* nf_flow on big-endian (was: Re: linux-next: build warning after merge of the net-next tree) [not found] <20191121183404.6e183d06@canb.auug.org.au> @ 2019-11-26 11:06 ` Geert Uytterhoeven 2019-12-07 16:41 ` Pablo Neira Ayuso 0 siblings, 1 reply; 3+ messages in thread From: Geert Uytterhoeven @ 2019-11-26 11:06 UTC (permalink / raw) To: Stephen Rothwell, Pablo Neira Ayuso Cc: David Miller, Networking, Linux Next Mailing List, Linux Kernel Mailing List, NetFilter, Jiri Pirko, Jozsef Kadlecsik, Florian Westphal On Thu, Nov 21, 2019 at 8:36 AM Stephen Rothwell <sfr@canb.auug.org.au> wrote: > After merging the net-next tree, today's linux-next build (powerpc > allyesconfig) produced this warning: > > net/netfilter/nf_flow_table_offload.c: In function 'nf_flow_rule_match': > net/netfilter/nf_flow_table_offload.c:80:21: warning: unsigned conversion from 'int' to '__be16' {aka 'short unsigned int'} changes value from '327680' to '0' [-Woverflow] > 80 | mask->tcp.flags = TCP_FLAG_RST | TCP_FLAG_FIN; > | ^~~~~~~~~~~~ > > Introduced by commit > > c29f74e0df7a ("netfilter: nf_flow_table: hardware offload support") This is now upstream, and must be completely broken on big-endian platforms. The other user of the flags field looks buggy, too (net/core/flow_dissector.c:__skb_flow_dissect_tcp()[*]): key_tcp->flags = (*(__be16 *) &tcp_flag_word(th) & htons(0x0FFF)); Disclaimer: I'm not familiar with the code or protocol, so below are just my gut feelings. struct flow_dissector_key_tcp { __be16 flags; }; Does this have to be __be16, i.e. does it go over the wire? If not, this should probably be __u16, and set using "be32_to_cpu(flags) >> 16"? If yes, "cpu_to_be16(be32_to_cpu(flags) >> 16)"? (Ugh, needs convenience macros) [*] ac4bb5de27010e41 ("net: flow_dissector: add support for dissection of tcp flags") Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds ^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: nf_flow on big-endian (was: Re: linux-next: build warning after merge of the net-next tree) 2019-11-26 11:06 ` nf_flow on big-endian (was: Re: linux-next: build warning after merge of the net-next tree) Geert Uytterhoeven @ 2019-12-07 16:41 ` Pablo Neira Ayuso 2019-12-08 10:33 ` Geert Uytterhoeven 0 siblings, 1 reply; 3+ messages in thread From: Pablo Neira Ayuso @ 2019-12-07 16:41 UTC (permalink / raw) To: Geert Uytterhoeven Cc: Stephen Rothwell, David Miller, Networking, Linux Next Mailing List, Linux Kernel Mailing List, NetFilter, Jiri Pirko, Jozsef Kadlecsik, Florian Westphal [-- Attachment #1: Type: text/plain, Size: 1621 bytes --] Hi Geert, On Tue, Nov 26, 2019 at 12:06:03PM +0100, Geert Uytterhoeven wrote: > On Thu, Nov 21, 2019 at 8:36 AM Stephen Rothwell <sfr@canb.auug.org.au> wrote: > > After merging the net-next tree, today's linux-next build (powerpc > > allyesconfig) produced this warning: > > > > net/netfilter/nf_flow_table_offload.c: In function 'nf_flow_rule_match': > > net/netfilter/nf_flow_table_offload.c:80:21: warning: unsigned conversion from 'int' to '__be16' {aka 'short unsigned int'} changes value from '327680' to '0' [-Woverflow] > > 80 | mask->tcp.flags = TCP_FLAG_RST | TCP_FLAG_FIN; > > | ^~~~~~~~~~~~ > > > > Introduced by commit > > > > c29f74e0df7a ("netfilter: nf_flow_table: hardware offload support") > > This is now upstream, and must be completely broken on big-endian > platforms. > > The other user of the flags field looks buggy, too > (net/core/flow_dissector.c:__skb_flow_dissect_tcp()[*]): > > key_tcp->flags = (*(__be16 *) &tcp_flag_word(th) & htons(0x0FFF)); > > Disclaimer: I'm not familiar with the code or protocol, so below are just > my gut feelings. > > struct flow_dissector_key_tcp { > __be16 flags; > }; > > Does this have to be __be16, i.e. does it go over the wire? > If not, this should probably be __u16, and set using > "be32_to_cpu(flags) >> 16"? > If yes, "cpu_to_be16(be32_to_cpu(flags) >> 16)"? > (Ugh, needs convenience macros) > > [*] ac4bb5de27010e41 ("net: flow_dissector: add support for dissection > of tcp flags") I'm attaching a tentative patch, please let me know this is fixing up this issue there. Thanks. [-- Attachment #2: x.patch --] [-- Type: text/x-diff, Size: 1674 bytes --] diff --git a/include/net/flow_dissector.h b/include/net/flow_dissector.h index b8c20e9f343e..30ad4e07ff52 100644 --- a/include/net/flow_dissector.h +++ b/include/net/flow_dissector.h @@ -189,10 +189,17 @@ struct flow_dissector_key_eth_addrs { /** * struct flow_dissector_key_tcp: - * @flags: flags + * @flags: TCP flags (16-bit, including the initial Data offset field bits) + * @word: Data offset + reserved bits + TCP flags + window */ struct flow_dissector_key_tcp { - __be16 flags; + union { + struct { + __be16 flags; + __be16 __pad; + }; + __be32 flag_word; + }; }; /** diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c index ca871657a4c4..83af4633f306 100644 --- a/net/core/flow_dissector.c +++ b/net/core/flow_dissector.c @@ -756,7 +756,7 @@ __skb_flow_dissect_tcp(const struct sk_buff *skb, key_tcp = skb_flow_dissector_target(flow_dissector, FLOW_DISSECTOR_KEY_TCP, target_container); - key_tcp->flags = (*(__be16 *) &tcp_flag_word(th) & htons(0x0FFF)); + key_tcp->flag_word = tcp_flag_word(th); } static void diff --git a/net/netfilter/nf_flow_table_offload.c b/net/netfilter/nf_flow_table_offload.c index c94ebad78c5c..30205d57226d 100644 --- a/net/netfilter/nf_flow_table_offload.c +++ b/net/netfilter/nf_flow_table_offload.c @@ -87,8 +87,8 @@ static int nf_flow_rule_match(struct nf_flow_match *match, switch (tuple->l4proto) { case IPPROTO_TCP: - key->tcp.flags = 0; - mask->tcp.flags = TCP_FLAG_RST | TCP_FLAG_FIN; + key->tcp.flag_word = 0; + mask->tcp.flag_word = TCP_FLAG_RST | TCP_FLAG_FIN; match->dissector.used_keys |= BIT(FLOW_DISSECTOR_KEY_TCP); break; case IPPROTO_UDP: ^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: nf_flow on big-endian (was: Re: linux-next: build warning after merge of the net-next tree) 2019-12-07 16:41 ` Pablo Neira Ayuso @ 2019-12-08 10:33 ` Geert Uytterhoeven 0 siblings, 0 replies; 3+ messages in thread From: Geert Uytterhoeven @ 2019-12-08 10:33 UTC (permalink / raw) To: Pablo Neira Ayuso Cc: Stephen Rothwell, David Miller, Networking, Linux Next Mailing List, Linux Kernel Mailing List, NetFilter, Jiri Pirko, Jozsef Kadlecsik, Florian Westphal Hi Pablo, On Sat, Dec 7, 2019 at 5:41 PM Pablo Neira Ayuso <pablo@netfilter.org> wrote: > On Tue, Nov 26, 2019 at 12:06:03PM +0100, Geert Uytterhoeven wrote: > > On Thu, Nov 21, 2019 at 8:36 AM Stephen Rothwell <sfr@canb.auug.org.au> wrote: > > > After merging the net-next tree, today's linux-next build (powerpc > > > allyesconfig) produced this warning: > > > > > > net/netfilter/nf_flow_table_offload.c: In function 'nf_flow_rule_match': > > > net/netfilter/nf_flow_table_offload.c:80:21: warning: unsigned conversion from 'int' to '__be16' {aka 'short unsigned int'} changes value from '327680' to '0' [-Woverflow] > > > 80 | mask->tcp.flags = TCP_FLAG_RST | TCP_FLAG_FIN; > > > | ^~~~~~~~~~~~ > > > > > > Introduced by commit > > > > > > c29f74e0df7a ("netfilter: nf_flow_table: hardware offload support") > > > > This is now upstream, and must be completely broken on big-endian > > platforms. > > > > The other user of the flags field looks buggy, too > > (net/core/flow_dissector.c:__skb_flow_dissect_tcp()[*]): > > > > key_tcp->flags = (*(__be16 *) &tcp_flag_word(th) & htons(0x0FFF)); > > > > Disclaimer: I'm not familiar with the code or protocol, so below are just > > my gut feelings. > > > > struct flow_dissector_key_tcp { > > __be16 flags; > > }; > > > > Does this have to be __be16, i.e. does it go over the wire? > > If not, this should probably be __u16, and set using > > "be32_to_cpu(flags) >> 16"? > > If yes, "cpu_to_be16(be32_to_cpu(flags) >> 16)"? > > (Ugh, needs convenience macros) > > > > [*] ac4bb5de27010e41 ("net: flow_dissector: add support for dissection > > of tcp flags") > > I'm attaching a tentative patch, please let me know this is fixing up > this issue there. Thanks, this looks good to me, and fixes the build warning. For this localized change (not for the global interaction), with the nits below fixed: Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org> > --- a/include/net/flow_dissector.h > +++ b/include/net/flow_dissector.h > @@ -189,10 +189,17 @@ struct flow_dissector_key_eth_addrs { > > /** > * struct flow_dissector_key_tcp: > - * @flags: flags > + * @flags: TCP flags (16-bit, including the initial Data offset field bits) @pad? > + * @word: Data offset + reserved bits + TCP flags + window flag_word > */ > struct flow_dissector_key_tcp { > - __be16 flags; > + union { > + struct { > + __be16 flags; > + __be16 __pad; > + }; > + __be32 flag_word; > + }; > }; > > /** > diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c > index ca871657a4c4..83af4633f306 100644 > --- a/net/core/flow_dissector.c > +++ b/net/core/flow_dissector.c > @@ -756,7 +756,7 @@ __skb_flow_dissect_tcp(const struct sk_buff *skb, > key_tcp = skb_flow_dissector_target(flow_dissector, > FLOW_DISSECTOR_KEY_TCP, > target_container); > - key_tcp->flags = (*(__be16 *) &tcp_flag_word(th) & htons(0x0FFF)); > + key_tcp->flag_word = tcp_flag_word(th); > } > > static void > diff --git a/net/netfilter/nf_flow_table_offload.c b/net/netfilter/nf_flow_table_offload.c > index c94ebad78c5c..30205d57226d 100644 > --- a/net/netfilter/nf_flow_table_offload.c > +++ b/net/netfilter/nf_flow_table_offload.c > @@ -87,8 +87,8 @@ static int nf_flow_rule_match(struct nf_flow_match *match, > > switch (tuple->l4proto) { > case IPPROTO_TCP: > - key->tcp.flags = 0; > - mask->tcp.flags = TCP_FLAG_RST | TCP_FLAG_FIN; > + key->tcp.flag_word = 0; > + mask->tcp.flag_word = TCP_FLAG_RST | TCP_FLAG_FIN; > match->dissector.used_keys |= BIT(FLOW_DISSECTOR_KEY_TCP); > break; > case IPPROTO_UDP: Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds ^ permalink raw reply [flat|nested] 3+ messages in thread
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2019-11-26 11:06 ` nf_flow on big-endian (was: Re: linux-next: build warning after merge of the net-next tree) Geert Uytterhoeven
2019-12-07 16:41 ` Pablo Neira Ayuso
2019-12-08 10:33 ` Geert Uytterhoeven
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