linux-kernel - Re: [PATCH 5.4 03/74] module: merge repetitive strings in module_sig

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Message-ID: <b54f4a70-60df-be44-c88f-1f60f338ff12@omprussia.ru>
Date:   Mon, 5 Apr 2021 17:11:13 +0300
From:   Sergey Shtylyov <s.shtylyov@...russia.ru>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
CC:     <linux-kernel@...r.kernel.org>, <stable@...r.kernel.org>,
        Joe Perches <joe@...ches.com>, Miroslav Benes <mbenes@...e.cz>,
        Jessica Yu <jeyu@...nel.org>, Sasha Levin <sashal@...nel.org>
Subject: Re: [PATCH 5.4 03/74] module: merge repetitive strings in
 module_sig_check()

On 4/5/21 4:40 PM, Greg Kroah-Hartman wrote:

[...]
>>> [ Upstream commit 705e9195187d85249fbb0eaa844b1604a98fbc9a ]
>>>
>>> The 'reason' variable in module_sig_check() points to 3 strings across
>>> the *switch* statement, all needlessly starting with the same text.
>>> Let's put the starting text into the pr_notice() call -- it saves 21
>>> bytes of the object code (x86 gcc 10.2.1).
>>>
>>> Suggested-by: Joe Perches <joe@...ches.com>
>>> Reviewed-by: Miroslav Benes <mbenes@...e.cz>
>>> Signed-off-by: Sergey Shtylyov <s.shtylyov@...russia.ru>
>>> Signed-off-by: Jessica Yu <jeyu@...nel.org>
>>> Signed-off-by: Sasha Levin <sashal@...nel.org>
>>> ---
>>>  kernel/module.c | 9 +++++----
>>>  1 file changed, 5 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/kernel/module.c b/kernel/module.c
>>> index ab1f97cfe18d..9fe3e9b85348 100644
>>> --- a/kernel/module.c
>>> +++ b/kernel/module.c
>>> @@ -2908,16 +2908,17 @@ static int module_sig_check(struct load_info *info, int flags)
>>>  		 * enforcing, certain errors are non-fatal.
>>>  		 */
>>>  	case -ENODATA:
>>> -		reason = "Loading of unsigned module";
>>> +		reason = "unsigned module";
>>>  		goto decide;
>>>  	case -ENOPKG:
>>> -		reason = "Loading of module with unsupported crypto";
>>> +		reason = "module with unsupported crypto";
>>>  		goto decide;
>>>  	case -ENOKEY:
>>> -		reason = "Loading of module with unavailable key";
>>> +		reason = "module with unavailable key";
>>>  	decide:
>>>  		if (is_module_sig_enforced()) {
>>> -			pr_notice("%s is rejected\n", reason);
>>> +			pr_notice("%s: loading of %s is rejected\n",
>>> +				  info->name, reason);
>>
>>    Mhm, in 5.4 there was no printing of 'info->name'...
> 
> Is that now a problem?

   Looking at 5.4.y, it probably shouldn't be a problem... but I had to go and look. :-)
   I've found a simple commit that added 'info->name' printing (perhaps should also be
considered for inclusion?):

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=e9f35f634e099894f4d6c3b039cd3de5281ee637


> thanks,
> 
> greg k-h

MBR, Sergey