linux-kernel - Re: [PATCH v2 4/7] arm64/modules: Add rlimit checking for arm64 modules

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Message-ID: <20181012143254.idy65qbvaaw5k3ge@linux-8ccs>
Date:   Fri, 12 Oct 2018 16:32:54 +0200
From:   Jessica Yu <jeyu@...nel.org>
To:     Dave Hansen <dave.hansen@...el.com>
Cc:     Rick Edgecombe <rick.p.edgecombe@...el.com>,
        kernel-hardening@...ts.openwall.com, daniel@...earbox.net,
        keescook@...omium.org, catalin.marinas@....com,
        will.deacon@....com, davem@...emloft.net, tglx@...utronix.de,
        mingo@...hat.com, bp@...en8.de, x86@...nel.org, arnd@...db.de,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-mips@...ux-mips.org, linux-s390@...r.kernel.org,
        sparclinux@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-arch@...r.kernel.org, kristen@...ux.intel.com,
        arjan@...ux.intel.com, deneen.t.dock@...el.com
Subject: Re: [PATCH v2 4/7] arm64/modules: Add rlimit checking for arm64
 modules

+++ Dave Hansen [11/10/18 16:47 -0700]:
>On 10/11/2018 04:31 PM, Rick Edgecombe wrote:
>> +	if (check_inc_mod_rlimit(size))
>> +		return NULL;
>> +
>>  	p = __vmalloc_node_range(size, MODULE_ALIGN, module_alloc_base,
>>  				module_alloc_base + MODULES_VSIZE,
>>  				gfp_mask, PAGE_KERNEL_EXEC, 0,
>> @@ -65,6 +68,8 @@ void *module_alloc(unsigned long size)
>>  		return NULL;
>>  	}
>>
>> +	update_mod_rlimit(p, size);
>
>Is there a reason we couldn't just rename all of the existing per-arch
>module_alloc() calls to be called, say, "arch_module_alloc()", then put
>this new rlimit code in a generic helper that does:
>
>
>	if (check_inc_mod_rlimit(size))
>		return NULL;
>
>	p = arch_module_alloc(...);
>
>	...
>
>	update_mod_rlimit(p, size);
>

I second this suggestion. Just make module_{alloc,memfree} generic,
non-weak functions that call the rlimit helpers in addition to the
arch-specific arch_module_{alloc,memfree} functions.

Jessica