a8fc927780
The SO_ATTACH_FILTER option is set only. I propose to add the get ability by using SO_ATTACH_FILTER in getsockopt. To be less irritating to eyes the SO_GET_FILTER alias to it is declared. This ability is required by checkpoint-restore project to be able to save full state of a socket. There are two issues with getting filter back. First, kernel modifies the sock_filter->code on filter load, thus in order to return the filter element back to user we have to decode it into user-visible constants. Fortunately the modification in question is interconvertible. Second, the BPF_S_ALU_DIV_K code modifies the command argument k to speed up the run-time division by doing kernel_k = reciprocal(user_k). Bad news is that different user_k may result in same kernel_k, so we can't get the original user_k back. Good news is that we don't have to do it. What we need to is calculate a user2_k so, that reciprocal(user2_k) == reciprocal(user_k) == kernel_k i.e. if it's re-loaded back the compiled again value will be exactly the same as it was. That said, the user2_k can be calculated like this user2_k = reciprocal(kernel_k) with an exception, that if kernel_k == 0, then user2_k == 1. The optlen argument is treated like this -- when zero, kernel returns the amount of sock_fprog elements in filter, otherwise it should be large enough for the sock_fprog array. changes since v1: * Declared SO_GET_FILTER in all arch headers * Added decode of vlan-tag codes Signed-off-by: Pavel Emelyanov <xemul@parallels.com> Signed-off-by: David S. Miller <davem@davemloft.net>
132 lines
2.9 KiB
C
132 lines
2.9 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/atomic.h>
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#include <linux/compat.h>
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#include <uapi/linux/filter.h>
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#ifdef CONFIG_COMPAT
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/*
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* A struct sock_filter is architecture independent.
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*/
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struct compat_sock_fprog {
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u16 len;
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compat_uptr_t filter; /* struct sock_filter * */
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};
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#endif
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struct sk_buff;
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struct sock;
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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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unsigned int (*bpf_func)(const struct sk_buff *skb,
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const struct sock_filter *filter);
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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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extern int sk_filter(struct sock *sk, struct sk_buff *skb);
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extern unsigned int sk_run_filter(const struct sk_buff *skb,
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const struct sock_filter *filter);
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extern int sk_unattached_filter_create(struct sk_filter **pfp,
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struct sock_fprog *fprog);
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extern void sk_unattached_filter_destroy(struct sk_filter *fp);
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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, unsigned int flen);
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extern int sk_get_filter(struct sock *sk, struct sock_filter __user *filter, unsigned len);
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#ifdef CONFIG_BPF_JIT
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extern void bpf_jit_compile(struct sk_filter *fp);
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extern void bpf_jit_free(struct sk_filter *fp);
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#define SK_RUN_FILTER(FILTER, SKB) (*FILTER->bpf_func)(SKB, FILTER->insns)
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#else
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static inline void bpf_jit_compile(struct sk_filter *fp)
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{
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}
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static inline void bpf_jit_free(struct sk_filter *fp)
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{
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}
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#define SK_RUN_FILTER(FILTER, SKB) sk_run_filter(SKB, FILTER->insns)
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#endif
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enum {
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BPF_S_RET_K = 1,
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BPF_S_RET_A,
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BPF_S_ALU_ADD_K,
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BPF_S_ALU_ADD_X,
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BPF_S_ALU_SUB_K,
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BPF_S_ALU_SUB_X,
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BPF_S_ALU_MUL_K,
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BPF_S_ALU_MUL_X,
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BPF_S_ALU_DIV_X,
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BPF_S_ALU_MOD_K,
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BPF_S_ALU_MOD_X,
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BPF_S_ALU_AND_K,
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BPF_S_ALU_AND_X,
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BPF_S_ALU_OR_K,
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BPF_S_ALU_OR_X,
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BPF_S_ALU_XOR_K,
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BPF_S_ALU_XOR_X,
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BPF_S_ALU_LSH_K,
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BPF_S_ALU_LSH_X,
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BPF_S_ALU_RSH_K,
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BPF_S_ALU_RSH_X,
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BPF_S_ALU_NEG,
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BPF_S_LD_W_ABS,
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BPF_S_LD_H_ABS,
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BPF_S_LD_B_ABS,
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BPF_S_LD_W_LEN,
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BPF_S_LD_W_IND,
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BPF_S_LD_H_IND,
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BPF_S_LD_B_IND,
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BPF_S_LD_IMM,
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BPF_S_LDX_W_LEN,
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BPF_S_LDX_B_MSH,
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BPF_S_LDX_IMM,
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BPF_S_MISC_TAX,
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BPF_S_MISC_TXA,
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BPF_S_ALU_DIV_K,
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BPF_S_LD_MEM,
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BPF_S_LDX_MEM,
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BPF_S_ST,
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BPF_S_STX,
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BPF_S_JMP_JA,
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BPF_S_JMP_JEQ_K,
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BPF_S_JMP_JEQ_X,
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BPF_S_JMP_JGE_K,
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BPF_S_JMP_JGE_X,
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BPF_S_JMP_JGT_K,
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BPF_S_JMP_JGT_X,
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BPF_S_JMP_JSET_K,
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BPF_S_JMP_JSET_X,
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/* Ancillary data */
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BPF_S_ANC_PROTOCOL,
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BPF_S_ANC_PKTTYPE,
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BPF_S_ANC_IFINDEX,
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BPF_S_ANC_NLATTR,
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BPF_S_ANC_NLATTR_NEST,
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BPF_S_ANC_MARK,
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BPF_S_ANC_QUEUE,
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BPF_S_ANC_HATYPE,
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BPF_S_ANC_RXHASH,
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BPF_S_ANC_CPU,
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BPF_S_ANC_ALU_XOR_X,
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BPF_S_ANC_SECCOMP_LD_W,
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BPF_S_ANC_VLAN_TAG,
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BPF_S_ANC_VLAN_TAG_PRESENT,
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};
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#endif /* __LINUX_FILTER_H__ */
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