![Chema Gonzalez](/assets/img/avatar_default.png)
Added a new ancillary load (bpf call in eBPF parlance) that produces a 32-bit random number. We are implementing it as an ancillary load (instead of an ISA opcode) because (a) it is simpler, (b) allows easy JITing, and (c) seems more in line with generic ISAs that do not have "get a random number" as a instruction, but as an OS call. The main use for this ancillary load is to perform random packet sampling. Signed-off-by: Chema Gonzalez <chema@google.com> Acked-by: Alexei Starovoitov <ast@plumgrid.com> Acked-by: Daniel Borkmann <dborkman@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
230 lines
5.5 KiB
C
230 lines
5.5 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 <linux/workqueue.h>
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#include <uapi/linux/filter.h>
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/* Internally used and optimized filter representation with extended
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* instruction set based on top of classic BPF.
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*/
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/* instruction classes */
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#define BPF_ALU64 0x07 /* alu mode in double word width */
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/* ld/ldx fields */
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#define BPF_DW 0x18 /* double word */
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#define BPF_XADD 0xc0 /* exclusive add */
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/* alu/jmp fields */
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#define BPF_MOV 0xb0 /* mov reg to reg */
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#define BPF_ARSH 0xc0 /* sign extending arithmetic shift right */
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/* change endianness of a register */
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#define BPF_END 0xd0 /* flags for endianness conversion: */
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#define BPF_TO_LE 0x00 /* convert to little-endian */
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#define BPF_TO_BE 0x08 /* convert to big-endian */
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#define BPF_FROM_LE BPF_TO_LE
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#define BPF_FROM_BE BPF_TO_BE
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#define BPF_JNE 0x50 /* jump != */
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#define BPF_JSGT 0x60 /* SGT is signed '>', GT in x86 */
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#define BPF_JSGE 0x70 /* SGE is signed '>=', GE in x86 */
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#define BPF_CALL 0x80 /* function call */
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#define BPF_EXIT 0x90 /* function return */
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/* BPF has 10 general purpose 64-bit registers and stack frame. */
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#define MAX_BPF_REG 11
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/* BPF program can access up to 512 bytes of stack space. */
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#define MAX_BPF_STACK 512
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/* Arg1, context and stack frame pointer register positions. */
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#define ARG1_REG 1
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#define CTX_REG 6
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#define FP_REG 10
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struct sock_filter_int {
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__u8 code; /* opcode */
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__u8 a_reg:4; /* dest register */
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__u8 x_reg:4; /* source register */
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__s16 off; /* signed offset */
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__s32 imm; /* signed immediate constant */
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};
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#ifdef CONFIG_COMPAT
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/* A struct sock_filter is architecture independent. */
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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 sock_fprog_kern {
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u16 len;
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struct sock_filter *filter;
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};
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struct sk_buff;
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struct sock;
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struct seccomp_data;
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struct sk_filter {
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atomic_t refcnt;
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u32 jited:1, /* Is our filter JIT'ed? */
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len:31; /* Number of filter blocks */
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struct sock_fprog_kern *orig_prog; /* Original BPF program */
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struct rcu_head rcu;
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unsigned int (*bpf_func)(const struct sk_buff *skb,
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const struct sock_filter_int *filter);
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union {
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struct sock_filter insns[0];
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struct sock_filter_int insnsi[0];
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struct work_struct work;
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};
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};
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static inline unsigned int sk_filter_size(unsigned int proglen)
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{
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return max(sizeof(struct sk_filter),
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offsetof(struct sk_filter, insns[proglen]));
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}
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#define sk_filter_proglen(fprog) \
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(fprog->len * sizeof(fprog->filter[0]))
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#define SK_RUN_FILTER(filter, ctx) \
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(*filter->bpf_func)(ctx, filter->insnsi)
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int sk_filter(struct sock *sk, struct sk_buff *skb);
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u32 sk_run_filter_int_seccomp(const struct seccomp_data *ctx,
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const struct sock_filter_int *insni);
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u32 sk_run_filter_int_skb(const struct sk_buff *ctx,
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const struct sock_filter_int *insni);
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int sk_convert_filter(struct sock_filter *prog, int len,
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struct sock_filter_int *new_prog, int *new_len);
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int sk_unattached_filter_create(struct sk_filter **pfp,
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struct sock_fprog *fprog);
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void sk_unattached_filter_destroy(struct sk_filter *fp);
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int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk);
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int sk_detach_filter(struct sock *sk);
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int sk_chk_filter(struct sock_filter *filter, unsigned int flen);
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int sk_get_filter(struct sock *sk, struct sock_filter __user *filter,
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unsigned int len);
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void sk_decode_filter(struct sock_filter *filt, struct sock_filter *to);
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void sk_filter_charge(struct sock *sk, struct sk_filter *fp);
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void sk_filter_uncharge(struct sock *sk, struct sk_filter *fp);
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#ifdef CONFIG_BPF_JIT
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#include <stdarg.h>
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#include <linux/linkage.h>
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#include <linux/printk.h>
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void bpf_jit_compile(struct sk_filter *fp);
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void bpf_jit_free(struct sk_filter *fp);
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static inline void bpf_jit_dump(unsigned int flen, unsigned int proglen,
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u32 pass, void *image)
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{
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pr_err("flen=%u proglen=%u pass=%u image=%pK\n",
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flen, proglen, pass, image);
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if (image)
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print_hex_dump(KERN_ERR, "JIT code: ", DUMP_PREFIX_OFFSET,
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16, 1, image, proglen, false);
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}
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#else
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#include <linux/slab.h>
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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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kfree(fp);
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}
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#endif
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static inline int bpf_tell_extensions(void)
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{
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return SKF_AD_MAX;
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}
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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_VLAN_TAG,
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BPF_S_ANC_VLAN_TAG_PRESENT,
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BPF_S_ANC_PAY_OFFSET,
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BPF_S_ANC_RANDOM,
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};
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#endif /* __LINUX_FILTER_H__ */
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