| Message ID | 20230521-nolibc-automatic-stack-protector-v1-7-dad6c80c51c1@weissschuh.net (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | tools/nolibc: autodetect stackprotector availability from compiler | expand |
On 2023-05-21 11:36:35+0200, Thomas Weißschuh wrote: > Now that nolibc enable stackprotector support automatically when the > compiler enables it we only have to get the -fstack-protector flags > correct. > > The cc-options are structured so that -fstack-protector-all is only > enabled if -mstack-protector=guard works, as that is the only mode > supported by nolibc. > > Signed-off-by: Thomas Weißschuh <linux@weissschuh.net> > --- > tools/testing/selftests/nolibc/Makefile | 13 ++----------- > 1 file changed, 2 insertions(+), 11 deletions(-) > > diff --git a/tools/testing/selftests/nolibc/Makefile b/tools/testing/selftests/nolibc/Makefile > index bd41102ea299..445c352b1b33 100644 > --- a/tools/testing/selftests/nolibc/Makefile > +++ b/tools/testing/selftests/nolibc/Makefile > @@ -76,20 +76,11 @@ else > Q=@ > endif > > -CFLAGS_STACKPROTECTOR = -DNOLIBC_STACKPROTECTOR \ > - $(call cc-option,-mstack-protector-guard=global) \ > - $(call cc-option,-fstack-protector-all) > -CFLAGS_STKP_i386 = $(CFLAGS_STACKPROTECTOR) > -CFLAGS_STKP_x86_64 = $(CFLAGS_STACKPROTECTOR) > -CFLAGS_STKP_x86 = $(CFLAGS_STACKPROTECTOR) > -CFLAGS_STKP_arm64 = $(CFLAGS_STACKPROTECTOR) > -CFLAGS_STKP_arm = $(CFLAGS_STACKPROTECTOR) > -CFLAGS_STKP_mips = $(CFLAGS_STACKPROTECTOR) > -CFLAGS_STKP_riscv = $(CFLAGS_STACKPROTECTOR) > -CFLAGS_STKP_loongarch = $(CFLAGS_STACKPROTECTOR) > +CFLAGS_STACKPROTECTOR = $(call cc-option,-mstack-protector-guard=global -fstack-protector-all) > CFLAGS_s390 = -m64 > CFLAGS ?= -Os -fno-ident -fno-asynchronous-unwind-tables -std=c89 \ > $(call cc-option,-fno-stack-protector) \ > + $(call cc-option,-mstack-protector-guard=global $(call cc-option,-fstack-protector-all)) \ > $(CFLAGS_STKP_$(ARCH)) $(CFLAGS_$(ARCH)) > LDFLAGS := -s I noticed, of course after having sent the series, that the cleanup here was not done properly. CFLAGS_STACKPROTECTOR and CFLAGS_STKP should be deleted completely. This will be fixed in v2, or feel free to fix it up when applying the series.
Hi Thomas, Zhangjin, I merged and pushed this series on top of the previous series, it's in branch 20230523-nolibc-rv32+stkp3. However, Thomas, I found an issue with this last patch that I partially reverted in a last patch I pushed as well so that we can discuss it: On Sun, May 21, 2023 at 11:36:35AM +0200, Thomas Weißschuh wrote: > > -CFLAGS_STACKPROTECTOR = -DNOLIBC_STACKPROTECTOR \ > - $(call cc-option,-mstack-protector-guard=global) \ > - $(call cc-option,-fstack-protector-all) > -CFLAGS_STKP_i386 = $(CFLAGS_STACKPROTECTOR) > -CFLAGS_STKP_x86_64 = $(CFLAGS_STACKPROTECTOR) > -CFLAGS_STKP_x86 = $(CFLAGS_STACKPROTECTOR) > -CFLAGS_STKP_arm64 = $(CFLAGS_STACKPROTECTOR) > -CFLAGS_STKP_arm = $(CFLAGS_STACKPROTECTOR) > -CFLAGS_STKP_mips = $(CFLAGS_STACKPROTECTOR) > -CFLAGS_STKP_riscv = $(CFLAGS_STACKPROTECTOR) > -CFLAGS_STKP_loongarch = $(CFLAGS_STACKPROTECTOR) > +CFLAGS_STACKPROTECTOR = $(call cc-option,-mstack-protector-guard=global -fstack-protector-all) > CFLAGS_s390 = -m64 > CFLAGS ?= -Os -fno-ident -fno-asynchronous-unwind-tables -std=c89 \ > $(call cc-option,-fno-stack-protector) \ > + $(call cc-option,-mstack-protector-guard=global $(call cc-option,-fstack-protector-all)) \ > $(CFLAGS_STKP_$(ARCH)) $(CFLAGS_$(ARCH)) By doing so, we reintroduce the forced stack-protector mechanism that cannot be disabled anymore. The ability to disable it was the main point of the options above. In fact checking __SSP__* was a solution to save the user from having to set -DNOLIBC_STACKPROTECTOR to match their compiler's flags, but here in the nolibc-test we still want to be able to forcefully disable stkp for a run (at least to unbreak gcc-9, and possibly to confirm that non-stkp builds still continue to work when your local toolchain has it by default). So I reverted that part and only dropped -DNOLIBC_STACKPROTECTOR. This way I could run the test on all archs with gcc-9 by forcing CFLAGS_STACKPROTECTOR= and verified it was still possible to disable it for a specific arch only by setting CFLAGS_STKP_$ARCH. If you're fine with this we can squash this one into your cleanup patch. Zhangjin I think this branch should work well enough for you to serve as a base for your upcoming series. We'll clean it up later once we all agree on the stat() replacement for syscall() and on the various remaining points including your time32 alternatives. Thanks to you both, Willy PS: we're still carrying a long CC list of individuals who are likely not that much interested in our discussion, I propose that we trim it on next exchanges and only keep us 3 and the lists, in order to remove some of their e-mail pollution.
On 2023-05-23 22:12:38+0200, Willy Tarreau wrote: > Hi Thomas, Zhangjin, > > I merged and pushed this series on top of the previous series, it's in > branch 20230523-nolibc-rv32+stkp3. > > However, Thomas, I found an issue with this last patch that I partially > reverted in a last patch I pushed as well so that we can discuss it: > > On Sun, May 21, 2023 at 11:36:35AM +0200, Thomas Weißschuh wrote: > > > > -CFLAGS_STACKPROTECTOR = -DNOLIBC_STACKPROTECTOR \ > > - $(call cc-option,-mstack-protector-guard=global) \ > > - $(call cc-option,-fstack-protector-all) > > -CFLAGS_STKP_i386 = $(CFLAGS_STACKPROTECTOR) > > -CFLAGS_STKP_x86_64 = $(CFLAGS_STACKPROTECTOR) > > -CFLAGS_STKP_x86 = $(CFLAGS_STACKPROTECTOR) > > -CFLAGS_STKP_arm64 = $(CFLAGS_STACKPROTECTOR) > > -CFLAGS_STKP_arm = $(CFLAGS_STACKPROTECTOR) > > -CFLAGS_STKP_mips = $(CFLAGS_STACKPROTECTOR) > > -CFLAGS_STKP_riscv = $(CFLAGS_STACKPROTECTOR) > > -CFLAGS_STKP_loongarch = $(CFLAGS_STACKPROTECTOR) > > +CFLAGS_STACKPROTECTOR = $(call cc-option,-mstack-protector-guard=global -fstack-protector-all) > > CFLAGS_s390 = -m64 > > CFLAGS ?= -Os -fno-ident -fno-asynchronous-unwind-tables -std=c89 \ > > $(call cc-option,-fno-stack-protector) \ > > + $(call cc-option,-mstack-protector-guard=global $(call cc-option,-fstack-protector-all)) \ > > $(CFLAGS_STKP_$(ARCH)) $(CFLAGS_$(ARCH)) > > By doing so, we reintroduce the forced stack-protector mechanism > that cannot be disabled anymore. The ability to disable it was the > main point of the options above. In fact checking __SSP__* was a > solution to save the user from having to set -DNOLIBC_STACKPROTECTOR > to match their compiler's flags, but here in the nolibc-test we still > want to be able to forcefully disable stkp for a run (at least to > unbreak gcc-9, and possibly to confirm that non-stkp builds still > continue to work when your local toolchain has it by default). Wouldn't this work? make CFLAGS_x86=-fno-stack-protector nolibc-test Or we do CFLAGS_STACKPROTECTOR ?= $(call cc-option,-mstack-protector-guard=global $(call cc-option,-fstack-protector-all)) CFLAGS ?= ... $(CFLAGS_STACKPROTECTOR) And then it is always: make CFLAGS_STACKPROTECTOR= nolibc-test An alternative would also be to use a GCC 9 compatible mechanism: #if __has_attribute(no_stack_protector) #define __no_stack_protector __attribute__((no_stack_protector)) #else #define __no_stack_protector __attribute__((__optimize__("-fno-stack-protector"))) #endif Or we combine CFLAGS_STACKPROTECTOR and __no_stack_protector. > So I reverted that part and only dropped -DNOLIBC_STACKPROTECTOR. > This way I could run the test on all archs with gcc-9 by forcing > CFLAGS_STACKPROTECTOR= and verified it was still possible to > disable it for a specific arch only by setting CFLAGS_STKP_$ARCH. > > If you're fine with this we can squash this one into your cleanup > patch. To be honest I was happy to get rid of all these architecture specific variables. > Zhangjin I think this branch should work well enough for you to > serve as a base for your upcoming series. We'll clean it up later > once we all agree on the stat() replacement for syscall() and on > the various remaining points including your time32 alternatives. > > Thanks to you both, > Willy > > PS: we're still carrying a long CC list of individuals who are likely > not that much interested in our discussion, I propose that we trim > it on next exchanges and only keep us 3 and the lists, in order to > remove some of their e-mail pollution. I trimmed the list a bit. Thomas
On Tue, May 23, 2023 at 10:38:48PM +0200, Thomas Weißschuh wrote: > On 2023-05-23 22:12:38+0200, Willy Tarreau wrote: > > Hi Thomas, Zhangjin, > > > > I merged and pushed this series on top of the previous series, it's in > > branch 20230523-nolibc-rv32+stkp3. > > > > However, Thomas, I found an issue with this last patch that I partially > > reverted in a last patch I pushed as well so that we can discuss it: > > > > On Sun, May 21, 2023 at 11:36:35AM +0200, Thomas Weißschuh wrote: > > > > > > -CFLAGS_STACKPROTECTOR = -DNOLIBC_STACKPROTECTOR \ > > > - $(call cc-option,-mstack-protector-guard=global) \ > > > - $(call cc-option,-fstack-protector-all) > > > -CFLAGS_STKP_i386 = $(CFLAGS_STACKPROTECTOR) > > > -CFLAGS_STKP_x86_64 = $(CFLAGS_STACKPROTECTOR) > > > -CFLAGS_STKP_x86 = $(CFLAGS_STACKPROTECTOR) > > > -CFLAGS_STKP_arm64 = $(CFLAGS_STACKPROTECTOR) > > > -CFLAGS_STKP_arm = $(CFLAGS_STACKPROTECTOR) > > > -CFLAGS_STKP_mips = $(CFLAGS_STACKPROTECTOR) > > > -CFLAGS_STKP_riscv = $(CFLAGS_STACKPROTECTOR) > > > -CFLAGS_STKP_loongarch = $(CFLAGS_STACKPROTECTOR) > > > +CFLAGS_STACKPROTECTOR = $(call cc-option,-mstack-protector-guard=global -fstack-protector-all) > > > CFLAGS_s390 = -m64 > > > CFLAGS ?= -Os -fno-ident -fno-asynchronous-unwind-tables -std=c89 \ > > > $(call cc-option,-fno-stack-protector) \ > > > + $(call cc-option,-mstack-protector-guard=global $(call cc-option,-fstack-protector-all)) \ > > > $(CFLAGS_STKP_$(ARCH)) $(CFLAGS_$(ARCH)) > > > > By doing so, we reintroduce the forced stack-protector mechanism > > that cannot be disabled anymore. The ability to disable it was the > > main point of the options above. In fact checking __SSP__* was a > > solution to save the user from having to set -DNOLIBC_STACKPROTECTOR > > to match their compiler's flags, but here in the nolibc-test we still > > want to be able to forcefully disable stkp for a run (at least to > > unbreak gcc-9, and possibly to confirm that non-stkp builds still > > continue to work when your local toolchain has it by default). > > Wouldn't this work? > > make CFLAGS_x86=-fno-stack-protector nolibc-test Not that much because as you can see, CFLAGS is more of an accumulator than an input cflags. Once it starts to accumulate automatic flags detected for various reasons it becomes a huge burden for end users to figure what to manually put there. > Or we do > > CFLAGS_STACKPROTECTOR ?= $(call cc-option,-mstack-protector-guard=global $(call cc-option,-fstack-protector-all)) > CFLAGS ?= ... $(CFLAGS_STACKPROTECTOR) > And then it is always: > > make CFLAGS_STACKPROTECTOR= nolibc-test This one is more in line with the partial revert. I don't have a *strong* feeling for the per-arch setting but it did make sense when not all archs were supporting it, and I've used per-arch setting when I was having different compiler versions for certain archs (e.g. for loongarch I used gcc12). > An alternative would also be to use a GCC 9 compatible mechanism: > > #if __has_attribute(no_stack_protector) > #define __no_stack_protector __attribute__((no_stack_protector)) > #else > #define __no_stack_protector __attribute__((__optimize__("-fno-stack-protector"))) > #endif I tried this one but I remember some initial failures and a possible later success when instrumenting the correct function, so my memory is not intact on this one. However if we manage to find a working solution for gcc-9 and it affects the nolibc part (not the test part), we definitely need to merge it because if some users have working stkp on gcc-9 and we break it, that will not be cool. > Or we combine CFLAGS_STACKPROTECTOR and __no_stack_protector. I think that CFLAGS_STACKPROTECTOR should only be a makefile variable to forcefully enable/disable that but not separately exposed in the code. > > So I reverted that part and only dropped -DNOLIBC_STACKPROTECTOR. > > This way I could run the test on all archs with gcc-9 by forcing > > CFLAGS_STACKPROTECTOR= and verified it was still possible to > > disable it for a specific arch only by setting CFLAGS_STKP_$ARCH. > > > > If you're fine with this we can squash this one into your cleanup > > patch. > > To be honest I was happy to get rid of all these architecture specific > variables. I generally agree with the principle and I think I can live with that. So let's summarize: how about: - we only keep the CFLAGS_STACKPROTECTOR variable that is easy to reset from the make command line. Those with multiple compilers are free to globally enable/disable or pass that on multiple make command lines if needed, but we decide it's the users' test instrumentation problem, not the maintainers'. - we try our best to make sure that gcc-9 with stkp enabled still produces working code (with/without stkp I don't know but not something that smashes the stack at least). IMHO this would be clean enough and sufficiently maintainable for the long term. > I trimmed the list a bit. Thanks for them ;-) Willy
diff --git a/tools/testing/selftests/nolibc/Makefile b/tools/testing/selftests/nolibc/Makefile index bd41102ea299..445c352b1b33 100644 --- a/tools/testing/selftests/nolibc/Makefile +++ b/tools/testing/selftests/nolibc/Makefile @@ -76,20 +76,11 @@ else Q=@ endif -CFLAGS_STACKPROTECTOR = -DNOLIBC_STACKPROTECTOR \ - $(call cc-option,-mstack-protector-guard=global) \ - $(call cc-option,-fstack-protector-all) -CFLAGS_STKP_i386 = $(CFLAGS_STACKPROTECTOR) -CFLAGS_STKP_x86_64 = $(CFLAGS_STACKPROTECTOR) -CFLAGS_STKP_x86 = $(CFLAGS_STACKPROTECTOR) -CFLAGS_STKP_arm64 = $(CFLAGS_STACKPROTECTOR) -CFLAGS_STKP_arm = $(CFLAGS_STACKPROTECTOR) -CFLAGS_STKP_mips = $(CFLAGS_STACKPROTECTOR) -CFLAGS_STKP_riscv = $(CFLAGS_STACKPROTECTOR) -CFLAGS_STKP_loongarch = $(CFLAGS_STACKPROTECTOR) +CFLAGS_STACKPROTECTOR = $(call cc-option,-mstack-protector-guard=global -fstack-protector-all) CFLAGS_s390 = -m64 CFLAGS ?= -Os -fno-ident -fno-asynchronous-unwind-tables -std=c89 \ $(call cc-option,-fno-stack-protector) \ + $(call cc-option,-mstack-protector-guard=global $(call cc-option,-fstack-protector-all)) \ $(CFLAGS_STKP_$(ARCH)) $(CFLAGS_$(ARCH)) LDFLAGS := -s
Now that nolibc enable stackprotector support automatically when the compiler enables it we only have to get the -fstack-protector flags correct. The cc-options are structured so that -fstack-protector-all is only enabled if -mstack-protector=guard works, as that is the only mode supported by nolibc. Signed-off-by: Thomas Weißschuh <linux@weissschuh.net> --- tools/testing/selftests/nolibc/Makefile | 13 ++----------- 1 file changed, 2 insertions(+), 11 deletions(-)