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32 results

core.c

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  • core.c 16.89 KiB
    /*
     * Linux Socket Filter - Kernel level socket filtering
     *
     * Based on the design of the Berkeley Packet Filter. The new
     * internal format has been designed by PLUMgrid:
     *
     *	Copyright (c) 2011 - 2014 PLUMgrid, http://plumgrid.com
     *
     * Authors:
     *
     *	Jay Schulist <jschlst@samba.org>
     *	Alexei Starovoitov <ast@plumgrid.com>
     *	Daniel Borkmann <dborkman@redhat.com>
     *
     * This program is free software; you can redistribute it and/or
     * modify it under the terms of the GNU General Public License
     * as published by the Free Software Foundation; either version
     * 2 of the License, or (at your option) any later version.
     *
     * Andi Kleen - Fix a few bad bugs and races.
     * Kris Katterjohn - Added many additional checks in bpf_check_classic()
     */
    
    #include <linux/filter.h>
    #include <linux/skbuff.h>
    #include <linux/vmalloc.h>
    #include <linux/random.h>
    #include <linux/moduleloader.h>
    #include <asm/unaligned.h>
    #include <linux/bpf.h>
    
    /* Registers */
    #define BPF_R0	regs[BPF_REG_0]
    #define BPF_R1	regs[BPF_REG_1]
    #define BPF_R2	regs[BPF_REG_2]
    #define BPF_R3	regs[BPF_REG_3]
    #define BPF_R4	regs[BPF_REG_4]
    #define BPF_R5	regs[BPF_REG_5]
    #define BPF_R6	regs[BPF_REG_6]
    #define BPF_R7	regs[BPF_REG_7]
    #define BPF_R8	regs[BPF_REG_8]
    #define BPF_R9	regs[BPF_REG_9]
    #define BPF_R10	regs[BPF_REG_10]
    
    /* Named registers */
    #define DST	regs[insn->dst_reg]
    #define SRC	regs[insn->src_reg]
    #define FP	regs[BPF_REG_FP]
    #define ARG1	regs[BPF_REG_ARG1]
    #define CTX	regs[BPF_REG_CTX]
    #define IMM	insn->imm
    
    /* No hurry in this branch
     *
     * Exported for the bpf jit load helper.
     */
    void *bpf_internal_load_pointer_neg_helper(const struct sk_buff *skb, int k, unsigned int size)
    {
    	u8 *ptr = NULL;
    
    	if (k >= SKF_NET_OFF)
    		ptr = skb_network_header(skb) + k - SKF_NET_OFF;
    	else if (k >= SKF_LL_OFF)
    		ptr = skb_mac_header(skb) + k - SKF_LL_OFF;
    	if (ptr >= skb->head && ptr + size <= skb_tail_pointer(skb))
    		return ptr;
    
    	return NULL;
    }
    
    struct bpf_prog *bpf_prog_alloc(unsigned int size, gfp_t gfp_extra_flags)
    {
    	gfp_t gfp_flags = GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO |
    			  gfp_extra_flags;
    	struct bpf_prog_aux *aux;
    	struct bpf_prog *fp;
    
    	size = round_up(size, PAGE_SIZE);
    	fp = __vmalloc(size, gfp_flags, PAGE_KERNEL);
    	if (fp == NULL)
    		return NULL;
    
    	aux = kzalloc(sizeof(*aux), GFP_KERNEL | gfp_extra_flags);
    	if (aux == NULL) {
    		vfree(fp);
    		return NULL;
    	}
    
    	fp->pages = size / PAGE_SIZE;
    	fp->aux = aux;
    
    	return fp;
    }
    EXPORT_SYMBOL_GPL(bpf_prog_alloc);
    
    struct bpf_prog *bpf_prog_realloc(struct bpf_prog *fp_old, unsigned int size,
    				  gfp_t gfp_extra_flags)
    {
    	gfp_t gfp_flags = GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO |
    			  gfp_extra_flags;
    	struct bpf_prog *fp;
    
    	BUG_ON(fp_old == NULL);
    
    	size = round_up(size, PAGE_SIZE);
    	if (size <= fp_old->pages * PAGE_SIZE)
    		return fp_old;
    
    	fp = __vmalloc(size, gfp_flags, PAGE_KERNEL);
    	if (fp != NULL) {
    		memcpy(fp, fp_old, fp_old->pages * PAGE_SIZE);
    		fp->pages = size / PAGE_SIZE;
    
    		/* We keep fp->aux from fp_old around in the new
    		 * reallocated structure.
    		 */
    		fp_old->aux = NULL;
    		__bpf_prog_free(fp_old);
    	}
    
    	return fp;
    }
    EXPORT_SYMBOL_GPL(bpf_prog_realloc);
    
    void __bpf_prog_free(struct bpf_prog *fp)
    {
    	kfree(fp->aux);
    	vfree(fp);
    }
    EXPORT_SYMBOL_GPL(__bpf_prog_free);
    
    #ifdef CONFIG_BPF_JIT
    struct bpf_binary_header *
    bpf_jit_binary_alloc(unsigned int proglen, u8 **image_ptr,
    		     unsigned int alignment,
    		     bpf_jit_fill_hole_t bpf_fill_ill_insns)
    {
    	struct bpf_binary_header *hdr;
    	unsigned int size, hole, start;
    
    	/* Most of BPF filters are really small, but if some of them
    	 * fill a page, allow at least 128 extra bytes to insert a
    	 * random section of illegal instructions.
    	 */
    	size = round_up(proglen + sizeof(*hdr) + 128, PAGE_SIZE);
    	hdr = module_alloc(size);
    	if (hdr == NULL)
    		return NULL;
    
    	/* Fill space with illegal/arch-dep instructions. */
    	bpf_fill_ill_insns(hdr, size);
    
    	hdr->pages = size / PAGE_SIZE;
    	hole = min_t(unsigned int, size - (proglen + sizeof(*hdr)),
    		     PAGE_SIZE - sizeof(*hdr));
    	start = (prandom_u32() % hole) & ~(alignment - 1);
    
    	/* Leave a random number of instructions before BPF code. */
    	*image_ptr = &hdr->image[start];
    
    	return hdr;
    }
    
    void bpf_jit_binary_free(struct bpf_binary_header *hdr)
    {
    	module_memfree(hdr);
    }
    #endif /* CONFIG_BPF_JIT */
    
    /* Base function for offset calculation. Needs to go into .text section,
     * therefore keeping it non-static as well; will also be used by JITs
     * anyway later on, so do not let the compiler omit it.
     */
    noinline u64 __bpf_call_base(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
    {
    	return 0;
    }
    
    /**
     *	__bpf_prog_run - run eBPF program on a given context
     *	@ctx: is the data we are operating on
     *	@insn: is the array of eBPF instructions
     *
     * Decode and execute eBPF instructions.
     */
    static unsigned int __bpf_prog_run(void *ctx, const struct bpf_insn *insn)
    {
    	u64 stack[MAX_BPF_STACK / sizeof(u64)];
    	u64 regs[MAX_BPF_REG], tmp;
    	static const void *jumptable[256] = {
    		[0 ... 255] = &&default_label,
    		/* Now overwrite non-defaults ... */
    		/* 32 bit ALU operations */
    		[BPF_ALU | BPF_ADD | BPF_X] = &&ALU_ADD_X,
    		[BPF_ALU | BPF_ADD | BPF_K] = &&ALU_ADD_K,
    		[BPF_ALU | BPF_SUB | BPF_X] = &&ALU_SUB_X,
    		[BPF_ALU | BPF_SUB | BPF_K] = &&ALU_SUB_K,
    		[BPF_ALU | BPF_AND | BPF_X] = &&ALU_AND_X,
    		[BPF_ALU | BPF_AND | BPF_K] = &&ALU_AND_K,
    		[BPF_ALU | BPF_OR | BPF_X]  = &&ALU_OR_X,
    		[BPF_ALU | BPF_OR | BPF_K]  = &&ALU_OR_K,
    		[BPF_ALU | BPF_LSH | BPF_X] = &&ALU_LSH_X,
    		[BPF_ALU | BPF_LSH | BPF_K] = &&ALU_LSH_K,
    		[BPF_ALU | BPF_RSH | BPF_X] = &&ALU_RSH_X,
    		[BPF_ALU | BPF_RSH | BPF_K] = &&ALU_RSH_K,
    		[BPF_ALU | BPF_XOR | BPF_X] = &&ALU_XOR_X,
    		[BPF_ALU | BPF_XOR | BPF_K] = &&ALU_XOR_K,
    		[BPF_ALU | BPF_MUL | BPF_X] = &&ALU_MUL_X,
    		[BPF_ALU | BPF_MUL | BPF_K] = &&ALU_MUL_K,
    		[BPF_ALU | BPF_MOV | BPF_X] = &&ALU_MOV_X,
    		[BPF_ALU | BPF_MOV | BPF_K] = &&ALU_MOV_K,
    		[BPF_ALU | BPF_DIV | BPF_X] = &&ALU_DIV_X,
    		[BPF_ALU | BPF_DIV | BPF_K] = &&ALU_DIV_K,
    		[BPF_ALU | BPF_MOD | BPF_X] = &&ALU_MOD_X,
    		[BPF_ALU | BPF_MOD | BPF_K] = &&ALU_MOD_K,
    		[BPF_ALU | BPF_NEG] = &&ALU_NEG,
    		[BPF_ALU | BPF_END | BPF_TO_BE] = &&ALU_END_TO_BE,
    		[BPF_ALU | BPF_END | BPF_TO_LE] = &&ALU_END_TO_LE,
    		/* 64 bit ALU operations */
    		[BPF_ALU64 | BPF_ADD | BPF_X] = &&ALU64_ADD_X,
    		[BPF_ALU64 | BPF_ADD | BPF_K] = &&ALU64_ADD_K,
    		[BPF_ALU64 | BPF_SUB | BPF_X] = &&ALU64_SUB_X,
    		[BPF_ALU64 | BPF_SUB | BPF_K] = &&ALU64_SUB_K,
    		[BPF_ALU64 | BPF_AND | BPF_X] = &&ALU64_AND_X,
    		[BPF_ALU64 | BPF_AND | BPF_K] = &&ALU64_AND_K,
    		[BPF_ALU64 | BPF_OR | BPF_X] = &&ALU64_OR_X,
    		[BPF_ALU64 | BPF_OR | BPF_K] = &&ALU64_OR_K,
    		[BPF_ALU64 | BPF_LSH | BPF_X] = &&ALU64_LSH_X,
    		[BPF_ALU64 | BPF_LSH | BPF_K] = &&ALU64_LSH_K,
    		[BPF_ALU64 | BPF_RSH | BPF_X] = &&ALU64_RSH_X,
    		[BPF_ALU64 | BPF_RSH | BPF_K] = &&ALU64_RSH_K,
    		[BPF_ALU64 | BPF_XOR | BPF_X] = &&ALU64_XOR_X,
    		[BPF_ALU64 | BPF_XOR | BPF_K] = &&ALU64_XOR_K,
    		[BPF_ALU64 | BPF_MUL | BPF_X] = &&ALU64_MUL_X,
    		[BPF_ALU64 | BPF_MUL | BPF_K] = &&ALU64_MUL_K,
    		[BPF_ALU64 | BPF_MOV | BPF_X] = &&ALU64_MOV_X,
    		[BPF_ALU64 | BPF_MOV | BPF_K] = &&ALU64_MOV_K,
    		[BPF_ALU64 | BPF_ARSH | BPF_X] = &&ALU64_ARSH_X,
    		[BPF_ALU64 | BPF_ARSH | BPF_K] = &&ALU64_ARSH_K,
    		[BPF_ALU64 | BPF_DIV | BPF_X] = &&ALU64_DIV_X,
    		[BPF_ALU64 | BPF_DIV | BPF_K] = &&ALU64_DIV_K,
    		[BPF_ALU64 | BPF_MOD | BPF_X] = &&ALU64_MOD_X,
    		[BPF_ALU64 | BPF_MOD | BPF_K] = &&ALU64_MOD_K,
    		[BPF_ALU64 | BPF_NEG] = &&ALU64_NEG,
    		/* Call instruction */
    		[BPF_JMP | BPF_CALL] = &&JMP_CALL,
    		/* Jumps */
    		[BPF_JMP | BPF_JA] = &&JMP_JA,
    		[BPF_JMP | BPF_JEQ | BPF_X] = &&JMP_JEQ_X,
    		[BPF_JMP | BPF_JEQ | BPF_K] = &&JMP_JEQ_K,
    		[BPF_JMP | BPF_JNE | BPF_X] = &&JMP_JNE_X,
    		[BPF_JMP | BPF_JNE | BPF_K] = &&JMP_JNE_K,
    		[BPF_JMP | BPF_JGT | BPF_X] = &&JMP_JGT_X,
    		[BPF_JMP | BPF_JGT | BPF_K] = &&JMP_JGT_K,
    		[BPF_JMP | BPF_JGE | BPF_X] = &&JMP_JGE_X,
    		[BPF_JMP | BPF_JGE | BPF_K] = &&JMP_JGE_K,
    		[BPF_JMP | BPF_JSGT | BPF_X] = &&JMP_JSGT_X,
    		[BPF_JMP | BPF_JSGT | BPF_K] = &&JMP_JSGT_K,
    		[BPF_JMP | BPF_JSGE | BPF_X] = &&JMP_JSGE_X,
    		[BPF_JMP | BPF_JSGE | BPF_K] = &&JMP_JSGE_K,
    		[BPF_JMP | BPF_JSET | BPF_X] = &&JMP_JSET_X,
    		[BPF_JMP | BPF_JSET | BPF_K] = &&JMP_JSET_K,
    		/* Program return */
    		[BPF_JMP | BPF_EXIT] = &&JMP_EXIT,
    		/* Store instructions */
    		[BPF_STX | BPF_MEM | BPF_B] = &&STX_MEM_B,
    		[BPF_STX | BPF_MEM | BPF_H] = &&STX_MEM_H,
    		[BPF_STX | BPF_MEM | BPF_W] = &&STX_MEM_W,
    		[BPF_STX | BPF_MEM | BPF_DW] = &&STX_MEM_DW,
    		[BPF_STX | BPF_XADD | BPF_W] = &&STX_XADD_W,
    		[BPF_STX | BPF_XADD | BPF_DW] = &&STX_XADD_DW,
    		[BPF_ST | BPF_MEM | BPF_B] = &&ST_MEM_B,
    		[BPF_ST | BPF_MEM | BPF_H] = &&ST_MEM_H,
    		[BPF_ST | BPF_MEM | BPF_W] = &&ST_MEM_W,
    		[BPF_ST | BPF_MEM | BPF_DW] = &&ST_MEM_DW,
    		/* Load instructions */
    		[BPF_LDX | BPF_MEM | BPF_B] = &&LDX_MEM_B,
    		[BPF_LDX | BPF_MEM | BPF_H] = &&LDX_MEM_H,
    		[BPF_LDX | BPF_MEM | BPF_W] = &&LDX_MEM_W,
    		[BPF_LDX | BPF_MEM | BPF_DW] = &&LDX_MEM_DW,
    		[BPF_LD | BPF_ABS | BPF_W] = &&LD_ABS_W,
    		[BPF_LD | BPF_ABS | BPF_H] = &&LD_ABS_H,
    		[BPF_LD | BPF_ABS | BPF_B] = &&LD_ABS_B,
    		[BPF_LD | BPF_IND | BPF_W] = &&LD_IND_W,
    		[BPF_LD | BPF_IND | BPF_H] = &&LD_IND_H,
    		[BPF_LD | BPF_IND | BPF_B] = &&LD_IND_B,
    		[BPF_LD | BPF_IMM | BPF_DW] = &&LD_IMM_DW,
    	};
    	void *ptr;
    	int off;
    
    #define CONT	 ({ insn++; goto select_insn; })
    #define CONT_JMP ({ insn++; goto select_insn; })
    
    	FP = (u64) (unsigned long) &stack[ARRAY_SIZE(stack)];
    	ARG1 = (u64) (unsigned long) ctx;
    
    	/* Registers used in classic BPF programs need to be reset first. */
    	regs[BPF_REG_A] = 0;
    	regs[BPF_REG_X] = 0;
    
    select_insn:
    	goto *jumptable[insn->code];
    
    	/* ALU */
    #define ALU(OPCODE, OP)			\
    	ALU64_##OPCODE##_X:		\
    		DST = DST OP SRC;	\
    		CONT;			\
    	ALU_##OPCODE##_X:		\
    		DST = (u32) DST OP (u32) SRC;	\
    		CONT;			\
    	ALU64_##OPCODE##_K:		\
    		DST = DST OP IMM;		\
    		CONT;			\
    	ALU_##OPCODE##_K:		\
    		DST = (u32) DST OP (u32) IMM;	\
    		CONT;
    
    	ALU(ADD,  +)
    	ALU(SUB,  -)
    	ALU(AND,  &)
    	ALU(OR,   |)
    	ALU(LSH, <<)
    	ALU(RSH, >>)
    	ALU(XOR,  ^)
    	ALU(MUL,  *)
    #undef ALU
    	ALU_NEG:
    		DST = (u32) -DST;
    		CONT;
    	ALU64_NEG:
    		DST = -DST;
    		CONT;
    	ALU_MOV_X:
    		DST = (u32) SRC;
    		CONT;
    	ALU_MOV_K:
    		DST = (u32) IMM;
    		CONT;
    	ALU64_MOV_X:
    		DST = SRC;
    		CONT;
    	ALU64_MOV_K:
    		DST = IMM;
    		CONT;
    	LD_IMM_DW:
    		DST = (u64) (u32) insn[0].imm | ((u64) (u32) insn[1].imm) << 32;
    		insn++;
    		CONT;
    	ALU64_ARSH_X:
    		(*(s64 *) &DST) >>= SRC;
    		CONT;
    	ALU64_ARSH_K:
    		(*(s64 *) &DST) >>= IMM;
    		CONT;
    	ALU64_MOD_X:
    		if (unlikely(SRC == 0))
    			return 0;
    		tmp = DST;
    		DST = do_div(tmp, SRC);
    		CONT;
    	ALU_MOD_X:
    		if (unlikely(SRC == 0))
    			return 0;
    		tmp = (u32) DST;
    		DST = do_div(tmp, (u32) SRC);
    		CONT;
    	ALU64_MOD_K:
    		tmp = DST;
    		DST = do_div(tmp, IMM);
    		CONT;
    	ALU_MOD_K:
    		tmp = (u32) DST;
    		DST = do_div(tmp, (u32) IMM);
    		CONT;
    	ALU64_DIV_X:
    		if (unlikely(SRC == 0))
    			return 0;
    		do_div(DST, SRC);
    		CONT;
    	ALU_DIV_X:
    		if (unlikely(SRC == 0))
    			return 0;
    		tmp = (u32) DST;
    		do_div(tmp, (u32) SRC);
    		DST = (u32) tmp;
    		CONT;
    	ALU64_DIV_K:
    		do_div(DST, IMM);
    		CONT;
    	ALU_DIV_K:
    		tmp = (u32) DST;
    		do_div(tmp, (u32) IMM);
    		DST = (u32) tmp;
    		CONT;
    	ALU_END_TO_BE:
    		switch (IMM) {
    		case 16:
    			DST = (__force u16) cpu_to_be16(DST);
    			break;
    		case 32:
    			DST = (__force u32) cpu_to_be32(DST);
    			break;
    		case 64:
    			DST = (__force u64) cpu_to_be64(DST);
    			break;
    		}
    		CONT;
    	ALU_END_TO_LE:
    		switch (IMM) {
    		case 16:
    			DST = (__force u16) cpu_to_le16(DST);
    			break;
    		case 32:
    			DST = (__force u32) cpu_to_le32(DST);
    			break;
    		case 64:
    			DST = (__force u64) cpu_to_le64(DST);
    			break;
    		}
    		CONT;
    
    	/* CALL */
    	JMP_CALL:
    		/* Function call scratches BPF_R1-BPF_R5 registers,
    		 * preserves BPF_R6-BPF_R9, and stores return value
    		 * into BPF_R0.
    		 */
    		BPF_R0 = (__bpf_call_base + insn->imm)(BPF_R1, BPF_R2, BPF_R3,
    						       BPF_R4, BPF_R5);
    		CONT;
    
    	/* JMP */
    	JMP_JA:
    		insn += insn->off;
    		CONT;
    	JMP_JEQ_X:
    		if (DST == SRC) {
    			insn += insn->off;
    			CONT_JMP;
    		}
    		CONT;
    	JMP_JEQ_K:
    		if (DST == IMM) {
    			insn += insn->off;
    			CONT_JMP;
    		}
    		CONT;
    	JMP_JNE_X:
    		if (DST != SRC) {
    			insn += insn->off;
    			CONT_JMP;
    		}
    		CONT;
    	JMP_JNE_K:
    		if (DST != IMM) {
    			insn += insn->off;
    			CONT_JMP;
    		}
    		CONT;
    	JMP_JGT_X:
    		if (DST > SRC) {
    			insn += insn->off;
    			CONT_JMP;
    		}
    		CONT;
    	JMP_JGT_K:
    		if (DST > IMM) {
    			insn += insn->off;
    			CONT_JMP;
    		}
    		CONT;
    	JMP_JGE_X:
    		if (DST >= SRC) {
    			insn += insn->off;
    			CONT_JMP;
    		}
    		CONT;
    	JMP_JGE_K:
    		if (DST >= IMM) {
    			insn += insn->off;
    			CONT_JMP;
    		}
    		CONT;
    	JMP_JSGT_X:
    		if (((s64) DST) > ((s64) SRC)) {
    			insn += insn->off;
    			CONT_JMP;
    		}
    		CONT;
    	JMP_JSGT_K:
    		if (((s64) DST) > ((s64) IMM)) {
    			insn += insn->off;
    			CONT_JMP;
    		}
    		CONT;
    	JMP_JSGE_X:
    		if (((s64) DST) >= ((s64) SRC)) {
    			insn += insn->off;
    			CONT_JMP;
    		}
    		CONT;
    	JMP_JSGE_K:
    		if (((s64) DST) >= ((s64) IMM)) {
    			insn += insn->off;
    			CONT_JMP;
    		}
    		CONT;
    	JMP_JSET_X:
    		if (DST & SRC) {
    			insn += insn->off;
    			CONT_JMP;
    		}
    		CONT;
    	JMP_JSET_K:
    		if (DST & IMM) {
    			insn += insn->off;
    			CONT_JMP;
    		}
    		CONT;
    	JMP_EXIT:
    		return BPF_R0;
    
    	/* STX and ST and LDX*/
    #define LDST(SIZEOP, SIZE)						\
    	STX_MEM_##SIZEOP:						\
    		*(SIZE *)(unsigned long) (DST + insn->off) = SRC;	\
    		CONT;							\
    	ST_MEM_##SIZEOP:						\
    		*(SIZE *)(unsigned long) (DST + insn->off) = IMM;	\
    		CONT;							\
    	LDX_MEM_##SIZEOP:						\
    		DST = *(SIZE *)(unsigned long) (SRC + insn->off);	\
    		CONT;
    
    	LDST(B,   u8)
    	LDST(H,  u16)
    	LDST(W,  u32)
    	LDST(DW, u64)
    #undef LDST
    	STX_XADD_W: /* lock xadd *(u32 *)(dst_reg + off16) += src_reg */
    		atomic_add((u32) SRC, (atomic_t *)(unsigned long)
    			   (DST + insn->off));
    		CONT;
    	STX_XADD_DW: /* lock xadd *(u64 *)(dst_reg + off16) += src_reg */
    		atomic64_add((u64) SRC, (atomic64_t *)(unsigned long)
    			     (DST + insn->off));
    		CONT;
    	LD_ABS_W: /* BPF_R0 = ntohl(*(u32 *) (skb->data + imm32)) */
    		off = IMM;
    load_word:
    		/* BPF_LD + BPD_ABS and BPF_LD + BPF_IND insns are
    		 * only appearing in the programs where ctx ==
    		 * skb. All programs keep 'ctx' in regs[BPF_REG_CTX]
    		 * == BPF_R6, bpf_convert_filter() saves it in BPF_R6,
    		 * internal BPF verifier will check that BPF_R6 ==
    		 * ctx.
    		 *
    		 * BPF_ABS and BPF_IND are wrappers of function calls,
    		 * so they scratch BPF_R1-BPF_R5 registers, preserve
    		 * BPF_R6-BPF_R9, and store return value into BPF_R0.
    		 *
    		 * Implicit input:
    		 *   ctx == skb == BPF_R6 == CTX
    		 *
    		 * Explicit input:
    		 *   SRC == any register
    		 *   IMM == 32-bit immediate
    		 *
    		 * Output:
    		 *   BPF_R0 - 8/16/32-bit skb data converted to cpu endianness
    		 */
    
    		ptr = bpf_load_pointer((struct sk_buff *) (unsigned long) CTX, off, 4, &tmp);
    		if (likely(ptr != NULL)) {
    			BPF_R0 = get_unaligned_be32(ptr);
    			CONT;
    		}
    
    		return 0;
    	LD_ABS_H: /* BPF_R0 = ntohs(*(u16 *) (skb->data + imm32)) */
    		off = IMM;
    load_half:
    		ptr = bpf_load_pointer((struct sk_buff *) (unsigned long) CTX, off, 2, &tmp);
    		if (likely(ptr != NULL)) {
    			BPF_R0 = get_unaligned_be16(ptr);
    			CONT;
    		}
    
    		return 0;
    	LD_ABS_B: /* BPF_R0 = *(u8 *) (skb->data + imm32) */
    		off = IMM;
    load_byte:
    		ptr = bpf_load_pointer((struct sk_buff *) (unsigned long) CTX, off, 1, &tmp);
    		if (likely(ptr != NULL)) {
    			BPF_R0 = *(u8 *)ptr;
    			CONT;
    		}
    
    		return 0;
    	LD_IND_W: /* BPF_R0 = ntohl(*(u32 *) (skb->data + src_reg + imm32)) */
    		off = IMM + SRC;
    		goto load_word;
    	LD_IND_H: /* BPF_R0 = ntohs(*(u16 *) (skb->data + src_reg + imm32)) */
    		off = IMM + SRC;
    		goto load_half;
    	LD_IND_B: /* BPF_R0 = *(u8 *) (skb->data + src_reg + imm32) */
    		off = IMM + SRC;
    		goto load_byte;
    
    	default_label:
    		/* If we ever reach this, we have a bug somewhere. */
    		WARN_RATELIMIT(1, "unknown opcode %02x\n", insn->code);
    		return 0;
    }
    
    void __weak bpf_int_jit_compile(struct bpf_prog *prog)
    {
    }
    
    /**
     *	bpf_prog_select_runtime - select execution runtime for BPF program
     *	@fp: bpf_prog populated with internal BPF program
     *
     * try to JIT internal BPF program, if JIT is not available select interpreter
     * BPF program will be executed via BPF_PROG_RUN() macro
     */
    void bpf_prog_select_runtime(struct bpf_prog *fp)
    {
    	fp->bpf_func = (void *) __bpf_prog_run;
    
    	/* Probe if internal BPF can be JITed */
    	bpf_int_jit_compile(fp);
    	/* Lock whole bpf_prog as read-only */
    	bpf_prog_lock_ro(fp);
    }
    EXPORT_SYMBOL_GPL(bpf_prog_select_runtime);
    
    static void bpf_prog_free_deferred(struct work_struct *work)
    {
    	struct bpf_prog_aux *aux;
    
    	aux = container_of(work, struct bpf_prog_aux, work);
    	bpf_jit_free(aux->prog);
    }
    
    /* Free internal BPF program */
    void bpf_prog_free(struct bpf_prog *fp)
    {
    	struct bpf_prog_aux *aux = fp->aux;
    
    	INIT_WORK(&aux->work, bpf_prog_free_deferred);
    	aux->prog = fp;
    	schedule_work(&aux->work);
    }
    EXPORT_SYMBOL_GPL(bpf_prog_free);
    
    /* Weak definitions of helper functions in case we don't have bpf syscall. */
    const struct bpf_func_proto bpf_map_lookup_elem_proto __weak;
    const struct bpf_func_proto bpf_map_update_elem_proto __weak;
    const struct bpf_func_proto bpf_map_delete_elem_proto __weak;
    
    const struct bpf_func_proto bpf_get_prandom_u32_proto __weak;
    
    /* To execute LD_ABS/LD_IND instructions __bpf_prog_run() may call
     * skb_copy_bits(), so provide a weak definition of it for NET-less config.
     */
    int __weak skb_copy_bits(const struct sk_buff *skb, int offset, void *to,
    			 int len)
    {
    	return -EFAULT;
    }