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

Jason A. Donenfeld
2024-08-27T14:28:38Z

On Tue, Aug 27, 2024 at 11:14:27AM -0300, Adhemerval Zanella Netto wrote:
>
>
> On 27/08/24 11:10, Christophe Leroy wrote:
> >
> >
> > 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
>
> The issue is Ubuntu linker is configure to use --as-needed by default, this
> patch fixes the issue:
>
> diff --git a/tools/testing/selftests/vDSO/Makefile b/tools/testing/selftests/vDSO/Makefile
> index 10ffdda3f2fa..151baf650e4c 100644
> --- a/tools/testing/selftests/vDSO/Makefile
> +++ b/tools/testing/selftests/vDSO/Makefile
> @@ -45,4 +45,4 @@ $(OUTPUT)/vdso_test_chacha: CFLAGS += -idirafter $(top_srcdir)/tools/include \
> -idirafter $(top_srcdir)/arch/$(ARCH)/include \
> -idirafter $(top_srcdir)/include \
> -D__ASSEMBLY__ -DBULID_VDSO -DCONFIG_FUNCTION_ALIGNMENT=0 \
> - -Wa,--noexecstack $(SODIUM)
> + -Wa,--noexecstack -Wl,-no-as-needed $(SODIUM)

Oh, it's an as-needed thing. In that case, does this fix it for you?

diff --git a/tools/testing/selftests/vDSO/Makefile b/tools/testing/selftests/vDSO/Makefile
index 10ffdda3f2fa..834aa862ba2c 100644
--- a/tools/testing/selftests/vDSO/Makefile
+++ b/tools/testing/selftests/vDSO/Makefile
@@ -1,7 +1,8 @@
# SPDX-License-Identifier: GPL-2.0
uname_M := $(shell uname -m 2>/dev/null || echo not)
ARCH ?= $(shell echo $(uname_M) | sed -e s/i.86/x86/ -e s/x86_64/x86/)
-SODIUM := $(shell pkg-config --libs libsodium 2>/dev/null)
+SODIUM_LIBS := $(shell pkg-config --libs libsodium 2>/dev/null)
+SODIUM_CFLAGS := $(shell pkg-config --cflags libsodium 2>/dev/null)

TEST_GEN_PROGS := vdso_test_gettimeofday
TEST_GEN_PROGS += vdso_test_getcpu
@@ -13,7 +14,7 @@ endif
TEST_GEN_PROGS += vdso_test_correctness
ifeq ($(uname_M),x86_64)
TEST_GEN_PROGS += vdso_test_getrandom
-ifneq ($(SODIUM),)
+ifneq ($(SODIUM_LIBS),)
TEST_GEN_PROGS += vdso_test_chacha
endif
endif
@@ -41,8 +42,9 @@ $(OUTPUT)/vdso_test_getrandom: CFLAGS += -isystem $(top_srcdir)/tools/include \
-isystem $(top_srcdir)/include/uapi

$(OUTPUT)/vdso_test_chacha: $(top_srcdir)/tools/arch/$(ARCH)/vdso/vgetrandom-chacha.S
+$(OUTPUT)/vdso_test_chacha: LDLIBS += $(SODIUM_LIBS)
$(OUTPUT)/vdso_test_chacha: CFLAGS += -idirafter $(top_srcdir)/tools/include \
-idirafter $(top_srcdir)/arch/$(ARCH)/include \
-idirafter $(top_srcdir)/include \
-D__ASSEMBLY__ -DBULID_VDSO -DCONFIG_FUNCTION_ALIGNMENT=0 \
- -Wa,--noexecstack $(SODIUM)
+ -Wa,--noexecstack $(SODIUM_CFLAGS)