Re: [RFC v6 35/62] powerpc: Deliver SEGV signal on pkey violation

From	ebiederm@xmission.com (Eric W. Biederman)
Newsgroups	linux.kernel
Subject	Re: [RFC v6 35/62] powerpc: Deliver SEGV signal on pkey violation
Date	2017-08-19 21:20 +0200
Message-ID	<ughrP-5ey-3@gated-at.bofh.it> (permalink)
References	<u3ISR-1St-3@gated-at.bofh.it> <u3ISS-1St-9@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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Ram Pai <linuxram@us.ibm.com> writes:

> diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
> index d4e545d..fe1e7c7 100644
> --- a/arch/powerpc/kernel/traps.c
> +++ b/arch/powerpc/kernel/traps.c
> @@ -20,6 +20,7 @@
>  #include <linux/sched/debug.h>
>  #include <linux/kernel.h>
>  #include <linux/mm.h>
> +#include <linux/pkeys.h>
>  #include <linux/stddef.h>
>  #include <linux/unistd.h>
>  #include <linux/ptrace.h>
> @@ -247,6 +248,15 @@ void user_single_step_siginfo(struct task_struct *tsk,
>  	info->si_addr = (void __user *)regs->nip;
>  }
>  
> +#ifdef CONFIG_PPC64_MEMORY_PROTECTION_KEYS
> +static void fill_sig_info_pkey(int si_code, siginfo_t *info, unsigned long addr)
> +{
> +	if (si_code != SEGV_PKUERR)
> +		return;

Given that SEGV_PKUERR is a signal specific si_code this test is
insufficient to detect an pkey error.  You also need to check
that signr == SIGSEGV

> +	info->si_pkey = get_paca()->paca_pkey;
> +}
> +#endif /* CONFIG_PPC64_MEMORY_PROTECTION_KEYS */
> +
>  void _exception(int signr, struct pt_regs *regs, int code, unsigned long addr)
>  {
>  	siginfo_t info;
> @@ -274,6 +284,11 @@ void _exception(int signr, struct pt_regs *regs, int code, unsigned long addr)
>  	info.si_signo = signr;
>  	info.si_code = code;
>  	info.si_addr = (void __user *) addr;
> +
> +#ifdef CONFIG_PPC64_MEMORY_PROTECTION_KEYS
> +	fill_sig_info_pkey(code, &info, addr);
> +#endif /* CONFIG_PPC64_MEMORY_PROTECTION_KEYS */
> +
>  	force_sig_info(signr, &info, current);
>  }

Eric

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Re: [RFC v6 35/62] powerpc: Deliver SEGV signal on pkey violation ebiederm@xmission.com (Eric W. Biederman) - 2017-08-19 21:20 +0200
  Re: [RFC v6 35/62] powerpc: Deliver SEGV signal on pkey violation Ram Pai <linuxram@us.ibm.com> - 2017-08-22 20:10 +0200

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