Messages in this thread | | | Subject | Re: [PATCH v2 1/2] arm64/crash_core: Export KERNELPACMASK in vmcoreinfo | From | Amit Kachhap <> | Date | Thu, 30 Apr 2020 17:05:55 +0530 |
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Hi Will/Catalin,
On 4/27/20 11:55 AM, Amit Daniel Kachhap wrote: > Recently arm64 linux kernel added support for Armv8.3-A Pointer > Authentication feature. If this feature is enabled in the kernel and the > hardware supports address authentication then the return addresses are > signed and stored in the stack to prevent ROP kind of attack. Kdump tool > will now dump the kernel with signed lr values in the stack. > > Any user analysis tool for this kernel dump may need the kernel pac mask > information in vmcoreinfo to generate the correct return address for > stacktrace purpose as well as to resolve the symbol name. > > This patch is similar to commit ec6e822d1a22d0eef ("arm64: expose user PAC > bit positions via ptrace") which exposes pac mask information via ptrace > interfaces. > > Cc: Catalin Marinas <catalin.marinas@arm.com> > Cc: Will Deacon <will@kernel.org> > Cc: Mark Rutland <mark.rutland@arm.com> > Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
This patch user side changes are accepted by crash-utility maintainer [1] so I think this is in a good shape to go in.
Thanks, Amit Daniel
[1]: https://www.redhat.com/archives/crash-utility/2020-April/msg00099.html
> --- > Changes since v1: > * Rebased to kernel 5.7-rc3. > * commit log change. > > An implementation of this new KERNELPACMASK vmcoreinfo field used by crash > tool can be found here[1]. This change is accepted by crash utility > maintainer [2]. > > [1]: https://www.redhat.com/archives/crash-utility/2020-April/msg00095.html > [2]: https://www.redhat.com/archives/crash-utility/2020-April/msg00099.html > > arch/arm64/include/asm/compiler.h | 3 +++ > arch/arm64/kernel/crash_core.c | 4 ++++ > 2 files changed, 7 insertions(+) > > diff --git a/arch/arm64/include/asm/compiler.h b/arch/arm64/include/asm/compiler.h > index eece20d..32d5900 100644 > --- a/arch/arm64/include/asm/compiler.h > +++ b/arch/arm64/include/asm/compiler.h > @@ -19,6 +19,9 @@ > #define __builtin_return_address(val) \ > (void *)(ptrauth_clear_pac((unsigned long)__builtin_return_address(val))) > > +#else /* !CONFIG_ARM64_PTR_AUTH */ > +#define ptrauth_user_pac_mask() 0ULL > +#define ptrauth_kernel_pac_mask() 0ULL > #endif /* CONFIG_ARM64_PTR_AUTH */ > > #endif /* __ASM_COMPILER_H */ > diff --git a/arch/arm64/kernel/crash_core.c b/arch/arm64/kernel/crash_core.c > index ca4c3e1..25cf2ce 100644 > --- a/arch/arm64/kernel/crash_core.c > +++ b/arch/arm64/kernel/crash_core.c > @@ -6,6 +6,7 @@ > > #include <linux/crash_core.h> > #include <asm/memory.h> > +#include <asm/pointer_auth.h> > > void arch_crash_save_vmcoreinfo(void) > { > @@ -16,4 +17,7 @@ void arch_crash_save_vmcoreinfo(void) > vmcoreinfo_append_str("NUMBER(PHYS_OFFSET)=0x%llx\n", > PHYS_OFFSET); > vmcoreinfo_append_str("KERNELOFFSET=%lx\n", kaslr_offset()); > + vmcoreinfo_append_str("NUMBER(KERNELPACMASK)=0x%llx\n", > + system_supports_address_auth() ? > + ptrauth_kernel_pac_mask() : 0); > } >
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