glibc/sysdeps/x86_64/Makefile
Jason A. Donenfeld eaad4f9e8f arc4random: simplify design for better safety
Rather than buffering 16 MiB of entropy in userspace (by way of
chacha20), simply call getrandom() every time.

This approach is doubtlessly slower, for now, but trying to prematurely
optimize arc4random appears to be leading toward all sorts of nasty
properties and gotchas. Instead, this patch takes a much more
conservative approach. The interface is added as a basic loop wrapper
around getrandom(), and then later, the kernel and libc together can
work together on optimizing that.

This prevents numerous issues in which userspace is unaware of when it
really must throw away its buffer, since we avoid buffering all
together. Future improvements may include userspace learning more from
the kernel about when to do that, which might make these sorts of
chacha20-based optimizations more possible. The current heuristic of 16
MiB is meaningless garbage that doesn't correspond to anything the
kernel might know about. So for now, let's just do something
conservative that we know is correct and won't lead to cryptographic
issues for users of this function.

This patch might be considered along the lines of, "optimization is the
root of all evil," in that the much more complex implementation it
replaces moves too fast without considering security implications,
whereas the incremental approach done here is a much safer way of going
about things. Once this lands, we can take our time in optimizing this
properly using new interplay between the kernel and userspace.

getrandom(0) is used, since that's the one that ensures the bytes
returned are cryptographically secure. But on systems without it, we
fallback to using /dev/urandom. This is unfortunate because it means
opening a file descriptor, but there's not much of a choice. Secondly,
as part of the fallback, in order to get more or less the same
properties of getrandom(0), we poll on /dev/random, and if the poll
succeeds at least once, then we assume the RNG is initialized. This is a
rough approximation, as the ancient "non-blocking pool" initialized
after the "blocking pool", not before, and it may not port back to all
ancient kernels, though it does to all kernels supported by glibc
(≥3.2), so generally it's the best approximation we can do.

The motivation for including arc4random, in the first place, is to have
source-level compatibility with existing code. That means this patch
doesn't attempt to litigate the interface itself. It does, however,
choose a conservative approach for implementing it.

Cc: Adhemerval Zanella Netto <adhemerval.zanella@linaro.org>
Cc: Florian Weimer <fweimer@redhat.com>
Cc: Cristian Rodríguez <crrodriguez@opensuse.org>
Cc: Paul Eggert <eggert@cs.ucla.edu>
Cc: Mark Harris <mark.hsj@gmail.com>
Cc: Eric Biggers <ebiggers@kernel.org>
Cc: linux-crypto@vger.kernel.org
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
2022-07-27 08:58:27 -03:00

226 lines
7 KiB
Makefile

# The i387 `long double' is a distinct type we support.
long-double-fcts = yes
ifeq ($(subdir),csu)
gen-as-const-headers += link-defines.sym
endif
ifeq ($(subdir),gmon)
sysdep_routines += _mcount
# We cannot compile _mcount.S with -pg because that would create
# recursive calls when ENTRY is used. Just copy the normal static
# object.
sysdep_noprof += _mcount
endif
ifeq ($(subdir),string)
sysdep_routines += \
strcasecmp_l-nonascii \
strcspn-generic \
strncase_l-nonascii \
strpbrk-generic \
strspn-generic \
varshift \
# sysdep_routines
gen-as-const-headers += locale-defines.sym
tests += \
tst-rsi-strlen
endif
ifeq ($(subdir),elf)
# There is no good reason to use MMX in x86-64 ld.so with GCC.
CFLAGS-.os += $(if $(filter $(@F),$(patsubst %,%.os,$(all-rtld-routines))),\
-mno-mmx)
sysdep-dl-routines += tlsdesc dl-tlsdesc tls_get_addr
tests += ifuncmain8
modules-names += ifuncmod8
$(objpfx)ifuncmain8: $(objpfx)ifuncmod8.so
tests += tst-quad1 tst-quad2
modules-names += tst-quadmod1 tst-quadmod2
$(objpfx)tst-quad1: $(objpfx)tst-quadmod1.so
$(objpfx)tst-quad2: $(objpfx)tst-quadmod2.so
quad-pie-test += tst-quad1pie tst-quad2pie
tests += $(quad-pie-test)
tests-pie += $(quad-pie-test)
test-extras += tst-quadmod1pie tst-quadmod2pie
extra-test-objs += tst-quadmod1pie.o tst-quadmod2pie.o
$(objpfx)tst-quad1pie: $(objpfx)tst-quadmod1pie.o
$(objpfx)tst-quad2pie: $(objpfx)tst-quadmod2pie.o
CFLAGS-tst-quad1pie.c = $(PIE-ccflag)
CFLAGS-tst-quad2pie.c = $(PIE-ccflag)
tests += tst-x86_64-1
modules-names += x86_64/tst-x86_64mod-1
extra-test-objs += tst-x86_64mod-1.o
LDFLAGS-tst-x86_64mod-1.so = -Wl,-soname,tst-x86_64mod-1.so
ifneq (no,$(have-tunables))
# Test the state size for XSAVE when XSAVEC is disabled.
tst-x86_64-1-ENV = GLIBC_TUNABLES=glibc.cpu.hwcaps=-XSAVEC
endif
$(objpfx)tst-x86_64-1: $(objpfx)x86_64/tst-x86_64mod-1.so
ifneq (no,$(have-tunables))
tests += tst-platform-1
modules-names += tst-platformmod-1 x86_64/tst-platformmod-2
extra-test-objs += tst-platformmod-2.o
CFLAGS-tst-platform-1.c = -mno-avx
CFLAGS-tst-platformmod-1.c = -mno-avx
CFLAGS-tst-platformmod-2.c = -mno-avx
LDFLAGS-tst-platformmod-2.so = -Wl,-soname,tst-platformmod-2.so
$(objpfx)tst-platform-1: $(objpfx)tst-platformmod-1.so
$(objpfx)tst-platform-1.out: $(objpfx)x86_64/tst-platformmod-2.so
# Turn off AVX512F and AVX2 so that GLRO(dl_platform) is
# always set to x86_64.
tst-platform-1-ENV = LD_PRELOAD=$(objpfx)\$$PLATFORM/tst-platformmod-2.so \
GLIBC_TUNABLES=glibc.cpu.hwcaps=-AVX512F,-AVX2
endif
tests += tst-audit3 tst-audit4 tst-audit5 tst-audit6 tst-audit7 \
tst-audit10 tst-sse tst-avx tst-avx512
test-extras += tst-audit4-aux tst-audit10-aux \
tst-avx-aux tst-avx512-aux
extra-test-objs += tst-audit4-aux.o tst-audit10-aux.o \
tst-avx-aux.o tst-avx512-aux.o
ifeq ($(have-insert),yes)
tests += tst-split-dynreloc
LDFLAGS-tst-split-dynreloc = -Wl,-T,$(..)sysdeps/x86_64/tst-split-dynreloc.lds
tst-split-dynreloc-ENV = LD_BIND_NOW=1
endif
modules-names += tst-auditmod3a tst-auditmod3b \
tst-auditmod4a tst-auditmod4b \
tst-auditmod5a tst-auditmod5b \
tst-auditmod6a tst-auditmod6b tst-auditmod6c \
tst-auditmod7a tst-auditmod7b \
tst-auditmod10a tst-auditmod10b \
tst-ssemod tst-avxmod tst-avx512mod
$(objpfx)tst-audit3: $(objpfx)tst-auditmod3a.so
$(objpfx)tst-audit3.out: $(objpfx)tst-auditmod3b.so
tst-audit3-ENV = LD_AUDIT=$(objpfx)tst-auditmod3b.so
$(objpfx)tst-audit4: $(objpfx)tst-audit4-aux.o $(objpfx)tst-auditmod4a.so
$(objpfx)tst-audit4.out: $(objpfx)tst-auditmod4b.so
tst-audit4-ENV = LD_AUDIT=$(objpfx)tst-auditmod4b.so
$(objpfx)tst-audit5: $(objpfx)tst-auditmod5a.so
$(objpfx)tst-audit5.out: $(objpfx)tst-auditmod5b.so
tst-audit5-ENV = LD_AUDIT=$(objpfx)tst-auditmod5b.so
$(objpfx)tst-audit6: $(objpfx)tst-auditmod6a.so
$(objpfx)tst-audit6.out: $(objpfx)tst-auditmod6b.so \
$(objpfx)tst-auditmod6c.so
tst-audit6-ENV = LD_AUDIT=$(objpfx)tst-auditmod6b.so:$(objpfx)tst-auditmod6c.so
$(objpfx)tst-audit7: $(objpfx)tst-auditmod7a.so
$(objpfx)tst-audit7.out: $(objpfx)tst-auditmod7b.so
tst-audit7-ENV = LD_AUDIT=$(objpfx)tst-auditmod7b.so
$(objpfx)tst-audit10: $(objpfx)tst-audit10-aux.o $(objpfx)tst-auditmod10a.so
$(objpfx)tst-audit10.out: $(objpfx)tst-auditmod10b.so
tst-audit10-ENV = LD_AUDIT=$(objpfx)tst-auditmod10b.so
$(objpfx)tst-sse: $(objpfx)tst-ssemod.so
$(objpfx)tst-avx: $(objpfx)tst-avx-aux.o $(objpfx)tst-avxmod.so
$(objpfx)tst-avx512: $(objpfx)tst-avx512-aux.o $(objpfx)tst-avx512mod.so
AVX-CFLAGS=-mavx -mno-vzeroupper
CFLAGS-tst-audit4-aux.c += $(AVX-CFLAGS)
CFLAGS-tst-auditmod4a.c += $(AVX-CFLAGS)
CFLAGS-tst-auditmod4b.c += $(AVX-CFLAGS)
CFLAGS-tst-auditmod6b.c += $(AVX-CFLAGS)
CFLAGS-tst-auditmod6c.c += $(AVX-CFLAGS)
CFLAGS-tst-auditmod7b.c += $(AVX-CFLAGS)
CFLAGS-tst-avx-aux.c += $(AVX-CFLAGS)
CFLAGS-tst-avxmod.c += $(AVX-CFLAGS)
AVX512-CFLAGS = -mavx512f
CFLAGS-tst-audit10-aux.c += $(AVX512-CFLAGS)
CFLAGS-tst-auditmod10a.c += $(AVX512-CFLAGS)
CFLAGS-tst-auditmod10b.c += $(AVX512-CFLAGS)
CFLAGS-tst-avx512-aux.c += $(AVX512-CFLAGS)
CFLAGS-tst-avx512mod.c += $(AVX512-CFLAGS)
$(objpfx)tst-glibc-hwcaps: $(objpfx)libmarkermod2-1.so \
$(objpfx)libmarkermod3-1.so $(objpfx)libmarkermod4-1.so
$(objpfx)tst-glibc-hwcaps.out: \
$(objpfx)libmarkermod2.so \
$(objpfx)glibc-hwcaps/x86-64-v2/libmarkermod2.so \
$(objpfx)libmarkermod3.so \
$(objpfx)glibc-hwcaps/x86-64-v2/libmarkermod3.so \
$(objpfx)glibc-hwcaps/x86-64-v3/libmarkermod3.so \
$(objpfx)libmarkermod4.so \
$(objpfx)glibc-hwcaps/x86-64-v2/libmarkermod4.so \
$(objpfx)glibc-hwcaps/x86-64-v3/libmarkermod4.so \
$(objpfx)glibc-hwcaps/x86-64-v4/libmarkermod4.so \
$(objpfx)glibc-hwcaps/x86-64-v2/libmarkermod2.so: $(objpfx)libmarkermod2-2.so
$(make-target-directory)
cp $< $@
$(objpfx)glibc-hwcaps/x86-64-v2/libmarkermod3.so: $(objpfx)libmarkermod3-2.so
$(make-target-directory)
cp $< $@
$(objpfx)glibc-hwcaps/x86-64-v3/libmarkermod3.so: $(objpfx)libmarkermod3-3.so
$(make-target-directory)
cp $< $@
$(objpfx)glibc-hwcaps/x86-64-v2/libmarkermod4.so: $(objpfx)libmarkermod4-2.so
$(make-target-directory)
cp $< $@
$(objpfx)glibc-hwcaps/x86-64-v3/libmarkermod4.so: $(objpfx)libmarkermod4-3.so
$(make-target-directory)
cp $< $@
$(objpfx)glibc-hwcaps/x86-64-v4/libmarkermod4.so: $(objpfx)libmarkermod4-4.so
$(make-target-directory)
cp $< $@
ifeq (no,$(build-hardcoded-path-in-tests))
# This is an ld.so.cache test, and RPATH/RUNPATH in the executable
# interferes with its test objectives.
tests-container += tst-glibc-hwcaps-cache
endif
tests-internal += tst-x86-64-tls-1
endif # $(subdir) == elf
ifeq ($(subdir),csu)
gen-as-const-headers += tlsdesc.sym rtld-offsets.sym
endif
ifeq ($(subdir),wcsmbs)
sysdep_routines += \
wcscpy-generic \
wcsncmp-generic \
wcsnlen-generic \
# sysdep_routines
tests += \
tst-rsi-wcslen
endif
$(objpfx)x86_64/tst-x86_64mod-1.os: $(objpfx)tst-x86_64mod-1.os
$(make-target-directory)
rm -f $@
ln $< $@
do-tests-clean common-mostlyclean: tst-x86_64-1-clean
.PHONY: tst-x86_64-1-clean
tst-x86_64-1-clean:
-rm -rf $(objpfx)x86_64
$(objpfx)x86_64/tst-platformmod-2.os: $(objpfx)tst-platformmod-2.os
$(make-target-directory)
rm -f $@
ln $< $@