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![Willem de Bruijn](/assets/img/avatar_default.png)
xt_entry_target, xt_entry_match and their private data may contain kernel data. Introduce helper functions xt_match_to_user, xt_target_to_user and xt_data_to_user that copy only the expected fields. These replace existing logic that calls copy_to_user on entire structs, then overwrites select fields. Private data is defined in xt_match and xt_target. All matches and targets that maintain kernel data store this at the tail of their private structure. Extend xt_match and xt_target with .usersize to limit how many bytes of data are copied. The remainder is cleared. If compatsize is specified, usersize can only safely be used if all fields up to usersize use platform-independent types. Otherwise, the compat_to_user callback must be defined. This patch does not yet enable the support logic. Signed-off-by: Willem de Bruijn <willemb@google.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
526 lines
14 KiB
C
526 lines
14 KiB
C
#ifndef _X_TABLES_H
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#define _X_TABLES_H
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#include <linux/netdevice.h>
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#include <linux/static_key.h>
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#include <linux/netfilter.h>
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#include <uapi/linux/netfilter/x_tables.h>
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/* Test a struct->invflags and a boolean for inequality */
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#define NF_INVF(ptr, flag, boolean) \
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((boolean) ^ !!((ptr)->invflags & (flag)))
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/**
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* struct xt_action_param - parameters for matches/targets
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*
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* @match: the match extension
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* @target: the target extension
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* @matchinfo: per-match data
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* @targetinfo: per-target data
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* @state: pointer to hook state this packet came from
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* @fragoff: packet is a fragment, this is the data offset
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* @thoff: position of transport header relative to skb->data
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*
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* Fields written to by extensions:
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*
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* @hotdrop: drop packet if we had inspection problems
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*/
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struct xt_action_param {
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union {
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const struct xt_match *match;
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const struct xt_target *target;
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};
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union {
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const void *matchinfo, *targinfo;
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};
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const struct nf_hook_state *state;
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int fragoff;
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unsigned int thoff;
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bool hotdrop;
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};
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static inline struct net *xt_net(const struct xt_action_param *par)
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{
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return par->state->net;
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}
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static inline struct net_device *xt_in(const struct xt_action_param *par)
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{
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return par->state->in;
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}
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static inline const char *xt_inname(const struct xt_action_param *par)
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{
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return par->state->in->name;
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}
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static inline struct net_device *xt_out(const struct xt_action_param *par)
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{
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return par->state->out;
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}
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static inline const char *xt_outname(const struct xt_action_param *par)
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{
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return par->state->out->name;
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}
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static inline unsigned int xt_hooknum(const struct xt_action_param *par)
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{
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return par->state->hook;
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}
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static inline u_int8_t xt_family(const struct xt_action_param *par)
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{
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return par->state->pf;
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}
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/**
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* struct xt_mtchk_param - parameters for match extensions'
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* checkentry functions
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*
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* @net: network namespace through which the check was invoked
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* @table: table the rule is tried to be inserted into
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* @entryinfo: the family-specific rule data
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* (struct ipt_ip, ip6t_ip, arpt_arp or (note) ebt_entry)
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* @match: struct xt_match through which this function was invoked
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* @matchinfo: per-match data
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* @hook_mask: via which hooks the new rule is reachable
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* Other fields as above.
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*/
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struct xt_mtchk_param {
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struct net *net;
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const char *table;
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const void *entryinfo;
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const struct xt_match *match;
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void *matchinfo;
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unsigned int hook_mask;
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u_int8_t family;
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bool nft_compat;
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};
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/**
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* struct xt_mdtor_param - match destructor parameters
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* Fields as above.
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*/
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struct xt_mtdtor_param {
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struct net *net;
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const struct xt_match *match;
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void *matchinfo;
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u_int8_t family;
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};
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/**
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* struct xt_tgchk_param - parameters for target extensions'
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* checkentry functions
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*
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* @entryinfo: the family-specific rule data
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* (struct ipt_entry, ip6t_entry, arpt_entry, ebt_entry)
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*
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* Other fields see above.
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*/
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struct xt_tgchk_param {
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struct net *net;
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const char *table;
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const void *entryinfo;
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const struct xt_target *target;
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void *targinfo;
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unsigned int hook_mask;
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u_int8_t family;
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bool nft_compat;
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};
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/* Target destructor parameters */
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struct xt_tgdtor_param {
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struct net *net;
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const struct xt_target *target;
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void *targinfo;
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u_int8_t family;
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};
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struct xt_match {
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struct list_head list;
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const char name[XT_EXTENSION_MAXNAMELEN];
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u_int8_t revision;
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/* Return true or false: return FALSE and set *hotdrop = 1 to
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force immediate packet drop. */
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/* Arguments changed since 2.6.9, as this must now handle
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non-linear skb, using skb_header_pointer and
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skb_ip_make_writable. */
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bool (*match)(const struct sk_buff *skb,
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struct xt_action_param *);
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/* Called when user tries to insert an entry of this type. */
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int (*checkentry)(const struct xt_mtchk_param *);
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/* Called when entry of this type deleted. */
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void (*destroy)(const struct xt_mtdtor_param *);
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#ifdef CONFIG_COMPAT
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/* Called when userspace align differs from kernel space one */
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void (*compat_from_user)(void *dst, const void *src);
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int (*compat_to_user)(void __user *dst, const void *src);
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#endif
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/* Set this to THIS_MODULE if you are a module, otherwise NULL */
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struct module *me;
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const char *table;
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unsigned int matchsize;
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unsigned int usersize;
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#ifdef CONFIG_COMPAT
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unsigned int compatsize;
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#endif
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unsigned int hooks;
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unsigned short proto;
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unsigned short family;
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};
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/* Registration hooks for targets. */
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struct xt_target {
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struct list_head list;
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const char name[XT_EXTENSION_MAXNAMELEN];
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u_int8_t revision;
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/* Returns verdict. Argument order changed since 2.6.9, as this
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must now handle non-linear skbs, using skb_copy_bits and
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skb_ip_make_writable. */
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unsigned int (*target)(struct sk_buff *skb,
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const struct xt_action_param *);
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/* Called when user tries to insert an entry of this type:
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hook_mask is a bitmask of hooks from which it can be
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called. */
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/* Should return 0 on success or an error code otherwise (-Exxxx). */
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int (*checkentry)(const struct xt_tgchk_param *);
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/* Called when entry of this type deleted. */
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void (*destroy)(const struct xt_tgdtor_param *);
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#ifdef CONFIG_COMPAT
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/* Called when userspace align differs from kernel space one */
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void (*compat_from_user)(void *dst, const void *src);
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int (*compat_to_user)(void __user *dst, const void *src);
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#endif
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/* Set this to THIS_MODULE if you are a module, otherwise NULL */
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struct module *me;
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const char *table;
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unsigned int targetsize;
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unsigned int usersize;
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#ifdef CONFIG_COMPAT
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unsigned int compatsize;
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#endif
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unsigned int hooks;
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unsigned short proto;
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unsigned short family;
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};
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/* Furniture shopping... */
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struct xt_table {
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struct list_head list;
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/* What hooks you will enter on */
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unsigned int valid_hooks;
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/* Man behind the curtain... */
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struct xt_table_info *private;
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/* Set this to THIS_MODULE if you are a module, otherwise NULL */
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struct module *me;
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u_int8_t af; /* address/protocol family */
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int priority; /* hook order */
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/* called when table is needed in the given netns */
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int (*table_init)(struct net *net);
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/* A unique name... */
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const char name[XT_TABLE_MAXNAMELEN];
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};
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#include <linux/netfilter_ipv4.h>
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/* The table itself */
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struct xt_table_info {
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/* Size per table */
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unsigned int size;
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/* Number of entries: FIXME. --RR */
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unsigned int number;
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/* Initial number of entries. Needed for module usage count */
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unsigned int initial_entries;
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/* Entry points and underflows */
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unsigned int hook_entry[NF_INET_NUMHOOKS];
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unsigned int underflow[NF_INET_NUMHOOKS];
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/*
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* Number of user chains. Since tables cannot have loops, at most
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* @stacksize jumps (number of user chains) can possibly be made.
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*/
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unsigned int stacksize;
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void ***jumpstack;
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unsigned char entries[0] __aligned(8);
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};
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int xt_register_target(struct xt_target *target);
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void xt_unregister_target(struct xt_target *target);
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int xt_register_targets(struct xt_target *target, unsigned int n);
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void xt_unregister_targets(struct xt_target *target, unsigned int n);
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int xt_register_match(struct xt_match *target);
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void xt_unregister_match(struct xt_match *target);
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int xt_register_matches(struct xt_match *match, unsigned int n);
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void xt_unregister_matches(struct xt_match *match, unsigned int n);
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int xt_check_entry_offsets(const void *base, const char *elems,
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unsigned int target_offset,
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unsigned int next_offset);
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unsigned int *xt_alloc_entry_offsets(unsigned int size);
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bool xt_find_jump_offset(const unsigned int *offsets,
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unsigned int target, unsigned int size);
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int xt_check_match(struct xt_mtchk_param *, unsigned int size, u_int8_t proto,
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bool inv_proto);
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int xt_check_target(struct xt_tgchk_param *, unsigned int size, u_int8_t proto,
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bool inv_proto);
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int xt_match_to_user(const struct xt_entry_match *m,
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struct xt_entry_match __user *u);
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int xt_target_to_user(const struct xt_entry_target *t,
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struct xt_entry_target __user *u);
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int xt_data_to_user(void __user *dst, const void *src,
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int usersize, int size);
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void *xt_copy_counters_from_user(const void __user *user, unsigned int len,
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struct xt_counters_info *info, bool compat);
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struct xt_table *xt_register_table(struct net *net,
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const struct xt_table *table,
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struct xt_table_info *bootstrap,
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struct xt_table_info *newinfo);
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void *xt_unregister_table(struct xt_table *table);
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struct xt_table_info *xt_replace_table(struct xt_table *table,
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unsigned int num_counters,
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struct xt_table_info *newinfo,
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int *error);
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struct xt_match *xt_find_match(u8 af, const char *name, u8 revision);
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struct xt_target *xt_find_target(u8 af, const char *name, u8 revision);
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struct xt_match *xt_request_find_match(u8 af, const char *name, u8 revision);
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struct xt_target *xt_request_find_target(u8 af, const char *name, u8 revision);
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int xt_find_revision(u8 af, const char *name, u8 revision, int target,
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int *err);
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struct xt_table *xt_find_table_lock(struct net *net, u_int8_t af,
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const char *name);
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void xt_table_unlock(struct xt_table *t);
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int xt_proto_init(struct net *net, u_int8_t af);
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void xt_proto_fini(struct net *net, u_int8_t af);
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struct xt_table_info *xt_alloc_table_info(unsigned int size);
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void xt_free_table_info(struct xt_table_info *info);
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/**
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* xt_recseq - recursive seqcount for netfilter use
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*
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* Packet processing changes the seqcount only if no recursion happened
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* get_counters() can use read_seqcount_begin()/read_seqcount_retry(),
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* because we use the normal seqcount convention :
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* Low order bit set to 1 if a writer is active.
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*/
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DECLARE_PER_CPU(seqcount_t, xt_recseq);
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/* xt_tee_enabled - true if x_tables needs to handle reentrancy
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*
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* Enabled if current ip(6)tables ruleset has at least one -j TEE rule.
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*/
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extern struct static_key xt_tee_enabled;
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/**
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* xt_write_recseq_begin - start of a write section
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*
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* Begin packet processing : all readers must wait the end
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* 1) Must be called with preemption disabled
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* 2) softirqs must be disabled too (or we should use this_cpu_add())
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* Returns :
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* 1 if no recursion on this cpu
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* 0 if recursion detected
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*/
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static inline unsigned int xt_write_recseq_begin(void)
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{
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unsigned int addend;
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/*
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* Low order bit of sequence is set if we already
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* called xt_write_recseq_begin().
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*/
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addend = (__this_cpu_read(xt_recseq.sequence) + 1) & 1;
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/*
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* This is kind of a write_seqcount_begin(), but addend is 0 or 1
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* We dont check addend value to avoid a test and conditional jump,
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* since addend is most likely 1
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*/
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__this_cpu_add(xt_recseq.sequence, addend);
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smp_wmb();
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return addend;
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}
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/**
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* xt_write_recseq_end - end of a write section
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* @addend: return value from previous xt_write_recseq_begin()
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*
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* End packet processing : all readers can proceed
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* 1) Must be called with preemption disabled
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* 2) softirqs must be disabled too (or we should use this_cpu_add())
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*/
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static inline void xt_write_recseq_end(unsigned int addend)
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{
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/* this is kind of a write_seqcount_end(), but addend is 0 or 1 */
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smp_wmb();
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__this_cpu_add(xt_recseq.sequence, addend);
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}
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/*
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* This helper is performance critical and must be inlined
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*/
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static inline unsigned long ifname_compare_aligned(const char *_a,
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const char *_b,
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const char *_mask)
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{
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const unsigned long *a = (const unsigned long *)_a;
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const unsigned long *b = (const unsigned long *)_b;
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const unsigned long *mask = (const unsigned long *)_mask;
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unsigned long ret;
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ret = (a[0] ^ b[0]) & mask[0];
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if (IFNAMSIZ > sizeof(unsigned long))
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ret |= (a[1] ^ b[1]) & mask[1];
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if (IFNAMSIZ > 2 * sizeof(unsigned long))
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ret |= (a[2] ^ b[2]) & mask[2];
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if (IFNAMSIZ > 3 * sizeof(unsigned long))
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ret |= (a[3] ^ b[3]) & mask[3];
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BUILD_BUG_ON(IFNAMSIZ > 4 * sizeof(unsigned long));
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return ret;
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}
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struct xt_percpu_counter_alloc_state {
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unsigned int off;
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const char __percpu *mem;
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};
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bool xt_percpu_counter_alloc(struct xt_percpu_counter_alloc_state *state,
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struct xt_counters *counter);
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void xt_percpu_counter_free(struct xt_counters *cnt);
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static inline struct xt_counters *
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xt_get_this_cpu_counter(struct xt_counters *cnt)
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{
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if (nr_cpu_ids > 1)
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return this_cpu_ptr((void __percpu *) (unsigned long) cnt->pcnt);
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return cnt;
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}
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static inline struct xt_counters *
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xt_get_per_cpu_counter(struct xt_counters *cnt, unsigned int cpu)
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{
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if (nr_cpu_ids > 1)
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return per_cpu_ptr((void __percpu *) (unsigned long) cnt->pcnt, cpu);
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return cnt;
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}
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struct nf_hook_ops *xt_hook_ops_alloc(const struct xt_table *, nf_hookfn *);
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#ifdef CONFIG_COMPAT
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#include <net/compat.h>
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struct compat_xt_entry_match {
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union {
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struct {
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u_int16_t match_size;
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char name[XT_FUNCTION_MAXNAMELEN - 1];
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u_int8_t revision;
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} user;
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struct {
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u_int16_t match_size;
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compat_uptr_t match;
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} kernel;
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u_int16_t match_size;
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} u;
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unsigned char data[0];
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};
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struct compat_xt_entry_target {
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union {
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struct {
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u_int16_t target_size;
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char name[XT_FUNCTION_MAXNAMELEN - 1];
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u_int8_t revision;
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} user;
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struct {
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u_int16_t target_size;
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compat_uptr_t target;
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} kernel;
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u_int16_t target_size;
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} u;
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unsigned char data[0];
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};
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/* FIXME: this works only on 32 bit tasks
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* need to change whole approach in order to calculate align as function of
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* current task alignment */
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struct compat_xt_counters {
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compat_u64 pcnt, bcnt; /* Packet and byte counters */
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};
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struct compat_xt_counters_info {
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char name[XT_TABLE_MAXNAMELEN];
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compat_uint_t num_counters;
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struct compat_xt_counters counters[0];
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};
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struct _compat_xt_align {
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__u8 u8;
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__u16 u16;
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__u32 u32;
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compat_u64 u64;
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};
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#define COMPAT_XT_ALIGN(s) __ALIGN_KERNEL((s), __alignof__(struct _compat_xt_align))
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void xt_compat_lock(u_int8_t af);
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void xt_compat_unlock(u_int8_t af);
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int xt_compat_add_offset(u_int8_t af, unsigned int offset, int delta);
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void xt_compat_flush_offsets(u_int8_t af);
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void xt_compat_init_offsets(u_int8_t af, unsigned int number);
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int xt_compat_calc_jump(u_int8_t af, unsigned int offset);
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int xt_compat_match_offset(const struct xt_match *match);
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void xt_compat_match_from_user(struct xt_entry_match *m, void **dstptr,
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unsigned int *size);
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int xt_compat_match_to_user(const struct xt_entry_match *m,
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void __user **dstptr, unsigned int *size);
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int xt_compat_target_offset(const struct xt_target *target);
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void xt_compat_target_from_user(struct xt_entry_target *t, void **dstptr,
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unsigned int *size);
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int xt_compat_target_to_user(const struct xt_entry_target *t,
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void __user **dstptr, unsigned int *size);
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int xt_compat_check_entry_offsets(const void *base, const char *elems,
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unsigned int target_offset,
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unsigned int next_offset);
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#endif /* CONFIG_COMPAT */
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#endif /* _X_TABLES_H */
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