Re: [PATCH 5.4 03/74] module: merge repetitive strings in module_sig_check()

Sergey Shtylyov
2021-04-05T14:11:18Z

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@perches.com>
>>> Reviewed-by: Miroslav Benes <mbenes@suse.cz>
>>> Signed-off-by: Sergey Shtylyov <s.shtylyov@omprussia.ru>
>>> Signed-off-by: Jessica Yu <jeyu@kernel.org>
>>> Signed-off-by: Sasha Levin <sashal@kernel.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