From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: [PATCH] netfilter: factorize ifname_compare() Date: Wed, 25 Mar 2009 12:27:07 +0100 Message-ID: <49CA150B.2080203@cosmosbay.com> References: <20090324.132954.148903398.davem@davemloft.net> <49C94B6A.5020304@cosmosbay.com> <20090324.141848.119353425.davem@davemloft.net> <49C952FE.7070202@cosmosbay.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Jan Engelhardt , kaber@trash.net, netdev@vger.kernel.org, netfilter-devel@vger.kernel.org To: David Miller Return-path: Received: from gw1.cosmosbay.com ([212.99.114.194]:55456 "EHLO gw1.cosmosbay.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753086AbZCYL1S convert rfc822-to-8bit (ORCPT ); Wed, 25 Mar 2009 07:27:18 -0400 In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: Jan Engelhardt a =E9crit : > On Tuesday 2009-03-24 22:39, Eric Dumazet wrote: >> memcmp() is fine, but how is it solving the masking problem we have = ? >=20 > You are right; we would have to calculate the prefix length of the > mask first. (And I think we can assume that there will not be any 1s > in the mask after the first 0.) It would consume CPU indeed. >=20 >> Also in the case of arp_tables, _a is long word aligned, while _b an= d _mask >> are not. >> >> If you look various ifname_compare(), we have two different implemen= tations. >> >> So yes, a factorization is possible for three ip_tables.c, ip6_table= s.c and >> xt_physdev.c. >=20 > Very well. Here is a patch to factorize these functions, as suggested by Jan Thank you [PATCH] netfilter: factorize ifname_compare() We use same not trivial helper function in four places. We can factoriz= e it. Signed-off-by: Eric Dumazet --- include/linux/netfilter/x_tables.h | 23 +++++++++++++++++++++++ net/ipv4/netfilter/arp_tables.c | 14 +------------- net/ipv4/netfilter/ip_tables.c | 23 ++--------------------- net/ipv6/netfilter/ip6_tables.c | 23 ++--------------------- net/netfilter/xt_physdev.c | 21 ++------------------- 5 files changed, 30 insertions(+), 74 deletions(-) diff --git a/include/linux/netfilter/x_tables.h b/include/linux/netfilt= er/x_tables.h index e8e08d0..72918b7 100644 --- a/include/linux/netfilter/x_tables.h +++ b/include/linux/netfilter/x_tables.h @@ -435,6 +435,29 @@ extern void xt_free_table_info(struct xt_table_inf= o *info); extern void xt_table_entry_swap_rcu(struct xt_table_info *old, struct xt_table_info *new); =20 +/* + * This helper is performance critical and must be inlined + */ +static inline unsigned long ifname_compare_aligned(const char *_a, + const char *_b, + const char *_mask) +{ + const unsigned long *a =3D (const unsigned long *)_a; + const unsigned long *b =3D (const unsigned long *)_b; + const unsigned long *mask =3D (const unsigned long *)_mask; + unsigned long ret; + + ret =3D (a[0] ^ b[0]) & mask[0]; + if (IFNAMSIZ > sizeof(unsigned long)) + ret |=3D (a[1] ^ b[1]) & mask[1]; + if (IFNAMSIZ > 2 * sizeof(unsigned long)) + ret |=3D (a[2] ^ b[2]) & mask[2]; + if (IFNAMSIZ > 3 * sizeof(unsigned long)) + ret |=3D (a[3] ^ b[3]) & mask[3]; + BUILD_BUG_ON(IFNAMSIZ > 4 * sizeof(unsigned long)); + return ret; +} + #ifdef CONFIG_COMPAT #include =20 diff --git a/net/ipv4/netfilter/arp_tables.c b/net/ipv4/netfilter/arp_t= ables.c index 84b9c17..ee1133c 100644 --- a/net/ipv4/netfilter/arp_tables.c +++ b/net/ipv4/netfilter/arp_tables.c @@ -81,19 +81,7 @@ static inline int arp_devaddr_compare(const struct a= rpt_devaddr_info *ap, static unsigned long ifname_compare(const char *_a, const char *_b, co= nst char *_mask) { #ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS - const unsigned long *a =3D (const unsigned long *)_a; - const unsigned long *b =3D (const unsigned long *)_b; - const unsigned long *mask =3D (const unsigned long *)_mask; - unsigned long ret; - - ret =3D (a[0] ^ b[0]) & mask[0]; - if (IFNAMSIZ > sizeof(unsigned long)) - ret |=3D (a[1] ^ b[1]) & mask[1]; - if (IFNAMSIZ > 2 * sizeof(unsigned long)) - ret |=3D (a[2] ^ b[2]) & mask[2]; - if (IFNAMSIZ > 3 * sizeof(unsigned long)) - ret |=3D (a[3] ^ b[3]) & mask[3]; - BUILD_BUG_ON(IFNAMSIZ > 4 * sizeof(unsigned long)); + unsigned long ret =3D ifname_compare_aligned(_a, _b, _mask); #else unsigned long ret =3D 0; const u16 *a =3D (const u16 *)_a; diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tab= les.c index e5294ae..41c59e3 100644 --- a/net/ipv4/netfilter/ip_tables.c +++ b/net/ipv4/netfilter/ip_tables.c @@ -74,25 +74,6 @@ do { \ =20 Hence the start of any table is given by get_table() below. */ =20 -static unsigned long ifname_compare(const char *_a, const char *_b, - const unsigned char *_mask) -{ - const unsigned long *a =3D (const unsigned long *)_a; - const unsigned long *b =3D (const unsigned long *)_b; - const unsigned long *mask =3D (const unsigned long *)_mask; - unsigned long ret; - - ret =3D (a[0] ^ b[0]) & mask[0]; - if (IFNAMSIZ > sizeof(unsigned long)) - ret |=3D (a[1] ^ b[1]) & mask[1]; - if (IFNAMSIZ > 2 * sizeof(unsigned long)) - ret |=3D (a[2] ^ b[2]) & mask[2]; - if (IFNAMSIZ > 3 * sizeof(unsigned long)) - ret |=3D (a[3] ^ b[3]) & mask[3]; - BUILD_BUG_ON(IFNAMSIZ > 4 * sizeof(unsigned long)); - return ret; -} - /* Returns whether matches rule or not. */ /* Performance critical - called for every packet */ static inline bool @@ -121,7 +102,7 @@ ip_packet_match(const struct iphdr *ip, return false; } =20 - ret =3D ifname_compare(indev, ipinfo->iniface, ipinfo->iniface_mask); + ret =3D ifname_compare_aligned(indev, ipinfo->iniface, ipinfo->inifac= e_mask); =20 if (FWINV(ret !=3D 0, IPT_INV_VIA_IN)) { dprintf("VIA in mismatch (%s vs %s).%s\n", @@ -130,7 +111,7 @@ ip_packet_match(const struct iphdr *ip, return false; } =20 - ret =3D ifname_compare(outdev, ipinfo->outiface, ipinfo->outiface_mas= k); + ret =3D ifname_compare_aligned(outdev, ipinfo->outiface, ipinfo->outi= face_mask); =20 if (FWINV(ret !=3D 0, IPT_INV_VIA_OUT)) { dprintf("VIA out mismatch (%s vs %s).%s\n", diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_t= ables.c index 34af7bb..e59662b 100644 --- a/net/ipv6/netfilter/ip6_tables.c +++ b/net/ipv6/netfilter/ip6_tables.c @@ -89,25 +89,6 @@ ip6t_ext_hdr(u8 nexthdr) (nexthdr =3D=3D IPPROTO_DSTOPTS) ); } =20 -static unsigned long ifname_compare(const char *_a, const char *_b, - const unsigned char *_mask) -{ - const unsigned long *a =3D (const unsigned long *)_a; - const unsigned long *b =3D (const unsigned long *)_b; - const unsigned long *mask =3D (const unsigned long *)_mask; - unsigned long ret; - - ret =3D (a[0] ^ b[0]) & mask[0]; - if (IFNAMSIZ > sizeof(unsigned long)) - ret |=3D (a[1] ^ b[1]) & mask[1]; - if (IFNAMSIZ > 2 * sizeof(unsigned long)) - ret |=3D (a[2] ^ b[2]) & mask[2]; - if (IFNAMSIZ > 3 * sizeof(unsigned long)) - ret |=3D (a[3] ^ b[3]) & mask[3]; - BUILD_BUG_ON(IFNAMSIZ > 4 * sizeof(unsigned long)); - return ret; -} - /* Returns whether matches rule or not. */ /* Performance critical - called for every packet */ static inline bool @@ -138,7 +119,7 @@ ip6_packet_match(const struct sk_buff *skb, return false; } =20 - ret =3D ifname_compare(indev, ip6info->iniface, ip6info->iniface_mask= ); + ret =3D ifname_compare_aligned(indev, ip6info->iniface, ip6info->inif= ace_mask); =20 if (FWINV(ret !=3D 0, IP6T_INV_VIA_IN)) { dprintf("VIA in mismatch (%s vs %s).%s\n", @@ -147,7 +128,7 @@ ip6_packet_match(const struct sk_buff *skb, return false; } =20 - ret =3D ifname_compare(outdev, ip6info->outiface, ip6info->outiface_m= ask); + ret =3D ifname_compare_aligned(outdev, ip6info->outiface, ip6info->ou= tiface_mask); =20 if (FWINV(ret !=3D 0, IP6T_INV_VIA_OUT)) { dprintf("VIA out mismatch (%s vs %s).%s\n", diff --git a/net/netfilter/xt_physdev.c b/net/netfilter/xt_physdev.c index 44a234e..8d28ca5 100644 --- a/net/netfilter/xt_physdev.c +++ b/net/netfilter/xt_physdev.c @@ -20,23 +20,6 @@ MODULE_DESCRIPTION("Xtables: Bridge physical device = match"); MODULE_ALIAS("ipt_physdev"); MODULE_ALIAS("ip6t_physdev"); =20 -static unsigned long ifname_compare(const char *_a, const char *_b, co= nst char *_mask) -{ - const unsigned long *a =3D (const unsigned long *)_a; - const unsigned long *b =3D (const unsigned long *)_b; - const unsigned long *mask =3D (const unsigned long *)_mask; - unsigned long ret; - - ret =3D (a[0] ^ b[0]) & mask[0]; - if (IFNAMSIZ > sizeof(unsigned long)) - ret |=3D (a[1] ^ b[1]) & mask[1]; - if (IFNAMSIZ > 2 * sizeof(unsigned long)) - ret |=3D (a[2] ^ b[2]) & mask[2]; - if (IFNAMSIZ > 3 * sizeof(unsigned long)) - ret |=3D (a[3] ^ b[3]) & mask[3]; - BUILD_BUG_ON(IFNAMSIZ > 4 * sizeof(unsigned long)); - return ret; -} =20 static bool physdev_mt(const struct sk_buff *skb, const struct xt_match_param *par= ) @@ -85,7 +68,7 @@ physdev_mt(const struct sk_buff *skb, const struct xt= _match_param *par) if (!(info->bitmask & XT_PHYSDEV_OP_IN)) goto match_outdev; indev =3D nf_bridge->physindev ? nf_bridge->physindev->name : nulldev= name; - ret =3D ifname_compare(indev, info->physindev, info->in_mask); + ret =3D ifname_compare_aligned(indev, info->physindev, info->in_mask)= ; =20 if (!ret ^ !(info->invert & XT_PHYSDEV_OP_IN)) return false; @@ -95,7 +78,7 @@ match_outdev: return true; outdev =3D nf_bridge->physoutdev ? nf_bridge->physoutdev->name : nulldevname; - ret =3D ifname_compare(outdev, info->physoutdev, info->out_mask); + ret =3D ifname_compare_aligned(outdev, info->physoutdev, info->out_ma= sk); =20 return (!!ret ^ !(info->invert & XT_PHYSDEV_OP_OUT)); }