Re: [PATCH] aarch64: vdso: Wire up getrandom() vDSO implementation

Christophe Leroy
2024-08-27T14:00:44Z

Le 27/08/2024 à 15:39, Adhemerval Zanella Netto a écrit :
> [Vous ne recevez pas souvent de courriers de adhemerval.zanella@linaro.org. Découvrez pourquoi ceci est important à https://aka.ms/LearnAboutSenderIdentification ]
>
> On 27/08/24 10:34, Jason A. Donenfeld wrote:
>> On Tue, Aug 27, 2024 at 10:17:18AM -0300, Adhemerval Zanella Netto wrote:
>>>
>>>
>>> On 26/08/24 17:27, Jason A. Donenfeld wrote:
>>>> Hi Adhemerval,
>>>>
>>>> Thanks for posting this! Exciting to have it here.
>>>>
>>>> Just some small nits for now:
>>>>
>>>> On Mon, Aug 26, 2024 at 06:10:40PM +0000, Adhemerval Zanella wrote:
>>>>> +static __always_inline ssize_t getrandom_syscall(void *buffer, size_t len, unsigned int flags)
>>>>> +{
>>>>> + register long int x8 asm ("x8") = __NR_getrandom;
>>>>> + register long int x0 asm ("x0") = (long int) buffer;
>>>>> + register long int x1 asm ("x1") = (long int) len;
>>>>> + register long int x2 asm ("x2") = (long int) flags;
>>>>
>>>> Usually it's written just as `long` or `unsigned long`, and likewise
>>>> with the cast. Also, no space after the cast.
>>>
>>> Ack.
>>>
>>>>
>>>>> +#define __VDSO_RND_DATA_OFFSET 480
>>>>
>>>> This is the size of the data currently there?
>>>
>>> Yes, I used the same strategy x86 did.
>>>
>>>>
>>>>> #include <asm/page.h>
>>>>> #include <asm/vdso.h>
>>>>> #include <asm-generic/vmlinux.lds.h>
>>>>> +#include <vdso/datapage.h>
>>>>> +#include <asm/vdso/vsyscall.h>
>>>>
>>>> Possible to keep the asm/ together?
>>>
>>> Ack.
>>>
>>>>
>>>>> + * ARM64 ChaCha20 implementation meant for vDSO. Produces a given positive
>>>>> + * number of blocks of output with nonnce 0, taking an input key and 8-bytes
>>>>
>>>> nonnce -> nonce
>>>
>>> Ack.
>>>
>>>>
>>>>> -ARCH ?= $(shell echo $(uname_M) | sed -e s/i.86/x86/ -e s/x86_64/x86/)
>>>>> +ARCH ?= $(shell echo $(uname_M) | sed -e s/i.86/x86/ -e s/x86_64/x86/ -e s/aarch64.*/arm64/)
>>>>> SODIUM := $(shell pkg-config --libs libsodium 2>/dev/null)
>>>>>
>>>>> TEST_GEN_PROGS := vdso_test_gettimeofday
>>>>> @@ -11,7 +11,7 @@ ifeq ($(ARCH),$(filter $(ARCH),x86 x86_64))
>>>>> TEST_GEN_PROGS += vdso_standalone_test_x86
>>>>> endif
>>>>> TEST_GEN_PROGS += vdso_test_correctness
>>>>> -ifeq ($(uname_M),x86_64)
>>>>> +ifeq ($(uname_M), $(filter x86_64 aarch64, $(uname_M)))
>>>>> TEST_GEN_PROGS += vdso_test_getrandom
>>>>> ifneq ($(SODIUM),)
>>>>> TEST_GEN_PROGS += vdso_test_chacha
>>>>
>>>> You'll need to add the symlink to get the chacha selftest running:
>>>>
>>>> $ ln -s ../../../arch/arm64/kernel/vdso tools/arch/arm64/vdso
>>>> $ git add tools/arch/arm64/vdso
>>>>
>>>> Also, can you confirm that the chacha selftest runs and works?
>>>
>>> Yes, last time I has to built it manually since the Makefile machinery seem
>>> to be broken even on x86_64. In a Ubuntu vm I have:
>>>
>>> tools/testing/selftests/vDSO$ make
>>> CC vdso_test_gettimeofday
>>> CC vdso_test_getcpu
>>> CC vdso_test_abi
>>> CC vdso_test_clock_getres
>>> CC vdso_standalone_test_x86
>>> CC vdso_test_correctness
>>> CC vdso_test_getrandom
>>> CC vdso_test_chacha
>>> In file included from /home/azanella/Projects/linux/linux-git/include/linux/limits.h:7,
>>> from /usr/include/x86_64-linux-gnu/bits/local_lim.h:38,
>>> from /usr/include/x86_64-linux-gnu/bits/posix1_lim.h:161,
>>> from /usr/include/limits.h:195,
>>> from /usr/lib/gcc/x86_64-linux-gnu/13/include/limits.h:205,
>>> from /usr/lib/gcc/x86_64-linux-gnu/13/include/syslimits.h:7,
>>> from /usr/lib/gcc/x86_64-linux-gnu/13/include/limits.h:34,
>>> from /usr/include/sodium/export.h:7,
>>> from /usr/include/sodium/crypto_stream_chacha20.h:14,
>>> from vdso_test_chacha.c:6:
>>> /usr/include/x86_64-linux-gnu/bits/xopen_lim.h:99:6: error: missing binary operator before token "("
>>> 99 | # if INT_MAX == 32767
>>> | ^~~~~~~
>>> /usr/include/x86_64-linux-gnu/bits/xopen_lim.h:102:7: error: missing binary operator before token "("
>>> 102 | # if INT_MAX == 2147483647
>>> | ^~~~~~~
>>> /usr/include/x86_64-linux-gnu/bits/xopen_lim.h:126:6: error: missing binary operator before token "("
>>> 126 | # if LONG_MAX == 2147483647
>>> | ^~~~~~~~
>>> make: *** [../lib.mk:222: /home/azanella/Projects/linux/linux-git/tools/testing/selftests/vDSO/vdso_test_chacha] Error 1
>>
>> You get that even with the latest random.git? I thought Christophe's
>> patch fixed that, but maybe not and I should just remove the dependency
>> on the sodium header instead.
>
> On x86_64 I tested with Linux master. With random.git it is a different issue:
>
> linux-git/tools/testing/selftests/vDSO$ make
> CC vdso_test_gettimeofday
> CC vdso_test_getcpu
> CC vdso_test_abi
> CC vdso_test_clock_getres
> CC vdso_standalone_test_x86
> CC vdso_test_correctness
> CC vdso_test_getrandom
> CC vdso_test_chacha
> /usr/bin/ld: /tmp/ccKpjnSM.o: in function `main':
> vdso_test_chacha.c:(.text+0x276): undefined reference to `crypto_stream_chacha20'
> collect2: error: ld returned 1 exit status
>
> If I move -lsodium to the end of the compiler command it works.
>
>

Try a "make clean" maybe ?

I have Fedora 38 and no build problem with latest random tree:

$ make V=1
gcc -std=gnu99 -D_GNU_SOURCE= vdso_test_gettimeofday.c parse_vdso.c
-o
/home/chleroy/linux-powerpc/tools/testing/selftests/vDSO/vdso_test_gettimeofday
gcc -std=gnu99 -D_GNU_SOURCE= vdso_test_getcpu.c parse_vdso.c -o
/home/chleroy/linux-powerpc/tools/testing/selftests/vDSO/vdso_test_getcpu
gcc -std=gnu99 -D_GNU_SOURCE= vdso_test_abi.c parse_vdso.c -o
/home/chleroy/linux-powerpc/tools/testing/selftests/vDSO/vdso_test_abi
gcc -std=gnu99 -D_GNU_SOURCE= vdso_test_clock_getres.c -o
/home/chleroy/linux-powerpc/tools/testing/selftests/vDSO/vdso_test_clock_getres
gcc -std=gnu99 -D_GNU_SOURCE= -nostdlib -fno-asynchronous-unwind-tables
-fno-stack-protector vdso_standalone_test_x86.c parse_vdso.c -o
/home/chleroy/linux-powerpc/tools/testing/selftests/vDSO/vdso_standalone_test_x86
gcc -std=gnu99 -D_GNU_SOURCE= -ldl vdso_test_correctness.c -o
/home/chleroy/linux-powerpc/tools/testing/selftests/vDSO/vdso_test_correctness
gcc -std=gnu99 -D_GNU_SOURCE= -isystem
/home/chleroy/linux-powerpc/tools/testing/selftests/../../../tools/include
-isystem
/home/chleroy/linux-powerpc/tools/testing/selftests/../../../include/uapi
vdso_test_getrandom.c parse_vdso.c -o
/home/chleroy/linux-powerpc/tools/testing/selftests/vDSO/vdso_test_getrandom
gcc -std=gnu99 -D_GNU_SOURCE= -idirafter
/home/chleroy/linux-powerpc/tools/testing/selftests/../../../tools/include
-idirafter
/home/chleroy/linux-powerpc/tools/testing/selftests/../../../arch/x86/include
-idirafter
/home/chleroy/linux-powerpc/tools/testing/selftests/../../../include
-D__ASSEMBLY__ -DBULID_VDSO -DCONFIG_FUNCTION_ALIGNMENT=0
-Wa,--noexecstack -lsodium vdso_test_chacha.c
/home/chleroy/linux-powerpc/tools/testing/selftests/../../../tools/arch/x86/vdso/vgetrandom-chacha.S
-o
/home/chleroy/linux-powerpc/tools/testing/selftests/vDSO/vdso_test_chacha
$