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

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Message-ID: <b0e44997-06e0-4b03-b94a-1c54da5516ac@linaro.org>
Date: Tue, 27 Aug 2024 11:01:59 -0300
From: Adhemerval Zanella Netto <adhemerval.zanella@...aro.org>
To: Christophe Leroy <christophe.leroy@...roup.eu>,
 "Jason A. Donenfeld" <Jason@...c4.com>
Cc: Theodore Ts'o <tytso@....edu>, linux-kernel@...r.kernel.org,
 linux-crypto@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
 linux-arch@...r.kernel.org, Catalin Marinas <catalin.marinas@....com>,
 Will Deacon <will@...nel.org>, Thomas Gleixner <tglx@...utronix.de>,
 Eric Biggers <ebiggers@...nel.org>
Subject: Re: [PATCH] aarch64: vdso: Wire up getrandom() vDSO implementation



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@...aro.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.