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

Christophe Leroy
2024-08-27T14:10:57Z

Le 27/08/2024 à 16:01, 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 11:00, Christophe Leroy wrote:
>>
>>
>> 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
>> $
>
> It is a clean tree (git clean -dfx), and I take there is no need to build a kernel
> prior hand.

I meeant 'make clean'

Right, I have not built any x86 kernel at the moment.

Just :
$ pwd
/home/chleroy/linux-powerpc/tools/testing/selftests/vDSO

$ make clean

then

$ make V=1

Christophe