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arm64: initialize and switch ptrauth kernel keys

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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>
This commit is contained in:
Kristina Martsenko
2020-03-13 14:34:56 +05:30
committed by Catalin Marinas
parent 6982934e19
commit 33e4523498
9 changed files with 62 additions and 0 deletions
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13
arch/arm64/include/asm/pointer_auth.h
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@@ -30,6 +30,10 @@ struct ptrauth_keys_user {
struct ptrauth_key apga;
};
struct ptrauth_keys_kernel {
struct ptrauth_key apia;
};
static inline void ptrauth_keys_init_user(struct ptrauth_keys_user *keys)
{
if (system_supports_address_auth()) {
@@ -50,6 +54,12 @@ do { \
write_sysreg_s(__pki_v.hi, SYS_ ## k ## KEYHI_EL1); \
} while (0)
static inline void ptrauth_keys_init_kernel(struct ptrauth_keys_kernel *keys)
{
if (system_supports_address_auth())
get_random_bytes(&keys->apia, sizeof(keys->apia));
}
extern int ptrauth_prctl_reset_keys(struct task_struct *tsk, unsigned long arg);
/*
@@ -66,11 +76,14 @@ static inline unsigned long ptrauth_strip_insn_pac(unsigned long ptr)
#define ptrauth_thread_init_user(tsk) \
ptrauth_keys_init_user(&(tsk)->thread.keys_user)
#define ptrauth_thread_init_kernel(tsk) \
ptrauth_keys_init_kernel(&(tsk)->thread.keys_kernel)
#else /* CONFIG_ARM64_PTR_AUTH */
#define ptrauth_prctl_reset_keys(tsk, arg) (-EINVAL)
#define ptrauth_strip_insn_pac(lr) (lr)
#define ptrauth_thread_init_user(tsk)
#define ptrauth_thread_init_kernel(tsk)
#endif /* CONFIG_ARM64_PTR_AUTH */
#endif /* __ASM_POINTER_AUTH_H */