| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <CAA3XUr0byMWN-QfYKke+6bmu-_ukYpTdpRJN37Gk6JtxXtoA7w@mail.gmail.com>
Date: Wed, 20 Aug 2014 22:36:59 -0700
From: Victor Kamensky <victor.kamensky@...aro.org>
To: Daniel Thompson <daniel.thompson@...aro.org>
Cc: Russell King <linux@....linux.org.uk>,
Nicolas Pitre <nicolas.pitre@...aro.org>,
"linaro-kernel@...ts.linaro.org" <linaro-kernel@...ts.linaro.org>,
Patch Tracking <patches@...aro.org>,
open list <linux-kernel@...r.kernel.org>,
Rob Clark <robdclark@...il.com>,
John Stultz <john.stultz@...aro.org>,
Arnd Bergmann <arnd.bergmann@...aro.org>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH 3.16.0-rc3-rmk v5] ARM: add get_user() support for 8 byte types
On 10 July 2014 12:47, Daniel Thompson <daniel.thompson@...aro.org> wrote:
> Recent contributions, including to DRM and binder, introduce 64-bit
> values in their interfaces. A common motivation for this is to allow
> the same ABI for 32- and 64-bit userspaces (and therefore also a shared
> ABI for 32/64 hybrid userspaces). Anyhow, the developers would like to
> avoid gotchas like having to use copy_from_user().
>
> This feature is already implemented on x86-32 and the majority of other
> 32-bit architectures. The current list of get_user_8 hold out
> architectures are: arm, avr32, blackfin, m32r, metag, microblaze,
> mn10300, sh.
>
> Credit:
>
> My name sits rather uneasily at the top of this patch. The v1 and
> v2 versions of the patch were written by Rob Clark and to produce v4
> I mostly copied code from Russell King and H. Peter Anvin. However I
> have mangled the patch sufficiently that *blame* is rightfully mine
> even if credit should more widely shared.
>
> Changelog:
>
> v5: updated to use the ret macro (requested by Russell King)
> v4: remove an inlined add on big endian systems (spotted by Russell King),
> used __ARMEB__ rather than BIG_ENDIAN (to match rest of file),
> cleared r3 on EFAULT during __get_user_8.
> v3: fix a couple of checkpatch issues
> v2: pass correct size to check_uaccess, and better handling of narrowing
> double word read with __get_user_xb() (Russell King's suggestion)
> v1: original
>
> Signed-off-by: Rob Clark <robdclark@...il.com>
> Signed-off-by: Daniel Thompson <daniel.thompson@...aro.org>
> Cc: Russell King - ARM Linux <linux@....linux.org.uk>
> ---
> arch/arm/include/asm/uaccess.h | 20 +++++++++++++++++++-
> arch/arm/lib/getuser.S | 37 ++++++++++++++++++++++++++++++++++++-
> 2 files changed, 55 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm/include/asm/uaccess.h b/arch/arm/include/asm/uaccess.h
> index 75d9579..7057cf8 100644
> --- a/arch/arm/include/asm/uaccess.h
> +++ b/arch/arm/include/asm/uaccess.h
> @@ -107,6 +107,8 @@ static inline void set_fs(mm_segment_t fs)
> extern int __get_user_1(void *);
> extern int __get_user_2(void *);
> extern int __get_user_4(void *);
> +extern int __get_user_lo8(void *);
> +extern int __get_user_8(void *);
>
> #define __GUP_CLOBBER_1 "lr", "cc"
> #ifdef CONFIG_CPU_USE_DOMAINS
> @@ -115,6 +117,8 @@ extern int __get_user_4(void *);
> #define __GUP_CLOBBER_2 "lr", "cc"
> #endif
> #define __GUP_CLOBBER_4 "lr", "cc"
> +#define __GUP_CLOBBER_lo8 "lr", "cc"
> +#define __GUP_CLOBBER_8 "lr", "cc"
>
> #define __get_user_x(__r2,__p,__e,__l,__s) \
> __asm__ __volatile__ ( \
> @@ -125,11 +129,19 @@ extern int __get_user_4(void *);
> : "0" (__p), "r" (__l) \
> : __GUP_CLOBBER_##__s)
>
> +/* narrowing a double-word get into a single 32bit word register: */
> +#ifdef __ARMEB__
> +#define __get_user_xb(__r2, __p, __e, __l, __s) \
> + __get_user_x(__r2, __p, __e, __l, lo8)
> +#else
> +#define __get_user_xb __get_user_x
> +#endif
> +
> #define __get_user_check(x,p) \
> ({ \
> unsigned long __limit = current_thread_info()->addr_limit - 1; \
> register const typeof(*(p)) __user *__p asm("r0") = (p);\
> - register unsigned long __r2 asm("r2"); \
> + register typeof(x) __r2 asm("r2"); \
Above breaks V7 BE case when get_user called for target
variable of 64 bit in size but '*__p' is 32 bit or smaller. Please
look at [1] for more details.
Thanks,
Victor
[1] http://lists.infradead.org/pipermail/linux-arm-kernel/2014-August/280806.html
> register unsigned long __l asm("r1") = __limit; \
> register int __e asm("r0"); \
> switch (sizeof(*(__p))) { \
> @@ -142,6 +154,12 @@ extern int __get_user_4(void *);
> case 4: \
> __get_user_x(__r2, __p, __e, __l, 4); \
> break; \
> + case 8: \
> + if (sizeof((x)) < 8) \
> + __get_user_xb(__r2, __p, __e, __l, 4); \
> + else \
> + __get_user_x(__r2, __p, __e, __l, 8); \
> + break; \
> default: __e = __get_user_bad(); break; \
> } \
> x = (typeof(*(p))) __r2; \
> diff --git a/arch/arm/lib/getuser.S b/arch/arm/lib/getuser.S
> index 0f958e3..9386000 100644
> --- a/arch/arm/lib/getuser.S
> +++ b/arch/arm/lib/getuser.S
> @@ -18,7 +18,7 @@
> * Inputs: r0 contains the address
> * r1 contains the address limit, which must be preserved
> * Outputs: r0 is the error code
> - * r2 contains the zero-extended value
> + * r2, r3 contains the zero-extended value
> * lr corrupted
> *
> * No other registers must be altered. (see <asm/uaccess.h>
> @@ -66,15 +66,50 @@ ENTRY(__get_user_4)
> ret lr
> ENDPROC(__get_user_4)
>
> +ENTRY(__get_user_8)
> + check_uaccess r0, 8, r1, r2, __get_user_bad
> +#ifdef CONFIG_THUMB2_KERNEL
> +5: TUSER(ldr) r2, [r0]
> +6: TUSER(ldr) r3, [r0, #4]
> +#else
> +5: TUSER(ldr) r2, [r0], #4
> +6: TUSER(ldr) r3, [r0]
> +#endif
> + mov r0, #0
> + ret lr
> +ENDPROC(__get_user_8)
> +
> +#ifdef __ARMEB__
> +ENTRY(__get_user_lo8)
> + check_uaccess r0, 8, r1, r2, __get_user_bad
> +#ifdef CONFIG_CPU_USE_DOMAINS
> + add r0, r0, #4
> +7: ldrt r2, [r0]
> +#else
> +7: ldr r2, [r0, #4]
> +#endif
> + mov r0, #0
> + ret lr
> +ENDPROC(__get_user_lo8)
> +#endif
> +
> +__get_user_bad8:
> + mov r3, #0
> __get_user_bad:
> mov r2, #0
> mov r0, #-EFAULT
> ret lr
> ENDPROC(__get_user_bad)
> +ENDPROC(__get_user_bad8)
>
> .pushsection __ex_table, "a"
> .long 1b, __get_user_bad
> .long 2b, __get_user_bad
> .long 3b, __get_user_bad
> .long 4b, __get_user_bad
> + .long 5b, __get_user_bad8
> + .long 6b, __get_user_bad8
> +#ifdef __ARMEB__
> + .long 7b, __get_user_bad
> +#endif
> .popsection
> --
> 1.9.3
>
>
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists