[PATCH] netfilter: xt_TPROXY: fix clang -Wformat warnings:

[PATCH] netfilter: xt_TPROXY: fix clang -Wformat warnings:

[Justin Stitt]

When building with Clang we encounter these warnings:
| net/netfilter/xt_TPROXY.c:173:5: error: format specifies type 'unsigned
| char' but the argument has type 'int' [-Werror,-Wformat] tproto,
| &iph->saddr, ntohs(hp->source),
-
| net/netfilter/xt_TPROXY.c:181:4: error: format specifies type 'unsigned
| char' but the argument has type 'int' [-Werror,-Wformat] tproto,
| &iph->saddr, ntohs(hp->source),

The format specifier `%hhu` refers to a u8 while tproto is an int. In
this case we weren't losing any data because ipv6_find_hdr returns an
int but its return value (nexthdr) is a u8. This u8 gets widened to an
int when returned from ipv6_find_hdr and assigned to tproto. The
previous format specifier is functionally fine but still produces a
warning due to a type mismatch.

The fix is simply to listen to Clang and change `%hhu` to `%d` for both
instances of the warning.

Link: https://github.com/ClangBuiltLinux/linux/issues/378
Signed-off-by: Justin Stitt <justinstitt@google.com>
---
It should be noted that for this entire file to build without -Wformat
warnings you should apply this `ntohs` patch which fixed many, many
-Wformat warnings in the kernel.
https://lore.kernel.org/all/20220608223539.470472-1-justinstitt@google.com/

 net/netfilter/xt_TPROXY.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/netfilter/xt_TPROXY.c b/net/netfilter/xt_TPROXY.c
index 459d0696c91a..5d74abffc94f 100644
--- a/net/netfilter/xt_TPROXY.c
+++ b/net/netfilter/xt_TPROXY.c
@@ -169,7 +169,7 @@ tproxy_tg6_v1(struct sk_buff *skb, const struct xt_action_param *par)
 		   targets on the same rule yet */
 		skb->mark = (skb->mark & ~tgi->mark_mask) ^ tgi->mark_value;
 
-		pr_debug("redirecting: proto %hhu %pI6:%hu -> %pI6:%hu, mark: %x\n",
+		pr_debug("redirecting: proto %d %pI6:%hu -> %pI6:%hu, mark: %x\n",
 			 tproto, &iph->saddr, ntohs(hp->source),
 			 laddr, ntohs(lport), skb->mark);
 
@@ -177,7 +177,7 @@ tproxy_tg6_v1(struct sk_buff *skb, const struct xt_action_param *par)
 		return NF_ACCEPT;
 	}
 
-	pr_debug("no socket, dropping: proto %hhu %pI6:%hu -> %pI6:%hu, mark: %x\n",
+	pr_debug("no socket, dropping: proto %d %pI6:%hu -> %pI6:%hu, mark: %x\n",
 		 tproto, &iph->saddr, ntohs(hp->source),
 		 &iph->daddr, ntohs(hp->dest), skb->mark);
 
-- 
2.37.0.rc0.161.g10f37bed90-goog

Re: [PATCH] netfilter: xt_TPROXY: fix clang -Wformat warnings:

[Nick Desaulniers]

On Thu, Jul 7, 2022 at 12:18 PM Justin Stitt <justinstitt@google.com> wrote:
>
> When building with Clang we encounter these warnings:
> | net/netfilter/xt_TPROXY.c:173:5: error: format specifies type 'unsigned
> | char' but the argument has type 'int' [-Werror,-Wformat] tproto,
> | &iph->saddr, ntohs(hp->source),
> -
> | net/netfilter/xt_TPROXY.c:181:4: error: format specifies type 'unsigned
> | char' but the argument has type 'int' [-Werror,-Wformat] tproto,
> | &iph->saddr, ntohs(hp->source),
>
> The format specifier `%hhu` refers to a u8 while tproto is an int. In
> this case we weren't losing any data because ipv6_find_hdr returns an
> int but its return value (nexthdr) is a u8. This u8 gets widened to an
> int when returned from ipv6_find_hdr and assigned to tproto. The
> previous format specifier is functionally fine but still produces a
> warning due to a type mismatch.
>
> The fix is simply to listen to Clang and change `%hhu` to `%d` for both
> instances of the warning.
>
> Link: https://github.com/ClangBuiltLinux/linux/issues/378
> Signed-off-by: Justin Stitt <justinstitt@google.com>

Thanks for the patch, this fixes the warning I observe when building
ARCH=arm64 allmodconfig with -Wno-format removed!
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>

> ---
> It should be noted that for this entire file to build without -Wformat
> warnings you should apply this `ntohs` patch which fixed many, many
> -Wformat warnings in the kernel.
> https://lore.kernel.org/all/20220608223539.470472-1-justinstitt@google.com/
>
>  net/netfilter/xt_TPROXY.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/net/netfilter/xt_TPROXY.c b/net/netfilter/xt_TPROXY.c
> index 459d0696c91a..5d74abffc94f 100644
> --- a/net/netfilter/xt_TPROXY.c
> +++ b/net/netfilter/xt_TPROXY.c
> @@ -169,7 +169,7 @@ tproxy_tg6_v1(struct sk_buff *skb, const struct xt_action_param *par)
>                    targets on the same rule yet */
>                 skb->mark = (skb->mark & ~tgi->mark_mask) ^ tgi->mark_value;
>
> -               pr_debug("redirecting: proto %hhu %pI6:%hu -> %pI6:%hu, mark: %x\n",
> +               pr_debug("redirecting: proto %d %pI6:%hu -> %pI6:%hu, mark: %x\n",
>                          tproto, &iph->saddr, ntohs(hp->source),
>                          laddr, ntohs(lport), skb->mark);
>
> @@ -177,7 +177,7 @@ tproxy_tg6_v1(struct sk_buff *skb, const struct xt_action_param *par)
>                 return NF_ACCEPT;
>         }
>
> -       pr_debug("no socket, dropping: proto %hhu %pI6:%hu -> %pI6:%hu, mark: %x\n",
> +       pr_debug("no socket, dropping: proto %d %pI6:%hu -> %pI6:%hu, mark: %x\n",
>                  tproto, &iph->saddr, ntohs(hp->source),
>                  &iph->daddr, ntohs(hp->dest), skb->mark);
>
> --
> 2.37.0.rc0.161.g10f37bed90-goog
>


-- 
Thanks,
~Nick Desaulniers

Re: [PATCH] netfilter: xt_TPROXY: fix clang -Wformat warnings:

[Pablo Neira Ayuso]

On Thu, Jul 07, 2022 at 12:17:45PM -0700, Justin Stitt wrote:
> diff --git a/net/netfilter/xt_TPROXY.c b/net/netfilter/xt_TPROXY.c
> index 459d0696c91a..5d74abffc94f 100644
> --- a/net/netfilter/xt_TPROXY.c
> +++ b/net/netfilter/xt_TPROXY.c
> @@ -169,7 +169,7 @@ tproxy_tg6_v1(struct sk_buff *skb, const struct xt_action_param *par)
>  		   targets on the same rule yet */
>  		skb->mark = (skb->mark & ~tgi->mark_mask) ^ tgi->mark_value;
>  
> -		pr_debug("redirecting: proto %hhu %pI6:%hu -> %pI6:%hu, mark: %x\n",
> +		pr_debug("redirecting: proto %d %pI6:%hu -> %pI6:%hu, mark: %x\n",
>  			 tproto, &iph->saddr, ntohs(hp->source),
>  			 laddr, ntohs(lport), skb->mark);
>  
> @@ -177,7 +177,7 @@ tproxy_tg6_v1(struct sk_buff *skb, const struct xt_action_param *par)
>  		return NF_ACCEPT;
>  	}
>  
> -	pr_debug("no socket, dropping: proto %hhu %pI6:%hu -> %pI6:%hu, mark: %x\n",
> +	pr_debug("no socket, dropping: proto %d %pI6:%hu -> %pI6:%hu, mark: %x\n",
>  		 tproto, &iph->saddr, ntohs(hp->source),
>  		 &iph->daddr, ntohs(hp->dest), skb->mark);

Could you instead send a patch to remove these pr_debug calls?

Thanks.

Re: [PATCH] netfilter: xt_TPROXY: fix clang -Wformat warnings:

[Justin Stitt]

On Mon, Jul 11, 2022 at 2:04 AM Pablo Neira Ayuso <pablo@netfilter.org> wrote:
>
> On Thu, Jul 07, 2022 at 12:17:45PM -0700, Justin Stitt wrote:
> > diff --git a/net/netfilter/xt_TPROXY.c b/net/netfilter/xt_TPROXY.c
> > index 459d0696c91a..5d74abffc94f 100644
> > --- a/net/netfilter/xt_TPROXY.c
> > +++ b/net/netfilter/xt_TPROXY.c
> > @@ -169,7 +169,7 @@ tproxy_tg6_v1(struct sk_buff *skb, const struct xt_action_param *par)
> >                  targets on the same rule yet */
> >               skb->mark = (skb->mark & ~tgi->mark_mask) ^ tgi->mark_value;
> >
> > -             pr_debug("redirecting: proto %hhu %pI6:%hu -> %pI6:%hu, mark: %x\n",
> > +             pr_debug("redirecting: proto %d %pI6:%hu -> %pI6:%hu, mark: %x\n",
> >                        tproto, &iph->saddr, ntohs(hp->source),
> >                        laddr, ntohs(lport), skb->mark);
> >
> > @@ -177,7 +177,7 @@ tproxy_tg6_v1(struct sk_buff *skb, const struct xt_action_param *par)
> >               return NF_ACCEPT;
> >       }
> >
> > -     pr_debug("no socket, dropping: proto %hhu %pI6:%hu -> %pI6:%hu, mark: %x\n",
> > +     pr_debug("no socket, dropping: proto %d %pI6:%hu -> %pI6:%hu, mark: %x\n",
> >                tproto, &iph->saddr, ntohs(hp->source),
> >                &iph->daddr, ntohs(hp->dest), skb->mark);
>
> Could you instead send a patch to remove these pr_debug calls?
Do you mean all Instances of pr_debug in `xt_TPROXY.c` (of which there
are six) or just these two specific cases @ +169 and +177.
> Thanks.

Re: [PATCH] netfilter: xt_TPROXY: fix clang -Wformat warnings:

[Pablo Neira Ayuso]

On Mon, Jul 11, 2022 at 12:44:05PM -0700, Justin Stitt wrote:
> On Mon, Jul 11, 2022 at 2:04 AM Pablo Neira Ayuso <pablo@netfilter.org> wrote:
> >
> > On Thu, Jul 07, 2022 at 12:17:45PM -0700, Justin Stitt wrote:
> > > diff --git a/net/netfilter/xt_TPROXY.c b/net/netfilter/xt_TPROXY.c
> > > index 459d0696c91a..5d74abffc94f 100644
> > > --- a/net/netfilter/xt_TPROXY.c
> > > +++ b/net/netfilter/xt_TPROXY.c
> > > @@ -169,7 +169,7 @@ tproxy_tg6_v1(struct sk_buff *skb, const struct xt_action_param *par)
> > >                  targets on the same rule yet */
> > >               skb->mark = (skb->mark & ~tgi->mark_mask) ^ tgi->mark_value;
> > >
> > > -             pr_debug("redirecting: proto %hhu %pI6:%hu -> %pI6:%hu, mark: %x\n",
> > > +             pr_debug("redirecting: proto %d %pI6:%hu -> %pI6:%hu, mark: %x\n",
> > >                        tproto, &iph->saddr, ntohs(hp->source),
> > >                        laddr, ntohs(lport), skb->mark);
> > >
> > > @@ -177,7 +177,7 @@ tproxy_tg6_v1(struct sk_buff *skb, const struct xt_action_param *par)
> > >               return NF_ACCEPT;
> > >       }
> > >
> > > -     pr_debug("no socket, dropping: proto %hhu %pI6:%hu -> %pI6:%hu, mark: %x\n",
> > > +     pr_debug("no socket, dropping: proto %d %pI6:%hu -> %pI6:%hu, mark: %x\n",
> > >                tproto, &iph->saddr, ntohs(hp->source),
> > >                &iph->daddr, ntohs(hp->dest), skb->mark);
> >
> > Could you instead send a patch to remove these pr_debug calls?
>
> Do you mean all Instances of pr_debug in `xt_TPROXY.c` (of which there
> are six) or just these two specific cases @ +169 and +177.

Yes, remove all pr_debug instances, thanks.

[PATCH] netfilter: xt_TPROXY: remove pr_debug invocations

[Justin Stitt]

pr_debug calls are no longer needed in this file.

Pablo suggested "a patch to remove these pr_debug calls". This patch has
some other beneficial collateral as it also silences multiple Clang
-Wformat warnings that were present in the pr_debug calls.

Suggested-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Justin Stitt <justinstitt@google.com>
---
Suggestion here: https://lore.kernel.org/all/Ys0zZACWwGilTwHx@salvia/

 net/netfilter/xt_TPROXY.c | 19 -------------------
 1 file changed, 19 deletions(-)

diff --git a/net/netfilter/xt_TPROXY.c b/net/netfilter/xt_TPROXY.c
index 459d0696c91a..dc7284e6357b 100644
--- a/net/netfilter/xt_TPROXY.c
+++ b/net/netfilter/xt_TPROXY.c
@@ -74,18 +74,10 @@ tproxy_tg4(struct net *net, struct sk_buff *skb, __be32 laddr, __be16 lport,
 		/* This should be in a separate target, but we don't do multiple
 		   targets on the same rule yet */
 		skb->mark = (skb->mark & ~mark_mask) ^ mark_value;
-
-		pr_debug("redirecting: proto %hhu %pI4:%hu -> %pI4:%hu, mark: %x\n",
-			 iph->protocol, &iph->daddr, ntohs(hp->dest),
-			 &laddr, ntohs(lport), skb->mark);
-
 		nf_tproxy_assign_sock(skb, sk);
 		return NF_ACCEPT;
 	}
 
-	pr_debug("no socket, dropping: proto %hhu %pI4:%hu -> %pI4:%hu, mark: %x\n",
-		 iph->protocol, &iph->saddr, ntohs(hp->source),
-		 &iph->daddr, ntohs(hp->dest), skb->mark);
 	return NF_DROP;
 }
 
@@ -123,13 +115,11 @@ tproxy_tg6_v1(struct sk_buff *skb, const struct xt_action_param *par)
 
 	tproto = ipv6_find_hdr(skb, &thoff, -1, NULL, NULL);
 	if (tproto < 0) {
-		pr_debug("unable to find transport header in IPv6 packet, dropping\n");
 		return NF_DROP;
 	}
 
 	hp = skb_header_pointer(skb, thoff, sizeof(_hdr), &_hdr);
 	if (hp == NULL) {
-		pr_debug("unable to grab transport header contents in IPv6 packet, dropping\n");
 		return NF_DROP;
 	}
 
@@ -168,19 +158,10 @@ tproxy_tg6_v1(struct sk_buff *skb, const struct xt_action_param *par)
 		/* This should be in a separate target, but we don't do multiple
 		   targets on the same rule yet */
 		skb->mark = (skb->mark & ~tgi->mark_mask) ^ tgi->mark_value;
-
-		pr_debug("redirecting: proto %hhu %pI6:%hu -> %pI6:%hu, mark: %x\n",
-			 tproto, &iph->saddr, ntohs(hp->source),
-			 laddr, ntohs(lport), skb->mark);
-
 		nf_tproxy_assign_sock(skb, sk);
 		return NF_ACCEPT;
 	}
 
-	pr_debug("no socket, dropping: proto %hhu %pI6:%hu -> %pI6:%hu, mark: %x\n",
-		 tproto, &iph->saddr, ntohs(hp->source),
-		 &iph->daddr, ntohs(hp->dest), skb->mark);
-
 	return NF_DROP;
 }
 
-- 
2.37.0.144.g8ac04bfd2-goog

Re: [PATCH] netfilter: xt_TPROXY: remove pr_debug invocations

[Nathan Chancellor]

Hi Justin,

On Tue, Jul 12, 2022 at 11:34:52AM -0700, Justin Stitt wrote:
> pr_debug calls are no longer needed in this file.
> 
> Pablo suggested "a patch to remove these pr_debug calls". This patch has
> some other beneficial collateral as it also silences multiple Clang
> -Wformat warnings that were present in the pr_debug calls.
> 
> Suggested-by: Pablo Neira Ayuso <pablo@netfilter.org>
> Signed-off-by: Justin Stitt <justinstitt@google.com>

Thanks for the patch!

Reviewed-by: Nathan Chancellor <nathan@kernel.org>

Couple of style comments below that probably warrant a v2, you can carry
the above tag forward for future revisions. No need to give me a
"Suggested-by".

> ---
> Suggestion here: https://lore.kernel.org/all/Ys0zZACWwGilTwHx@salvia/
> 
>  net/netfilter/xt_TPROXY.c | 19 -------------------
>  1 file changed, 19 deletions(-)
> 
> diff --git a/net/netfilter/xt_TPROXY.c b/net/netfilter/xt_TPROXY.c
> index 459d0696c91a..dc7284e6357b 100644
> --- a/net/netfilter/xt_TPROXY.c
> +++ b/net/netfilter/xt_TPROXY.c
> @@ -74,18 +74,10 @@ tproxy_tg4(struct net *net, struct sk_buff *skb, __be32 laddr, __be16 lport,
>  		/* This should be in a separate target, but we don't do multiple
>  		   targets on the same rule yet */
>  		skb->mark = (skb->mark & ~mark_mask) ^ mark_value;
> -
> -		pr_debug("redirecting: proto %hhu %pI4:%hu -> %pI4:%hu, mark: %x\n",
> -			 iph->protocol, &iph->daddr, ntohs(hp->dest),
> -			 &laddr, ntohs(lport), skb->mark);
> -
>  		nf_tproxy_assign_sock(skb, sk);
>  		return NF_ACCEPT;
>  	}
>  
> -	pr_debug("no socket, dropping: proto %hhu %pI4:%hu -> %pI4:%hu, mark: %x\n",
> -		 iph->protocol, &iph->saddr, ntohs(hp->source),
> -		 &iph->daddr, ntohs(hp->dest), skb->mark);
>  	return NF_DROP;
>  }
>  
> @@ -123,13 +115,11 @@ tproxy_tg6_v1(struct sk_buff *skb, const struct xt_action_param *par)
>  
>  	tproto = ipv6_find_hdr(skb, &thoff, -1, NULL, NULL);
>  	if (tproto < 0) {

checkpatch.pl should have warned that these if statement braces here and
below are no longer necessary because there is only one statement within
them now.

	if (tproto < 0)
		return NF_DROP;

I believe it is important to do these types of style cleanups when doing
a larger change so that people do not try to do them as standalone
changes, which can irritate maintainers.

> -		pr_debug("unable to find transport header in IPv6 packet, dropping\n");
>  		return NF_DROP;
>  	}
>  
>  	hp = skb_header_pointer(skb, thoff, sizeof(_hdr), &_hdr);
>  	if (hp == NULL) {
> -		pr_debug("unable to grab transport header contents in IPv6 packet, dropping\n");
>  		return NF_DROP;
>  	}

	if (hp == NULL)
		return NF_DROP;

could even go a step farther and make it

	if (!hp)
		return NF_DROP;

if there is a warning about that.

>  
> @@ -168,19 +158,10 @@ tproxy_tg6_v1(struct sk_buff *skb, const struct xt_action_param *par)
>  		/* This should be in a separate target, but we don't do multiple
>  		   targets on the same rule yet */
>  		skb->mark = (skb->mark & ~tgi->mark_mask) ^ tgi->mark_value;
> -
> -		pr_debug("redirecting: proto %hhu %pI6:%hu -> %pI6:%hu, mark: %x\n",
> -			 tproto, &iph->saddr, ntohs(hp->source),
> -			 laddr, ntohs(lport), skb->mark);
> -
>  		nf_tproxy_assign_sock(skb, sk);
>  		return NF_ACCEPT;
>  	}
>  
> -	pr_debug("no socket, dropping: proto %hhu %pI6:%hu -> %pI6:%hu, mark: %x\n",
> -		 tproto, &iph->saddr, ntohs(hp->source),
> -		 &iph->daddr, ntohs(hp->dest), skb->mark);
> -
>  	return NF_DROP;
>  }
>  
> -- 
> 2.37.0.144.g8ac04bfd2-goog
> 

Re: [PATCH] netfilter: xt_TPROXY: remove pr_debug invocations

[Justin Stitt]

On Tue, Jul 12, 2022 at 11:56 AM Nathan Chancellor <nathan@kernel.org> wrote:
>
> Hi Justin,
>
> On Tue, Jul 12, 2022 at 11:34:52AM -0700, Justin Stitt wrote:
> > pr_debug calls are no longer needed in this file.
> >
> > Pablo suggested "a patch to remove these pr_debug calls". This patch has
> > some other beneficial collateral as it also silences multiple Clang
> > -Wformat warnings that were present in the pr_debug calls.
> >
> > Suggested-by: Pablo Neira Ayuso <pablo@netfilter.org>
> > Signed-off-by: Justin Stitt <justinstitt@google.com>
>
> Thanks for the patch!
>
> Reviewed-by: Nathan Chancellor <nathan@kernel.org>
>
> Couple of style comments below that probably warrant a v2, you can carry
> the above tag forward for future revisions. No need to give me a
> "Suggested-by".
>
> > ---
> > Suggestion here: https://lore.kernel.org/all/Ys0zZACWwGilTwHx@salvia/
> >
> >  net/netfilter/xt_TPROXY.c | 19 -------------------
> >  1 file changed, 19 deletions(-)
> >
> > diff --git a/net/netfilter/xt_TPROXY.c b/net/netfilter/xt_TPROXY.c
> > index 459d0696c91a..dc7284e6357b 100644
> > --- a/net/netfilter/xt_TPROXY.c
> > +++ b/net/netfilter/xt_TPROXY.c
> > @@ -74,18 +74,10 @@ tproxy_tg4(struct net *net, struct sk_buff *skb, __be32 laddr, __be16 lport,
> >               /* This should be in a separate target, but we don't do multiple
> >                  targets on the same rule yet */
> >               skb->mark = (skb->mark & ~mark_mask) ^ mark_value;
> > -
> > -             pr_debug("redirecting: proto %hhu %pI4:%hu -> %pI4:%hu, mark: %x\n",
> > -                      iph->protocol, &iph->daddr, ntohs(hp->dest),
> > -                      &laddr, ntohs(lport), skb->mark);
> > -
> >               nf_tproxy_assign_sock(skb, sk);
> >               return NF_ACCEPT;
> >       }
> >
> > -     pr_debug("no socket, dropping: proto %hhu %pI4:%hu -> %pI4:%hu, mark: %x\n",
> > -              iph->protocol, &iph->saddr, ntohs(hp->source),
> > -              &iph->daddr, ntohs(hp->dest), skb->mark);
> >       return NF_DROP;
> >  }
> >
> > @@ -123,13 +115,11 @@ tproxy_tg6_v1(struct sk_buff *skb, const struct xt_action_param *par)
> >
> >       tproto = ipv6_find_hdr(skb, &thoff, -1, NULL, NULL);
> >       if (tproto < 0) {
>
> checkpatch.pl should have warned that these if statement braces here and
> below are no longer necessary because there is only one statement within
> them now.
Weirdly, checkpatch.pl gave 0 warnings regarding this patch. At any
rate, v2 is coming shortly. Thanks for the review!

>
>         if (tproto < 0)
>                 return NF_DROP;
>
> I believe it is important to do these types of style cleanups when doing
> a larger change so that people do not try to do them as standalone
> changes, which can irritate maintainers.
>
> > -             pr_debug("unable to find transport header in IPv6 packet, dropping\n");
> >               return NF_DROP;
> >       }
> >
> >       hp = skb_header_pointer(skb, thoff, sizeof(_hdr), &_hdr);
> >       if (hp == NULL) {
> > -             pr_debug("unable to grab transport header contents in IPv6 packet, dropping\n");
> >               return NF_DROP;
> >       }
>
>         if (hp == NULL)
>                 return NF_DROP;
>
> could even go a step farther and make it
>
>         if (!hp)
>                 return NF_DROP;
>
> if there is a warning about that.
>
> >
> > @@ -168,19 +158,10 @@ tproxy_tg6_v1(struct sk_buff *skb, const struct xt_action_param *par)
> >               /* This should be in a separate target, but we don't do multiple
> >                  targets on the same rule yet */
> >               skb->mark = (skb->mark & ~tgi->mark_mask) ^ tgi->mark_value;
> > -
> > -             pr_debug("redirecting: proto %hhu %pI6:%hu -> %pI6:%hu, mark: %x\n",
> > -                      tproto, &iph->saddr, ntohs(hp->source),
> > -                      laddr, ntohs(lport), skb->mark);
> > -
> >               nf_tproxy_assign_sock(skb, sk);
> >               return NF_ACCEPT;
> >       }
> >
> > -     pr_debug("no socket, dropping: proto %hhu %pI6:%hu -> %pI6:%hu, mark: %x\n",
> > -              tproto, &iph->saddr, ntohs(hp->source),
> > -              &iph->daddr, ntohs(hp->dest), skb->mark);
> > -
> >       return NF_DROP;
> >  }
> >
> > --
> > 2.37.0.144.g8ac04bfd2-goog
> >

[PATCH v2] netfilter: xt_TPROXY: remove pr_debug invocations

[Justin Stitt]

pr_debug calls are no longer needed in this file.

Pablo suggested "a patch to remove these pr_debug calls". This patch has
some other beneficial collateral as it also silences multiple Clang
-Wformat warnings that were present in the pr_debug calls.

Suggested-by: Pablo Neira Ayuso <pablo@netfilter.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Justin Stitt <justinstitt@google.com>
---
diff from v1 -> v2:
* converted if statement one-liner style
* x == NULL is now !x

 net/netfilter/xt_TPROXY.c | 25 ++-----------------------
 1 file changed, 2 insertions(+), 23 deletions(-)

diff --git a/net/netfilter/xt_TPROXY.c b/net/netfilter/xt_TPROXY.c
index 459d0696c91a..e4bea1d346cf 100644
--- a/net/netfilter/xt_TPROXY.c
+++ b/net/netfilter/xt_TPROXY.c
@@ -74,18 +74,10 @@ tproxy_tg4(struct net *net, struct sk_buff *skb, __be32 laddr, __be16 lport,
 		/* This should be in a separate target, but we don't do multiple
 		   targets on the same rule yet */
 		skb->mark = (skb->mark & ~mark_mask) ^ mark_value;
-
-		pr_debug("redirecting: proto %hhu %pI4:%hu -> %pI4:%hu, mark: %x\n",
-			 iph->protocol, &iph->daddr, ntohs(hp->dest),
-			 &laddr, ntohs(lport), skb->mark);
-
 		nf_tproxy_assign_sock(skb, sk);
 		return NF_ACCEPT;
 	}
 
-	pr_debug("no socket, dropping: proto %hhu %pI4:%hu -> %pI4:%hu, mark: %x\n",
-		 iph->protocol, &iph->saddr, ntohs(hp->source),
-		 &iph->daddr, ntohs(hp->dest), skb->mark);
 	return NF_DROP;
 }
 
@@ -122,16 +114,12 @@ tproxy_tg6_v1(struct sk_buff *skb, const struct xt_action_param *par)
 	int tproto;
 
 	tproto = ipv6_find_hdr(skb, &thoff, -1, NULL, NULL);
-	if (tproto < 0) {
-		pr_debug("unable to find transport header in IPv6 packet, dropping\n");
+	if (tproto < 0)
 		return NF_DROP;
-	}
 
 	hp = skb_header_pointer(skb, thoff, sizeof(_hdr), &_hdr);
-	if (hp == NULL) {
-		pr_debug("unable to grab transport header contents in IPv6 packet, dropping\n");
+	if (!hp)
 		return NF_DROP;
-	}
 
 	/* check if there's an ongoing connection on the packet
 	 * addresses, this happens if the redirect already happened
@@ -168,19 +156,10 @@ tproxy_tg6_v1(struct sk_buff *skb, const struct xt_action_param *par)
 		/* This should be in a separate target, but we don't do multiple
 		   targets on the same rule yet */
 		skb->mark = (skb->mark & ~tgi->mark_mask) ^ tgi->mark_value;
-
-		pr_debug("redirecting: proto %hhu %pI6:%hu -> %pI6:%hu, mark: %x\n",
-			 tproto, &iph->saddr, ntohs(hp->source),
-			 laddr, ntohs(lport), skb->mark);
-
 		nf_tproxy_assign_sock(skb, sk);
 		return NF_ACCEPT;
 	}
 
-	pr_debug("no socket, dropping: proto %hhu %pI6:%hu -> %pI6:%hu, mark: %x\n",
-		 tproto, &iph->saddr, ntohs(hp->source),
-		 &iph->daddr, ntohs(hp->dest), skb->mark);
-
 	return NF_DROP;
 }
 
-- 
2.37.0.144.g8ac04bfd2-goog

Re: [PATCH v2] netfilter: xt_TPROXY: remove pr_debug invocations

[Justin Stitt]

Any chance a maintainer could take a look at this patch? I am trying
to get it through this cycle and we are so close to enabling the
-Wformat option for Clang. There's only a handful of patches remaining
until the patch enabling this warning can be sent!

Re: [PATCH v2] netfilter: xt_TPROXY: remove pr_debug invocations

[Pablo Neira Ayuso]

On Mon, Jul 18, 2022 at 10:43:17AM -0700, Justin Stitt wrote:
> Any chance a maintainer could take a look at this patch? I am trying
> to get it through this cycle and we are so close to enabling the
> -Wformat option for Clang. There's only a handful of patches remaining
> until the patch enabling this warning can be sent!

I'll place this into nf-next, thanks.