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* [PATCH v2] netfilter: ebtables: fix fortify warnings
@ 2023-08-08 13:30 GONG, Ruiqi
  2023-08-08 16:32 ` Gustavo A. R. Silva
  0 siblings, 1 reply; 7+ messages in thread
From: GONG, Ruiqi @ 2023-08-08 13:30 UTC (permalink / raw)
  To: Pablo Neira Ayuso, Jozsef Kadlecsik, Florian Westphal,
	Roopa Prabhu, Nikolay Aleksandrov, Kees Cook,
	Gustavo A . R . Silva
  Cc: netfilter-devel, coreteam, netdev, linux-hardening, linux-kernel,
	Wang Weiyang, Xiu Jianfeng, gongruiqi1

From: "GONG, Ruiqi" <gongruiqi1@huawei.com>

When compiling with gcc 13 and CONFIG_FORTIFY_SOURCE=y, the following
warning appears:

In function ‘fortify_memcpy_chk’,
    inlined from ‘size_entry_mwt’ at net/bridge/netfilter/ebtables.c:2118:2:
./include/linux/fortify-string.h:592:25: error: call to ‘__read_overflow2_field’
declared with attribute warning: detected read beyond size of field (2nd parameter);
maybe use struct_group()? [-Werror=attribute-warning]
  592 |                         __read_overflow2_field(q_size_field, size);
      |                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The compiler is complaining:

memcpy(&offsets[1], &entry->watchers_offset,
                       sizeof(offsets) - sizeof(offsets[0]));

where memcpy reads beyong &entry->watchers_offset to copy
{watchers,target,next}_offset altogether into offsets[]. Silence the
warning by wrapping these three up via struct_group().

Signed-off-by: GONG, Ruiqi <gongruiqi1@huawei.com>
---

v2: fix HDRTEST error by replacing struct_group() with __struct_group(),
since it's a uapi header.

 include/uapi/linux/netfilter_bridge/ebtables.h | 14 ++++++++------
 net/bridge/netfilter/ebtables.c                |  3 +--
 2 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/include/uapi/linux/netfilter_bridge/ebtables.h b/include/uapi/linux/netfilter_bridge/ebtables.h
index a494cf43a755..b0caad82b693 100644
--- a/include/uapi/linux/netfilter_bridge/ebtables.h
+++ b/include/uapi/linux/netfilter_bridge/ebtables.h
@@ -182,12 +182,14 @@ struct ebt_entry {
 	unsigned char sourcemsk[ETH_ALEN];
 	unsigned char destmac[ETH_ALEN];
 	unsigned char destmsk[ETH_ALEN];
-	/* sizeof ebt_entry + matches */
-	unsigned int watchers_offset;
-	/* sizeof ebt_entry + matches + watchers */
-	unsigned int target_offset;
-	/* sizeof ebt_entry + matches + watchers + target */
-	unsigned int next_offset;
+	__struct_group(/* no tag */, offsets, /* no attrs */,
+		/* sizeof ebt_entry + matches */
+		unsigned int watchers_offset;
+		/* sizeof ebt_entry + matches + watchers */
+		unsigned int target_offset;
+		/* sizeof ebt_entry + matches + watchers + target */
+		unsigned int next_offset;
+	);
 	unsigned char elems[0] __attribute__ ((aligned (__alignof__(struct ebt_replace))));
 };
 
diff --git a/net/bridge/netfilter/ebtables.c b/net/bridge/netfilter/ebtables.c
index 757ec46fc45a..5ec66b1ebb64 100644
--- a/net/bridge/netfilter/ebtables.c
+++ b/net/bridge/netfilter/ebtables.c
@@ -2115,8 +2115,7 @@ static int size_entry_mwt(const struct ebt_entry *entry, const unsigned char *ba
 		return ret;
 
 	offsets[0] = sizeof(struct ebt_entry); /* matches come first */
-	memcpy(&offsets[1], &entry->watchers_offset,
-			sizeof(offsets) - sizeof(offsets[0]));
+	memcpy(&offsets[1], &entry->offsets, sizeof(offsets) - sizeof(offsets[0]));
 
 	if (state->buf_kern_start) {
 		buf_start = state->buf_kern_start + state->buf_kern_offset;
-- 
2.41.0


^ permalink raw reply related	[flat|nested] 7+ messages in thread
* Re: [PATCH v2] netfilter: ebtables: fix fortify warnings
  2023-08-08 13:30 [PATCH v2] netfilter: ebtables: fix fortify warnings GONG, Ruiqi
@ 2023-08-08 16:32 ` Gustavo A. R. Silva
  2023-08-08 22:53   ` Kees Cook
                     ` (2 more replies)
  0 siblings, 3 replies; 7+ messages in thread
From: Gustavo A. R. Silva @ 2023-08-08 16:32 UTC (permalink / raw)
  To: GONG, Ruiqi
  Cc: Pablo Neira Ayuso, Jozsef Kadlecsik, Florian Westphal,
	Roopa Prabhu, Nikolay Aleksandrov, Kees Cook, netfilter-devel,
	coreteam, netdev, linux-hardening, linux-kernel, Wang Weiyang,
	Xiu Jianfeng, gongruiqi1

On Tue, Aug 08, 2023 at 09:30:38PM +0800, GONG, Ruiqi wrote:
> From: "GONG, Ruiqi" <gongruiqi1@huawei.com>
> 
> When compiling with gcc 13 and CONFIG_FORTIFY_SOURCE=y, the following
> warning appears:
> 
> In function ‘fortify_memcpy_chk’,
>     inlined from ‘size_entry_mwt’ at net/bridge/netfilter/ebtables.c:2118:2:
> ./include/linux/fortify-string.h:592:25: error: call to ‘__read_overflow2_field’
> declared with attribute warning: detected read beyond size of field (2nd parameter);
> maybe use struct_group()? [-Werror=attribute-warning]
>   592 |                         __read_overflow2_field(q_size_field, size);
>       |                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 
> The compiler is complaining:
> 
> memcpy(&offsets[1], &entry->watchers_offset,
>                        sizeof(offsets) - sizeof(offsets[0]));
> 
> where memcpy reads beyong &entry->watchers_offset to copy
> {watchers,target,next}_offset altogether into offsets[]. Silence the
> warning by wrapping these three up via struct_group().
> 
> Signed-off-by: GONG, Ruiqi <gongruiqi1@huawei.com>
> ---
> 
> v2: fix HDRTEST error by replacing struct_group() with __struct_group(),
> since it's a uapi header.
> 
>  include/uapi/linux/netfilter_bridge/ebtables.h | 14 ++++++++------
>  net/bridge/netfilter/ebtables.c                |  3 +--
>  2 files changed, 9 insertions(+), 8 deletions(-)
> 
> diff --git a/include/uapi/linux/netfilter_bridge/ebtables.h b/include/uapi/linux/netfilter_bridge/ebtables.h
> index a494cf43a755..b0caad82b693 100644
> --- a/include/uapi/linux/netfilter_bridge/ebtables.h
> +++ b/include/uapi/linux/netfilter_bridge/ebtables.h
> @@ -182,12 +182,14 @@ struct ebt_entry {
>  	unsigned char sourcemsk[ETH_ALEN];
>  	unsigned char destmac[ETH_ALEN];
>  	unsigned char destmsk[ETH_ALEN];
> -	/* sizeof ebt_entry + matches */
> -	unsigned int watchers_offset;
> -	/* sizeof ebt_entry + matches + watchers */
> -	unsigned int target_offset;
> -	/* sizeof ebt_entry + matches + watchers + target */
> -	unsigned int next_offset;
> +	__struct_group(/* no tag */, offsets, /* no attrs */,
> +		/* sizeof ebt_entry + matches */
> +		unsigned int watchers_offset;
> +		/* sizeof ebt_entry + matches + watchers */
> +		unsigned int target_offset;
> +		/* sizeof ebt_entry + matches + watchers + target */
> +		unsigned int next_offset;
> +	);
>  	unsigned char elems[0] __attribute__ ((aligned (__alignof__(struct ebt_replace))));
>  };
>  
> diff --git a/net/bridge/netfilter/ebtables.c b/net/bridge/netfilter/ebtables.c
> index 757ec46fc45a..5ec66b1ebb64 100644
> --- a/net/bridge/netfilter/ebtables.c
> +++ b/net/bridge/netfilter/ebtables.c
> @@ -2115,8 +2115,7 @@ static int size_entry_mwt(const struct ebt_entry *entry, const unsigned char *ba
>  		return ret;
>  
>  	offsets[0] = sizeof(struct ebt_entry); /* matches come first */
> -	memcpy(&offsets[1], &entry->watchers_offset,
> -			sizeof(offsets) - sizeof(offsets[0]));
> +	memcpy(&offsets[1], &entry->offsets, sizeof(offsets) - sizeof(offsets[0]));
							^^^^^^^^^^^^
You now can replace this ____________________________________|
with just `sizeof(entry->offsets)`

With that change you can add my
Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>

Thank you
--
Gustavo

>  
>  	if (state->buf_kern_start) {
>  		buf_start = state->buf_kern_start + state->buf_kern_offset;
> -- 
> 2.41.0
> 

^ permalink raw reply	[flat|nested] 7+ messages in thread
* Re: [PATCH v2] netfilter: ebtables: fix fortify warnings
  2023-08-08 16:32 ` Gustavo A. R. Silva
@ 2023-08-08 22:53   ` Kees Cook
  2023-08-09  7:00     ` GONG, Ruiqi
  2023-08-09  7:31     ` GONG, Ruiqi
  2023-08-08 23:00   ` Kees Cook
  2023-08-09  3:25   ` GONG, Ruiqi
  2 siblings, 2 replies; 7+ messages in thread
From: Kees Cook @ 2023-08-08 22:53 UTC (permalink / raw)
  To: Gustavo A. R. Silva, GONG, Ruiqi
  Cc: Pablo Neira Ayuso, Jozsef Kadlecsik, Florian Westphal,
	Roopa Prabhu, Nikolay Aleksandrov, Kees Cook, netfilter-devel,
	coreteam, netdev, linux-hardening, linux-kernel, Wang Weiyang,
	Xiu Jianfeng, gongruiqi1

On August 8, 2023 9:32:50 AM PDT, "Gustavo A. R. Silva" <gustavoars@kernel.org> wrote:
>On Tue, Aug 08, 2023 at 09:30:38PM +0800, GONG, Ruiqi wrote:
>> From: "GONG, Ruiqi" <gongruiqi1@huawei.com>
>> 
>> When compiling with gcc 13 and CONFIG_FORTIFY_SOURCE=y, the following
>> warning appears:
>> 
>> In function ‘fortify_memcpy_chk’,
>>     inlined from ‘size_entry_mwt’ at net/bridge/netfilter/ebtables.c:2118:2:
>> ./include/linux/fortify-string.h:592:25: error: call to ‘__read_overflow2_field’
>> declared with attribute warning: detected read beyond size of field (2nd parameter);
>> maybe use struct_group()? [-Werror=attribute-warning]
>>   592 |                         __read_overflow2_field(q_size_field, size);
>>       |                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> 
>> The compiler is complaining:
>> 
>> memcpy(&offsets[1], &entry->watchers_offset,
>>                        sizeof(offsets) - sizeof(offsets[0]));
>> 
>> where memcpy reads beyong &entry->watchers_offset to copy
>> {watchers,target,next}_offset altogether into offsets[]. Silence the
>> warning by wrapping these three up via struct_group().
>> 
>> Signed-off-by: GONG, Ruiqi <gongruiqi1@huawei.com>
>> ---
>> 
>> v2: fix HDRTEST error by replacing struct_group() with __struct_group(),
>> since it's a uapi header.
>> 
>>  include/uapi/linux/netfilter_bridge/ebtables.h | 14 ++++++++------
>>  net/bridge/netfilter/ebtables.c                |  3 +--
>>  2 files changed, 9 insertions(+), 8 deletions(-)
>> 
>> diff --git a/include/uapi/linux/netfilter_bridge/ebtables.h b/include/uapi/linux/netfilter_bridge/ebtables.h
>> index a494cf43a755..b0caad82b693 100644
>> --- a/include/uapi/linux/netfilter_bridge/ebtables.h
>> +++ b/include/uapi/linux/netfilter_bridge/ebtables.h
>> @@ -182,12 +182,14 @@ struct ebt_entry {
>>  	unsigned char sourcemsk[ETH_ALEN];
>>  	unsigned char destmac[ETH_ALEN];
>>  	unsigned char destmsk[ETH_ALEN];
>> -	/* sizeof ebt_entry + matches */
>> -	unsigned int watchers_offset;
>> -	/* sizeof ebt_entry + matches + watchers */
>> -	unsigned int target_offset;
>> -	/* sizeof ebt_entry + matches + watchers + target */
>> -	unsigned int next_offset;
>> +	__struct_group(/* no tag */, offsets, /* no attrs */,
>> +		/* sizeof ebt_entry + matches */
>> +		unsigned int watchers_offset;
>> +		/* sizeof ebt_entry + matches + watchers */
>> +		unsigned int target_offset;
>> +		/* sizeof ebt_entry + matches + watchers + target */
>> +		unsigned int next_offset;
>> +	);
>>  	unsigned char elems[0] __attribute__ ((aligned (__alignof__(struct ebt_replace))));

While we're here, can we drop this [0] in favor of []?

-Kees

>>  };
>>  
>> diff --git a/net/bridge/netfilter/ebtables.c b/net/bridge/netfilter/ebtables.c
>> index 757ec46fc45a..5ec66b1ebb64 100644
>> --- a/net/bridge/netfilter/ebtables.c
>> +++ b/net/bridge/netfilter/ebtables.c
>> @@ -2115,8 +2115,7 @@ static int size_entry_mwt(const struct ebt_entry *entry, const unsigned char *ba
>>  		return ret;
>>  
>>  	offsets[0] = sizeof(struct ebt_entry); /* matches come first */
>> -	memcpy(&offsets[1], &entry->watchers_offset,
>> -			sizeof(offsets) - sizeof(offsets[0]));
>> +	memcpy(&offsets[1], &entry->offsets, sizeof(offsets) - sizeof(offsets[0]));
>							^^^^^^^^^^^^
>You now can replace this ____________________________________|
>with just `sizeof(entry->offsets)`
>
>With that change you can add my
>Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
>
>Thank you
>--
>Gustavo
>
>>  
>>  	if (state->buf_kern_start) {
>>  		buf_start = state->buf_kern_start + state->buf_kern_offset;
>> -- 
>> 2.41.0
>> 


-- 
Kees Cook

^ permalink raw reply	[flat|nested] 7+ messages in thread
* Re: [PATCH v2] netfilter: ebtables: fix fortify warnings
  2023-08-08 16:32 ` Gustavo A. R. Silva
  2023-08-08 22:53   ` Kees Cook
@ 2023-08-08 23:00   ` Kees Cook
  2023-08-09  3:25   ` GONG, Ruiqi
  2 siblings, 0 replies; 7+ messages in thread
From: Kees Cook @ 2023-08-08 23:00 UTC (permalink / raw)
  To: Gustavo A. R. Silva, GONG, Ruiqi
  Cc: Pablo Neira Ayuso, Jozsef Kadlecsik, Florian Westphal,
	Roopa Prabhu, Nikolay Aleksandrov, Kees Cook, netfilter-devel,
	coreteam, netdev, linux-hardening, linux-kernel, Wang Weiyang,
	Xiu Jianfeng, gongruiqi1

On August 8, 2023 9:32:50 AM PDT, "Gustavo A. R. Silva" <gustavoars@kernel.org> wrote:
>On Tue, Aug 08, 2023 at 09:30:38PM +0800, GONG, Ruiqi wrote:
>> From: "GONG, Ruiqi" <gongruiqi1@huawei.com>
>> 
>> When compiling with gcc 13 and CONFIG_FORTIFY_SOURCE=y, the following
>> warning appears:
>> 
>> In function ‘fortify_memcpy_chk’,
>>     inlined from ‘size_entry_mwt’ at net/bridge/netfilter/ebtables.c:2118:2:
>> ./include/linux/fortify-string.h:592:25: error: call to ‘__read_overflow2_field’
>> declared with attribute warning: detected read beyond size of field (2nd parameter);
>> maybe use struct_group()? [-Werror=attribute-warning]
>>   592 |                         __read_overflow2_field(q_size_field, size);
>>       |                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> 
>> The compiler is complaining:
>> 
>> memcpy(&offsets[1], &entry->watchers_offset,
>>                        sizeof(offsets) - sizeof(offsets[0]));
>> 
>> where memcpy reads beyong &entry->watchers_offset to copy
>> {watchers,target,next}_offset altogether into offsets[]. Silence the
>> warning by wrapping these three up via struct_group().
>> 
>> Signed-off-by: GONG, Ruiqi <gongruiqi1@huawei.com>
>> ---
>> 
>> v2: fix HDRTEST error by replacing struct_group() with __struct_group(),
>> since it's a uapi header.
>> 
>>  include/uapi/linux/netfilter_bridge/ebtables.h | 14 ++++++++------
>>  net/bridge/netfilter/ebtables.c                |  3 +--
>>  2 files changed, 9 insertions(+), 8 deletions(-)
>> 
>> diff --git a/include/uapi/linux/netfilter_bridge/ebtables.h b/include/uapi/linux/netfilter_bridge/ebtables.h
>> index a494cf43a755..b0caad82b693 100644
>> --- a/include/uapi/linux/netfilter_bridge/ebtables.h
>> +++ b/include/uapi/linux/netfilter_bridge/ebtables.h
>> @@ -182,12 +182,14 @@ struct ebt_entry {
>>  	unsigned char sourcemsk[ETH_ALEN];
>>  	unsigned char destmac[ETH_ALEN];
>>  	unsigned char destmsk[ETH_ALEN];
>> -	/* sizeof ebt_entry + matches */
>> -	unsigned int watchers_offset;
>> -	/* sizeof ebt_entry + matches + watchers */
>> -	unsigned int target_offset;
>> -	/* sizeof ebt_entry + matches + watchers + target */
>> -	unsigned int next_offset;
>> +	__struct_group(/* no tag */, offsets, /* no attrs */,
>> +		/* sizeof ebt_entry + matches */
>> +		unsigned int watchers_offset;
>> +		/* sizeof ebt_entry + matches + watchers */
>> +		unsigned int target_offset;
>> +		/* sizeof ebt_entry + matches + watchers + target */
>> +		unsigned int next_offset;
>> +	);
>>  	unsigned char elems[0] __attribute__ ((aligned (__alignof__(struct ebt_replace))));
>>  };

Actually, looking at what size_entry_mwt() is doing, I think you probably DO want a tag for this and to use a real structure for the manipulations instead of doing array indexing? I dunno. This is a weird function! :)

-Kees

>>  
>> diff --git a/net/bridge/netfilter/ebtables.c b/net/bridge/netfilter/ebtables.c
>> index 757ec46fc45a..5ec66b1ebb64 100644
>> --- a/net/bridge/netfilter/ebtables.c
>> +++ b/net/bridge/netfilter/ebtables.c
>> @@ -2115,8 +2115,7 @@ static int size_entry_mwt(const struct ebt_entry *entry, const unsigned char *ba
>>  		return ret;
>>  
>>  	offsets[0] = sizeof(struct ebt_entry); /* matches come first */
>> -	memcpy(&offsets[1], &entry->watchers_offset,
>> -			sizeof(offsets) - sizeof(offsets[0]));
>> +	memcpy(&offsets[1], &entry->offsets, sizeof(offsets) - sizeof(offsets[0]));
>							^^^^^^^^^^^^
>You now can replace this ____________________________________|
>with just `sizeof(entry->offsets)`
>
>With that change you can add my
>Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
>
>Thank you
>--
>Gustavo
>
>>  
>>  	if (state->buf_kern_start) {
>>  		buf_start = state->buf_kern_start + state->buf_kern_offset;
>> -- 
>> 2.41.0
>> 


-- 
Kees Cook

^ permalink raw reply	[flat|nested] 7+ messages in thread
* Re: [PATCH v2] netfilter: ebtables: fix fortify warnings
  2023-08-08 16:32 ` Gustavo A. R. Silva
  2023-08-08 22:53   ` Kees Cook
  2023-08-08 23:00   ` Kees Cook
@ 2023-08-09  3:25   ` GONG, Ruiqi
  2 siblings, 0 replies; 7+ messages in thread
From: GONG, Ruiqi @ 2023-08-09  3:25 UTC (permalink / raw)
  To: Gustavo A. R. Silva
  Cc: Pablo Neira Ayuso, Jozsef Kadlecsik, Florian Westphal,
	Roopa Prabhu, Nikolay Aleksandrov, Kees Cook, netfilter-devel,
	coreteam, netdev, linux-hardening, linux-kernel, Wang Weiyang,
	Xiu Jianfeng, gongruiqi1


On 2023/08/09 0:32, Gustavo A. R. Silva wrote:
>
> [...]
>
>> diff --git a/net/bridge/netfilter/ebtables.c b/net/bridge/netfilter/ebtables.c
>> index 757ec46fc45a..5ec66b1ebb64 100644
>> --- a/net/bridge/netfilter/ebtables.c
>> +++ b/net/bridge/netfilter/ebtables.c
>> @@ -2115,8 +2115,7 @@ static int size_entry_mwt(const struct ebt_entry *entry, const unsigned char *ba
>>  		return ret;
>>  
>>  	offsets[0] = sizeof(struct ebt_entry); /* matches come first */
>> -	memcpy(&offsets[1], &entry->watchers_offset,
>> -			sizeof(offsets) - sizeof(offsets[0]));
>> +	memcpy(&offsets[1], &entry->offsets, sizeof(offsets) - sizeof(offsets[0]));
> 							^^^^^^^^^^^^
> You now can replace this ____________________________________|
> with just `sizeof(entry->offsets)`
> 
> With that change you can add my
> Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
> 
> Thank you
> --
> Gustavo
> 

Will do. Thanks for the suggestion & review!

>>  
>>  	if (state->buf_kern_start) {
>>  		buf_start = state->buf_kern_start + state->buf_kern_offset;
>> -- 
>> 2.41.0
>>


^ permalink raw reply	[flat|nested] 7+ messages in thread
* Re: [PATCH v2] netfilter: ebtables: fix fortify warnings
  2023-08-08 22:53   ` Kees Cook
@ 2023-08-09  7:00     ` GONG, Ruiqi
  2023-08-09  7:31     ` GONG, Ruiqi
  1 sibling, 0 replies; 7+ messages in thread
From: GONG, Ruiqi @ 2023-08-09  7:00 UTC (permalink / raw)
  To: Kees Cook, Gustavo A. R. Silva
  Cc: Pablo Neira Ayuso, Jozsef Kadlecsik, Florian Westphal,
	Roopa Prabhu, Nikolay Aleksandrov, Kees Cook, netfilter-devel,
	coreteam, netdev, linux-hardening, linux-kernel, Wang Weiyang,
	Xiu Jianfeng, gongruiqi1


On 2023/08/09 6:53, Kees Cook wrote:
> 
> [...]
>>>
>>> diff --git a/include/uapi/linux/netfilter_bridge/ebtables.h b/include/uapi/linux/netfilter_bridge/ebtables.h
>>> index a494cf43a755..b0caad82b693 100644
>>> --- a/include/uapi/linux/netfilter_bridge/ebtables.h
>>> +++ b/include/uapi/linux/netfilter_bridge/ebtables.h
>>> @@ -182,12 +182,14 @@ struct ebt_entry {
>>>  	unsigned char sourcemsk[ETH_ALEN];
>>>  	unsigned char destmac[ETH_ALEN];
>>>  	unsigned char destmsk[ETH_ALEN];
>>> -	/* sizeof ebt_entry + matches */
>>> -	unsigned int watchers_offset;
>>> -	/* sizeof ebt_entry + matches + watchers */
>>> -	unsigned int target_offset;
>>> -	/* sizeof ebt_entry + matches + watchers + target */
>>> -	unsigned int next_offset;
>>> +	__struct_group(/* no tag */, offsets, /* no attrs */,
>>> +		/* sizeof ebt_entry + matches */
>>> +		unsigned int watchers_offset;
>>> +		/* sizeof ebt_entry + matches + watchers */
>>> +		unsigned int target_offset;
>>> +		/* sizeof ebt_entry + matches + watchers + target */
>>> +		unsigned int next_offset;
>>> +	);
>>>  	unsigned char elems[0] __attribute__ ((aligned (__alignof__(struct ebt_replace))));
> 
> While we're here, can we drop this [0] in favor of []?
> 
> -Kees
> 

Look like it could be done. Will do in v3. Thanks!

>>>  };
>>>  
>>> diff --git a/net/bridge/netfilter/ebtables.c b/net/bridge/netfilter/ebtables.c
>>> index 757ec46fc45a..5ec66b1ebb64 100644
>>> --- a/net/bridge/netfilter/ebtables.c
>>> +++ b/net/bridge/netfilter/ebtables.c
>>> @@ -2115,8 +2115,7 @@ static int size_entry_mwt(const struct ebt_entry *entry, const unsigned char *ba
>>>  		return ret;
>>>  
>>>  	offsets[0] = sizeof(struct ebt_entry); /* matches come first */
>>> -	memcpy(&offsets[1], &entry->watchers_offset,
>>> -			sizeof(offsets) - sizeof(offsets[0]));
>>> +	memcpy(&offsets[1], &entry->offsets, sizeof(offsets) - sizeof(offsets[0]));
>> 							^^^^^^^^^^^^
>> You now can replace this ____________________________________|
>> with just `sizeof(entry->offsets)`
>>
>> With that change you can add my
>> Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
>>
>> Thank you
>> --
>> Gustavo
>>
>>>  
>>>  	if (state->buf_kern_start) {
>>>  		buf_start = state->buf_kern_start + state->buf_kern_offset;
>>> -- 
>>> 2.41.0
>>>
> 
> 


^ permalink raw reply	[flat|nested] 7+ messages in thread
* Re: [PATCH v2] netfilter: ebtables: fix fortify warnings
  2023-08-08 22:53   ` Kees Cook
  2023-08-09  7:00     ` GONG, Ruiqi
@ 2023-08-09  7:31     ` GONG, Ruiqi
  1 sibling, 0 replies; 7+ messages in thread
From: GONG, Ruiqi @ 2023-08-09  7:31 UTC (permalink / raw)
  To: Kees Cook, Gustavo A. R. Silva, GONG, Ruiqi
  Cc: Pablo Neira Ayuso, Jozsef Kadlecsik, Florian Westphal,
	Roopa Prabhu, Nikolay Aleksandrov, Kees Cook, netfilter-devel,
	coreteam, netdev, linux-hardening, linux-kernel, Wang Weiyang,
	Xiu Jianfeng



On 2023/08/09 6:53, Kees Cook wrote:
> 
> [...]
>>>
>>> diff --git a/include/uapi/linux/netfilter_bridge/ebtables.h b/include/uapi/linux/netfilter_bridge/ebtables.h
>>> index a494cf43a755..b0caad82b693 100644
>>> --- a/include/uapi/linux/netfilter_bridge/ebtables.h
>>> +++ b/include/uapi/linux/netfilter_bridge/ebtables.h
>>> @@ -182,12 +182,14 @@ struct ebt_entry {
>>>  	unsigned char sourcemsk[ETH_ALEN];
>>>  	unsigned char destmac[ETH_ALEN];
>>>  	unsigned char destmsk[ETH_ALEN];
>>> -	/* sizeof ebt_entry + matches */
>>> -	unsigned int watchers_offset;
>>> -	/* sizeof ebt_entry + matches + watchers */
>>> -	unsigned int target_offset;
>>> -	/* sizeof ebt_entry + matches + watchers + target */
>>> -	unsigned int next_offset;
>>> +	__struct_group(/* no tag */, offsets, /* no attrs */,
>>> +		/* sizeof ebt_entry + matches */
>>> +		unsigned int watchers_offset;
>>> +		/* sizeof ebt_entry + matches + watchers */
>>> +		unsigned int target_offset;
>>> +		/* sizeof ebt_entry + matches + watchers + target */
>>> +		unsigned int next_offset;
>>> +	);
>>>  	unsigned char elems[0] __attribute__ ((aligned (__alignof__(struct ebt_replace))));
> 
> While we're here, can we drop this [0] in favor of []?
> 
> -Kees
> 

There are still quite a lot of zero-element array in
include/uapi/linux/netfilter_bridge/ebtables.h. I will submit another
patch to change them altogether.

>>>  };
>>>  
>>> diff --git a/net/bridge/netfilter/ebtables.c b/net/bridge/netfilter/ebtables.c
>>> index 757ec46fc45a..5ec66b1ebb64 100644
>>> --- a/net/bridge/netfilter/ebtables.c
>>> +++ b/net/bridge/netfilter/ebtables.c
>>> @@ -2115,8 +2115,7 @@ static int size_entry_mwt(const struct ebt_entry *entry, const unsigned char *ba
>>>  		return ret;
>>>  
>>>  	offsets[0] = sizeof(struct ebt_entry); /* matches come first */
>>> -	memcpy(&offsets[1], &entry->watchers_offset,
>>> -			sizeof(offsets) - sizeof(offsets[0]));
>>> +	memcpy(&offsets[1], &entry->offsets, sizeof(offsets) - sizeof(offsets[0]));
>> 							^^^^^^^^^^^^
>> You now can replace this ____________________________________|
>> with just `sizeof(entry->offsets)`
>>
>> With that change you can add my
>> Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
>>
>> Thank you
>> --
>> Gustavo
>>
>>>  
>>>  	if (state->buf_kern_start) {
>>>  		buf_start = state->buf_kern_start + state->buf_kern_offset;
>>> -- 
>>> 2.41.0
>>>
> 
> 


^ permalink raw reply	[flat|nested] 7+ messages in thread
end of thread, other threads:[~2023-08-09  7:32 UTC | newest]

Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2023-08-08 13:30 [PATCH v2] netfilter: ebtables: fix fortify warnings GONG, Ruiqi
2023-08-08 16:32 ` Gustavo A. R. Silva
2023-08-08 22:53   ` Kees Cook
2023-08-09  7:00     ` GONG, Ruiqi
2023-08-09  7:31     ` GONG, Ruiqi
2023-08-08 23:00   ` Kees Cook
2023-08-09  3:25   ` GONG, Ruiqi

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