linux-kernel - Re: [PATCH RFC 4/6] arm64: Add kernel return probes support(kretprobes)

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Mon, 11 Nov 2013 09:59:22 +0530
From:	Sandeepa Prabhu <sandeepa.prabhu@...aro.org>
To:	Will Deacon <will.deacon@....com>
Cc:	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"patches@...aro.org" <patches@...aro.org>,
	"linaro-kernel@...ts.linaro.org" <linaro-kernel@...ts.linaro.org>,
	Catalin Marinas <Catalin.Marinas@....com>,
	"steve.capper@...aro.org" <steve.capper@...aro.org>,
	"nico@...aro.org" <nico@...aro.org>,
	"srikar@...ux.vnet.ibm.com" <srikar@...ux.vnet.ibm.com>,
	"rostedt@...dmis.org" <rostedt@...dmis.org>,
	"masami.hiramatsu.pt@...achi.com" <masami.hiramatsu.pt@...achi.com>,
	"dsaxena@...aro.org" <dsaxena@...aro.org>,
	"jiang.liu@...wei.com" <jiang.liu@...wei.com>,
	"Vijaya.Kumar@...iumnetworks.com" <Vijaya.Kumar@...iumnetworks.com>
Subject: Re: [PATCH RFC 4/6] arm64: Add kernel return probes support(kretprobes)

On 8 November 2013 22:34, Will Deacon <will.deacon@....com> wrote:
> On Thu, Oct 17, 2013 at 12:17:49PM +0100, Sandeepa Prabhu wrote:
>> AArch64 ISA does not instructions to pop PC register value
>> from stack(like ARM v7 has ldmia {...,pc}) without using
>> one of the general purpose registers. This means return probes
>> cannot return to the actual return address directly without
>> modifying register context, and without trapping into debug exception.
>>
>> So like many other architectures, we prepare a global routine
>> with NOPs, which serve as trampoline to hack away the
>> function return address, by placing an extra kprobe on the
>> trampoline entry.
>>
>> The pre-handler of this special trampoline' kprobe execute return
>> probe handler functions and restore original return address in ELR_EL1,
>> this way, saved pt_regs still hold the original register context to be
>> carried back to the probed kernel function.
>>
>> Signed-off-by: Sandeepa Prabhu <sandeepa.prabhu@...aro.org>
>> ---
>>  arch/arm64/Kconfig               |   1 +
>>  arch/arm64/include/asm/kprobes.h |   1 +
>>  arch/arm64/include/asm/ptrace.h  |   5 ++
>>  arch/arm64/kernel/kprobes.c      | 125 ++++++++++++++++++++++++++++++++++++++-
>>  4 files changed, 129 insertions(+), 3 deletions(-)
>>
>> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
>> index 2e89059..73eff55 100644
>> --- a/arch/arm64/Kconfig
>> +++ b/arch/arm64/Kconfig
>> @@ -28,6 +28,7 @@ config ARM64
>>       select HAVE_MEMBLOCK
>>       select HAVE_PERF_EVENTS
>>       select HAVE_KPROBES if !XIP_KERNEL
>> +     select HAVE_KRETPROBES if (HAVE_KPROBES)
>
> Don't need the brackets.
OK.
>
>>       select IRQ_DOMAIN
>>       select MODULES_USE_ELF_RELA
>>       select NO_BOOTMEM
>> diff --git a/arch/arm64/include/asm/kprobes.h b/arch/arm64/include/asm/kprobes.h
>> index 9b491d0..eaca849 100644
>> --- a/arch/arm64/include/asm/kprobes.h
>> +++ b/arch/arm64/include/asm/kprobes.h
>> @@ -55,5 +55,6 @@ void arch_remove_kprobe(struct kprobe *);
>>  int kprobe_fault_handler(struct pt_regs *regs, unsigned int fsr);
>>  int kprobe_exceptions_notify(struct notifier_block *self,
>>                            unsigned long val, void *data);
>> +void kretprobe_trampoline(void);
>>
>>  #endif /* _ARM_KPROBES_H */
>> diff --git a/arch/arm64/include/asm/ptrace.h b/arch/arm64/include/asm/ptrace.h
>> index 89f1727..58b2589 100644
>> --- a/arch/arm64/include/asm/ptrace.h
>> +++ b/arch/arm64/include/asm/ptrace.h
>> @@ -166,6 +166,11 @@ static inline int valid_user_regs(struct user_pt_regs *regs)
>>  #define instruction_pointer(regs)    (regs)->pc
>>  #define stack_pointer(regs)          ((regs)->sp)
>>
>> +static inline long regs_return_value(struct pt_regs *regs)
>> +{
>> +     return regs->regs[0];
>> +}
>
> This is also being implemented by another patch series (I think the audit
> stuff?).
Not sure, I did not see this being implemented in audit(audit adds for
'syscallno',  not for return value in x0)
I can rebase my code if this change is implemented and queued in other patchset.

>
> Will
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@...r.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/