| /* |
| * 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/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> |
| #include <linux/bpf.h> |
| |
| /** |
| * 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); |
| |
| 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 bpf_insn **insnp) |
| { |
| struct bpf_insn *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()); |
| *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; |
| } |
| |
| /** |
| * bpf_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: |
| * bpf_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 bpf_insn) * new_len); |
| * bpf_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 bpf_convert_filter(struct sock_filter *prog, int len, |
| struct bpf_insn *new_prog, int *new_len) |
| { |
| int new_flen = 0, pass = 0, target, i; |
| struct bpf_insn *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 bpf_insn tmp_insns[6] = { }; |
| struct bpf_insn *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: |
| * |
| * As we dont want to clear mem[] array for each packet going through |
| * __bpf_prog_run(), 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(const 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]; |
| } |
| |
| /** |
| * bpf_check_classic - 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 bpf_check_classic(const 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++) { |
| const 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(bpf_check_classic); |
| |
| static int bpf_prog_store_orig_filter(struct bpf_prog *fp, |
| const struct sock_fprog *fprog) |
| { |
| unsigned int fsize = bpf_classic_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 bpf_release_orig_filter(struct bpf_prog *fp) |
| { |
| struct sock_fprog_kern *fprog = fp->orig_prog; |
| |
| if (fprog) { |
| kfree(fprog->filter); |
| kfree(fprog); |
| } |
| } |
| |
| static void __bpf_prog_release(struct bpf_prog *prog) |
| { |
| if (prog->aux->prog_type == BPF_PROG_TYPE_SOCKET_FILTER) { |
| bpf_prog_put(prog); |
| } else { |
| bpf_release_orig_filter(prog); |
| bpf_prog_free(prog); |
| } |
| } |
| |
| static void __sk_filter_release(struct sk_filter *fp) |
| { |
| __bpf_prog_release(fp->prog); |
| kfree(fp); |
| } |
| |
| /** |
| * 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_filter_release(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) |
| { |
| u32 filter_size = bpf_prog_size(fp->prog->len); |
| |
| atomic_sub(filter_size, &sk->sk_omem_alloc); |
| sk_filter_release(fp); |
| } |
| |
| /* try to charge the socket memory if there is space available |
| * return true on success |
| */ |
| bool sk_filter_charge(struct sock *sk, struct sk_filter *fp) |
| { |
| u32 filter_size = bpf_prog_size(fp->prog->len); |
| |
| /* same check as in sock_kmalloc() */ |
| if (filter_size <= sysctl_optmem_max && |
| atomic_read(&sk->sk_omem_alloc) + filter_size < sysctl_optmem_max) { |
| atomic_inc(&fp->refcnt); |
| atomic_add(filter_size, &sk->sk_omem_alloc); |
| return true; |
| } |
| return false; |
| } |
| |
| static struct bpf_prog *bpf_migrate_filter(struct bpf_prog *fp) |
| { |
| struct sock_filter *old_prog; |
| struct bpf_prog *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 bpf_insn)); |
| |
| /* 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 = bpf_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 = bpf_prog_realloc(old_fp, bpf_prog_size(new_len), 0); |
| 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 bpf_insn insns. */ |
| err = bpf_convert_filter(old_prog, old_len, fp->insnsi, &new_len); |
| if (err) |
| /* 2nd bpf_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 krealloc(). |
| */ |
| goto out_err_free; |
| |
| bpf_prog_select_runtime(fp); |
| |
| kfree(old_prog); |
| return fp; |
| |
| out_err_free: |
| kfree(old_prog); |
| out_err: |
| __bpf_prog_release(fp); |
| return ERR_PTR(err); |
| } |
| |
| static struct bpf_prog *bpf_prepare_filter(struct bpf_prog *fp) |
| { |
| int err; |
| |
| fp->bpf_func = NULL; |
| fp->jited = false; |
| |
| err = bpf_check_classic(fp->insns, fp->len); |
| if (err) { |
| __bpf_prog_release(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 = bpf_migrate_filter(fp); |
| |
| return fp; |
| } |
| |
| /** |
| * bpf_prog_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 bpf_prog_create(struct bpf_prog **pfp, struct sock_fprog_kern *fprog) |
| { |
| unsigned int fsize = bpf_classic_proglen(fprog); |
| struct bpf_prog *fp; |
| |
| /* Make sure new filter is there and in the right amounts. */ |
| if (fprog->filter == NULL) |
| return -EINVAL; |
| |
| fp = bpf_prog_alloc(bpf_prog_size(fprog->len), 0); |
| if (!fp) |
| return -ENOMEM; |
| |
| memcpy(fp->insns, fprog->filter, fsize); |
| |
| 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; |
| |
| /* bpf_prepare_filter() already takes care of freeing |
| * memory in case something goes wrong. |
| */ |
| fp = bpf_prepare_filter(fp); |
| if (IS_ERR(fp)) |
| return PTR_ERR(fp); |
| |
| *pfp = fp; |
| return 0; |
| } |
| EXPORT_SYMBOL_GPL(bpf_prog_create); |
| |
| void bpf_prog_destroy(struct bpf_prog *fp) |
| { |
| __bpf_prog_release(fp); |
| } |
| EXPORT_SYMBOL_GPL(bpf_prog_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 = bpf_classic_proglen(fprog); |
| unsigned int bpf_fsize = bpf_prog_size(fprog->len); |
| struct bpf_prog *prog; |
| 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; |
| |
| prog = bpf_prog_alloc(bpf_fsize, 0); |
| if (!prog) |
| return -ENOMEM; |
| |
| if (copy_from_user(prog->insns, fprog->filter, fsize)) { |
| __bpf_prog_free(prog); |
| return -EFAULT; |
| } |
| |
| prog->len = fprog->len; |
| |
| err = bpf_prog_store_orig_filter(prog, fprog); |
| if (err) { |
| __bpf_prog_free(prog); |
| return -ENOMEM; |
| } |
| |
| /* bpf_prepare_filter() already takes care of freeing |
| * memory in case something goes wrong. |
| */ |
| prog = bpf_prepare_filter(prog); |
| if (IS_ERR(prog)) |
| return PTR_ERR(prog); |
| |
| fp = kmalloc(sizeof(*fp), GFP_KERNEL); |
| if (!fp) { |
| __bpf_prog_release(prog); |
| return -ENOMEM; |
| } |
| fp->prog = prog; |
| |
| atomic_set(&fp->refcnt, 0); |
| |
| if (!sk_filter_charge(sk, fp)) { |
| __sk_filter_release(fp); |
| return -ENOMEM; |
| } |
| |
| 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); |
| |
| #ifdef CONFIG_BPF_SYSCALL |
| int sk_attach_bpf(u32 ufd, struct sock *sk) |
| { |
| struct sk_filter *fp, *old_fp; |
| struct bpf_prog *prog; |
| |
| if (sock_flag(sk, SOCK_FILTER_LOCKED)) |
| return -EPERM; |
| |
| prog = bpf_prog_get(ufd); |
| if (!prog) |
| return -EINVAL; |
| |
| if (prog->aux->prog_type != BPF_PROG_TYPE_SOCKET_FILTER) { |
| /* valid fd, but invalid program type */ |
| bpf_prog_put(prog); |
| return -EINVAL; |
| } |
| |
| fp = kmalloc(sizeof(*fp), GFP_KERNEL); |
| if (!fp) { |
| bpf_prog_put(prog); |
| return -ENOMEM; |
| } |
| fp->prog = prog; |
| |
| atomic_set(&fp->refcnt, 0); |
| |
| if (!sk_filter_charge(sk, fp)) { |
| __sk_filter_release(fp); |
| return -ENOMEM; |
| } |
| |
| 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; |
| } |
| |
| /* allow socket filters to call |
| * bpf_map_lookup_elem(), bpf_map_update_elem(), bpf_map_delete_elem() |
| */ |
| static const struct bpf_func_proto *sock_filter_func_proto(enum bpf_func_id func_id) |
| { |
| switch (func_id) { |
| case BPF_FUNC_map_lookup_elem: |
| return &bpf_map_lookup_elem_proto; |
| case BPF_FUNC_map_update_elem: |
| return &bpf_map_update_elem_proto; |
| case BPF_FUNC_map_delete_elem: |
| return &bpf_map_delete_elem_proto; |
| default: |
| return NULL; |
| } |
| } |
| |
| static bool sock_filter_is_valid_access(int off, int size, enum bpf_access_type type) |
| { |
| /* skb fields cannot be accessed yet */ |
| return false; |
| } |
| |
| static struct bpf_verifier_ops sock_filter_ops = { |
| .get_func_proto = sock_filter_func_proto, |
| .is_valid_access = sock_filter_is_valid_access, |
| }; |
| |
| static struct bpf_prog_type_list tl = { |
| .ops = &sock_filter_ops, |
| .type = BPF_PROG_TYPE_SOCKET_FILTER, |
| }; |
| |
| static int __init register_sock_filter_ops(void) |
| { |
| bpf_register_prog_type(&tl); |
| return 0; |
| } |
| late_initcall(register_sock_filter_ops); |
| #else |
| int sk_attach_bpf(u32 ufd, struct sock *sk) |
| { |
| return -EOPNOTSUPP; |
| } |
| #endif |
| 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->prog->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, bpf_classic_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; |
| } |