ct_sip_parse_numerical_param() returns only 0 or 1 now.
But process_register_request() and process_register_response() imply
checking for a negative value if parsing of a numerical header parameter
failed. Let's fix it.
Found by InfoTeCS on behalf of Linux Verification Center
(linuxtesting.org) with SVACE.
Fixes: 0f32a40fc91a ("[NETFILTER]: nf_conntrack_sip: create signalling expectations")
Signed-off-by: Ilia.Gavrilov <[email protected]>
---
net/netfilter/nf_conntrack_sip.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/netfilter/nf_conntrack_sip.c b/net/netfilter/nf_conntrack_sip.c
index 77f5e82d8e3f..d0eac27f6ba0 100644
--- a/net/netfilter/nf_conntrack_sip.c
+++ b/net/netfilter/nf_conntrack_sip.c
@@ -611,7 +611,7 @@ int ct_sip_parse_numerical_param(const struct nf_conn *ct, const char *dptr,
start += strlen(name);
*val = simple_strtoul(start, &end, 0);
if (start == end)
- return 0;
+ return -1;
if (matchoff && matchlen) {
*matchoff = start - dptr;
*matchlen = end - start;
--
2.30.2
On Wed, Apr 26, 2023 at 03:04:31PM +0000, Gavrilov Ilia wrote:
> ct_sip_parse_numerical_param() returns only 0 or 1 now.
> But process_register_request() and process_register_response() imply
> checking for a negative value if parsing of a numerical header parameter
> failed. Let's fix it.
>
> Found by InfoTeCS on behalf of Linux Verification Center
> (linuxtesting.org) with SVACE.
>
> Fixes: 0f32a40fc91a ("[NETFILTER]: nf_conntrack_sip: create signalling expectations")
> Signed-off-by: Ilia.Gavrilov <[email protected]>
Hi Gavrilov,
although it is a slightly unusual convention for kernel code,
I believe the intention is that this function returns 0 when
it fails (to parse) and 1 on success. So I think that part is fine.
What seems a bit broken is the way that callers use the return value.
1. The call in process_register_response() looks like this:
ret = ct_sip_parse_numerical_param(...)
if (ret < 0) {
nf_ct_helper_log(skb, ct, "cannot parse expires");
return NF_DROP;
}
But ret can only be 0 or 1, so the error handling is never inoked,
and a failure to parse is ignored. I guess failure doesn't occur in
practice.
I suspect this should be:
ret = ct_sip_parse_numerical_param(...)
if (!ret) {
nf_ct_helper_log(skb, ct, "cannot parse expires");
return NF_DROP;
}
2. The callprocess_register_request() looks like this:
if (ct_sip_parse_numerical_param(...)) {
nf_ct_helper_log(skb, ct, "cannot parse expires");
return NF_DROP;
}
But this seems to treat success as an error and vice versa.
if (!ct_sip_parse_numerical_param(...)) {
nf_ct_helper_log(skb, ct, "cannot parse expires");
return NF_DROP;
}
Or, better:
ret = ct_sip_parse_numerical_param(...);
if (!ret) {
...
}
3. The invocation in nf_nat_sip() looks like this:
if (ct_sip_parse_numerical_param(...) > 0 &&
...)
...
This seems correct to me.
> ---
> net/netfilter/nf_conntrack_sip.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/netfilter/nf_conntrack_sip.c b/net/netfilter/nf_conntrack_sip.c
> index 77f5e82d8e3f..d0eac27f6ba0 100644
> --- a/net/netfilter/nf_conntrack_sip.c
> +++ b/net/netfilter/nf_conntrack_sip.c
> @@ -611,7 +611,7 @@ int ct_sip_parse_numerical_param(const struct nf_conn *ct, const char *dptr,
> start += strlen(name);
> *val = simple_strtoul(start, &end, 0);
> if (start == end)
> - return 0;
> + return -1;
> if (matchoff && matchlen) {
> *matchoff = start - dptr;
> *matchlen = end - start;
> --
> 2.30.2
>
On 4/28/23 22:24, Simon Horman wrote:
> On Wed, Apr 26, 2023 at 03:04:31PM +0000, Gavrilov Ilia wrote:
>> ct_sip_parse_numerical_param() returns only 0 or 1 now.
>> But process_register_request() and process_register_response() imply
>> checking for a negative value if parsing of a numerical header parameter
>> failed. Let's fix it.
>>
>> Found by InfoTeCS on behalf of Linux Verification Center
>> (linuxtesting.org) with SVACE.
>>
>> Fixes: 0f32a40fc91a ("[NETFILTER]: nf_conntrack_sip: create signalling expectations")
>> Signed-off-by: Ilia.Gavrilov <[email protected]>
>
> Hi Gavrilov,
>
Hi Simon, thank you for your answer.
> although it is a slightly unusual convention for kernel code,
> I believe the intention is that this function returns 0 when
> it fails (to parse) and 1 on success. So I think that part is fine.
>
> What seems a bit broken is the way that callers use the return value.
>
> 1. The call in process_register_response() looks like this:
>
> ret = ct_sip_parse_numerical_param(...)
> if (ret < 0) {
> nf_ct_helper_log(skb, ct, "cannot parse expires");
> return NF_DROP;
> }
>
> But ret can only be 0 or 1, so the error handling is never inoked,
> and a failure to parse is ignored. I guess failure doesn't occur in
> practice.
>
> I suspect this should be:
>
> ret = ct_sip_parse_numerical_param(...)
> if (!ret) {
> nf_ct_helper_log(skb, ct, "cannot parse expires");
> return NF_DROP;
> }
>
ct_sip_parse_numerical_param() returns 0 in to cases 1) when the
parameter 'expires=' isn't found in the header or 2) it's incorrectly set.
In the first case, the return value should be ignored, since this is a
normal situation
In the second case, it's better to write to the log and return NF_DROP,
or ignore it too, then checking the return value can be removed as
unnecessary.
> 2. The callprocess_register_request() looks like this:
>
> if (ct_sip_parse_numerical_param(...)) {
> nf_ct_helper_log(skb, ct, "cannot parse expires");
> return NF_DROP;
> }
>
> But this seems to treat success as an error and vice versa.
>
> if (!ct_sip_parse_numerical_param(...)) {
> nf_ct_helper_log(skb, ct, "cannot parse expires");
> return NF_DROP;
> }
>
> Or, better:
>
> ret = ct_sip_parse_numerical_param(...);
> if (!ret) {
> ...
> }
>
Here is the same as in process_register_response()
ret = ct_sip_parse_numerical_param(...);
if (ret < 0) {
...
return NF_DROP;
}
Maybe it's better to remove the check altogether?
>
> 3. The invocation in nf_nat_sip() looks like this:
>
> if (ct_sip_parse_numerical_param(...) > 0 &&
> ...)
> ...
>
> This seems correct to me.
I agree, everything seems correct here
>
>> ---
>> net/netfilter/nf_conntrack_sip.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/net/netfilter/nf_conntrack_sip.c b/net/netfilter/nf_conntrack_sip.c
>> index 77f5e82d8e3f..d0eac27f6ba0 100644
>> --- a/net/netfilter/nf_conntrack_sip.c
>> +++ b/net/netfilter/nf_conntrack_sip.c
>> @@ -611,7 +611,7 @@ int ct_sip_parse_numerical_param(const struct nf_conn *ct, const char *dptr,
>> start += strlen(name);
>> *val = simple_strtoul(start, &end, 0);
>> if (start == end)
>> - return 0;
>> + return -1;
>> if (matchoff && matchlen) {
>> *matchoff = start - dptr;
>> *matchlen = end - start;
>> --
>> 2.30.2
>>
On Tue, May 02, 2023 at 11:43:19AM +0000, Gavrilov Ilia wrote:
> On 4/28/23 22:24, Simon Horman wrote:
> > On Wed, Apr 26, 2023 at 03:04:31PM +0000, Gavrilov Ilia wrote:
> >> ct_sip_parse_numerical_param() returns only 0 or 1 now.
> >> But process_register_request() and process_register_response() imply
> >> checking for a negative value if parsing of a numerical header parameter
> >> failed. Let's fix it.
> >>
> >> Found by InfoTeCS on behalf of Linux Verification Center
> >> (linuxtesting.org) with SVACE.
> >>
> >> Fixes: 0f32a40fc91a ("[NETFILTER]: nf_conntrack_sip: create signalling expectations")
> >> Signed-off-by: Ilia.Gavrilov <[email protected]>
> >
> > Hi Gavrilov,
> >
>
> Hi Simon, thank you for your answer.
>
> > although it is a slightly unusual convention for kernel code,
> > I believe the intention is that this function returns 0 when
> > it fails (to parse) and 1 on success. So I think that part is fine.
> >
> > What seems a bit broken is the way that callers use the return value.
> >
> > 1. The call in process_register_response() looks like this:
> >
> > ret = ct_sip_parse_numerical_param(...)
> > if (ret < 0) {
> > nf_ct_helper_log(skb, ct, "cannot parse expires");
> > return NF_DROP;
> > }
> >
> > But ret can only be 0 or 1, so the error handling is never inoked,
> > and a failure to parse is ignored. I guess failure doesn't occur in
> > practice.
> >
> > I suspect this should be:
> >
> > ret = ct_sip_parse_numerical_param(...)
> > if (!ret) {
> > nf_ct_helper_log(skb, ct, "cannot parse expires");
> > return NF_DROP;
> > }
> >
>
> ct_sip_parse_numerical_param() returns 0 in to cases 1) when the
> parameter 'expires=' isn't found in the header or 2) it's incorrectly set.
> In the first case, the return value should be ignored, since this is a
> normal situation
> In the second case, it's better to write to the log and return NF_DROP,
> or ignore it too, then checking the return value can be removed as
> unnecessary.
Sorry, I think I misunderstood the intention of your patch earlier.
Do I (now) understand correctly that you are proposing a tristate?
a) return 1 if value is found; *val is set
b) return 0 if value is not found; *val is unchanged
c) return -1 on error; *val is undefined
On 5/2/23 17:05, Simon Horman wrote:
> On Tue, May 02, 2023 at 11:43:19AM +0000, Gavrilov Ilia wrote:
>> On 4/28/23 22:24, Simon Horman wrote:
>>> On Wed, Apr 26, 2023 at 03:04:31PM +0000, Gavrilov Ilia wrote:
>>>> ct_sip_parse_numerical_param() returns only 0 or 1 now.
>>>> But process_register_request() and process_register_response() imply
>>>> checking for a negative value if parsing of a numerical header parameter
>>>> failed. Let's fix it.
>>>>
>>>> Found by InfoTeCS on behalf of Linux Verification Center
>>>> (linuxtesting.org) with SVACE.
>>>>
>>>> Fixes: 0f32a40fc91a ("[NETFILTER]: nf_conntrack_sip: create signalling expectations")
>>>> Signed-off-by: Ilia.Gavrilov <[email protected]>
>>>
>>> Hi Gavrilov,
>>>
>>
>> Hi Simon, thank you for your answer.
>>
>>> although it is a slightly unusual convention for kernel code,
>>> I believe the intention is that this function returns 0 when
>>> it fails (to parse) and 1 on success. So I think that part is fine.
>>>
>>> What seems a bit broken is the way that callers use the return value.
>>>
>>> 1. The call in process_register_response() looks like this:
>>>
>>> ret = ct_sip_parse_numerical_param(...)
>>> if (ret < 0) {
>>> nf_ct_helper_log(skb, ct, "cannot parse expires");
>>> return NF_DROP;
>>> }
>>>
>>> But ret can only be 0 or 1, so the error handling is never inoked,
>>> and a failure to parse is ignored. I guess failure doesn't occur in
>>> practice.
>>>
>>> I suspect this should be:
>>>
>>> ret = ct_sip_parse_numerical_param(...)
>>> if (!ret) {
>>> nf_ct_helper_log(skb, ct, "cannot parse expires");
>>> return NF_DROP;
>>> }
>>>
>>
>> ct_sip_parse_numerical_param() returns 0 in to cases 1) when the
>> parameter 'expires=' isn't found in the header or 2) it's incorrectly set.
>> In the first case, the return value should be ignored, since this is a
>> normal situation
>> In the second case, it's better to write to the log and return NF_DROP,
>> or ignore it too, then checking the return value can be removed as
>> unnecessary.
>
> Sorry, I think I misunderstood the intention of your patch earlier.
>
> Do I (now) understand correctly that you are proposing a tristate?
>
> a) return 1 if value is found; *val is set
> b) return 0 if value is not found; *val is unchanged
> c) return -1 on error; *val is undefined
Yes, it seems to me that this was originally intended.
On Tue, May 02, 2023 at 02:16:09PM +0000, Gavrilov Ilia wrote:
> On 5/2/23 17:05, Simon Horman wrote:
> > On Tue, May 02, 2023 at 11:43:19AM +0000, Gavrilov Ilia wrote:
> >> On 4/28/23 22:24, Simon Horman wrote:
> >>> On Wed, Apr 26, 2023 at 03:04:31PM +0000, Gavrilov Ilia wrote:
> >>>> ct_sip_parse_numerical_param() returns only 0 or 1 now.
> >>>> But process_register_request() and process_register_response() imply
> >>>> checking for a negative value if parsing of a numerical header parameter
> >>>> failed. Let's fix it.
> >>>>
> >>>> Found by InfoTeCS on behalf of Linux Verification Center
> >>>> (linuxtesting.org) with SVACE.
> >>>>
> >>>> Fixes: 0f32a40fc91a ("[NETFILTER]: nf_conntrack_sip: create signalling expectations")
> >>>> Signed-off-by: Ilia.Gavrilov <[email protected]>
> >>>
> >>> Hi Gavrilov,
> >>>
> >>
> >> Hi Simon, thank you for your answer.
> >>
> >>> although it is a slightly unusual convention for kernel code,
> >>> I believe the intention is that this function returns 0 when
> >>> it fails (to parse) and 1 on success. So I think that part is fine.
> >>>
> >>> What seems a bit broken is the way that callers use the return value.
> >>>
> >>> 1. The call in process_register_response() looks like this:
> >>>
> >>> ret = ct_sip_parse_numerical_param(...)
> >>> if (ret < 0) {
> >>> nf_ct_helper_log(skb, ct, "cannot parse expires");
> >>> return NF_DROP;
> >>> }
> >>>
> >>> But ret can only be 0 or 1, so the error handling is never inoked,
> >>> and a failure to parse is ignored. I guess failure doesn't occur in
> >>> practice.
> >>>
> >>> I suspect this should be:
> >>>
> >>> ret = ct_sip_parse_numerical_param(...)
> >>> if (!ret) {
> >>> nf_ct_helper_log(skb, ct, "cannot parse expires");
> >>> return NF_DROP;
> >>> }
> >>>
> >>
> >> ct_sip_parse_numerical_param() returns 0 in to cases 1) when the
> >> parameter 'expires=' isn't found in the header or 2) it's incorrectly set.
> >> In the first case, the return value should be ignored, since this is a
> >> normal situation
> >> In the second case, it's better to write to the log and return NF_DROP,
> >> or ignore it too, then checking the return value can be removed as
> >> unnecessary.
> >
> > Sorry, I think I misunderstood the intention of your patch earlier.
> >
> > Do I (now) understand correctly that you are proposing a tristate?
> >
> > a) return 1 if value is found; *val is set
> > b) return 0 if value is not found; *val is unchanged
> > c) return -1 on error; *val is undefined
>
> Yes, it seems to me that this was originally intended.
Thanks. With my new found understanding, this looks good to me.
Reviewed-by: Simon Horman <[email protected]>
On 5/2/23 18:38, Simon Horman wrote:
> On Tue, May 02, 2023 at 02:16:09PM +0000, Gavrilov Ilia wrote:
>> On 5/2/23 17:05, Simon Horman wrote:
>>> On Tue, May 02, 2023 at 11:43:19AM +0000, Gavrilov Ilia wrote:
>>>> On 4/28/23 22:24, Simon Horman wrote:
>>>>> On Wed, Apr 26, 2023 at 03:04:31PM +0000, Gavrilov Ilia wrote:
>>>>>> ct_sip_parse_numerical_param() returns only 0 or 1 now.
>>>>>> But process_register_request() and process_register_response() imply
>>>>>> checking for a negative value if parsing of a numerical header parameter
>>>>>> failed. Let's fix it.
>>>>>>
>>>>>> Found by InfoTeCS on behalf of Linux Verification Center
>>>>>> (linuxtesting.org) with SVACE.
>>>>>>
>>>>>> Fixes: 0f32a40fc91a ("[NETFILTER]: nf_conntrack_sip: create signalling expectations")
>>>>>> Signed-off-by: Ilia.Gavrilov <[email protected]>
>>>>>
>>>>> Hi Gavrilov,
>>>>>
>>>>
>>>> Hi Simon, thank you for your answer.
>>>>
>>>>> although it is a slightly unusual convention for kernel code,
>>>>> I believe the intention is that this function returns 0 when
>>>>> it fails (to parse) and 1 on success. So I think that part is fine.
>>>>>
>>>>> What seems a bit broken is the way that callers use the return value.
>>>>>
>>>>> 1. The call in process_register_response() looks like this:
>>>>>
>>>>> ret = ct_sip_parse_numerical_param(...)
>>>>> if (ret < 0) {
>>>>> nf_ct_helper_log(skb, ct, "cannot parse expires");
>>>>> return NF_DROP;
>>>>> }
>>>>>
>>>>> But ret can only be 0 or 1, so the error handling is never inoked,
>>>>> and a failure to parse is ignored. I guess failure doesn't occur in
>>>>> practice.
>>>>>
>>>>> I suspect this should be:
>>>>>
>>>>> ret = ct_sip_parse_numerical_param(...)
>>>>> if (!ret) {
>>>>> nf_ct_helper_log(skb, ct, "cannot parse expires");
>>>>> return NF_DROP;
>>>>> }
>>>>>
>>>>
>>>> ct_sip_parse_numerical_param() returns 0 in to cases 1) when the
>>>> parameter 'expires=' isn't found in the header or 2) it's incorrectly set.
>>>> In the first case, the return value should be ignored, since this is a
>>>> normal situation
>>>> In the second case, it's better to write to the log and return NF_DROP,
>>>> or ignore it too, then checking the return value can be removed as
>>>> unnecessary.
>>>
>>> Sorry, I think I misunderstood the intention of your patch earlier.
>>>
>>> Do I (now) understand correctly that you are proposing a tristate?
>>>
>>> a) return 1 if value is found; *val is set
>>> b) return 0 if value is not found; *val is unchanged
>>> c) return -1 on error; *val is undefined
>>
>> Yes, it seems to me that this was originally intended.
>
> Thanks. With my new found understanding, this looks good to me.
>
> Reviewed-by: Simon Horman <[email protected]>
>
Hi, Simon.
I'm sorry to bother you.
Will this patch be applied or rejected?
Đ’est regards, Ilya.
Gavrilov Ilia <[email protected]> wrote:
> Hi, Simon.
> I'm sorry to bother you.
> Will this patch be applied or rejected?
Please resend, keeping Simons Reviewd-by tag.
Please update the commit message as per your and Simons
conversation, i.e. that the return value is now a tristate,
0 for not found and -1 for 'malformed' and that you checked
all callers that they will do the right thing.