| /* |
| * 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 sk_chk_filter() |
| */ |
| |
| #include <linux/module.h> |
| #include <linux/types.h> |
| #include <linux/mm.h> |
| #include <linux/fcntl.h> |
| #include <linux/socket.h> |
| #include <linux/in.h> |
| #include <linux/inet.h> |
| #include <linux/netdevice.h> |
| #include <linux/if_packet.h> |
| #include <linux/gfp.h> |
| #include <net/ip.h> |
| #include <net/protocol.h> |
| #include <net/netlink.h> |
| #include <linux/skbuff.h> |
| #include <net/sock.h> |
| #include <linux/errno.h> |
| #include <linux/timer.h> |
| #include <asm/uaccess.h> |
| #include <asm/unaligned.h> |
| #include <linux/filter.h> |
| #include <linux/ratelimit.h> |
| #include <linux/seccomp.h> |
| #include <linux/if_vlan.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; |
| } |
| |
| static inline void *load_pointer(const struct sk_buff *skb, int k, |
| unsigned int size, void *buffer) |
| { |
| if (k >= 0) |
| return skb_header_pointer(skb, k, size, buffer); |
| |
| return bpf_internal_load_pointer_neg_helper(skb, k, size); |
| } |
| |
| /** |
| * sk_filter - run a packet through a socket filter |
| * @sk: sock associated with &sk_buff |
| * @skb: buffer to filter |
| * |
| * Run the filter code and then cut skb->data to correct size returned by |
| * sk_run_filter. If pkt_len is 0 we toss packet. If skb->len is smaller |
| * than pkt_len we keep whole skb->data. This is the socket level |
| * wrapper to sk_run_filter. It returns 0 if the packet should |
| * be accepted or -EPERM if the packet should be tossed. |
| * |
| */ |
| int sk_filter(struct sock *sk, struct sk_buff *skb) |
| { |
| int err; |
| struct sk_filter *filter; |
| |
| /* |
| * If the skb was allocated from pfmemalloc reserves, only |
| * allow SOCK_MEMALLOC sockets to use it as this socket is |
| * helping free memory |
| */ |
| if (skb_pfmemalloc(skb) && !sock_flag(sk, SOCK_MEMALLOC)) |
| return -ENOMEM; |
| |
| err = security_sock_rcv_skb(sk, skb); |
| if (err) |
| return err; |
| |
| rcu_read_lock(); |
| filter = rcu_dereference(sk->sk_filter); |
| if (filter) { |
| unsigned int pkt_len = SK_RUN_FILTER(filter, skb); |
| |
| err = pkt_len ? pskb_trim(skb, pkt_len) : -EPERM; |
| } |
| rcu_read_unlock(); |
| |
| return err; |
| } |
| EXPORT_SYMBOL(sk_filter); |
| |
| /* 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; |
| } |
| |
| /** |
| * __sk_run_filter - run a filter on a given context |
| * @ctx: buffer to run the filter on |
| * @insn: filter to apply |
| * |
| * Decode and apply filter instructions to the skb->data. Return length to |
| * keep, 0 for none. @ctx is the data we are operating on, @insn is the |
| * array of filter instructions. |
| */ |
| static unsigned int __sk_run_filter(void *ctx, const struct sock_filter_int *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, |
| }; |
| 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; |
| 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, sk_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 = 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 = 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 = 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; |
| } |
| |
| /* Helper to find the offset of pkt_type in sk_buff structure. We want |
| * to make sure its still a 3bit field starting at a byte boundary; |
| * taken from arch/x86/net/bpf_jit_comp.c. |
| */ |
| #ifdef __BIG_ENDIAN_BITFIELD |
| #define PKT_TYPE_MAX (7 << 5) |
| #else |
| #define PKT_TYPE_MAX 7 |
| #endif |
| static unsigned int pkt_type_offset(void) |
| { |
| struct sk_buff skb_probe = { .pkt_type = ~0, }; |
| u8 *ct = (u8 *) &skb_probe; |
| unsigned int off; |
| |
| for (off = 0; off < sizeof(struct sk_buff); off++) { |
| if (ct[off] == PKT_TYPE_MAX) |
| return off; |
| } |
| |
| pr_err_once("Please fix %s, as pkt_type couldn't be found!\n", __func__); |
| return -1; |
| } |
| |
| static u64 __skb_get_pay_offset(u64 ctx, u64 a, u64 x, u64 r4, u64 r5) |
| { |
| return __skb_get_poff((struct sk_buff *)(unsigned long) ctx); |
| } |
| |
| static u64 __skb_get_nlattr(u64 ctx, u64 a, u64 x, u64 r4, u64 r5) |
| { |
| struct sk_buff *skb = (struct sk_buff *)(unsigned long) ctx; |
| struct nlattr *nla; |
| |
| if (skb_is_nonlinear(skb)) |
| return 0; |
| |
| if (skb->len < sizeof(struct nlattr)) |
| return 0; |
| |
| if (a > skb->len - sizeof(struct nlattr)) |
| return 0; |
| |
| nla = nla_find((struct nlattr *) &skb->data[a], skb->len - a, x); |
| if (nla) |
| return (void *) nla - (void *) skb->data; |
| |
| return 0; |
| } |
| |
| static u64 __skb_get_nlattr_nest(u64 ctx, u64 a, u64 x, u64 r4, u64 r5) |
| { |
| struct sk_buff *skb = (struct sk_buff *)(unsigned long) ctx; |
| struct nlattr *nla; |
| |
| if (skb_is_nonlinear(skb)) |
| return 0; |
| |
| if (skb->len < sizeof(struct nlattr)) |
| return 0; |
| |
| if (a > skb->len - sizeof(struct nlattr)) |
| return 0; |
| |
| nla = (struct nlattr *) &skb->data[a]; |
| if (nla->nla_len > skb->len - a) |
| return 0; |
| |
| nla = nla_find_nested(nla, x); |
| if (nla) |
| return (void *) nla - (void *) skb->data; |
| |
| return 0; |
| } |
| |
| static u64 __get_raw_cpu_id(u64 ctx, u64 a, u64 x, u64 r4, u64 r5) |
| { |
| return raw_smp_processor_id(); |
| } |
| |
| /* note that this only generates 32-bit random numbers */ |
| static u64 __get_random_u32(u64 ctx, u64 a, u64 x, u64 r4, u64 r5) |
| { |
| return prandom_u32(); |
| } |
| |
| static bool convert_bpf_extensions(struct sock_filter *fp, |
| struct sock_filter_int **insnp) |
| { |
| struct sock_filter_int *insn = *insnp; |
| |
| switch (fp->k) { |
| case SKF_AD_OFF + SKF_AD_PROTOCOL: |
| BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, protocol) != 2); |
| |
| /* A = *(u16 *) (CTX + offsetof(protocol)) */ |
| *insn++ = BPF_LDX_MEM(BPF_H, BPF_REG_A, BPF_REG_CTX, |
| offsetof(struct sk_buff, protocol)); |
| /* A = ntohs(A) [emitting a nop or swap16] */ |
| *insn = BPF_ENDIAN(BPF_FROM_BE, BPF_REG_A, 16); |
| break; |
| |
| case SKF_AD_OFF + SKF_AD_PKTTYPE: |
| *insn = BPF_LDX_MEM(BPF_B, BPF_REG_A, BPF_REG_CTX, |
| pkt_type_offset()); |
| if (insn->off < 0) |
| return false; |
| insn++; |
| *insn = BPF_ALU32_IMM(BPF_AND, BPF_REG_A, PKT_TYPE_MAX); |
| #ifdef __BIG_ENDIAN_BITFIELD |
| insn++; |
| *insn = BPF_ALU32_IMM(BPF_RSH, BPF_REG_A, 5); |
| #endif |
| break; |
| |
| case SKF_AD_OFF + SKF_AD_IFINDEX: |
| case SKF_AD_OFF + SKF_AD_HATYPE: |
| BUILD_BUG_ON(FIELD_SIZEOF(struct net_device, ifindex) != 4); |
| BUILD_BUG_ON(FIELD_SIZEOF(struct net_device, type) != 2); |
| BUILD_BUG_ON(bytes_to_bpf_size(FIELD_SIZEOF(struct sk_buff, dev)) < 0); |
| |
| *insn++ = BPF_LDX_MEM(bytes_to_bpf_size(FIELD_SIZEOF(struct sk_buff, dev)), |
| BPF_REG_TMP, BPF_REG_CTX, |
| offsetof(struct sk_buff, dev)); |
| /* if (tmp != 0) goto pc + 1 */ |
| *insn++ = BPF_JMP_IMM(BPF_JNE, BPF_REG_TMP, 0, 1); |
| *insn++ = BPF_EXIT_INSN(); |
| if (fp->k == SKF_AD_OFF + SKF_AD_IFINDEX) |
| *insn = BPF_LDX_MEM(BPF_W, BPF_REG_A, BPF_REG_TMP, |
| offsetof(struct net_device, ifindex)); |
| else |
| *insn = BPF_LDX_MEM(BPF_H, BPF_REG_A, BPF_REG_TMP, |
| offsetof(struct net_device, type)); |
| break; |
| |
| case SKF_AD_OFF + SKF_AD_MARK: |
| BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, mark) != 4); |
| |
| *insn = BPF_LDX_MEM(BPF_W, BPF_REG_A, BPF_REG_CTX, |
| offsetof(struct sk_buff, mark)); |
| break; |
| |
| case SKF_AD_OFF + SKF_AD_RXHASH: |
| BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, hash) != 4); |
| |
| *insn = BPF_LDX_MEM(BPF_W, BPF_REG_A, BPF_REG_CTX, |
| offsetof(struct sk_buff, hash)); |
| break; |
| |
| case SKF_AD_OFF + SKF_AD_QUEUE: |
| BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, queue_mapping) != 2); |
| |
| *insn = BPF_LDX_MEM(BPF_H, BPF_REG_A, BPF_REG_CTX, |
| offsetof(struct sk_buff, queue_mapping)); |
| break; |
| |
| case SKF_AD_OFF + SKF_AD_VLAN_TAG: |
| case SKF_AD_OFF + SKF_AD_VLAN_TAG_PRESENT: |
| BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, vlan_tci) != 2); |
| BUILD_BUG_ON(VLAN_TAG_PRESENT != 0x1000); |
| |
| /* A = *(u16 *) (CTX + offsetof(vlan_tci)) */ |
| *insn++ = BPF_LDX_MEM(BPF_H, BPF_REG_A, BPF_REG_CTX, |
| offsetof(struct sk_buff, vlan_tci)); |
| if (fp->k == SKF_AD_OFF + SKF_AD_VLAN_TAG) { |
| *insn = BPF_ALU32_IMM(BPF_AND, BPF_REG_A, |
| ~VLAN_TAG_PRESENT); |
| } else { |
| /* A >>= 12 */ |
| *insn++ = BPF_ALU32_IMM(BPF_RSH, BPF_REG_A, 12); |
| /* A &= 1 */ |
| *insn = BPF_ALU32_IMM(BPF_AND, BPF_REG_A, 1); |
| } |
| break; |
| |
| case SKF_AD_OFF + SKF_AD_PAY_OFFSET: |
| case SKF_AD_OFF + SKF_AD_NLATTR: |
| case SKF_AD_OFF + SKF_AD_NLATTR_NEST: |
| case SKF_AD_OFF + SKF_AD_CPU: |
| case SKF_AD_OFF + SKF_AD_RANDOM: |
| /* arg1 = CTX */ |
| *insn++ = BPF_MOV64_REG(BPF_REG_ARG1, BPF_REG_CTX); |
| /* arg2 = A */ |
| *insn++ = BPF_MOV64_REG(BPF_REG_ARG2, BPF_REG_A); |
| /* arg3 = X */ |
| *insn++ = BPF_MOV64_REG(BPF_REG_ARG3, BPF_REG_X); |
| /* Emit call(arg1=CTX, arg2=A, arg3=X) */ |
| switch (fp->k) { |
| case SKF_AD_OFF + SKF_AD_PAY_OFFSET: |
| *insn = BPF_EMIT_CALL(__skb_get_pay_offset); |
| break; |
| case SKF_AD_OFF + SKF_AD_NLATTR: |
| *insn = BPF_EMIT_CALL(__skb_get_nlattr); |
| break; |
| case SKF_AD_OFF + SKF_AD_NLATTR_NEST: |
| *insn = BPF_EMIT_CALL(__skb_get_nlattr_nest); |
| break; |
| case SKF_AD_OFF + SKF_AD_CPU: |
| *insn = BPF_EMIT_CALL(__get_raw_cpu_id); |
| break; |
| case SKF_AD_OFF + SKF_AD_RANDOM: |
| *insn = BPF_EMIT_CALL(__get_random_u32); |
| break; |
| } |
| break; |
| |
| case SKF_AD_OFF + SKF_AD_ALU_XOR_X: |
| /* A ^= X */ |
| *insn = BPF_ALU32_REG(BPF_XOR, BPF_REG_A, BPF_REG_X); |
| break; |
| |
| default: |
| /* This is just a dummy call to avoid letting the compiler |
| * evict __bpf_call_base() as an optimization. Placed here |
| * where no-one bothers. |
| */ |
| BUG_ON(__bpf_call_base(0, 0, 0, 0, 0) != 0); |
| return false; |
| } |
| |
| *insnp = insn; |
| return true; |
| } |
| |
| /** |
| * sk_convert_filter - convert filter program |
| * @prog: the user passed filter program |
| * @len: the length of the user passed filter program |
| * @new_prog: buffer where converted program will be stored |
| * @new_len: pointer to store length of converted program |
| * |
| * Remap 'sock_filter' style BPF instruction set to 'sock_filter_ext' style. |
| * Conversion workflow: |
| * |
| * 1) First pass for calculating the new program length: |
| * sk_convert_filter(old_prog, old_len, NULL, &new_len) |
| * |
| * 2) 2nd pass to remap in two passes: 1st pass finds new |
| * jump offsets, 2nd pass remapping: |
| * new_prog = kmalloc(sizeof(struct sock_filter_int) * new_len); |
| * sk_convert_filter(old_prog, old_len, new_prog, &new_len); |
| * |
| * User BPF's register A is mapped to our BPF register 6, user BPF |
| * register X is mapped to BPF register 7; frame pointer is always |
| * register 10; Context 'void *ctx' is stored in register 1, that is, |
| * for socket filters: ctx == 'struct sk_buff *', for seccomp: |
| * ctx == 'struct seccomp_data *'. |
| */ |
| int sk_convert_filter(struct sock_filter *prog, int len, |
| struct sock_filter_int *new_prog, int *new_len) |
| { |
| int new_flen = 0, pass = 0, target, i; |
| struct sock_filter_int *new_insn; |
| struct sock_filter *fp; |
| int *addrs = NULL; |
| u8 bpf_src; |
| |
| BUILD_BUG_ON(BPF_MEMWORDS * sizeof(u32) > MAX_BPF_STACK); |
| BUILD_BUG_ON(BPF_REG_FP + 1 != MAX_BPF_REG); |
| |
| if (len <= 0 || len > BPF_MAXINSNS) |
| return -EINVAL; |
| |
| if (new_prog) { |
| addrs = kcalloc(len, sizeof(*addrs), GFP_KERNEL); |
| if (!addrs) |
| return -ENOMEM; |
| } |
| |
| do_pass: |
| new_insn = new_prog; |
| fp = prog; |
| |
| if (new_insn) |
| *new_insn = BPF_MOV64_REG(BPF_REG_CTX, BPF_REG_ARG1); |
| new_insn++; |
| |
| for (i = 0; i < len; fp++, i++) { |
| struct sock_filter_int tmp_insns[6] = { }; |
| struct sock_filter_int *insn = tmp_insns; |
| |
| if (addrs) |
| addrs[i] = new_insn - new_prog; |
| |
| switch (fp->code) { |
| /* All arithmetic insns and skb loads map as-is. */ |
| case BPF_ALU | BPF_ADD | BPF_X: |
| case BPF_ALU | BPF_ADD | BPF_K: |
| case BPF_ALU | BPF_SUB | BPF_X: |
| case BPF_ALU | BPF_SUB | BPF_K: |
| case BPF_ALU | BPF_AND | BPF_X: |
| case BPF_ALU | BPF_AND | BPF_K: |
| case BPF_ALU | BPF_OR | BPF_X: |
| case BPF_ALU | BPF_OR | BPF_K: |
| case BPF_ALU | BPF_LSH | BPF_X: |
| case BPF_ALU | BPF_LSH | BPF_K: |
| case BPF_ALU | BPF_RSH | BPF_X: |
| case BPF_ALU | BPF_RSH | BPF_K: |
| case BPF_ALU | BPF_XOR | BPF_X: |
| case BPF_ALU | BPF_XOR | BPF_K: |
| case BPF_ALU | BPF_MUL | BPF_X: |
| case BPF_ALU | BPF_MUL | BPF_K: |
| case BPF_ALU | BPF_DIV | BPF_X: |
| case BPF_ALU | BPF_DIV | BPF_K: |
| case BPF_ALU | BPF_MOD | BPF_X: |
| case BPF_ALU | BPF_MOD | BPF_K: |
| case BPF_ALU | BPF_NEG: |
| case BPF_LD | BPF_ABS | BPF_W: |
| case BPF_LD | BPF_ABS | BPF_H: |
| case BPF_LD | BPF_ABS | BPF_B: |
| case BPF_LD | BPF_IND | BPF_W: |
| case BPF_LD | BPF_IND | BPF_H: |
| case BPF_LD | BPF_IND | BPF_B: |
| /* Check for overloaded BPF extension and |
| * directly convert it if found, otherwise |
| * just move on with mapping. |
| */ |
| if (BPF_CLASS(fp->code) == BPF_LD && |
| BPF_MODE(fp->code) == BPF_ABS && |
| convert_bpf_extensions(fp, &insn)) |
| break; |
| |
| *insn = BPF_RAW_INSN(fp->code, BPF_REG_A, BPF_REG_X, 0, fp->k); |
| break; |
| |
| /* Jump transformation cannot use BPF block macros |
| * everywhere as offset calculation and target updates |
| * require a bit more work than the rest, i.e. jump |
| * opcodes map as-is, but offsets need adjustment. |
| */ |
| |
| #define BPF_EMIT_JMP \ |
| do { \ |
| if (target >= len || target < 0) \ |
| goto err; \ |
| insn->off = addrs ? addrs[target] - addrs[i] - 1 : 0; \ |
| /* Adjust pc relative offset for 2nd or 3rd insn. */ \ |
| insn->off -= insn - tmp_insns; \ |
| } while (0) |
| |
| case BPF_JMP | BPF_JA: |
| target = i + fp->k + 1; |
| insn->code = fp->code; |
| BPF_EMIT_JMP; |
| break; |
| |
| case BPF_JMP | BPF_JEQ | BPF_K: |
| case BPF_JMP | BPF_JEQ | BPF_X: |
| case BPF_JMP | BPF_JSET | BPF_K: |
| case BPF_JMP | BPF_JSET | BPF_X: |
| case BPF_JMP | BPF_JGT | BPF_K: |
| case BPF_JMP | BPF_JGT | BPF_X: |
| case BPF_JMP | BPF_JGE | BPF_K: |
| case BPF_JMP | BPF_JGE | BPF_X: |
| if (BPF_SRC(fp->code) == BPF_K && (int) fp->k < 0) { |
| /* BPF immediates are signed, zero extend |
| * immediate into tmp register and use it |
| * in compare insn. |
| */ |
| *insn++ = BPF_MOV32_IMM(BPF_REG_TMP, fp->k); |
| |
| insn->dst_reg = BPF_REG_A; |
| insn->src_reg = BPF_REG_TMP; |
| bpf_src = BPF_X; |
| } else { |
| insn->dst_reg = BPF_REG_A; |
| insn->src_reg = BPF_REG_X; |
| insn->imm = fp->k; |
| bpf_src = BPF_SRC(fp->code); |
| } |
| |
| /* Common case where 'jump_false' is next insn. */ |
| if (fp->jf == 0) { |
| insn->code = BPF_JMP | BPF_OP(fp->code) | bpf_src; |
| target = i + fp->jt + 1; |
| BPF_EMIT_JMP; |
| break; |
| } |
| |
| /* Convert JEQ into JNE when 'jump_true' is next insn. */ |
| if (fp->jt == 0 && BPF_OP(fp->code) == BPF_JEQ) { |
| insn->code = BPF_JMP | BPF_JNE | bpf_src; |
| target = i + fp->jf + 1; |
| BPF_EMIT_JMP; |
| break; |
| } |
| |
| /* Other jumps are mapped into two insns: Jxx and JA. */ |
| target = i + fp->jt + 1; |
| insn->code = BPF_JMP | BPF_OP(fp->code) | bpf_src; |
| BPF_EMIT_JMP; |
| insn++; |
| |
| insn->code = BPF_JMP | BPF_JA; |
| target = i + fp->jf + 1; |
| BPF_EMIT_JMP; |
| break; |
| |
| /* ldxb 4 * ([14] & 0xf) is remaped into 6 insns. */ |
| case BPF_LDX | BPF_MSH | BPF_B: |
| /* tmp = A */ |
| *insn++ = BPF_MOV64_REG(BPF_REG_TMP, BPF_REG_A); |
| /* A = BPF_R0 = *(u8 *) (skb->data + K) */ |
| *insn++ = BPF_LD_ABS(BPF_B, fp->k); |
| /* A &= 0xf */ |
| *insn++ = BPF_ALU32_IMM(BPF_AND, BPF_REG_A, 0xf); |
| /* A <<= 2 */ |
| *insn++ = BPF_ALU32_IMM(BPF_LSH, BPF_REG_A, 2); |
| /* X = A */ |
| *insn++ = BPF_MOV64_REG(BPF_REG_X, BPF_REG_A); |
| /* A = tmp */ |
| *insn = BPF_MOV64_REG(BPF_REG_A, BPF_REG_TMP); |
| break; |
| |
| /* RET_K, RET_A are remaped into 2 insns. */ |
| case BPF_RET | BPF_A: |
| case BPF_RET | BPF_K: |
| *insn++ = BPF_MOV32_RAW(BPF_RVAL(fp->code) == BPF_K ? |
| BPF_K : BPF_X, BPF_REG_0, |
| BPF_REG_A, fp->k); |
| *insn = BPF_EXIT_INSN(); |
| break; |
| |
| /* Store to stack. */ |
| case BPF_ST: |
| case BPF_STX: |
| *insn = BPF_STX_MEM(BPF_W, BPF_REG_FP, BPF_CLASS(fp->code) == |
| BPF_ST ? BPF_REG_A : BPF_REG_X, |
| -(BPF_MEMWORDS - fp->k) * 4); |
| break; |
| |
| /* Load from stack. */ |
| case BPF_LD | BPF_MEM: |
| case BPF_LDX | BPF_MEM: |
| *insn = BPF_LDX_MEM(BPF_W, BPF_CLASS(fp->code) == BPF_LD ? |
| BPF_REG_A : BPF_REG_X, BPF_REG_FP, |
| -(BPF_MEMWORDS - fp->k) * 4); |
| break; |
| |
| /* A = K or X = K */ |
| case BPF_LD | BPF_IMM: |
| case BPF_LDX | BPF_IMM: |
| *insn = BPF_MOV32_IMM(BPF_CLASS(fp->code) == BPF_LD ? |
| BPF_REG_A : BPF_REG_X, fp->k); |
| break; |
| |
| /* X = A */ |
| case BPF_MISC | BPF_TAX: |
| *insn = BPF_MOV64_REG(BPF_REG_X, BPF_REG_A); |
| break; |
| |
| /* A = X */ |
| case BPF_MISC | BPF_TXA: |
| *insn = BPF_MOV64_REG(BPF_REG_A, BPF_REG_X); |
| break; |
| |
| /* A = skb->len or X = skb->len */ |
| case BPF_LD | BPF_W | BPF_LEN: |
| case BPF_LDX | BPF_W | BPF_LEN: |
| *insn = BPF_LDX_MEM(BPF_W, BPF_CLASS(fp->code) == BPF_LD ? |
| BPF_REG_A : BPF_REG_X, BPF_REG_CTX, |
| offsetof(struct sk_buff, len)); |
| break; |
| |
| /* Access seccomp_data fields. */ |
| case BPF_LDX | BPF_ABS | BPF_W: |
| /* A = *(u32 *) (ctx + K) */ |
| *insn = BPF_LDX_MEM(BPF_W, BPF_REG_A, BPF_REG_CTX, fp->k); |
| break; |
| |
| /* Unkown instruction. */ |
| default: |
| goto err; |
| } |
| |
| insn++; |
| if (new_prog) |
| memcpy(new_insn, tmp_insns, |
| sizeof(*insn) * (insn - tmp_insns)); |
| new_insn += insn - tmp_insns; |
| } |
| |
| if (!new_prog) { |
| /* Only calculating new length. */ |
| *new_len = new_insn - new_prog; |
| return 0; |
| } |
| |
| pass++; |
| if (new_flen != new_insn - new_prog) { |
| new_flen = new_insn - new_prog; |
| if (pass > 2) |
| goto err; |
| goto do_pass; |
| } |
| |
| kfree(addrs); |
| BUG_ON(*new_len != new_flen); |
| return 0; |
| err: |
| kfree(addrs); |
| return -EINVAL; |
| } |
| |
| /* Security: |
| * |
| * A BPF program is able to use 16 cells of memory to store intermediate |
| * values (check u32 mem[BPF_MEMWORDS] in sk_run_filter()). |
| * |
| * As we dont want to clear mem[] array for each packet going through |
| * sk_run_filter(), we check that filter loaded by user never try to read |
| * a cell if not previously written, and we check all branches to be sure |
| * a malicious user doesn't try to abuse us. |
| */ |
| static int check_load_and_stores(struct sock_filter *filter, int flen) |
| { |
| u16 *masks, memvalid = 0; /* One bit per cell, 16 cells */ |
| int pc, ret = 0; |
| |
| BUILD_BUG_ON(BPF_MEMWORDS > 16); |
| |
| masks = kmalloc_array(flen, sizeof(*masks), GFP_KERNEL); |
| if (!masks) |
| return -ENOMEM; |
| |
| memset(masks, 0xff, flen * sizeof(*masks)); |
| |
| for (pc = 0; pc < flen; pc++) { |
| memvalid &= masks[pc]; |
| |
| switch (filter[pc].code) { |
| case BPF_ST: |
| case BPF_STX: |
| memvalid |= (1 << filter[pc].k); |
| break; |
| case BPF_LD | BPF_MEM: |
| case BPF_LDX | BPF_MEM: |
| if (!(memvalid & (1 << filter[pc].k))) { |
| ret = -EINVAL; |
| goto error; |
| } |
| break; |
| case BPF_JMP | BPF_JA: |
| /* A jump must set masks on target */ |
| masks[pc + 1 + filter[pc].k] &= memvalid; |
| memvalid = ~0; |
| break; |
| case BPF_JMP | BPF_JEQ | BPF_K: |
| case BPF_JMP | BPF_JEQ | BPF_X: |
| case BPF_JMP | BPF_JGE | BPF_K: |
| case BPF_JMP | BPF_JGE | BPF_X: |
| case BPF_JMP | BPF_JGT | BPF_K: |
| case BPF_JMP | BPF_JGT | BPF_X: |
| case BPF_JMP | BPF_JSET | BPF_K: |
| case BPF_JMP | BPF_JSET | BPF_X: |
| /* A jump must set masks on targets */ |
| masks[pc + 1 + filter[pc].jt] &= memvalid; |
| masks[pc + 1 + filter[pc].jf] &= memvalid; |
| memvalid = ~0; |
| break; |
| } |
| } |
| error: |
| kfree(masks); |
| return ret; |
| } |
| |
| static bool chk_code_allowed(u16 code_to_probe) |
| { |
| static const bool codes[] = { |
| /* 32 bit ALU operations */ |
| [BPF_ALU | BPF_ADD | BPF_K] = true, |
| [BPF_ALU | BPF_ADD | BPF_X] = true, |
| [BPF_ALU | BPF_SUB | BPF_K] = true, |
| [BPF_ALU | BPF_SUB | BPF_X] = true, |
| [BPF_ALU | BPF_MUL | BPF_K] = true, |
| [BPF_ALU | BPF_MUL | BPF_X] = true, |
| [BPF_ALU | BPF_DIV | BPF_K] = true, |
| [BPF_ALU | BPF_DIV | BPF_X] = true, |
| [BPF_ALU | BPF_MOD | BPF_K] = true, |
| [BPF_ALU | BPF_MOD | BPF_X] = true, |
| [BPF_ALU | BPF_AND | BPF_K] = true, |
| [BPF_ALU | BPF_AND | BPF_X] = true, |
| [BPF_ALU | BPF_OR | BPF_K] = true, |
| [BPF_ALU | BPF_OR | BPF_X] = true, |
| [BPF_ALU | BPF_XOR | BPF_K] = true, |
| [BPF_ALU | BPF_XOR | BPF_X] = true, |
| [BPF_ALU | BPF_LSH | BPF_K] = true, |
| [BPF_ALU | BPF_LSH | BPF_X] = true, |
| [BPF_ALU | BPF_RSH | BPF_K] = true, |
| [BPF_ALU | BPF_RSH | BPF_X] = true, |
| [BPF_ALU | BPF_NEG] = true, |
| /* Load instructions */ |
| [BPF_LD | BPF_W | BPF_ABS] = true, |
| [BPF_LD | BPF_H | BPF_ABS] = true, |
| [BPF_LD | BPF_B | BPF_ABS] = true, |
| [BPF_LD | BPF_W | BPF_LEN] = true, |
| [BPF_LD | BPF_W | BPF_IND] = true, |
| [BPF_LD | BPF_H | BPF_IND] = true, |
| [BPF_LD | BPF_B | BPF_IND] = true, |
| [BPF_LD | BPF_IMM] = true, |
| [BPF_LD | BPF_MEM] = true, |
| [BPF_LDX | BPF_W | BPF_LEN] = true, |
| [BPF_LDX | BPF_B | BPF_MSH] = true, |
| [BPF_LDX | BPF_IMM] = true, |
| [BPF_LDX | BPF_MEM] = true, |
| /* Store instructions */ |
| [BPF_ST] = true, |
| [BPF_STX] = true, |
| /* Misc instructions */ |
| [BPF_MISC | BPF_TAX] = true, |
| [BPF_MISC | BPF_TXA] = true, |
| /* Return instructions */ |
| [BPF_RET | BPF_K] = true, |
| [BPF_RET | BPF_A] = true, |
| /* Jump instructions */ |
| [BPF_JMP | BPF_JA] = true, |
| [BPF_JMP | BPF_JEQ | BPF_K] = true, |
| [BPF_JMP | BPF_JEQ | BPF_X] = true, |
| [BPF_JMP | BPF_JGE | BPF_K] = true, |
| [BPF_JMP | BPF_JGE | BPF_X] = true, |
| [BPF_JMP | BPF_JGT | BPF_K] = true, |
| [BPF_JMP | BPF_JGT | BPF_X] = true, |
| [BPF_JMP | BPF_JSET | BPF_K] = true, |
| [BPF_JMP | BPF_JSET | BPF_X] = true, |
| }; |
| |
| if (code_to_probe >= ARRAY_SIZE(codes)) |
| return false; |
| |
| return codes[code_to_probe]; |
| } |
| |
| /** |
| * sk_chk_filter - verify socket filter code |
| * @filter: filter to verify |
| * @flen: length of filter |
| * |
| * Check the user's filter code. If we let some ugly |
| * filter code slip through kaboom! The filter must contain |
| * no references or jumps that are out of range, no illegal |
| * instructions, and must end with a RET instruction. |
| * |
| * All jumps are forward as they are not signed. |
| * |
| * Returns 0 if the rule set is legal or -EINVAL if not. |
| */ |
| int sk_chk_filter(struct sock_filter *filter, unsigned int flen) |
| { |
| bool anc_found; |
| int pc; |
| |
| if (flen == 0 || flen > BPF_MAXINSNS) |
| return -EINVAL; |
| |
| /* Check the filter code now */ |
| for (pc = 0; pc < flen; pc++) { |
| struct sock_filter *ftest = &filter[pc]; |
| |
| /* May we actually operate on this code? */ |
| if (!chk_code_allowed(ftest->code)) |
| return -EINVAL; |
| |
| /* Some instructions need special checks */ |
| switch (ftest->code) { |
| case BPF_ALU | BPF_DIV | BPF_K: |
| case BPF_ALU | BPF_MOD | BPF_K: |
| /* Check for division by zero */ |
| if (ftest->k == 0) |
| return -EINVAL; |
| break; |
| case BPF_LD | BPF_MEM: |
| case BPF_LDX | BPF_MEM: |
| case BPF_ST: |
| case BPF_STX: |
| /* Check for invalid memory addresses */ |
| if (ftest->k >= BPF_MEMWORDS) |
| return -EINVAL; |
| break; |
| case BPF_JMP | BPF_JA: |
| /* Note, the large ftest->k might cause loops. |
| * Compare this with conditional jumps below, |
| * where offsets are limited. --ANK (981016) |
| */ |
| if (ftest->k >= (unsigned int)(flen - pc - 1)) |
| return -EINVAL; |
| break; |
| case BPF_JMP | BPF_JEQ | BPF_K: |
| case BPF_JMP | BPF_JEQ | BPF_X: |
| case BPF_JMP | BPF_JGE | BPF_K: |
| case BPF_JMP | BPF_JGE | BPF_X: |
| case BPF_JMP | BPF_JGT | BPF_K: |
| case BPF_JMP | BPF_JGT | BPF_X: |
| case BPF_JMP | BPF_JSET | BPF_K: |
| case BPF_JMP | BPF_JSET | BPF_X: |
| /* Both conditionals must be safe */ |
| if (pc + ftest->jt + 1 >= flen || |
| pc + ftest->jf + 1 >= flen) |
| return -EINVAL; |
| break; |
| case BPF_LD | BPF_W | BPF_ABS: |
| case BPF_LD | BPF_H | BPF_ABS: |
| case BPF_LD | BPF_B | BPF_ABS: |
| anc_found = false; |
| if (bpf_anc_helper(ftest) & BPF_ANC) |
| anc_found = true; |
| /* Ancillary operation unknown or unsupported */ |
| if (anc_found == false && ftest->k >= SKF_AD_OFF) |
| return -EINVAL; |
| } |
| } |
| |
| /* Last instruction must be a RET code */ |
| switch (filter[flen - 1].code) { |
| case BPF_RET | BPF_K: |
| case BPF_RET | BPF_A: |
| return check_load_and_stores(filter, flen); |
| } |
| |
| return -EINVAL; |
| } |
| EXPORT_SYMBOL(sk_chk_filter); |
| |
| static int sk_store_orig_filter(struct sk_filter *fp, |
| const struct sock_fprog *fprog) |
| { |
| unsigned int fsize = sk_filter_proglen(fprog); |
| struct sock_fprog_kern *fkprog; |
| |
| fp->orig_prog = kmalloc(sizeof(*fkprog), GFP_KERNEL); |
| if (!fp->orig_prog) |
| return -ENOMEM; |
| |
| fkprog = fp->orig_prog; |
| fkprog->len = fprog->len; |
| fkprog->filter = kmemdup(fp->insns, fsize, GFP_KERNEL); |
| if (!fkprog->filter) { |
| kfree(fp->orig_prog); |
| return -ENOMEM; |
| } |
| |
| return 0; |
| } |
| |
| static void sk_release_orig_filter(struct sk_filter *fp) |
| { |
| struct sock_fprog_kern *fprog = fp->orig_prog; |
| |
| if (fprog) { |
| kfree(fprog->filter); |
| kfree(fprog); |
| } |
| } |
| |
| /** |
| * sk_filter_release_rcu - Release a socket filter by rcu_head |
| * @rcu: rcu_head that contains the sk_filter to free |
| */ |
| static void sk_filter_release_rcu(struct rcu_head *rcu) |
| { |
| struct sk_filter *fp = container_of(rcu, struct sk_filter, rcu); |
| |
| sk_release_orig_filter(fp); |
| sk_filter_free(fp); |
| } |
| |
| /** |
| * sk_filter_release - release a socket filter |
| * @fp: filter to remove |
| * |
| * Remove a filter from a socket and release its resources. |
| */ |
| static void sk_filter_release(struct sk_filter *fp) |
| { |
| if (atomic_dec_and_test(&fp->refcnt)) |
| call_rcu(&fp->rcu, sk_filter_release_rcu); |
| } |
| |
| void sk_filter_uncharge(struct sock *sk, struct sk_filter *fp) |
| { |
| atomic_sub(sk_filter_size(fp->len), &sk->sk_omem_alloc); |
| sk_filter_release(fp); |
| } |
| |
| void sk_filter_charge(struct sock *sk, struct sk_filter *fp) |
| { |
| atomic_inc(&fp->refcnt); |
| atomic_add(sk_filter_size(fp->len), &sk->sk_omem_alloc); |
| } |
| |
| static struct sk_filter *__sk_migrate_realloc(struct sk_filter *fp, |
| struct sock *sk, |
| unsigned int len) |
| { |
| struct sk_filter *fp_new; |
| |
| if (sk == NULL) |
| return krealloc(fp, len, GFP_KERNEL); |
| |
| fp_new = sock_kmalloc(sk, len, GFP_KERNEL); |
| if (fp_new) { |
| *fp_new = *fp; |
| /* As we're keeping orig_prog in fp_new along, |
| * we need to make sure we're not evicting it |
| * from the old fp. |
| */ |
| fp->orig_prog = NULL; |
| sk_filter_uncharge(sk, fp); |
| } |
| |
| return fp_new; |
| } |
| |
| static struct sk_filter *__sk_migrate_filter(struct sk_filter *fp, |
| struct sock *sk) |
| { |
| struct sock_filter *old_prog; |
| struct sk_filter *old_fp; |
| int err, new_len, old_len = fp->len; |
| |
| /* We are free to overwrite insns et al right here as it |
| * won't be used at this point in time anymore internally |
| * after the migration to the internal BPF instruction |
| * representation. |
| */ |
| BUILD_BUG_ON(sizeof(struct sock_filter) != |
| sizeof(struct sock_filter_int)); |
| |
| /* Conversion cannot happen on overlapping memory areas, |
| * so we need to keep the user BPF around until the 2nd |
| * pass. At this time, the user BPF is stored in fp->insns. |
| */ |
| old_prog = kmemdup(fp->insns, old_len * sizeof(struct sock_filter), |
| GFP_KERNEL); |
| if (!old_prog) { |
| err = -ENOMEM; |
| goto out_err; |
| } |
| |
| /* 1st pass: calculate the new program length. */ |
| err = sk_convert_filter(old_prog, old_len, NULL, &new_len); |
| if (err) |
| goto out_err_free; |
| |
| /* Expand fp for appending the new filter representation. */ |
| old_fp = fp; |
| fp = __sk_migrate_realloc(old_fp, sk, sk_filter_size(new_len)); |
| if (!fp) { |
| /* The old_fp is still around in case we couldn't |
| * allocate new memory, so uncharge on that one. |
| */ |
| fp = old_fp; |
| err = -ENOMEM; |
| goto out_err_free; |
| } |
| |
| fp->len = new_len; |
| |
| /* 2nd pass: remap sock_filter insns into sock_filter_int insns. */ |
| err = sk_convert_filter(old_prog, old_len, fp->insnsi, &new_len); |
| if (err) |
| /* 2nd sk_convert_filter() can fail only if it fails |
| * to allocate memory, remapping must succeed. Note, |
| * that at this time old_fp has already been released |
| * by __sk_migrate_realloc(). |
| */ |
| goto out_err_free; |
| |
| sk_filter_select_runtime(fp); |
| |
| kfree(old_prog); |
| return fp; |
| |
| out_err_free: |
| kfree(old_prog); |
| out_err: |
| /* Rollback filter setup. */ |
| if (sk != NULL) |
| sk_filter_uncharge(sk, fp); |
| else |
| kfree(fp); |
| return ERR_PTR(err); |
| } |
| |
| void __weak bpf_int_jit_compile(struct sk_filter *prog) |
| { |
| } |
| |
| /** |
| * sk_filter_select_runtime - select execution runtime for BPF program |
| * @fp: sk_filter populated with internal BPF program |
| * |
| * try to JIT internal BPF program, if JIT is not available select interpreter |
| * BPF program will be executed via SK_RUN_FILTER() macro |
| */ |
| void sk_filter_select_runtime(struct sk_filter *fp) |
| { |
| fp->bpf_func = (void *) __sk_run_filter; |
| |
| /* Probe if internal BPF can be JITed */ |
| bpf_int_jit_compile(fp); |
| } |
| EXPORT_SYMBOL_GPL(sk_filter_select_runtime); |
| |
| /* free internal BPF program */ |
| void sk_filter_free(struct sk_filter *fp) |
| { |
| bpf_jit_free(fp); |
| } |
| EXPORT_SYMBOL_GPL(sk_filter_free); |
| |
| static struct sk_filter *__sk_prepare_filter(struct sk_filter *fp, |
| struct sock *sk) |
| { |
| int err; |
| |
| fp->bpf_func = NULL; |
| fp->jited = 0; |
| |
| err = sk_chk_filter(fp->insns, fp->len); |
| if (err) { |
| if (sk != NULL) |
| sk_filter_uncharge(sk, fp); |
| else |
| kfree(fp); |
| return ERR_PTR(err); |
| } |
| |
| /* Probe if we can JIT compile the filter and if so, do |
| * the compilation of the filter. |
| */ |
| bpf_jit_compile(fp); |
| |
| /* JIT compiler couldn't process this filter, so do the |
| * internal BPF translation for the optimized interpreter. |
| */ |
| if (!fp->jited) |
| fp = __sk_migrate_filter(fp, sk); |
| |
| return fp; |
| } |
| |
| /** |
| * sk_unattached_filter_create - create an unattached filter |
| * @pfp: the unattached filter that is created |
| * @fprog: the filter program |
| * |
| * Create a filter independent of any socket. We first run some |
| * sanity checks on it to make sure it does not explode on us later. |
| * If an error occurs or there is insufficient memory for the filter |
| * a negative errno code is returned. On success the return is zero. |
| */ |
| int sk_unattached_filter_create(struct sk_filter **pfp, |
| struct sock_fprog_kern *fprog) |
| { |
| unsigned int fsize = sk_filter_proglen(fprog); |
| struct sk_filter *fp; |
| |
| /* Make sure new filter is there and in the right amounts. */ |
| if (fprog->filter == NULL) |
| return -EINVAL; |
| |
| fp = kmalloc(sk_filter_size(fprog->len), GFP_KERNEL); |
| if (!fp) |
| return -ENOMEM; |
| |
| memcpy(fp->insns, fprog->filter, fsize); |
| |
| atomic_set(&fp->refcnt, 1); |
| fp->len = fprog->len; |
| /* Since unattached filters are not copied back to user |
| * space through sk_get_filter(), we do not need to hold |
| * a copy here, and can spare us the work. |
| */ |
| fp->orig_prog = NULL; |
| |
| /* __sk_prepare_filter() already takes care of uncharging |
| * memory in case something goes wrong. |
| */ |
| fp = __sk_prepare_filter(fp, NULL); |
| if (IS_ERR(fp)) |
| return PTR_ERR(fp); |
| |
| *pfp = fp; |
| return 0; |
| } |
| EXPORT_SYMBOL_GPL(sk_unattached_filter_create); |
| |
| void sk_unattached_filter_destroy(struct sk_filter *fp) |
| { |
| sk_filter_release(fp); |
| } |
| EXPORT_SYMBOL_GPL(sk_unattached_filter_destroy); |
| |
| /** |
| * sk_attach_filter - attach a socket filter |
| * @fprog: the filter program |
| * @sk: the socket to use |
| * |
| * Attach the user's filter code. We first run some sanity checks on |
| * it to make sure it does not explode on us later. If an error |
| * occurs or there is insufficient memory for the filter a negative |
| * errno code is returned. On success the return is zero. |
| */ |
| int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk) |
| { |
| struct sk_filter *fp, *old_fp; |
| unsigned int fsize = sk_filter_proglen(fprog); |
| unsigned int sk_fsize = sk_filter_size(fprog->len); |
| int err; |
| |
| if (sock_flag(sk, SOCK_FILTER_LOCKED)) |
| return -EPERM; |
| |
| /* Make sure new filter is there and in the right amounts. */ |
| if (fprog->filter == NULL) |
| return -EINVAL; |
| |
| fp = sock_kmalloc(sk, sk_fsize, GFP_KERNEL); |
| if (!fp) |
| return -ENOMEM; |
| |
| if (copy_from_user(fp->insns, fprog->filter, fsize)) { |
| sock_kfree_s(sk, fp, sk_fsize); |
| return -EFAULT; |
| } |
| |
| atomic_set(&fp->refcnt, 1); |
| fp->len = fprog->len; |
| |
| err = sk_store_orig_filter(fp, fprog); |
| if (err) { |
| sk_filter_uncharge(sk, fp); |
| return -ENOMEM; |
| } |
| |
| /* __sk_prepare_filter() already takes care of uncharging |
| * memory in case something goes wrong. |
| */ |
| fp = __sk_prepare_filter(fp, sk); |
| if (IS_ERR(fp)) |
| return PTR_ERR(fp); |
| |
| old_fp = rcu_dereference_protected(sk->sk_filter, |
| sock_owned_by_user(sk)); |
| rcu_assign_pointer(sk->sk_filter, fp); |
| |
| if (old_fp) |
| sk_filter_uncharge(sk, old_fp); |
| |
| return 0; |
| } |
| EXPORT_SYMBOL_GPL(sk_attach_filter); |
| |
| int sk_detach_filter(struct sock *sk) |
| { |
| int ret = -ENOENT; |
| struct sk_filter *filter; |
| |
| if (sock_flag(sk, SOCK_FILTER_LOCKED)) |
| return -EPERM; |
| |
| filter = rcu_dereference_protected(sk->sk_filter, |
| sock_owned_by_user(sk)); |
| if (filter) { |
| RCU_INIT_POINTER(sk->sk_filter, NULL); |
| sk_filter_uncharge(sk, filter); |
| ret = 0; |
| } |
| |
| return ret; |
| } |
| EXPORT_SYMBOL_GPL(sk_detach_filter); |
| |
| int sk_get_filter(struct sock *sk, struct sock_filter __user *ubuf, |
| unsigned int len) |
| { |
| struct sock_fprog_kern *fprog; |
| struct sk_filter *filter; |
| int ret = 0; |
| |
| lock_sock(sk); |
| filter = rcu_dereference_protected(sk->sk_filter, |
| sock_owned_by_user(sk)); |
| if (!filter) |
| goto out; |
| |
| /* We're copying the filter that has been originally attached, |
| * so no conversion/decode needed anymore. |
| */ |
| fprog = filter->orig_prog; |
| |
| ret = fprog->len; |
| if (!len) |
| /* User space only enquires number of filter blocks. */ |
| goto out; |
| |
| ret = -EINVAL; |
| if (len < fprog->len) |
| goto out; |
| |
| ret = -EFAULT; |
| if (copy_to_user(ubuf, fprog->filter, sk_filter_proglen(fprog))) |
| goto out; |
| |
| /* Instead of bytes, the API requests to return the number |
| * of filter blocks. |
| */ |
| ret = fprog->len; |
| out: |
| release_sock(sk); |
| return ret; |
| } |