[PATCH] netfilter: nf_nat_h323: fix logical-not-parentheses warning

[PATCH] netfilter: nf_nat_h323: fix logical-not-parentheses warning

[Nick Desaulniers]

Clang produces the following warning:

net/ipv4/netfilter/nf_nat_h323.c:553:6: error:
logical not is only applied to the left hand side of this comparison
  [-Werror,-Wlogical-not-parentheses]
if (!set_h225_addr(skb, protoff, data, dataoff, taddr,
    ^
add parentheses after the '!' to evaluate the comparison first
add parentheses around left hand side expression to silence this warning

There's not necessarily a bug here, but it's cleaner to use the form:

if (x != 0)

rather than:

if (!x == 0)

Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
---
Also, it's even cleaner to use the form:

if (x)

but then if the return codes change from treating 0 as success (unlikely),
then all call sites must be updated.

I'm happy to send v2 that changes to that form, and updates the other call
sites to be:

if (set_h225_addr())
  handle_failures()
else
  handle_success()

 net/ipv4/netfilter/nf_nat_h323.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/net/ipv4/netfilter/nf_nat_h323.c b/net/ipv4/netfilter/nf_nat_h323.c
index 574f7ebba0b6..d8fb251fa6e3 100644
--- a/net/ipv4/netfilter/nf_nat_h323.c
+++ b/net/ipv4/netfilter/nf_nat_h323.c
@@ -550,9 +550,9 @@ static int nat_callforwarding(struct sk_buff *skb, struct nf_conn *ct,
 	}
 
 	/* Modify signal */
-	if (!set_h225_addr(skb, protoff, data, dataoff, taddr,
-			   &ct->tuplehash[!dir].tuple.dst.u3,
-			   htons(nated_port)) == 0) {
+	if (set_h225_addr(skb, protoff, data, dataoff, taddr,
+			  &ct->tuplehash[!dir].tuple.dst.u3,
+			  htons(nated_port)) != 0) {
 		nf_ct_unexpect_related(exp);
 		return -1;
 	}
-- 
2.14.0.rc0.400.g1c36432dff-goog

Re: [PATCH] netfilter: nf_nat_h323: fix logical-not-parentheses warning

[Nick Desaulniers]

bumping for review

On Mon, Jul 31, 2017 at 11:39 AM, Nick Desaulniers
<ndesaulniers@google.com> wrote:
> Clang produces the following warning:
>
> net/ipv4/netfilter/nf_nat_h323.c:553:6: error:
> logical not is only applied to the left hand side of this comparison
>   [-Werror,-Wlogical-not-parentheses]
> if (!set_h225_addr(skb, protoff, data, dataoff, taddr,
>     ^
> add parentheses after the '!' to evaluate the comparison first
> add parentheses around left hand side expression to silence this warning
>
> There's not necessarily a bug here, but it's cleaner to use the form:
>
> if (x != 0)
>
> rather than:
>
> if (!x == 0)
>
> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
> ---
> Also, it's even cleaner to use the form:
>
> if (x)
>
> but then if the return codes change from treating 0 as success (unlikely),
> then all call sites must be updated.
>
> I'm happy to send v2 that changes to that form, and updates the other call
> sites to be:
>
> if (set_h225_addr())
>   handle_failures()
> else
>   handle_success()
>
>  net/ipv4/netfilter/nf_nat_h323.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/net/ipv4/netfilter/nf_nat_h323.c b/net/ipv4/netfilter/nf_nat_h323.c
> index 574f7ebba0b6..d8fb251fa6e3 100644
> --- a/net/ipv4/netfilter/nf_nat_h323.c
> +++ b/net/ipv4/netfilter/nf_nat_h323.c
> @@ -550,9 +550,9 @@ static int nat_callforwarding(struct sk_buff *skb, struct nf_conn *ct,
>         }
>
>         /* Modify signal */
> -       if (!set_h225_addr(skb, protoff, data, dataoff, taddr,
> -                          &ct->tuplehash[!dir].tuple.dst.u3,
> -                          htons(nated_port)) == 0) {
> +       if (set_h225_addr(skb, protoff, data, dataoff, taddr,
> +                         &ct->tuplehash[!dir].tuple.dst.u3,
> +                         htons(nated_port)) != 0) {
>                 nf_ct_unexpect_related(exp);
>                 return -1;
>         }
> --
> 2.14.0.rc0.400.g1c36432dff-goog
>



-- 
Thanks,
~Nick Desaulniers

Re: [PATCH] netfilter: nf_nat_h323: fix logical-not-parentheses warning

[Pablo Neira Ayuso]

Hi Nick,

On Mon, Jul 31, 2017 at 11:39:49AM -0700, Nick Desaulniers wrote:
> Clang produces the following warning:
[...]
> Also, it's even cleaner to use the form:
> 
> if (x)
> 
> but then if the return codes change from treating 0 as success (unlikely),
> then all call sites must be updated.
> 
> I'm happy to send v2 that changes to that form, and updates the other call
> sites to be:
> 
> if (set_h225_addr())
>   handle_failures()
> else
>   handle_success()

That sounds very reasonable, send a v2 if this triggers a larger
patch.

Or I can just take this patch, as you prefer.

Thanks!

[PATCH v2] netfilter: nf_nat_h323: fix logical-not-parentheses warning

[Nick Desaulniers]

Clang produces the following warning:

net/ipv4/netfilter/nf_nat_h323.c:553:6: error:
logical not is only applied to the left hand side of this comparison
  [-Werror,-Wlogical-not-parentheses]
if (!set_h225_addr(skb, protoff, data, dataoff, taddr,
    ^
add parentheses after the '!' to evaluate the comparison first
add parentheses around left hand side expression to silence this warning

There's not necessarily a bug here, but it's cleaner to return early,
ex:

if (x)
  return
...

rather than:

if (!x == 0)
  ...
else
  return

Also added a return code check that seemed to be missing in one
instance.

Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
---
Changes in v2:
* Reorder if/else blocks to return early.
* Also handle this for set_h245_addr(), not just set_h225_addr().
* Add return code check for the Gnomemeeting case.

 net/ipv4/netfilter/nf_nat_h323.c | 57 +++++++++++++++++++++-------------------
 1 file changed, 30 insertions(+), 27 deletions(-)

diff --git a/net/ipv4/netfilter/nf_nat_h323.c b/net/ipv4/netfilter/nf_nat_h323.c
index 574f7ebba0b6..ac8342dcb55e 100644
--- a/net/ipv4/netfilter/nf_nat_h323.c
+++ b/net/ipv4/netfilter/nf_nat_h323.c
@@ -252,16 +252,16 @@ static int nat_rtp_rtcp(struct sk_buff *skb, struct nf_conn *ct,
 	if (set_h245_addr(skb, protoff, data, dataoff, taddr,
 			  &ct->tuplehash[!dir].tuple.dst.u3,
 			  htons((port & htons(1)) ? nated_port + 1 :
-						    nated_port)) == 0) {
-		/* Save ports */
-		info->rtp_port[i][dir] = rtp_port;
-		info->rtp_port[i][!dir] = htons(nated_port);
-	} else {
+						    nated_port))) {
 		nf_ct_unexpect_related(rtp_exp);
 		nf_ct_unexpect_related(rtcp_exp);
 		return -1;
 	}
 
+	/* Save ports */
+	info->rtp_port[i][dir] = rtp_port;
+	info->rtp_port[i][!dir] = htons(nated_port);
+
 	/* Success */
 	pr_debug("nf_nat_h323: expect RTP %pI4:%hu->%pI4:%hu\n",
 		 &rtp_exp->tuple.src.u3.ip,
@@ -370,15 +370,15 @@ static int nat_h245(struct sk_buff *skb, struct nf_conn *ct,
 	/* Modify signal */
 	if (set_h225_addr(skb, protoff, data, dataoff, taddr,
 			  &ct->tuplehash[!dir].tuple.dst.u3,
-			  htons(nated_port)) == 0) {
-		/* Save ports */
-		info->sig_port[dir] = port;
-		info->sig_port[!dir] = htons(nated_port);
-	} else {
+			  htons(nated_port))) {
 		nf_ct_unexpect_related(exp);
 		return -1;
 	}
 
+	/* Save ports */
+	info->sig_port[dir] = port;
+	info->sig_port[!dir] = htons(nated_port);
+
 	pr_debug("nf_nat_q931: expect H.245 %pI4:%hu->%pI4:%hu\n",
 		 &exp->tuple.src.u3.ip,
 		 ntohs(exp->tuple.src.u.tcp.port),
@@ -462,24 +462,27 @@ static int nat_q931(struct sk_buff *skb, struct nf_conn *ct,
 	/* Modify signal */
 	if (set_h225_addr(skb, protoff, data, 0, &taddr[idx],
 			  &ct->tuplehash[!dir].tuple.dst.u3,
-			  htons(nated_port)) == 0) {
-		/* Save ports */
-		info->sig_port[dir] = port;
-		info->sig_port[!dir] = htons(nated_port);
-
-		/* Fix for Gnomemeeting */
-		if (idx > 0 &&
-		    get_h225_addr(ct, *data, &taddr[0], &addr, &port) &&
-		    (ntohl(addr.ip) & 0xff000000) == 0x7f000000) {
-			set_h225_addr(skb, protoff, data, 0, &taddr[0],
-				      &ct->tuplehash[!dir].tuple.dst.u3,
-				      info->sig_port[!dir]);
-		}
-	} else {
+			  htons(nated_port))) {
 		nf_ct_unexpect_related(exp);
 		return -1;
 	}
 
+	/* Save ports */
+	info->sig_port[dir] = port;
+	info->sig_port[!dir] = htons(nated_port);
+
+	/* Fix for Gnomemeeting */
+	if (idx > 0 &&
+	    get_h225_addr(ct, *data, &taddr[0], &addr, &port) &&
+	    (ntohl(addr.ip) & 0xff000000) == 0x7f000000) {
+		if (set_h225_addr(skb, protoff, data, 0, &taddr[0],
+				  &ct->tuplehash[!dir].tuple.dst.u3,
+				  info->sig_port[!dir])) {
+			nf_ct_unexpect_related(exp);
+			return -1;
+		}
+	}
+
 	/* Success */
 	pr_debug("nf_nat_ras: expect Q.931 %pI4:%hu->%pI4:%hu\n",
 		 &exp->tuple.src.u3.ip,
@@ -550,9 +553,9 @@ static int nat_callforwarding(struct sk_buff *skb, struct nf_conn *ct,
 	}
 
 	/* Modify signal */
-	if (!set_h225_addr(skb, protoff, data, dataoff, taddr,
-			   &ct->tuplehash[!dir].tuple.dst.u3,
-			   htons(nated_port)) == 0) {
+	if (set_h225_addr(skb, protoff, data, dataoff, taddr,
+			  &ct->tuplehash[!dir].tuple.dst.u3,
+			  htons(nated_port))) {
 		nf_ct_unexpect_related(exp);
 		return -1;
 	}
-- 
2.14.0.434.g98096fd7a8-goog

Re: [PATCH v2] netfilter: nf_nat_h323: fix logical-not-parentheses warning

[Nick Desaulniers]

Minor nit for the commit message that can get fixed up when being merged:

On Fri, Aug 11, 2017 at 11:16 AM, Nick Desaulniers
<ndesaulniers@google.com> wrote:

> if (x)
>   return
> ...
>
> rather than:
>
> if (!x == 0)

should remove the `!`, ex:

if (x == 0)

>   ...
> else
>   return

-- 
Thanks,
~Nick Desaulniers

Re: [PATCH v2] netfilter: nf_nat_h323: fix logical-not-parentheses warning

[Nick Desaulniers]

bumping for review (resending, had gmail set to html mode)

On Mon, Aug 14, 2017 at 10:36 AM, Nick Desaulniers
<ndesaulniers@google.com> wrote:
> Minor nit for the commit message that can get fixed up when being merged:
>
> On Fri, Aug 11, 2017 at 11:16 AM, Nick Desaulniers
> <ndesaulniers@google.com> wrote:
>
>> if (x)
>>   return
>> ...
>>
>> rather than:
>>
>> if (!x == 0)
>
> should remove the `!`, ex:
>
> if (x == 0)
>
>>   ...
>> else
>>   return
>
> --
> Thanks,
> ~Nick Desaulniers



-- 
Thanks,
~Nick Desaulniers

Re: [PATCH v2] netfilter: nf_nat_h323: fix logical-not-parentheses warning

[Pablo Neira Ayuso]

On Mon, Aug 14, 2017 at 10:36:03AM -0700, Nick Desaulniers wrote:
> Minor nit for the commit message that can get fixed up when being merged:
> 
> On Fri, Aug 11, 2017 at 11:16 AM, Nick Desaulniers
> <ndesaulniers@google.com> wrote:
> 
> > if (x)
> >   return
> > ...
> >
> > rather than:
> >
> > if (!x == 0)
> 
> should remove the `!`, ex:
> 
> if (x == 0)

Amended this here, and applied. Thanks!