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Subject: Re: [PATCH] sys_personality: Add a optional arch hook
 arch_check_personality()
To:     <mark.rutland@arm.com>, <hch@infradead.org>
CC:     <cj.chengjian@huawei.com>, <huawei.libin@huawei.com>,
        <xiexiuqi@huawei.com>, <yangyingliang@huawei.com>,
        <guohanjun@huawei.com>, <wcohen@redhat.com>,
        <linux-kernel@vger.kernel.org>, <mtk.manpages@gmail.com>,
        <wezhang@redhat.com>
References: <20191228084359.133745-1-bobo.shaobowang@huawei.com>
From:   "Wangshaobo (bobo)" <bobo.shaobowang@huawei.com>
Message-ID: <4c0865f6-9502-1750-f437-95405f0f699b@huawei.com>
Date:   Sat, 28 Dec 2019 17:02:42 +0800
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I am sorry for sending a wrong version, the correct version is v2.

?? 2019/12/28 16:43, Wang ShaoBo д??:
> currently arm64 use __arm64_sys_arm64_personality() as its default
> syscall. Now using a normal hook arch_check_personality() can reject
> personality settings for special case of different archs.
>
> Signed-off-by: Wang ShaoBo <bobo.shaobowang@huawei.com>
> ---
>   arch/arm64/kernel/sys.c |  6 +++---
>   kernel/exec_domain.c    | 11 +++++++++++
>   2 files changed, 14 insertions(+), 3 deletions(-)
>
> diff --git a/arch/arm64/kernel/sys.c b/arch/arm64/kernel/sys.c
> index d5ffaaab31a7..751fbd57eb1e 100644
> --- a/arch/arm64/kernel/sys.c
> +++ b/arch/arm64/kernel/sys.c
> @@ -28,12 +28,13 @@ SYSCALL_DEFINE6(mmap, unsigned long, addr, unsigned long, len,
>   	return ksys_mmap_pgoff(addr, len, prot, flags, fd, off >> PAGE_SHIFT);
>   }
>   
> -SYSCALL_DEFINE1(arm64_personality, unsigned int, personality)
> +int arch_check_personality(unsigned int personality)
>   {
>   	if (personality(personality) == PER_LINUX32 &&
>   		!system_supports_32bit_el0())
>   		return -EINVAL;
> -	return ksys_personality(personality);
> +
> +	return 0;
>   }
>   
>   asmlinkage long sys_ni_syscall(void);
> @@ -46,7 +47,6 @@ asmlinkage long __arm64_sys_ni_syscall(const struct pt_regs *__unused)
>   /*
>    * Wrappers to pass the pt_regs argument.
>    */
> -#define __arm64_sys_personality		__arm64_sys_arm64_personality
>   
>   #undef __SYSCALL
>   #define __SYSCALL(nr, sym)	asmlinkage long __arm64_##sym(const struct pt_regs *);
> diff --git a/kernel/exec_domain.c b/kernel/exec_domain.c
> index f7a0512ddc23..ec6b16e30ed1 100644
> --- a/kernel/exec_domain.c
> +++ b/kernel/exec_domain.c
> @@ -35,7 +35,18 @@ static int __init proc_execdomains_init(void)
>   module_init(proc_execdomains_init);
>   #endif
>   
> +static int __weak arch_check_personality(unsigned int personality)
> +{
> +	return 0;
> +}
> +
>   SYSCALL_DEFINE1(personality, unsigned int, personality)
>   {
> +	int check;
> +
> +	check = arch_check_personality(personality);
> +	if (check)
> +		return check;
> +
>   	return ksys_personality(personality);
>   }