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Re: [Qemu-devel] [PATCH v3 14/23] linux-user/aarch64: Use qemu_guest_get
From: |
Philippe Mathieu-Daudé |
Subject: |
Re: [Qemu-devel] [PATCH v3 14/23] linux-user/aarch64: Use qemu_guest_getrandom for PAUTH keys |
Date: |
Thu, 11 Apr 2019 11:50:47 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 |
On 3/15/19 4:26 AM, Richard Henderson wrote:
> Use a better interface for random numbers than rand() * 3.
>
> Cc: Laurent Vivier <address@hidden>
> Signed-off-by: Richard Henderson <address@hidden>
> ---
> linux-user/aarch64/target_syscall.h | 2 --
> linux-user/aarch64/cpu_loop.c | 29 ++++++---------------------
> linux-user/syscall.c | 31 ++++++++++++++++++++++++-----
> 3 files changed, 32 insertions(+), 30 deletions(-)
>
> diff --git a/linux-user/aarch64/target_syscall.h
> b/linux-user/aarch64/target_syscall.h
> index b595e5da82..995e475c73 100644
> --- a/linux-user/aarch64/target_syscall.h
> +++ b/linux-user/aarch64/target_syscall.h
> @@ -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 */
> diff --git a/linux-user/aarch64/cpu_loop.c b/linux-user/aarch64/cpu_loop.c
> index d75fd9d3e2..cedad39ca0 100644
> --- a/linux-user/aarch64/cpu_loop.c
> +++ b/linux-user/aarch64/cpu_loop.c
> @@ -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;
> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> index 8f7125cd67..c2168db1c8 100644
> --- a/linux-user/syscall.c
> +++ b/linux-user/syscall.c
> @@ -111,6 +111,7 @@
>
> #include "qemu.h"
> #include "qemu/guest-random.h"
> +#include "qapi/error.h"
> #include "fd-trans.h"
>
> #ifndef CLONE_IO
> @@ -9731,25 +9732,45 @@ 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;
Reviewed-by: Philippe Mathieu-Daudé <address@hidden>
> }
> return 0;
> }
>
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Philippe Mathieu-Daudé <=