Xtables cleanup patches

Xtables cleanup patches

[Jan Engelhardt]

I am posting here already the next round of pullable patches
(that I originally wanted to get in _much_ faster) for review.

This block is mostly cleanups, simplifications. It might be worth
testing these together with the previous set if there are concerns
about speed.

-----
The following changes since commit 7891b6c280d01d52be5ecefe0db79d4b1f671a1e:
  Jan Engelhardt (1):
        netfilter: xtables: generate initial table on-demand

are available in the git repository at:

  git://dev.medozas.de/linux next

Jan Engelhardt (6):
      netfilter: iptables: remove unused function arguments
      netfilter: reduce NF_HOOK by one argument
      netfilter: get rid of the grossness in netfilter.h
      netfilter: xtables: print details on size mismatch
      netfilter: xtables: constify args in compat copying functions
      netfilter: xtables: add const qualifiers

 include/linux/netfilter.h            |   55 +++++++++++---------
 include/linux/netfilter/x_tables.h   |   12 ++--
 net/bridge/netfilter/ebtables.c      |   56 +++++++++++---------
 net/ipv4/netfilter/arp_tables.c      |   73 +++++++++++++++------------
 net/ipv4/netfilter/ip_tables.c       |   92 +++++++++++++++++++---------------
 net/ipv4/netfilter/ipt_ULOG.c        |    4 +-
 net/ipv4/netfilter/iptable_mangle.c  |   10 +---
 net/ipv6/netfilter/ip6_tables.c      |   92 ++++++++++++++++++---------------
 net/ipv6/netfilter/ip6table_mangle.c |   10 +---
 net/netfilter/x_tables.c             |   16 ++++--
 net/netfilter/xt_hashlimit.c         |    4 +-
 net/netfilter/xt_limit.c             |    4 +-
 12 files changed, 232 insertions(+), 196 deletions(-)

[PATCH 1/6] netfilter: iptables: remove unused function arguments

[Jan Engelhardt]

Signed-off-by: Jan Engelhardt <jengelh@medozas.de>
---
 net/ipv4/netfilter/iptable_mangle.c  |   10 +++-------
 net/ipv6/netfilter/ip6table_mangle.c |   10 +++-------
 2 files changed, 6 insertions(+), 14 deletions(-)

diff --git a/net/ipv4/netfilter/iptable_mangle.c b/net/ipv4/netfilter/iptable_mangle.c
index 4708d8f..2f79301 100644
--- a/net/ipv4/netfilter/iptable_mangle.c
+++ b/net/ipv4/netfilter/iptable_mangle.c
@@ -36,11 +36,7 @@ static const struct xt_table packet_mangler = {
 };
 
 static unsigned int
-ipt_local_hook(unsigned int hook,
-		   struct sk_buff *skb,
-		   const struct net_device *in,
-		   const struct net_device *out,
-		   int (*okfn)(struct sk_buff *))
+ipt_mangle_out(struct sk_buff *skb, const struct net_device *out)
 {
 	unsigned int ret;
 	const struct iphdr *iph;
@@ -60,7 +56,7 @@ ipt_local_hook(unsigned int hook,
 	daddr = iph->daddr;
 	tos = iph->tos;
 
-	ret = ipt_do_table(skb, hook, in, out,
+	ret = ipt_do_table(skb, NF_INET_LOCAL_OUT, NULL, out,
 			   dev_net(out)->ipv4.iptable_mangle);
 	/* Reroute for ANY change. */
 	if (ret != NF_DROP && ret != NF_STOLEN && ret != NF_QUEUE) {
@@ -86,7 +82,7 @@ iptable_mangle_hook(unsigned int hook,
 		     int (*okfn)(struct sk_buff *))
 {
 	if (hook == NF_INET_LOCAL_OUT)
-		return ipt_local_hook(hook, skb, in, out, okfn);
+		return ipt_mangle_out(skb, out);
 
 	/* PREROUTING/INPUT/FORWARD: */
 	return ipt_do_table(skb, hook, in, out,
diff --git a/net/ipv6/netfilter/ip6table_mangle.c b/net/ipv6/netfilter/ip6table_mangle.c
index c86c838..cc6845e 100644
--- a/net/ipv6/netfilter/ip6table_mangle.c
+++ b/net/ipv6/netfilter/ip6table_mangle.c
@@ -30,12 +30,8 @@ static const struct xt_table packet_mangler = {
 };
 
 static unsigned int
-ip6t_local_out_hook(unsigned int hook,
-		   struct sk_buff *skb,
-		   const struct net_device *out,
-		   int (*okfn)(struct sk_buff *))
+ip6t_mangle_out(struct sk_buff *skb, const struct net_device *out)
 {
-
 	unsigned int ret;
 	struct in6_addr saddr, daddr;
 	u_int8_t hop_limit;
@@ -60,7 +56,7 @@ ip6t_local_out_hook(unsigned int hook,
 	/* flowlabel and prio (includes version, which shouldn't change either */
 	flowlabel = *((u_int32_t *)ipv6_hdr(skb));
 
-	ret = ip6t_do_table(skb, hook, NULL, out,
+	ret = ip6t_do_table(skb, NF_INET_LOCAL_OUT, NULL, out,
 			    dev_net(out)->ipv6.ip6table_mangle);
 
 	if (ret != NF_DROP && ret != NF_STOLEN
@@ -82,7 +78,7 @@ ip6table_mangle_hook(unsigned int hook,
 	 int (*okfn)(struct sk_buff *))
 {
 	if (hook == NF_INET_LOCAL_OUT)
-		return ip6t_local_out_hook(hook, skb, out, okfn);
+		return ip6t_mangle_out(skb, out);
 
 	/* INPUT/FORWARD */
 	return ip6t_do_table(skb, hook, in, out,
-- 
1.6.5.2

[PATCH 2/6] netfilter: reduce NF_HOOK by one argument

[Jan Engelhardt]

No changes in vmlinux filesize.

Signed-off-by: Jan Engelhardt <jengelh@medozas.de>
---
 include/linux/netfilter.h |   14 +++++---------
 1 files changed, 5 insertions(+), 9 deletions(-)

diff --git a/include/linux/netfilter.h b/include/linux/netfilter.h
index 6132b5e..d02dc03 100644
--- a/include/linux/netfilter.h
+++ b/include/linux/netfilter.h
@@ -163,11 +163,8 @@ static inline int nf_hook_thresh(u_int8_t pf, unsigned int hook,
 				 struct sk_buff *skb,
 				 struct net_device *indev,
 				 struct net_device *outdev,
-				 int (*okfn)(struct sk_buff *), int thresh,
-				 int cond)
+				 int (*okfn)(struct sk_buff *), int thresh)
 {
-	if (!cond)
-		return 1;
 #ifndef CONFIG_NETFILTER_DEBUG
 	if (list_empty(&nf_hooks[pf][hook]))
 		return 1;
@@ -179,7 +176,7 @@ static inline int nf_hook(u_int8_t pf, unsigned int hook, struct sk_buff *skb,
 			  struct net_device *indev, struct net_device *outdev,
 			  int (*okfn)(struct sk_buff *))
 {
-	return nf_hook_thresh(pf, hook, skb, indev, outdev, okfn, INT_MIN, 1);
+	return nf_hook_thresh(pf, hook, skb, indev, outdev, okfn, INT_MIN);
 }
                    
 /* Activate hook; either okfn or kfree_skb called, unless a hook
@@ -206,13 +203,13 @@ static inline int nf_hook(u_int8_t pf, unsigned int hook, struct sk_buff *skb,
 
 #define NF_HOOK_THRESH(pf, hook, skb, indev, outdev, okfn, thresh)	       \
 ({int __ret;								       \
-if ((__ret=nf_hook_thresh(pf, hook, (skb), indev, outdev, okfn, thresh, 1)) == 1)\
+if ((__ret=nf_hook_thresh(pf, hook, (skb), indev, outdev, okfn, thresh)) == 1)\
 	__ret = (okfn)(skb);						       \
 __ret;})
 
 #define NF_HOOK_COND(pf, hook, skb, indev, outdev, okfn, cond)		       \
 ({int __ret;								       \
-if ((__ret=nf_hook_thresh(pf, hook, (skb), indev, outdev, okfn, INT_MIN, cond)) == 1)\
+if ((cond) || (__ret = nf_hook_thresh(pf, hook, (skb), indev, outdev, okfn, INT_MIN)) == 1)\
 	__ret = (okfn)(skb);						       \
 __ret;})
 
@@ -327,8 +324,7 @@ static inline int nf_hook_thresh(u_int8_t pf, unsigned int hook,
 				 struct sk_buff *skb,
 				 struct net_device *indev,
 				 struct net_device *outdev,
-				 int (*okfn)(struct sk_buff *), int thresh,
-				 int cond)
+				 int (*okfn)(struct sk_buff *), int thresh)
 {
 	return okfn(skb);
 }
-- 
1.6.5.2

[PATCH 3/6] netfilter: get rid of the grossness in netfilter.h

[Jan Engelhardt]

GCC is now smart enough to follow the inline trail correctly.
vmlinux size remain the same.

Signed-off-by: Jan Engelhardt <jengelh@medozas.de>
---
 include/linux/netfilter.h |   45 ++++++++++++++++++++++++++++-----------------
 1 files changed, 28 insertions(+), 17 deletions(-)

diff --git a/include/linux/netfilter.h b/include/linux/netfilter.h
index d02dc03..bea0e0c 100644
--- a/include/linux/netfilter.h
+++ b/include/linux/netfilter.h
@@ -196,25 +196,36 @@ static inline int nf_hook(u_int8_t pf, unsigned int hook, struct sk_buff *skb,
    coders :)
 */
 
-/* This is gross, but inline doesn't cut it for avoiding the function
-   call in fast path: gcc doesn't inline (needs value tracking?). --RR */
-
-/* HX: It's slightly less gross now. */
-
-#define NF_HOOK_THRESH(pf, hook, skb, indev, outdev, okfn, thresh)	       \
-({int __ret;								       \
-if ((__ret=nf_hook_thresh(pf, hook, (skb), indev, outdev, okfn, thresh)) == 1)\
-	__ret = (okfn)(skb);						       \
-__ret;})
+static inline int
+NF_HOOK_THRESH(uint8_t pf, unsigned int hook, struct sk_buff *skb,
+	       struct net_device *in, struct net_device *out,
+	       int (*okfn)(struct sk_buff *), int thresh)
+{
+	int ret = nf_hook_thresh(pf, hook, skb, in, out, okfn, thresh);
+	if (ret == 1)
+		ret = okfn(skb);
+	return ret;
+}
 
-#define NF_HOOK_COND(pf, hook, skb, indev, outdev, okfn, cond)		       \
-({int __ret;								       \
-if ((cond) || (__ret = nf_hook_thresh(pf, hook, (skb), indev, outdev, okfn, INT_MIN)) == 1)\
-	__ret = (okfn)(skb);						       \
-__ret;})
+static inline int
+NF_HOOK_COND(uint8_t pf, unsigned int hook, struct sk_buff *skb,
+	     struct net_device *in, struct net_device *out,
+	     int (*okfn)(struct sk_buff *), bool cond)
+{
+	int ret = 1;
+	if (cond ||
+	    (ret = nf_hook_thresh(pf, hook, skb, in, out, okfn, INT_MIN) == 1))
+		ret = okfn(skb);
+	return ret;
+}
 
-#define NF_HOOK(pf, hook, skb, indev, outdev, okfn) \
-	NF_HOOK_THRESH(pf, hook, skb, indev, outdev, okfn, INT_MIN)
+static inline int
+NF_HOOK(uint8_t pf, unsigned int hook, struct sk_buff *skb,
+	struct net_device *in, struct net_device *out,
+	int (*okfn)(struct sk_buff *))
+{
+	return NF_HOOK_THRESH(pf, hook, skb, in, out, okfn, INT_MIN);
+}
 
 /* Call setsockopt() */
 int nf_setsockopt(struct sock *sk, u_int8_t pf, int optval, char __user *opt,
-- 
1.6.5.2

Re: [PATCH 3/6] netfilter: get rid of the grossness in netfilter.h

[Changli Gao]

On Wed, Nov 4, 2009 at 2:04 AM, Jan Engelhardt <jengelh@medozas.de> wrote:
>
> -#define NF_HOOK_COND(pf, hook, skb, indev, outdev, okfn, cond)                \
> -({int __ret;                                                                  \
> -if ((cond) || (__ret = nf_hook_thresh(pf, hook, (skb), indev, outdev, okfn, INT_MIN)) == 1)\
> -       __ret = (okfn)(skb);                                                   \
> -__ret;})
This code isn't the same as the linus tree's. And has a risk about
uninitialized variable __ret.

#define NF_HOOK_COND(pf, hook, skb, indev, outdev, okfn, cond)                 \
({int __ret;                                                                   \
if ((__ret=nf_hook_thresh(pf, hook, (skb), indev, outdev, okfn,
INT_MIN, cond)) == 1)\
        __ret = (okfn)(skb);                                                   \
__ret;})

/**
 *      nf_hook_thresh - call a netfilter hook
 *
 *      Returns 1 if the hook has allowed the packet to pass.  The function
 *      okfn must be invoked by the caller in this case.  Any other return
 *      value indicates the packet has been consumed by the hook.
 */
static inline int nf_hook_thresh(u_int8_t pf, unsigned int hook,
                                 struct sk_buff *skb,
                                 struct net_device *indev,
                                 struct net_device *outdev,
                                 int (*okfn)(struct sk_buff *), int thresh,
                                 int cond)
{
        if (!cond)
                return 1;
#ifndef CONFIG_NETFILTER_DEBUG
        if (list_empty(&nf_hooks[pf][hook]))
                return 1;
#endif
        return nf_hook_slow(pf, hook, skb, indev, outdev, okfn, thresh);
}


> +static inline int
> +NF_HOOK_COND(uint8_t pf, unsigned int hook, struct sk_buff *skb,
> +            struct net_device *in, struct net_device *out,
> +            int (*okfn)(struct sk_buff *), bool cond)
> +{
> +       int ret = 1;
> +       if (cond ||
> +           (ret = nf_hook_thresh(pf, hook, skb, in, out, okfn, INT_MIN) == 1))
> +               ret = okfn(skb);
> +       return ret;
> +}

The fact is: no matter the cond value, okfn(skb) should always be
called, and hf_hook_thresh() should be called only when cond is true.
So the code will be.

if (cond) {
   if (ret = nf_hook_thresh(pf, hook, skb, in, out, okfn, INT_MIN)) == 1)
       ret = okfn(skb);
} else {
    ret = okfn(skb);
}

-- 
Regards，
Changli Gao(xiaosuo@gmail.com)
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Re: [PATCH 3/6] netfilter: get rid of the grossness in netfilter.h

[Jan Engelhardt]

On Wednesday 2009-11-04 08:59, Changli Gao wrote:

>On Wed, Nov 4, 2009 at 2:04 AM, Jan Engelhardt <jengelh@medozas.de> wrote:
>>
>> -#define NF_HOOK_COND(pf, hook, skb, indev, outdev, okfn, cond)                \
>> -({int __ret;                                                                  \
>> -if ((cond) || (__ret = nf_hook_thresh(pf, hook, (skb), indev, outdev, okfn, INT_MIN)) == 1)\
>> -       __ret = (okfn)(skb);                                                   \
>> -__ret;})
>This code isn't the same as the linus tree's.

It sure is:

        git diff mdz/next~6..mdz/next include/linux/netfilter.h

=> no output, hence the same.

>And has a risk about uninitialized variable __ret.
>
>#define NF_HOOK_COND(pf, hook, skb, indev, outdev, okfn, cond)                 \
>({int __ret;                                                                   \
>if ((__ret=nf_hook_thresh(pf, hook, (skb), indev, outdev, okfn,
>INT_MIN, cond)) == 1)\
>        __ret = (okfn)(skb);                                                   \
>__ret;})

No uninitialized variable either there.

>The fact is: no matter the cond value, okfn(skb) should always be
>called, and hf_hook_thresh() should be called only when cond is true.

Yes, thank you for noticing. I will have that fixed up:

Subject: augment a3dc8cdef7c00d0340a0e6bc80211ce81b665f3b
---
diff --git a/include/linux/netfilter.h b/include/linux/netfilter.h
index d02dc03..6854000 100644
--- a/include/linux/netfilter.h
+++ b/include/linux/netfilter.h
@@ -209,7 +209,7 @@ __ret;})
 
 #define NF_HOOK_COND(pf, hook, skb, indev, outdev, okfn, cond)		       \
 ({int __ret;								       \
-if ((cond) || (__ret = nf_hook_thresh(pf, hook, (skb), indev, outdev, okfn, INT_MIN)) == 1)\
+if (!(cond) || (__ret = nf_hook_thresh(pf, hook, (skb), indev, outdev, okfn, INT_MIN)) == 1)\
 	__ret = (okfn)(skb);						       \
 __ret;})
 
-- 
# Created with git-export-patch
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[PATCH 4/6] netfilter: xtables: print details on size mismatch

[Jan Engelhardt]

Print which revision has been used and which size are which
(kernel/user) for easier debugging.

Signed-off-by: Jan Engelhardt <jengelh@medozas.de>
---
 net/netfilter/x_tables.c |    8 ++++++--
 1 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/net/netfilter/x_tables.c b/net/netfilter/x_tables.c
index aef0699..c8845d1 100644
--- a/net/netfilter/x_tables.c
+++ b/net/netfilter/x_tables.c
@@ -366,8 +366,10 @@ int xt_check_match(struct xt_mtchk_param *par,
 		 * ebt_among is exempt from centralized matchsize checking
 		 * because it uses a dynamic-size data set.
 		 */
-		pr_err("%s_tables: %s match: invalid size %Zu != %u\n",
+		pr_err("%s_tables: %s.%u match: invalid size "
+		       "(kernel) %zu != (user) %u\n",
 		       xt_prefix[par->family], par->match->name,
+		       par->match->revision,
 		       XT_ALIGN(par->match->matchsize), size);
 		return -EINVAL;
 	}
@@ -516,8 +518,10 @@ int xt_check_target(struct xt_tgchk_param *par,
 		    unsigned int size, u_int8_t proto, bool inv_proto)
 {
 	if (XT_ALIGN(par->target->targetsize) != size) {
-		pr_err("%s_tables: %s target: invalid size %Zu != %u\n",
+		pr_err("%s_tables: %s.%u target: invalid size "
+		       "(kernel) %zu != (user) %u\n",
 		       xt_prefix[par->family], par->target->name,
+		       par->target->revision,
 		       XT_ALIGN(par->target->targetsize), size);
 		return -EINVAL;
 	}
-- 
1.6.5.2

[PATCH 5/6] netfilter: xtables: constify args in compat copying functions

[Jan Engelhardt]

Signed-off-by: Jan Engelhardt <jengelh@medozas.de>
---
 include/linux/netfilter/x_tables.h |   12 ++++++------
 net/ipv4/netfilter/arp_tables.c    |    4 ++--
 net/ipv4/netfilter/ip_tables.c     |    4 ++--
 net/ipv4/netfilter/ipt_ULOG.c      |    4 ++--
 net/ipv6/netfilter/ip6_tables.c    |    4 ++--
 net/netfilter/x_tables.c           |    8 ++++----
 net/netfilter/xt_hashlimit.c       |    4 ++--
 net/netfilter/xt_limit.c           |    4 ++--
 8 files changed, 22 insertions(+), 22 deletions(-)

diff --git a/include/linux/netfilter/x_tables.h b/include/linux/netfilter/x_tables.h
index db92d8e..ebec4a5 100644
--- a/include/linux/netfilter/x_tables.h
+++ b/include/linux/netfilter/x_tables.h
@@ -291,8 +291,8 @@ struct xt_match
 	void (*destroy)(const struct xt_mtdtor_param *);
 
 	/* Called when userspace align differs from kernel space one */
-	void (*compat_from_user)(void *dst, void *src);
-	int (*compat_to_user)(void __user *dst, void *src);
+	void (*compat_from_user)(void *dst, const void *src);
+	int (*compat_to_user)(void __user *dst, const void *src);
 
 	/* Set this to THIS_MODULE if you are a module, otherwise NULL */
 	struct module *me;
@@ -332,8 +332,8 @@ struct xt_target
 	void (*destroy)(const struct xt_tgdtor_param *);
 
 	/* Called when userspace align differs from kernel space one */
-	void (*compat_from_user)(void *dst, void *src);
-	int (*compat_to_user)(void __user *dst, void *src);
+	void (*compat_from_user)(void *dst, const void *src);
+	int (*compat_to_user)(void __user *dst, const void *src);
 
 	/* Set this to THIS_MODULE if you are a module, otherwise NULL */
 	struct module *me;
@@ -600,13 +600,13 @@ extern short xt_compat_calc_jump(u_int8_t af, unsigned int offset);
 extern int xt_compat_match_offset(const struct xt_match *match);
 extern int xt_compat_match_from_user(struct xt_entry_match *m,
 				     void **dstptr, unsigned int *size);
-extern int xt_compat_match_to_user(struct xt_entry_match *m,
+extern int xt_compat_match_to_user(const struct xt_entry_match *m,
 				   void __user **dstptr, unsigned int *size);
 
 extern int xt_compat_target_offset(const struct xt_target *target);
 extern void xt_compat_target_from_user(struct xt_entry_target *t,
 				       void **dstptr, unsigned int *size);
-extern int xt_compat_target_to_user(struct xt_entry_target *t,
+extern int xt_compat_target_to_user(const struct xt_entry_target *t,
 				    void __user **dstptr, unsigned int *size);
 
 #endif /* CONFIG_COMPAT */
diff --git a/net/ipv4/netfilter/arp_tables.c b/net/ipv4/netfilter/arp_tables.c
index f5aa65d..52c96b3 100644
--- a/net/ipv4/netfilter/arp_tables.c
+++ b/net/ipv4/netfilter/arp_tables.c
@@ -842,7 +842,7 @@ static int copy_entries_to_user(unsigned int total_size,
 }
 
 #ifdef CONFIG_COMPAT
-static void compat_standard_from_user(void *dst, void *src)
+static void compat_standard_from_user(void *dst, const void *src)
 {
 	int v = *(compat_int_t *)src;
 
@@ -851,7 +851,7 @@ static void compat_standard_from_user(void *dst, void *src)
 	memcpy(dst, &v, sizeof(v));
 }
 
-static int compat_standard_to_user(void __user *dst, void *src)
+static int compat_standard_to_user(void __user *dst, const void *src)
 {
 	compat_int_t cv = *(int *)src;
 
diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c
index f2f6552..3e355fe 100644
--- a/net/ipv4/netfilter/ip_tables.c
+++ b/net/ipv4/netfilter/ip_tables.c
@@ -1042,7 +1042,7 @@ copy_entries_to_user(unsigned int total_size,
 }
 
 #ifdef CONFIG_COMPAT
-static void compat_standard_from_user(void *dst, void *src)
+static void compat_standard_from_user(void *dst, const void *src)
 {
 	int v = *(compat_int_t *)src;
 
@@ -1051,7 +1051,7 @@ static void compat_standard_from_user(void *dst, void *src)
 	memcpy(dst, &v, sizeof(v));
 }
 
-static int compat_standard_to_user(void __user *dst, void *src)
+static int compat_standard_to_user(void __user *dst, const void *src)
 {
 	compat_int_t cv = *(int *)src;
 
diff --git a/net/ipv4/netfilter/ipt_ULOG.c b/net/ipv4/netfilter/ipt_ULOG.c
index d32cc4b..0b02768 100644
--- a/net/ipv4/netfilter/ipt_ULOG.c
+++ b/net/ipv4/netfilter/ipt_ULOG.c
@@ -338,7 +338,7 @@ struct compat_ipt_ulog_info {
 	char		prefix[ULOG_PREFIX_LEN];
 };
 
-static void ulog_tg_compat_from_user(void *dst, void *src)
+static void ulog_tg_compat_from_user(void *dst, const void *src)
 {
 	const struct compat_ipt_ulog_info *cl = src;
 	struct ipt_ulog_info l = {
@@ -351,7 +351,7 @@ static void ulog_tg_compat_from_user(void *dst, void *src)
 	memcpy(dst, &l, sizeof(l));
 }
 
-static int ulog_tg_compat_to_user(void __user *dst, void *src)
+static int ulog_tg_compat_to_user(void __user *dst, const void *src)
 {
 	const struct ipt_ulog_info *l = src;
 	struct compat_ipt_ulog_info cl = {
diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c
index b311d87..07efff1 100644
--- a/net/ipv6/netfilter/ip6_tables.c
+++ b/net/ipv6/netfilter/ip6_tables.c
@@ -1074,7 +1074,7 @@ copy_entries_to_user(unsigned int total_size,
 }
 
 #ifdef CONFIG_COMPAT
-static void compat_standard_from_user(void *dst, void *src)
+static void compat_standard_from_user(void *dst, const void *src)
 {
 	int v = *(compat_int_t *)src;
 
@@ -1083,7 +1083,7 @@ static void compat_standard_from_user(void *dst, void *src)
 	memcpy(dst, &v, sizeof(v));
 }
 
-static int compat_standard_to_user(void __user *dst, void *src)
+static int compat_standard_to_user(void __user *dst, const void *src)
 {
 	compat_int_t cv = *(int *)src;
 
diff --git a/net/netfilter/x_tables.c b/net/netfilter/x_tables.c
index c8845d1..dbfc32d 100644
--- a/net/netfilter/x_tables.c
+++ b/net/netfilter/x_tables.c
@@ -485,8 +485,8 @@ int xt_compat_match_from_user(struct xt_entry_match *m, void **dstptr,
 }
 EXPORT_SYMBOL_GPL(xt_compat_match_from_user);
 
-int xt_compat_match_to_user(struct xt_entry_match *m, void __user **dstptr,
-			    unsigned int *size)
+int xt_compat_match_to_user(const struct xt_entry_match *m,
+			    void __user **dstptr, unsigned int *size)
 {
 	const struct xt_match *match = m->u.kernel.match;
 	struct compat_xt_entry_match __user *cm = *dstptr;
@@ -588,8 +588,8 @@ void xt_compat_target_from_user(struct xt_entry_target *t, void **dstptr,
 }
 EXPORT_SYMBOL_GPL(xt_compat_target_from_user);
 
-int xt_compat_target_to_user(struct xt_entry_target *t, void __user **dstptr,
-			     unsigned int *size)
+int xt_compat_target_to_user(const struct xt_entry_target *t,
+			     void __user **dstptr, unsigned int *size)
 {
 	const struct xt_target *target = t->u.kernel.target;
 	struct compat_xt_entry_target __user *ct = *dstptr;
diff --git a/net/netfilter/xt_hashlimit.c b/net/netfilter/xt_hashlimit.c
index dd16e40..abba093 100644
--- a/net/netfilter/xt_hashlimit.c
+++ b/net/netfilter/xt_hashlimit.c
@@ -767,7 +767,7 @@ struct compat_xt_hashlimit_info {
 	compat_uptr_t master;
 };
 
-static void hashlimit_mt_compat_from_user(void *dst, void *src)
+static void hashlimit_mt_compat_from_user(void *dst, const void *src)
 {
 	int off = offsetof(struct compat_xt_hashlimit_info, hinfo);
 
@@ -775,7 +775,7 @@ static void hashlimit_mt_compat_from_user(void *dst, void *src)
 	memset(dst + off, 0, sizeof(struct compat_xt_hashlimit_info) - off);
 }
 
-static int hashlimit_mt_compat_to_user(void __user *dst, void *src)
+static int hashlimit_mt_compat_to_user(void __user *dst, const void *src)
 {
 	int off = offsetof(struct compat_xt_hashlimit_info, hinfo);
 
diff --git a/net/netfilter/xt_limit.c b/net/netfilter/xt_limit.c
index 2e8089e..dad26f9 100644
--- a/net/netfilter/xt_limit.c
+++ b/net/netfilter/xt_limit.c
@@ -148,7 +148,7 @@ struct compat_xt_rateinfo {
 
 /* To keep the full "prev" timestamp, the upper 32 bits are stored in the
  * master pointer, which does not need to be preserved. */
-static void limit_mt_compat_from_user(void *dst, void *src)
+static void limit_mt_compat_from_user(void *dst, const void *src)
 {
 	const struct compat_xt_rateinfo *cm = src;
 	struct xt_rateinfo m = {
@@ -162,7 +162,7 @@ static void limit_mt_compat_from_user(void *dst, void *src)
 	memcpy(dst, &m, sizeof(m));
 }
 
-static int limit_mt_compat_to_user(void __user *dst, void *src)
+static int limit_mt_compat_to_user(void __user *dst, const void *src)
 {
 	const struct xt_rateinfo *m = src;
 	struct compat_xt_rateinfo cm = {
-- 
1.6.5.2

[PATCH 6/6] netfilter: xtables: add const qualifiers

[Jan Engelhardt]

This should make it easier to remove redundant arguments later.

Signed-off-by: Jan Engelhardt <jengelh@medozas.de>
---
 net/bridge/netfilter/ebtables.c |   56 ++++++++++++++-----------
 net/ipv4/netfilter/arp_tables.c |   69 +++++++++++++++++-------------
 net/ipv4/netfilter/ip_tables.c  |   88 +++++++++++++++++++++-----------------
 net/ipv6/netfilter/ip6_tables.c |   88 +++++++++++++++++++++------------------
 4 files changed, 167 insertions(+), 134 deletions(-)

diff --git a/net/bridge/netfilter/ebtables.c b/net/bridge/netfilter/ebtables.c
index bd1c654..9ed98d9 100644
--- a/net/bridge/netfilter/ebtables.c
+++ b/net/bridge/netfilter/ebtables.c
@@ -82,7 +82,8 @@ static inline int ebt_do_match (struct ebt_entry_match *m,
 	return m->u.match->match(skb, par) ? EBT_MATCH : EBT_NOMATCH;
 }
 
-static inline int ebt_dev_check(char *entry, const struct net_device *device)
+static inline int
+ebt_dev_check(const char *entry, const struct net_device *device)
 {
 	int i = 0;
 	const char *devname;
@@ -100,8 +101,9 @@ static inline int ebt_dev_check(char *entry, const struct net_device *device)
 
 #define FWINV2(bool,invflg) ((bool) ^ !!(e->invflags & invflg))
 /* process standard matches */
-static inline int ebt_basic_match(struct ebt_entry *e, struct ethhdr *h,
-   const struct net_device *in, const struct net_device *out)
+static inline int
+ebt_basic_match(const struct ebt_entry *e, const struct ethhdr *h,
+                const struct net_device *in, const struct net_device *out)
 {
 	int verdict, i;
 
@@ -156,12 +158,12 @@ unsigned int ebt_do_table (unsigned int hook, struct sk_buff *skb,
 	int i, nentries;
 	struct ebt_entry *point;
 	struct ebt_counter *counter_base, *cb_base;
-	struct ebt_entry_target *t;
+	const struct ebt_entry_target *t;
 	int verdict, sp = 0;
 	struct ebt_chainstack *cs;
 	struct ebt_entries *chaininfo;
-	char *base;
-	struct ebt_table_info *private;
+	const char *base;
+	const struct ebt_table_info *private;
 	bool hotdrop = false;
 	struct xt_match_param mtpar;
 	struct xt_target_param tgpar;
@@ -395,7 +397,7 @@ ebt_check_watcher(struct ebt_entry_watcher *w, struct xt_tgchk_param *par,
 	return 0;
 }
 
-static int ebt_verify_pointers(struct ebt_replace *repl,
+static int ebt_verify_pointers(const struct ebt_replace *repl,
 			       struct ebt_table_info *newinfo)
 {
 	unsigned int limit = repl->entries_size;
@@ -466,8 +468,8 @@ static int ebt_verify_pointers(struct ebt_replace *repl,
  * to parse the userspace data
  */
 static inline int
-ebt_check_entry_size_and_hooks(struct ebt_entry *e,
-   struct ebt_table_info *newinfo,
+ebt_check_entry_size_and_hooks(const struct ebt_entry *e,
+   const struct ebt_table_info *newinfo,
    unsigned int *n, unsigned int *cnt,
    unsigned int *totalcnt, unsigned int *udc_cnt)
 {
@@ -619,7 +621,7 @@ ebt_cleanup_entry(struct ebt_entry *e, unsigned int *cnt)
 }
 
 static inline int
-ebt_check_entry(struct ebt_entry *e, struct ebt_table_info *newinfo,
+ebt_check_entry(struct ebt_entry *e, const struct ebt_table_info *newinfo,
    const char *name, unsigned int *cnt,
    struct ebt_cl_stack *cl_s, unsigned int udc_cnt)
 {
@@ -737,12 +739,12 @@ cleanup_matches:
  * the hook mask for udc tells us from which base chains the udc can be
  * accessed. This mask is a parameter to the check() functions of the extensions
  */
-static int check_chainloops(struct ebt_entries *chain, struct ebt_cl_stack *cl_s,
+static int check_chainloops(const struct ebt_entries *chain, struct ebt_cl_stack *cl_s,
    unsigned int udc_cnt, unsigned int hooknr, char *base)
 {
 	int i, chain_nr = -1, pos = 0, nentries = chain->nentries, verdict;
-	struct ebt_entry *e = (struct ebt_entry *)chain->data;
-	struct ebt_entry_target *t;
+	const struct ebt_entry *e = (struct ebt_entry *)chain->data;
+	const struct ebt_entry_target *t;
 
 	while (pos < nentries || chain_nr != -1) {
 		/* end of udc, go back one 'recursion' step */
@@ -808,7 +810,7 @@ letscontinue:
 }
 
 /* do the parsing of the table/chains/entries/matches/watchers/targets, heh */
-static int translate_table(char *name, struct ebt_table_info *newinfo)
+static int translate_table(const char *name, struct ebt_table_info *newinfo)
 {
 	unsigned int i, j, k, udc_cnt;
 	int ret;
@@ -927,7 +929,7 @@ static int translate_table(char *name, struct ebt_table_info *newinfo)
 }
 
 /* called under write_lock */
-static void get_counters(struct ebt_counter *oldcounters,
+static void get_counters(const struct ebt_counter *oldcounters,
    struct ebt_counter *counters, unsigned int nentries)
 {
 	int i, cpu;
@@ -950,7 +952,8 @@ static void get_counters(struct ebt_counter *oldcounters,
 }
 
 /* replace the table */
-static int do_replace(struct net *net, void __user *user, unsigned int len)
+static int do_replace(struct net *net, const void __user *user,
+		      unsigned int len)
 {
 	int ret, i, countersize;
 	struct ebt_table_info *newinfo;
@@ -1230,7 +1233,8 @@ void ebt_unregister_table(struct ebt_table *table)
 }
 
 /* userspace just supplied us with counters */
-static int update_counters(struct net *net, void __user *user, unsigned int len)
+static int update_counters(struct net *net, const void __user *user,
+			   unsigned int len)
 {
 	int i, ret;
 	struct ebt_counter *tmp;
@@ -1285,8 +1289,8 @@ free_tmp:
 	return ret;
 }
 
-static inline int ebt_make_matchname(struct ebt_entry_match *m,
-   char *base, char __user *ubase)
+static inline int ebt_make_matchname(const struct ebt_entry_match *m,
+    const char *base, char __user *ubase)
 {
 	char __user *hlp = ubase + ((char *)m - base);
 	if (copy_to_user(hlp, m->u.match->name, EBT_FUNCTION_MAXNAMELEN))
@@ -1294,8 +1298,8 @@ static inline int ebt_make_matchname(struct ebt_entry_match *m,
 	return 0;
 }
 
-static inline int ebt_make_watchername(struct ebt_entry_watcher *w,
-   char *base, char __user *ubase)
+static inline int ebt_make_watchername(const struct ebt_entry_watcher *w,
+    const char *base, char __user *ubase)
 {
 	char __user *hlp = ubase + ((char *)w - base);
 	if (copy_to_user(hlp , w->u.watcher->name, EBT_FUNCTION_MAXNAMELEN))
@@ -1303,11 +1307,12 @@ static inline int ebt_make_watchername(struct ebt_entry_watcher *w,
 	return 0;
 }
 
-static inline int ebt_make_names(struct ebt_entry *e, char *base, char __user *ubase)
+static inline int
+ebt_make_names(struct ebt_entry *e, const char *base, char __user *ubase)
 {
 	int ret;
 	char __user *hlp;
-	struct ebt_entry_target *t;
+	const struct ebt_entry_target *t;
 
 	if (e->bitmask == 0)
 		return 0;
@@ -1328,10 +1333,11 @@ static inline int ebt_make_names(struct ebt_entry *e, char *base, char __user *u
 
 /* called with ebt_mutex locked */
 static int copy_everything_to_user(struct ebt_table *t, void __user *user,
-   int *len, int cmd)
+    const int *len, int cmd)
 {
 	struct ebt_replace tmp;
-	struct ebt_counter *counterstmp, *oldcounters;
+	struct ebt_counter *counterstmp;
+	const struct ebt_counter *oldcounters;
 	unsigned int entries_size, nentries;
 	char *entries;
 
diff --git a/net/ipv4/netfilter/arp_tables.c b/net/ipv4/netfilter/arp_tables.c
index 52c96b3..95c9645 100644
--- a/net/ipv4/netfilter/arp_tables.c
+++ b/net/ipv4/netfilter/arp_tables.c
@@ -233,7 +233,14 @@ arpt_error(struct sk_buff *skb, const struct xt_target_param *par)
 	return NF_DROP;
 }
 
-static inline struct arpt_entry *get_entry(void *base, unsigned int offset)
+static inline const struct arpt_entry_target *
+arpt_get_target_c(const struct arpt_entry *e)
+{
+	return arpt_get_target((struct arpt_entry *)e);
+}
+
+static inline struct arpt_entry *
+get_entry(const void *base, unsigned int offset)
 {
 	return (struct arpt_entry *)(base + offset);
 }
@@ -280,7 +287,7 @@ unsigned int arpt_do_table(struct sk_buff *skb,
 
 	arp = arp_hdr(skb);
 	do {
-		struct arpt_entry_target *t;
+		const struct arpt_entry_target *t;
 		int hdr_len;
 
 		if (!arp_packet_match(arp, skb->dev, indev, outdev, &e->arp)) {
@@ -292,7 +299,7 @@ unsigned int arpt_do_table(struct sk_buff *skb,
 			(2 * skb->dev->addr_len);
 		ADD_COUNTER(e->counters, hdr_len, 1);
 
-		t = arpt_get_target(e);
+		t = arpt_get_target_c(e);
 
 		/* Standard target? */
 		if (!t->u.kernel.target->target) {
@@ -358,7 +365,7 @@ static inline bool unconditional(const struct arpt_arp *arp)
 /* Figures out from what hook each rule can be called: returns 0 if
  * there are loops.  Puts hook bitmask in comefrom.
  */
-static int mark_source_chains(struct xt_table_info *newinfo,
+static int mark_source_chains(const struct xt_table_info *newinfo,
 			      unsigned int valid_hooks, void *entry0)
 {
 	unsigned int hook;
@@ -379,7 +386,7 @@ static int mark_source_chains(struct xt_table_info *newinfo,
 
 		for (;;) {
 			const struct arpt_standard_target *t
-				= (void *)arpt_get_target(e);
+				= (void *)arpt_get_target_c(e);
 			int visited = e->comefrom & (1 << hook);
 
 			if (e->comefrom & (1 << NF_ARP_NUMHOOKS)) {
@@ -463,7 +470,7 @@ static int mark_source_chains(struct xt_table_info *newinfo,
 	return 1;
 }
 
-static inline int check_entry(struct arpt_entry *e, const char *name)
+static inline int check_entry(const struct arpt_entry *e, const char *name)
 {
 	const struct arpt_entry_target *t;
 
@@ -475,7 +482,7 @@ static inline int check_entry(struct arpt_entry *e, const char *name)
 	if (e->target_offset + sizeof(struct arpt_entry_target) > e->next_offset)
 		return -EINVAL;
 
-	t = arpt_get_target(e);
+	t = arpt_get_target_c(e);
 	if (e->target_offset + t->u.target_size > e->next_offset)
 		return -EINVAL;
 
@@ -540,14 +547,14 @@ out:
 	return ret;
 }
 
-static bool check_underflow(struct arpt_entry *e)
+static bool check_underflow(const struct arpt_entry *e)
 {
 	const struct arpt_entry_target *t;
 	unsigned int verdict;
 
 	if (!unconditional(&e->arp))
 		return false;
-	t = arpt_get_target(e);
+	t = arpt_get_target_c(e);
 	if (strcmp(t->u.user.name, XT_STANDARD_TARGET) != 0)
 		return false;
 	verdict = ((struct arpt_standard_target *)t)->verdict;
@@ -557,8 +564,8 @@ static bool check_underflow(struct arpt_entry *e)
 
 static inline int check_entry_size_and_hooks(struct arpt_entry *e,
 					     struct xt_table_info *newinfo,
-					     unsigned char *base,
-					     unsigned char *limit,
+					     const unsigned char *base,
+					     const unsigned char *limit,
 					     const unsigned int *hook_entries,
 					     const unsigned int *underflows,
 					     unsigned int valid_hooks,
@@ -768,11 +775,11 @@ static void get_counters(const struct xt_table_info *t,
 	local_bh_enable();
 }
 
-static struct xt_counters *alloc_counters(struct xt_table *table)
+static struct xt_counters *alloc_counters(const struct xt_table *table)
 {
 	unsigned int countersize;
 	struct xt_counters *counters;
-	struct xt_table_info *private = table->private;
+	const struct xt_table_info *private = table->private;
 
 	/* We need atomic snapshot of counters: rest doesn't change
 	 * (other than comefrom, which userspace doesn't care
@@ -790,11 +797,11 @@ static struct xt_counters *alloc_counters(struct xt_table *table)
 }
 
 static int copy_entries_to_user(unsigned int total_size,
-				struct xt_table *table,
+				const struct xt_table *table,
 				void __user *userptr)
 {
 	unsigned int off, num;
-	struct arpt_entry *e;
+	const struct arpt_entry *e;
 	struct xt_counters *counters;
 	struct xt_table_info *private = table->private;
 	int ret = 0;
@@ -814,7 +821,7 @@ static int copy_entries_to_user(unsigned int total_size,
 	/* FIXME: use iterator macros --RR */
 	/* ... then go back and fix counters and names */
 	for (off = 0, num = 0; off < total_size; off += e->next_offset, num++){
-		struct arpt_entry_target *t;
+		const struct arpt_entry_target *t;
 
 		e = (struct arpt_entry *)(loc_cpu_entry + off);
 		if (copy_to_user(userptr + off
@@ -825,7 +832,7 @@ static int copy_entries_to_user(unsigned int total_size,
 			goto free_counters;
 		}
 
-		t = arpt_get_target(e);
+		t = arpt_get_target_c(e);
 		if (copy_to_user(userptr + off + e->target_offset
 				 + offsetof(struct arpt_entry_target,
 					    u.user.name),
@@ -860,18 +867,18 @@ static int compat_standard_to_user(void __user *dst, const void *src)
 	return copy_to_user(dst, &cv, sizeof(cv)) ? -EFAULT : 0;
 }
 
-static int compat_calc_entry(struct arpt_entry *e,
+static int compat_calc_entry(const struct arpt_entry *e,
 			     const struct xt_table_info *info,
-			     void *base, struct xt_table_info *newinfo)
+			     const void *base, struct xt_table_info *newinfo)
 {
-	struct arpt_entry_target *t;
+	const struct arpt_entry_target *t;
 	unsigned int entry_offset;
 	int off, i, ret;
 
 	off = sizeof(struct arpt_entry) - sizeof(struct compat_arpt_entry);
 	entry_offset = (void *)e - base;
 
-	t = arpt_get_target(e);
+	t = arpt_get_target_c(e);
 	off += xt_compat_target_offset(t->u.kernel.target);
 	newinfo->size -= off;
 	ret = xt_compat_add_offset(NFPROTO_ARP, entry_offset, off);
@@ -907,7 +914,8 @@ static int compat_table_info(const struct xt_table_info *info,
 }
 #endif
 
-static int get_info(struct net *net, void __user *user, int *len, int compat)
+static int get_info(struct net *net, void __user *user,
+                    const int *len, int compat)
 {
 	char name[ARPT_TABLE_MAXNAMELEN];
 	struct xt_table *t;
@@ -966,7 +974,7 @@ static int get_info(struct net *net, void __user *user, int *len, int compat)
 }
 
 static int get_entries(struct net *net, struct arpt_get_entries __user *uptr,
-		       int *len)
+		       const int *len)
 {
 	int ret;
 	struct arpt_get_entries get;
@@ -1080,7 +1088,8 @@ static int __do_replace(struct net *net, const char *name,
 	return ret;
 }
 
-static int do_replace(struct net *net, void __user *user, unsigned int len)
+static int do_replace(struct net *net, const void __user *user,
+                      unsigned int len)
 {
 	int ret;
 	struct arpt_replace tmp;
@@ -1140,8 +1149,8 @@ add_counter_to_entry(struct arpt_entry *e,
 	return 0;
 }
 
-static int do_add_counters(struct net *net, void __user *user, unsigned int len,
-			   int compat)
+static int do_add_counters(struct net *net, const void __user *user,
+			   unsigned int len, int compat)
 {
 	unsigned int i, curcpu;
 	struct xt_counters_info tmp;
@@ -1245,10 +1254,10 @@ static inline int
 check_compat_entry_size_and_hooks(struct compat_arpt_entry *e,
 				  struct xt_table_info *newinfo,
 				  unsigned int *size,
-				  unsigned char *base,
-				  unsigned char *limit,
-				  unsigned int *hook_entries,
-				  unsigned int *underflows,
+				  const unsigned char *base,
+				  const unsigned char *limit,
+				  const unsigned int *hook_entries,
+				  const unsigned int *underflows,
 				  unsigned int *i,
 				  const char *name)
 {
diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c
index 3e355fe..13574a8 100644
--- a/net/ipv4/netfilter/ip_tables.c
+++ b/net/ipv4/netfilter/ip_tables.c
@@ -176,7 +176,7 @@ ipt_error(struct sk_buff *skb, const struct xt_target_param *par)
 
 /* Performance critical - called for every packet */
 static inline bool
-do_match(struct ipt_entry_match *m, const struct sk_buff *skb,
+do_match(const struct ipt_entry_match *m, const struct sk_buff *skb,
 	 struct xt_match_param *par)
 {
 	par->match     = m->u.kernel.match;
@@ -191,7 +191,7 @@ do_match(struct ipt_entry_match *m, const struct sk_buff *skb,
 
 /* Performance critical */
 static inline struct ipt_entry *
-get_entry(void *base, unsigned int offset)
+get_entry(const void *base, unsigned int offset)
 {
 	return (struct ipt_entry *)(base + offset);
 }
@@ -206,6 +206,13 @@ static inline bool unconditional(const struct ipt_ip *ip)
 #undef FWINV
 }
 
+/* for const-correctness */
+static inline const struct ipt_entry_target *
+ipt_get_target_c(const struct ipt_entry *e)
+{
+	return ipt_get_target((struct ipt_entry *)e);
+}
+
 #if defined(CONFIG_NETFILTER_XT_TARGET_TRACE) || \
     defined(CONFIG_NETFILTER_XT_TARGET_TRACE_MODULE)
 static const char *const hooknames[] = {
@@ -240,11 +247,11 @@ static struct nf_loginfo trace_loginfo = {
 
 /* Mildly perf critical (only if packet tracing is on) */
 static inline int
-get_chainname_rulenum(struct ipt_entry *s, struct ipt_entry *e,
+get_chainname_rulenum(const struct ipt_entry *s, const struct ipt_entry *e,
 		      const char *hookname, const char **chainname,
 		      const char **comment, unsigned int *rulenum)
 {
-	struct ipt_standard_target *t = (void *)ipt_get_target(s);
+	const struct ipt_standard_target *t = (void *)ipt_get_target_c(s);
 
 	if (strcmp(t->target.u.kernel.target->name, IPT_ERROR_TARGET) == 0) {
 		/* Head of user chain: ERROR target with chainname */
@@ -270,15 +277,15 @@ get_chainname_rulenum(struct ipt_entry *s, struct ipt_entry *e,
 	return 0;
 }
 
-static void trace_packet(struct sk_buff *skb,
+static void trace_packet(const struct sk_buff *skb,
 			 unsigned int hook,
 			 const struct net_device *in,
 			 const struct net_device *out,
 			 const char *tablename,
-			 struct xt_table_info *private,
-			 struct ipt_entry *e)
+			 const struct xt_table_info *private,
+			 const struct ipt_entry *e)
 {
-	void *table_base;
+	const void *table_base;
 	const struct ipt_entry *root;
 	const char *hookname, *chainname, *comment;
 	unsigned int rulenum = 0;
@@ -322,9 +329,9 @@ ipt_do_table(struct sk_buff *skb,
 	/* Initializing verdict to NF_DROP keeps gcc happy. */
 	unsigned int verdict = NF_DROP;
 	const char *indev, *outdev;
-	void *table_base;
+	const void *table_base;
 	struct ipt_entry *e, *back;
-	struct xt_table_info *private;
+	const struct xt_table_info *private;
 	struct xt_match_param mtpar;
 	struct xt_target_param tgpar;
 
@@ -357,7 +364,7 @@ ipt_do_table(struct sk_buff *skb,
 	back = get_entry(table_base, private->underflow[hook]);
 
 	do {
-		struct ipt_entry_target *t;
+		const struct ipt_entry_target *t;
 
 		IP_NF_ASSERT(e);
 		IP_NF_ASSERT(back);
@@ -450,7 +457,7 @@ ipt_do_table(struct sk_buff *skb,
 /* Figures out from what hook each rule can be called: returns 0 if
    there are loops.  Puts hook bitmask in comefrom. */
 static int
-mark_source_chains(struct xt_table_info *newinfo,
+mark_source_chains(const struct xt_table_info *newinfo,
 		   unsigned int valid_hooks, void *entry0)
 {
 	unsigned int hook;
@@ -468,8 +475,8 @@ mark_source_chains(struct xt_table_info *newinfo,
 		e->counters.pcnt = pos;
 
 		for (;;) {
-			struct ipt_standard_target *t
-				= (void *)ipt_get_target(e);
+			const struct ipt_standard_target *t
+				= (void *)ipt_get_target_c(e);
 			int visited = e->comefrom & (1 << hook);
 
 			if (e->comefrom & (1 << NF_INET_NUMHOOKS)) {
@@ -577,9 +584,9 @@ cleanup_match(struct ipt_entry_match *m, unsigned int *i)
 }
 
 static int
-check_entry(struct ipt_entry *e, const char *name)
+check_entry(const struct ipt_entry *e, const char *name)
 {
-	struct ipt_entry_target *t;
+	const struct ipt_entry_target *t;
 
 	if (!ip_checkentry(&e->ip)) {
 		duprintf("ip_tables: ip check failed %p %s.\n", e, name);
@@ -590,7 +597,7 @@ check_entry(struct ipt_entry *e, const char *name)
 	    e->next_offset)
 		return -EINVAL;
 
-	t = ipt_get_target(e);
+	t = ipt_get_target_c(e);
 	if (e->target_offset + t->u.target_size > e->next_offset)
 		return -EINVAL;
 
@@ -715,14 +722,14 @@ find_check_entry(struct ipt_entry *e, const char *name, unsigned int size,
 	return ret;
 }
 
-static bool check_underflow(struct ipt_entry *e)
+static bool check_underflow(const struct ipt_entry *e)
 {
 	const struct ipt_entry_target *t;
 	unsigned int verdict;
 
 	if (!unconditional(&e->ip))
 		return false;
-	t = ipt_get_target(e);
+	t = ipt_get_target_c(e);
 	if (strcmp(t->u.user.name, XT_STANDARD_TARGET) != 0)
 		return false;
 	verdict = ((struct ipt_standard_target *)t)->verdict;
@@ -733,8 +740,8 @@ static bool check_underflow(struct ipt_entry *e)
 static int
 check_entry_size_and_hooks(struct ipt_entry *e,
 			   struct xt_table_info *newinfo,
-			   unsigned char *base,
-			   unsigned char *limit,
+			   const unsigned char *base,
+			   const unsigned char *limit,
 			   const unsigned int *hook_entries,
 			   const unsigned int *underflows,
 			   unsigned int valid_hooks,
@@ -947,11 +954,11 @@ get_counters(const struct xt_table_info *t,
 	local_bh_enable();
 }
 
-static struct xt_counters * alloc_counters(struct xt_table *table)
+static struct xt_counters *alloc_counters(const struct xt_table *table)
 {
 	unsigned int countersize;
 	struct xt_counters *counters;
-	struct xt_table_info *private = table->private;
+	const struct xt_table_info *private = table->private;
 
 	/* We need atomic snapshot of counters: rest doesn't change
 	   (other than comefrom, which userspace doesn't care
@@ -969,11 +976,11 @@ static struct xt_counters * alloc_counters(struct xt_table *table)
 
 static int
 copy_entries_to_user(unsigned int total_size,
-		     struct xt_table *table,
+		     const struct xt_table *table,
 		     void __user *userptr)
 {
 	unsigned int off, num;
-	struct ipt_entry *e;
+	const struct ipt_entry *e;
 	struct xt_counters *counters;
 	const struct xt_table_info *private = table->private;
 	int ret = 0;
@@ -1025,7 +1032,7 @@ copy_entries_to_user(unsigned int total_size,
 			}
 		}
 
-		t = ipt_get_target(e);
+		t = ipt_get_target_c(e);
 		if (copy_to_user(userptr + off + e->target_offset
 				 + offsetof(struct ipt_entry_target,
 					    u.user.name),
@@ -1061,24 +1068,24 @@ static int compat_standard_to_user(void __user *dst, const void *src)
 }
 
 static inline int
-compat_calc_match(struct ipt_entry_match *m, int *size)
+compat_calc_match(const struct ipt_entry_match *m, int *size)
 {
 	*size += xt_compat_match_offset(m->u.kernel.match);
 	return 0;
 }
 
-static int compat_calc_entry(struct ipt_entry *e,
+static int compat_calc_entry(const struct ipt_entry *e,
 			     const struct xt_table_info *info,
-			     void *base, struct xt_table_info *newinfo)
+			     const void *base, struct xt_table_info *newinfo)
 {
-	struct ipt_entry_target *t;
+	const struct ipt_entry_target *t;
 	unsigned int entry_offset;
 	int off, i, ret;
 
 	off = sizeof(struct ipt_entry) - sizeof(struct compat_ipt_entry);
 	entry_offset = (void *)e - base;
 	IPT_MATCH_ITERATE(e, compat_calc_match, &off);
-	t = ipt_get_target(e);
+	t = ipt_get_target_c(e);
 	off += xt_compat_target_offset(t->u.kernel.target);
 	newinfo->size -= off;
 	ret = xt_compat_add_offset(AF_INET, entry_offset, off);
@@ -1114,7 +1121,8 @@ static int compat_table_info(const struct xt_table_info *info,
 }
 #endif
 
-static int get_info(struct net *net, void __user *user, int *len, int compat)
+static int get_info(struct net *net, void __user *user,
+                    const int *len, int compat)
 {
 	char name[IPT_TABLE_MAXNAMELEN];
 	struct xt_table *t;
@@ -1174,7 +1182,8 @@ static int get_info(struct net *net, void __user *user, int *len, int compat)
 }
 
 static int
-get_entries(struct net *net, struct ipt_get_entries __user *uptr, int *len)
+get_entries(struct net *net, struct ipt_get_entries __user *uptr,
+	    const int *len)
 {
 	int ret;
 	struct ipt_get_entries get;
@@ -1284,7 +1293,7 @@ __do_replace(struct net *net, const char *name, unsigned int valid_hooks,
 }
 
 static int
-do_replace(struct net *net, void __user *user, unsigned int len)
+do_replace(struct net *net, const void __user *user, unsigned int len)
 {
 	int ret;
 	struct ipt_replace tmp;
@@ -1345,7 +1354,8 @@ add_counter_to_entry(struct ipt_entry *e,
 }
 
 static int
-do_add_counters(struct net *net, void __user *user, unsigned int len, int compat)
+do_add_counters(struct net *net, const void __user *user,
+                unsigned int len, int compat)
 {
 	unsigned int i, curcpu;
 	struct xt_counters_info tmp;
@@ -1541,10 +1551,10 @@ static int
 check_compat_entry_size_and_hooks(struct compat_ipt_entry *e,
 				  struct xt_table_info *newinfo,
 				  unsigned int *size,
-				  unsigned char *base,
-				  unsigned char *limit,
-				  unsigned int *hook_entries,
-				  unsigned int *underflows,
+				  const unsigned char *base,
+				  const unsigned char *limit,
+				  const unsigned int *hook_entries,
+				  const unsigned int *underflows,
 				  unsigned int *i,
 				  const char *name)
 {
diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c
index 07efff1..6e7908d 100644
--- a/net/ipv6/netfilter/ip6_tables.c
+++ b/net/ipv6/netfilter/ip6_tables.c
@@ -208,7 +208,7 @@ ip6t_error(struct sk_buff *skb, const struct xt_target_param *par)
 
 /* Performance critical - called for every packet */
 static inline bool
-do_match(struct ip6t_entry_match *m, const struct sk_buff *skb,
+do_match(const struct ip6t_entry_match *m, const struct sk_buff *skb,
 	 struct xt_match_param *par)
 {
 	par->match     = m->u.kernel.match;
@@ -222,7 +222,7 @@ do_match(struct ip6t_entry_match *m, const struct sk_buff *skb,
 }
 
 static inline struct ip6t_entry *
-get_entry(void *base, unsigned int offset)
+get_entry(const void *base, unsigned int offset)
 {
 	return (struct ip6t_entry *)(base + offset);
 }
@@ -236,6 +236,12 @@ static inline bool unconditional(const struct ip6t_ip6 *ipv6)
 	return memcmp(ipv6, &uncond, sizeof(uncond)) == 0;
 }
 
+static inline const struct ip6t_entry_target *
+ip6t_get_target_c(const struct ip6t_entry *e)
+{
+	return ip6t_get_target((struct ip6t_entry *)e);
+}
+
 #if defined(CONFIG_NETFILTER_XT_TARGET_TRACE) || \
     defined(CONFIG_NETFILTER_XT_TARGET_TRACE_MODULE)
 /* This cries for unification! */
@@ -271,11 +277,11 @@ static struct nf_loginfo trace_loginfo = {
 
 /* Mildly perf critical (only if packet tracing is on) */
 static inline int
-get_chainname_rulenum(struct ip6t_entry *s, struct ip6t_entry *e,
+get_chainname_rulenum(const struct ip6t_entry *s, const struct ip6t_entry *e,
 		      const char *hookname, const char **chainname,
 		      const char **comment, unsigned int *rulenum)
 {
-	struct ip6t_standard_target *t = (void *)ip6t_get_target(s);
+	const struct ip6t_standard_target *t = (void *)ip6t_get_target_c(s);
 
 	if (strcmp(t->target.u.kernel.target->name, IP6T_ERROR_TARGET) == 0) {
 		/* Head of user chain: ERROR target with chainname */
@@ -301,15 +307,15 @@ get_chainname_rulenum(struct ip6t_entry *s, struct ip6t_entry *e,
 	return 0;
 }
 
-static void trace_packet(struct sk_buff *skb,
+static void trace_packet(const struct sk_buff *skb,
 			 unsigned int hook,
 			 const struct net_device *in,
 			 const struct net_device *out,
 			 const char *tablename,
-			 struct xt_table_info *private,
-			 struct ip6t_entry *e)
+			 const struct xt_table_info *private,
+			 const struct ip6t_entry *e)
 {
-	void *table_base;
+	const void *table_base;
 	const struct ip6t_entry *root;
 	const char *hookname, *chainname, *comment;
 	unsigned int rulenum = 0;
@@ -352,9 +358,9 @@ ip6t_do_table(struct sk_buff *skb,
 	/* Initializing verdict to NF_DROP keeps gcc happy. */
 	unsigned int verdict = NF_DROP;
 	const char *indev, *outdev;
-	void *table_base;
+	const void *table_base;
 	struct ip6t_entry *e, *back;
-	struct xt_table_info *private;
+	const struct xt_table_info *private;
 	struct xt_match_param mtpar;
 	struct xt_target_param tgpar;
 
@@ -385,7 +391,7 @@ ip6t_do_table(struct sk_buff *skb,
 	back = get_entry(table_base, private->underflow[hook]);
 
 	do {
-		struct ip6t_entry_target *t;
+		const struct ip6t_entry_target *t;
 
 		IP_NF_ASSERT(e);
 		IP_NF_ASSERT(back);
@@ -400,7 +406,7 @@ ip6t_do_table(struct sk_buff *skb,
 			    ntohs(ipv6_hdr(skb)->payload_len) +
 			    sizeof(struct ipv6hdr), 1);
 
-		t = ip6t_get_target(e);
+		t = ip6t_get_target_c(e);
 		IP_NF_ASSERT(t->u.kernel.target);
 
 #if defined(CONFIG_NETFILTER_XT_TARGET_TRACE) || \
@@ -482,7 +488,7 @@ ip6t_do_table(struct sk_buff *skb,
 /* Figures out from what hook each rule can be called: returns 0 if
    there are loops.  Puts hook bitmask in comefrom. */
 static int
-mark_source_chains(struct xt_table_info *newinfo,
+mark_source_chains(const struct xt_table_info *newinfo,
 		   unsigned int valid_hooks, void *entry0)
 {
 	unsigned int hook;
@@ -500,8 +506,8 @@ mark_source_chains(struct xt_table_info *newinfo,
 		e->counters.pcnt = pos;
 
 		for (;;) {
-			struct ip6t_standard_target *t
-				= (void *)ip6t_get_target(e);
+			const struct ip6t_standard_target *t
+				= (void *)ip6t_get_target_c(e);
 			int visited = e->comefrom & (1 << hook);
 
 			if (e->comefrom & (1 << NF_INET_NUMHOOKS)) {
@@ -609,9 +615,9 @@ cleanup_match(struct ip6t_entry_match *m, unsigned int *i)
 }
 
 static int
-check_entry(struct ip6t_entry *e, const char *name)
+check_entry(const struct ip6t_entry *e, const char *name)
 {
-	struct ip6t_entry_target *t;
+	const struct ip6t_entry_target *t;
 
 	if (!ip6_checkentry(&e->ipv6)) {
 		duprintf("ip_tables: ip check failed %p %s.\n", e, name);
@@ -622,7 +628,7 @@ check_entry(struct ip6t_entry *e, const char *name)
 	    e->next_offset)
 		return -EINVAL;
 
-	t = ip6t_get_target(e);
+	t = ip6t_get_target_c(e);
 	if (e->target_offset + t->u.target_size > e->next_offset)
 		return -EINVAL;
 
@@ -747,14 +753,14 @@ find_check_entry(struct ip6t_entry *e, const char *name, unsigned int size,
 	return ret;
 }
 
-static bool check_underflow(struct ip6t_entry *e)
+static bool check_underflow(const struct ip6t_entry *e)
 {
 	const struct ip6t_entry_target *t;
 	unsigned int verdict;
 
 	if (!unconditional(&e->ipv6))
 		return false;
-	t = ip6t_get_target(e);
+	t = ip6t_get_target_c(e);
 	if (strcmp(t->u.user.name, XT_STANDARD_TARGET) != 0)
 		return false;
 	verdict = ((struct ip6t_standard_target *)t)->verdict;
@@ -765,8 +771,8 @@ static bool check_underflow(struct ip6t_entry *e)
 static int
 check_entry_size_and_hooks(struct ip6t_entry *e,
 			   struct xt_table_info *newinfo,
-			   unsigned char *base,
-			   unsigned char *limit,
+			   const unsigned char *base,
+			   const unsigned char *limit,
 			   const unsigned int *hook_entries,
 			   const unsigned int *underflows,
 			   unsigned int valid_hooks,
@@ -979,11 +985,11 @@ get_counters(const struct xt_table_info *t,
 	local_bh_enable();
 }
 
-static struct xt_counters *alloc_counters(struct xt_table *table)
+static struct xt_counters *alloc_counters(const struct xt_table *table)
 {
 	unsigned int countersize;
 	struct xt_counters *counters;
-	struct xt_table_info *private = table->private;
+	const struct xt_table_info *private = table->private;
 
 	/* We need atomic snapshot of counters: rest doesn't change
 	   (other than comefrom, which userspace doesn't care
@@ -1001,11 +1007,11 @@ static struct xt_counters *alloc_counters(struct xt_table *table)
 
 static int
 copy_entries_to_user(unsigned int total_size,
-		     struct xt_table *table,
+		     const struct xt_table *table,
 		     void __user *userptr)
 {
 	unsigned int off, num;
-	struct ip6t_entry *e;
+	const struct ip6t_entry *e;
 	struct xt_counters *counters;
 	const struct xt_table_info *private = table->private;
 	int ret = 0;
@@ -1057,7 +1063,7 @@ copy_entries_to_user(unsigned int total_size,
 			}
 		}
 
-		t = ip6t_get_target(e);
+		t = ip6t_get_target_c(e);
 		if (copy_to_user(userptr + off + e->target_offset
 				 + offsetof(struct ip6t_entry_target,
 					    u.user.name),
@@ -1093,24 +1099,24 @@ static int compat_standard_to_user(void __user *dst, const void *src)
 }
 
 static inline int
-compat_calc_match(struct ip6t_entry_match *m, int *size)
+compat_calc_match(const struct ip6t_entry_match *m, int *size)
 {
 	*size += xt_compat_match_offset(m->u.kernel.match);
 	return 0;
 }
 
-static int compat_calc_entry(struct ip6t_entry *e,
+static int compat_calc_entry(const struct ip6t_entry *e,
 			     const struct xt_table_info *info,
-			     void *base, struct xt_table_info *newinfo)
+			     const void *base, struct xt_table_info *newinfo)
 {
-	struct ip6t_entry_target *t;
+	const struct ip6t_entry_target *t;
 	unsigned int entry_offset;
 	int off, i, ret;
 
 	off = sizeof(struct ip6t_entry) - sizeof(struct compat_ip6t_entry);
 	entry_offset = (void *)e - base;
 	IP6T_MATCH_ITERATE(e, compat_calc_match, &off);
-	t = ip6t_get_target(e);
+	t = ip6t_get_target_c(e);
 	off += xt_compat_target_offset(t->u.kernel.target);
 	newinfo->size -= off;
 	ret = xt_compat_add_offset(AF_INET6, entry_offset, off);
@@ -1146,7 +1152,8 @@ static int compat_table_info(const struct xt_table_info *info,
 }
 #endif
 
-static int get_info(struct net *net, void __user *user, int *len, int compat)
+static int get_info(struct net *net, void __user *user,
+                    const int *len, int compat)
 {
 	char name[IP6T_TABLE_MAXNAMELEN];
 	struct xt_table *t;
@@ -1206,7 +1213,8 @@ static int get_info(struct net *net, void __user *user, int *len, int compat)
 }
 
 static int
-get_entries(struct net *net, struct ip6t_get_entries __user *uptr, int *len)
+get_entries(struct net *net, struct ip6t_get_entries __user *uptr,
+            const int *len)
 {
 	int ret;
 	struct ip6t_get_entries get;
@@ -1317,7 +1325,7 @@ __do_replace(struct net *net, const char *name, unsigned int valid_hooks,
 }
 
 static int
-do_replace(struct net *net, void __user *user, unsigned int len)
+do_replace(struct net *net, const void __user *user, unsigned int len)
 {
 	int ret;
 	struct ip6t_replace tmp;
@@ -1378,7 +1386,7 @@ add_counter_to_entry(struct ip6t_entry *e,
 }
 
 static int
-do_add_counters(struct net *net, void __user *user, unsigned int len,
+do_add_counters(struct net *net, const void __user *user, unsigned int len,
 		int compat)
 {
 	unsigned int i, curcpu;
@@ -1577,10 +1585,10 @@ static int
 check_compat_entry_size_and_hooks(struct compat_ip6t_entry *e,
 				  struct xt_table_info *newinfo,
 				  unsigned int *size,
-				  unsigned char *base,
-				  unsigned char *limit,
-				  unsigned int *hook_entries,
-				  unsigned int *underflows,
+				  const unsigned char *base,
+				  const unsigned char *limit,
+				  const unsigned int *hook_entries,
+				  const unsigned int *underflows,
 				  unsigned int *i,
 				  const char *name)
 {
-- 
1.6.5.2

Re: Xtables cleanup patches

[Patrick McHardy]

Jan Engelhardt wrote:
> I am posting here already the next round of pullable patches
> (that I originally wanted to get in _much_ faster) for review.

Well, you could speed things up by benchmarking your patches yourself
when concerns about adding overhead is raised. Otherwise you'll just
have to wait until someone else gets to do it.

> This block is mostly cleanups, simplifications. It might be worth
> testing these together with the previous set if there are concerns
> about speed.

Re: Xtables cleanup patches

[Jan Engelhardt]

On Tuesday 2009-11-03 19:27, Patrick McHardy wrote:

>Jan Engelhardt wrote:
>> I am posting here already the next round of pullable patches
>> (that I originally wanted to get in _much_ faster) for review.
>
>Well, you could speed things up by benchmarking your patches yourself
>when concerns about adding overhead is raised. Otherwise you'll just
>have to wait until someone else gets to do it.

What would you use for profiling? A wallclock, rdtsc around the 
section,-- or one of the fancy 
ftrace/oprofile/perfcounter/$yetanotherprofiler?