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d214c7537b
SKF_AD_NLATTR allows us to find the first matching attribute in a stream of netlink attributes from one offset to the end of the netlink message. This is not suitable to look for a specific matching inside a set of nested attributes. For example, in ctnetlink messages, if we look for the CTA_V6_SRC attribute in a message that talks about an IPv4 connection, SKF_AD_NLATTR returns the offset of CTA_STATUS which has the same value of CTA_V6_SRC but outside the nest. To differenciate CTA_STATUS and CTA_V6_SRC, we would have to make assumptions on the size of the attribute and the usual offset, resulting in horrible BSF code. This patch adds SKF_AD_NLATTR_NEST, which is a variant of SKF_AD_NLATTR, that looks for an attribute inside the limits of a nested attributes, but not further. This patch validates that we have enough room to look for the nested attributes - based on a suggestion from Patrick McHardy. Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> Acked-by: Patrick McHardy <kaber@trash.net> Signed-off-by: David S. Miller <davem@davemloft.net>
156 lines
4.0 KiB
C
156 lines
4.0 KiB
C
/*
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* Linux Socket Filter Data Structures
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*/
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#ifndef __LINUX_FILTER_H__
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#define __LINUX_FILTER_H__
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#include <linux/compiler.h>
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#include <linux/types.h>
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#ifdef __KERNEL__
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#include <asm/atomic.h>
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#endif
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/*
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* Current version of the filter code architecture.
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*/
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#define BPF_MAJOR_VERSION 1
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#define BPF_MINOR_VERSION 1
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/*
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* Try and keep these values and structures similar to BSD, especially
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* the BPF code definitions which need to match so you can share filters
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*/
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struct sock_filter /* Filter block */
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{
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__u16 code; /* Actual filter code */
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__u8 jt; /* Jump true */
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__u8 jf; /* Jump false */
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__u32 k; /* Generic multiuse field */
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};
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struct sock_fprog /* Required for SO_ATTACH_FILTER. */
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{
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unsigned short len; /* Number of filter blocks */
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struct sock_filter __user *filter;
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};
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/*
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* Instruction classes
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*/
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#define BPF_CLASS(code) ((code) & 0x07)
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#define BPF_LD 0x00
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#define BPF_LDX 0x01
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#define BPF_ST 0x02
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#define BPF_STX 0x03
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#define BPF_ALU 0x04
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#define BPF_JMP 0x05
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#define BPF_RET 0x06
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#define BPF_MISC 0x07
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/* ld/ldx fields */
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#define BPF_SIZE(code) ((code) & 0x18)
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#define BPF_W 0x00
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#define BPF_H 0x08
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#define BPF_B 0x10
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#define BPF_MODE(code) ((code) & 0xe0)
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#define BPF_IMM 0x00
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#define BPF_ABS 0x20
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#define BPF_IND 0x40
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#define BPF_MEM 0x60
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#define BPF_LEN 0x80
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#define BPF_MSH 0xa0
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/* alu/jmp fields */
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#define BPF_OP(code) ((code) & 0xf0)
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#define BPF_ADD 0x00
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#define BPF_SUB 0x10
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#define BPF_MUL 0x20
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#define BPF_DIV 0x30
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#define BPF_OR 0x40
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#define BPF_AND 0x50
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#define BPF_LSH 0x60
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#define BPF_RSH 0x70
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#define BPF_NEG 0x80
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#define BPF_JA 0x00
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#define BPF_JEQ 0x10
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#define BPF_JGT 0x20
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#define BPF_JGE 0x30
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#define BPF_JSET 0x40
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#define BPF_SRC(code) ((code) & 0x08)
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#define BPF_K 0x00
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#define BPF_X 0x08
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/* ret - BPF_K and BPF_X also apply */
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#define BPF_RVAL(code) ((code) & 0x18)
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#define BPF_A 0x10
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/* misc */
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#define BPF_MISCOP(code) ((code) & 0xf8)
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#define BPF_TAX 0x00
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#define BPF_TXA 0x80
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#ifndef BPF_MAXINSNS
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#define BPF_MAXINSNS 4096
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#endif
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/*
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* Macros for filter block array initializers.
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*/
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#ifndef BPF_STMT
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#define BPF_STMT(code, k) { (unsigned short)(code), 0, 0, k }
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#endif
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#ifndef BPF_JUMP
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#define BPF_JUMP(code, k, jt, jf) { (unsigned short)(code), jt, jf, k }
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#endif
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/*
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* Number of scratch memory words for: BPF_ST and BPF_STX
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*/
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#define BPF_MEMWORDS 16
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/* RATIONALE. Negative offsets are invalid in BPF.
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We use them to reference ancillary data.
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Unlike introduction new instructions, it does not break
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existing compilers/optimizers.
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*/
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#define SKF_AD_OFF (-0x1000)
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#define SKF_AD_PROTOCOL 0
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#define SKF_AD_PKTTYPE 4
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#define SKF_AD_IFINDEX 8
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#define SKF_AD_NLATTR 12
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#define SKF_AD_NLATTR_NEST 16
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#define SKF_AD_MAX 20
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#define SKF_NET_OFF (-0x100000)
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#define SKF_LL_OFF (-0x200000)
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#ifdef __KERNEL__
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struct sk_filter
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{
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atomic_t refcnt;
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unsigned int len; /* Number of filter blocks */
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struct rcu_head rcu;
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struct sock_filter insns[0];
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};
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static inline unsigned int sk_filter_len(const struct sk_filter *fp)
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{
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return fp->len * sizeof(struct sock_filter) + sizeof(*fp);
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}
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struct sk_buff;
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struct sock;
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extern int sk_filter(struct sock *sk, struct sk_buff *skb);
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extern unsigned int sk_run_filter(struct sk_buff *skb,
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struct sock_filter *filter, int flen);
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extern int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk);
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extern int sk_detach_filter(struct sock *sk);
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extern int sk_chk_filter(struct sock_filter *filter, int flen);
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#endif /* __KERNEL__ */
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#endif /* __LINUX_FILTER_H__ */
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