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linux-user/aarch64: Use qemu_guest_getrandom for PAUTH keys

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Use a better interface for random numbers than rand() * 3.

Reviewed-by: Laurent Vivier <lvivier@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Richard Henderson 2019-03-12 19:22:20 -07:00
parent c6a2377fb2
commit 51977e25f7
3 changed files with 32 additions and 30 deletions
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29
linux-user/aarch64/cpu_loop.c
View File

@ -20,6 +20,7 @@
#include "qemu/osdep.h"
#include "qemu.h"
#include "cpu_loop-common.h"
#include "qemu/guest-random.h"
#define get_user_code_u32(x, gaddr, env) \
({ abi_long __r = get_user_u32((x), (gaddr)); \
@ -147,24 +148,6 @@ void cpu_loop(CPUARMState *env)
}
}
static uint64_t arm_rand64(void)
{
int shift = 64 - clz64(RAND_MAX);
int i, n = 64 / shift + (64 % shift != 0);
uint64_t ret = 0;
for (i = 0; i < n; i++) {
ret = (ret << shift) | rand();
}
return ret;
}
void arm_init_pauth_key(ARMPACKey *key)
{
key->lo = arm_rand64();
key->hi = arm_rand64();
}
void target_cpu_copy_regs(CPUArchState *env, struct target_pt_regs *regs)
{
ARMCPU *cpu = arm_env_get_cpu(env);
@ -192,11 +175,11 @@ void target_cpu_copy_regs(CPUArchState *env, struct target_pt_regs *regs)
#endif
if (cpu_isar_feature(aa64_pauth, cpu)) {
arm_init_pauth_key(&env->apia_key);
arm_init_pauth_key(&env->apib_key);
arm_init_pauth_key(&env->apda_key);
arm_init_pauth_key(&env->apdb_key);
arm_init_pauth_key(&env->apga_key);
qemu_guest_getrandom_nofail(&env->apia_key, sizeof(ARMPACKey));
qemu_guest_getrandom_nofail(&env->apib_key, sizeof(ARMPACKey));
qemu_guest_getrandom_nofail(&env->apda_key, sizeof(ARMPACKey));
qemu_guest_getrandom_nofail(&env->apdb_key, sizeof(ARMPACKey));
qemu_guest_getrandom_nofail(&env->apga_key, sizeof(ARMPACKey));
}
ts->stack_base = info->start_stack;

2
linux-user/aarch64/target_syscall.h
View File

@ -29,6 +29,4 @@ struct target_pt_regs {
# define TARGET_PR_PAC_APDBKEY (1 << 3)
# define TARGET_PR_PAC_APGAKEY (1 << 4)
void arm_init_pauth_key(ARMPACKey *key);
#endif /* AARCH64_TARGET_SYSCALL_H */

31
linux-user/syscall.c
View File

@ -108,6 +108,7 @@
#include "qemu.h"
#include "qemu/guest-random.h"
#include "qapi/error.h"
#include "fd-trans.h"
#ifndef CLONE_IO
@ -9765,25 +9766,45 @@ static abi_long do_syscall1(void *cpu_env, int num, abi_long arg1,
int all = (TARGET_PR_PAC_APIAKEY | TARGET_PR_PAC_APIBKEY |
TARGET_PR_PAC_APDAKEY | TARGET_PR_PAC_APDBKEY |
TARGET_PR_PAC_APGAKEY);
int ret = 0;
Error *err = NULL;
if (arg2 == 0) {
arg2 = all;
} else if (arg2 & ~all) {
return -TARGET_EINVAL;
}
if (arg2 & TARGET_PR_PAC_APIAKEY) {
arm_init_pauth_key(&env->apia_key);
ret |= qemu_guest_getrandom(&env->apia_key,
sizeof(ARMPACKey), &err);
}
if (arg2 & TARGET_PR_PAC_APIBKEY) {
arm_init_pauth_key(&env->apib_key);
ret |= qemu_guest_getrandom(&env->apib_key,
sizeof(ARMPACKey), &err);
}
if (arg2 & TARGET_PR_PAC_APDAKEY) {
arm_init_pauth_key(&env->apda_key);
ret |= qemu_guest_getrandom(&env->apda_key,
sizeof(ARMPACKey), &err);
}
if (arg2 & TARGET_PR_PAC_APDBKEY) {
arm_init_pauth_key(&env->apdb_key);
ret |= qemu_guest_getrandom(&env->apdb_key,
sizeof(ARMPACKey), &err);
}
if (arg2 & TARGET_PR_PAC_APGAKEY) {
arm_init_pauth_key(&env->apga_key);
ret |= qemu_guest_getrandom(&env->apga_key,
sizeof(ARMPACKey), &err);
}
if (ret != 0) {
/*
* Some unknown failure in the crypto. The best
* we can do is log it and fail the syscall.
* The real syscall cannot fail this way.
*/
qemu_log_mask(LOG_UNIMP,
"PR_PAC_RESET_KEYS: Crypto failure: %s",
error_get_pretty(err));
error_free(err);
return -TARGET_EIO;
}
return 0;
}