to ensure that different processes still have different keys. Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2018-12-07 18:39:28 +00:00
#define ptrauth_prctl_reset_keys(tsk, arg) (-EINVAL)
arm64: Introduce prctl(PR_PAC_{SET,GET}_ENABLED_KEYS) This change introduces a prctl that allows the user program to control which PAC keys are enabled in a particular task. The main reason why this is useful is to enable a userspace ABI that uses PAC to sign and authenticate function pointers and other pointers exposed outside of the function, while still allowing binaries conforming to the ABI to interoperate with legacy binaries that do not sign or authenticate pointers. The idea is that a dynamic loader or early startup code would issue this prctl very early after establishing that a process may load legacy binaries, but before executing any PAC instructions. This change adds a small amount of overhead to kernel entry and exit due to additional required instruction sequences. On a DragonBoard 845c (Cortex-A75) with the powersave governor, the overhead of similar instruction sequences was measured as 4.9ns when simulating the common case where IA is left enabled, or 43.7ns when simulating the uncommon case where IA is disabled. These numbers can be seen as the worst case scenario, since in more realistic scenarios a better performing governor would be used and a newer chip would be used that would support PAC unlike Cortex-A75 and would be expected to be faster than Cortex-A75. On an Apple M1 under a hypervisor, the overhead of the entry/exit instruction sequences introduced by this patch was measured as 0.3ns in the case where IA is left enabled, and 33.0ns in the case where IA is disabled. Signed-off-by: Peter Collingbourne <pcc@google.com> Reviewed-by: Dave Martin <Dave.Martin@arm.com> Link: https://linux-review.googlesource.com/id/Ibc41a5e6a76b275efbaa126b31119dc197b927a5 Link: https://lore.kernel.org/r/d6609065f8f40397a4124654eb68c9f490b4d477.1616123271.git.pcc@google.com Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2021-03-19 03:10:53 +00:00
#define ptrauth_set_enabled_keys(tsk, keys, enabled) (-EINVAL)
#define ptrauth_get_enabled_keys(tsk) (-EINVAL)
arm64: perf: strip PAC when unwinding userspace When the kernel is unwinding userspace callchains, we can't expect that the userspace consumer of these callchains has the data necessary to strip the PAC from the stored LR. This patch has the kernel strip the PAC from user stackframes when the in-kernel unwinder is used. This only affects the LR value, and not the FP. This only affects the in-kernel unwinder. When userspace performs unwinding, it is up to userspace to strip PACs as necessary (which can be determined from DWARF information). Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Ramana Radhakrishnan <ramana.radhakrishnan@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2018-12-07 18:39:27 +00:00
#define ptrauth_strip_insn_pac(lr) (lr)
arm64: pac: Optimize kernel entry/exit key installation code paths The kernel does not use any keys besides IA so we don't need to install IB/DA/DB/GA on kernel exit if we arrange to install them on task switch instead, which we can expect to happen an order of magnitude less often. Furthermore we can avoid installing the user IA in the case where the user task has IA disabled and just leave the kernel IA installed. This also lets us avoid needing to install IA on kernel entry. On an Apple M1 under a hypervisor, the overhead of kernel entry/exit has been measured to be reduced by 15.6ns in the case where IA is enabled, and 31.9ns in the case where IA is disabled. Signed-off-by: Peter Collingbourne <pcc@google.com> Link: https://linux-review.googlesource.com/id/Ieddf6b580d23c9e0bed45a822dabe72d2ffc9a8e Link: https://lore.kernel.org/r/2d653d055f38f779937f2b92f8ddd5cf9e4af4f4.1616123271.git.pcc@google.com Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2021-03-19 03:10:54 +00:00
#define ptrauth_suspend_exit()
arm64: Introduce prctl(PR_PAC_{SET,GET}_ENABLED_KEYS) This change introduces a prctl that allows the user program to control which PAC keys are enabled in a particular task. The main reason why this is useful is to enable a userspace ABI that uses PAC to sign and authenticate function pointers and other pointers exposed outside of the function, while still allowing binaries conforming to the ABI to interoperate with legacy binaries that do not sign or authenticate pointers. The idea is that a dynamic loader or early startup code would issue this prctl very early after establishing that a process may load legacy binaries, but before executing any PAC instructions. This change adds a small amount of overhead to kernel entry and exit due to additional required instruction sequences. On a DragonBoard 845c (Cortex-A75) with the powersave governor, the overhead of similar instruction sequences was measured as 4.9ns when simulating the common case where IA is left enabled, or 43.7ns when simulating the uncommon case where IA is disabled. These numbers can be seen as the worst case scenario, since in more realistic scenarios a better performing governor would be used and a newer chip would be used that would support PAC unlike Cortex-A75 and would be expected to be faster than Cortex-A75. On an Apple M1 under a hypervisor, the overhead of the entry/exit instruction sequences introduced by this patch was measured as 0.3ns in the case where IA is left enabled, and 33.0ns in the case where IA is disabled. Signed-off-by: Peter Collingbourne <pcc@google.com> Reviewed-by: Dave Martin <Dave.Martin@arm.com> Link: https://linux-review.googlesource.com/id/Ibc41a5e6a76b275efbaa126b31119dc197b927a5 Link: https://lore.kernel.org/r/d6609065f8f40397a4124654eb68c9f490b4d477.1616123271.git.pcc@google.com Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2021-03-19 03:10:53 +00:00
#define ptrauth_thread_init_user()
arm64: initialize and switch ptrauth kernel keys Set up keys to use pointer authentication within the kernel. The kernel will be compiled with APIAKey instructions, the other keys are currently unused. Each task is given its own APIAKey, which is initialized during fork. The key is changed during context switch and on kernel entry from EL0. The keys for idle threads need to be set before calling any C functions, because it is not possible to enter and exit a function with different keys. Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Reviewed-by: Vincenzo Frascino <Vincenzo.Frascino@arm.com> Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com> [Amit: Modified secondary cores key structure, comments] Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2020-03-13 09:04:56 +00:00
#define ptrauth_thread_init_kernel(tsk)
arm64: pac: Optimize kernel entry/exit key installation code paths The kernel does not use any keys besides IA so we don't need to install IB/DA/DB/GA on kernel exit if we arrange to install them on task switch instead, which we can expect to happen an order of magnitude less often. Furthermore we can avoid installing the user IA in the case where the user task has IA disabled and just leave the kernel IA installed. This also lets us avoid needing to install IA on kernel entry. On an Apple M1 under a hypervisor, the overhead of kernel entry/exit has been measured to be reduced by 15.6ns in the case where IA is enabled, and 31.9ns in the case where IA is disabled. Signed-off-by: Peter Collingbourne <pcc@google.com> Link: https://linux-review.googlesource.com/id/Ieddf6b580d23c9e0bed45a822dabe72d2ffc9a8e Link: https://lore.kernel.org/r/2d653d055f38f779937f2b92f8ddd5cf9e4af4f4.1616123271.git.pcc@google.com Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2021-03-19 03:10:54 +00:00
#define ptrauth_thread_switch_user(tsk)
arm64: initialize ptrauth keys for kernel booting task This patch uses the existing boot_init_stack_canary arch function to initialize the ptrauth keys for the booting task in the primary core. The requirement here is that it should be always inline and the caller must never return. As pointer authentication too detects a subset of stack corruption so it makes sense to place this code here. Both pointer authentication and stack canary codes are protected by their respective config option. Suggested-by: Ard Biesheuvel <ardb@kernel.org> Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com> Reviewed-by: Vincenzo Frascino <Vincenzo.Frascino@arm.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2020-03-13 09:04:57 +00:00
#define ptrauth_thread_switch_kernel(tsk)
arm64: add basic pointer authentication support This patch adds basic support for pointer authentication, allowing userspace to make use of APIAKey, APIBKey, APDAKey, APDBKey, and APGAKey. The kernel maintains key values for each process (shared by all threads within), which are initialised to random values at exec() time. The ID_AA64ISAR1_EL1.{APA,API,GPA,GPI} fields are exposed to userspace, to describe that pointer authentication instructions are available and that the kernel is managing the keys. Two new hwcaps are added for the same reason: PACA (for address authentication) and PACG (for generic authentication). Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com> Tested-by: Adam Wallis <awallis@codeaurora.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Ramana Radhakrishnan <ramana.radhakrishnan@arm.com> Cc: Suzuki K Poulose <suzuki.poulose@arm.com> Cc: Will Deacon <will.deacon@arm.com> [will: Fix sizeof() usage and unroll address key initialisation] Signed-off-by: Will Deacon <will.deacon@arm.com>
2018-12-07 18:39:25 +00:00
#endif /* CONFIG_ARM64_PTR_AUTH */
arm64: Introduce prctl(PR_PAC_{SET,GET}_ENABLED_KEYS) This change introduces a prctl that allows the user program to control which PAC keys are enabled in a particular task. The main reason why this is useful is to enable a userspace ABI that uses PAC to sign and authenticate function pointers and other pointers exposed outside of the function, while still allowing binaries conforming to the ABI to interoperate with legacy binaries that do not sign or authenticate pointers. The idea is that a dynamic loader or early startup code would issue this prctl very early after establishing that a process may load legacy binaries, but before executing any PAC instructions. This change adds a small amount of overhead to kernel entry and exit due to additional required instruction sequences. On a DragonBoard 845c (Cortex-A75) with the powersave governor, the overhead of similar instruction sequences was measured as 4.9ns when simulating the common case where IA is left enabled, or 43.7ns when simulating the uncommon case where IA is disabled. These numbers can be seen as the worst case scenario, since in more realistic scenarios a better performing governor would be used and a newer chip would be used that would support PAC unlike Cortex-A75 and would be expected to be faster than Cortex-A75. On an Apple M1 under a hypervisor, the overhead of the entry/exit instruction sequences introduced by this patch was measured as 0.3ns in the case where IA is left enabled, and 33.0ns in the case where IA is disabled. Signed-off-by: Peter Collingbourne <pcc@google.com> Reviewed-by: Dave Martin <Dave.Martin@arm.com> Link: https://linux-review.googlesource.com/id/Ibc41a5e6a76b275efbaa126b31119dc197b927a5 Link: https://lore.kernel.org/r/d6609065f8f40397a4124654eb68c9f490b4d477.1616123271.git.pcc@google.com Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2021-03-19 03:10:53 +00:00
#define PR_PAC_ENABLED_KEYS_MASK \
(PR_PAC_APIAKEY | PR_PAC_APIBKEY | PR_PAC_APDAKEY | PR_PAC_APDBKEY)
arm64: add basic pointer authentication support This patch adds basic support for pointer authentication, allowing userspace to make use of APIAKey, APIBKey, APDAKey, APDBKey, and APGAKey. The kernel maintains key values for each process (shared by all threads within), which are initialised to random values at exec() time. The ID_AA64ISAR1_EL1.{APA,API,GPA,GPI} fields are exposed to userspace, to describe that pointer authentication instructions are available and that the kernel is managing the keys. Two new hwcaps are added for the same reason: PACA (for address authentication) and PACG (for generic authentication). Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com> Tested-by: Adam Wallis <awallis@codeaurora.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Ramana Radhakrishnan <ramana.radhakrishnan@arm.com> Cc: Suzuki K Poulose <suzuki.poulose@arm.com> Cc: Will Deacon <will.deacon@arm.com> [will: Fix sizeof() usage and unroll address key initialisation] Signed-off-by: Will Deacon <will.deacon@arm.com>
2018-12-07 18:39:25 +00:00
#endif /* __ASM_POINTER_AUTH_H */
Reference in New Issue Copy Permalink