8ea6e345a6
1. sk_run_filter has been renamed, sk_filter() is using SK_RUN_FILTER. 2. Remove wrong comments about storing intermediate value. 3. replace sk_run_filter with __bpf_prog_run for check_load_and_stores's comments Cc: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: Li RongQing <roy.qing.li@gmail.com> Acked-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
1150 lines
30 KiB
C
1150 lines
30 KiB
C
/*
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* Linux Socket Filter - Kernel level socket filtering
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*
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* Based on the design of the Berkeley Packet Filter. The new
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* internal format has been designed by PLUMgrid:
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*
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* Copyright (c) 2011 - 2014 PLUMgrid, http://plumgrid.com
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*
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* Authors:
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*
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* Jay Schulist <jschlst@samba.org>
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* Alexei Starovoitov <ast@plumgrid.com>
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* Daniel Borkmann <dborkman@redhat.com>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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* Andi Kleen - Fix a few bad bugs and races.
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* Kris Katterjohn - Added many additional checks in bpf_check_classic()
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*/
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#include <linux/module.h>
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#include <linux/types.h>
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#include <linux/mm.h>
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#include <linux/fcntl.h>
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#include <linux/socket.h>
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#include <linux/in.h>
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#include <linux/inet.h>
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#include <linux/netdevice.h>
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#include <linux/if_packet.h>
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#include <linux/gfp.h>
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#include <net/ip.h>
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#include <net/protocol.h>
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#include <net/netlink.h>
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#include <linux/skbuff.h>
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#include <net/sock.h>
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#include <linux/errno.h>
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#include <linux/timer.h>
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#include <asm/uaccess.h>
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#include <asm/unaligned.h>
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#include <linux/filter.h>
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#include <linux/ratelimit.h>
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#include <linux/seccomp.h>
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#include <linux/if_vlan.h>
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/**
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* sk_filter - run a packet through a socket filter
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* @sk: sock associated with &sk_buff
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* @skb: buffer to filter
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*
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* Run the filter code and then cut skb->data to correct size returned by
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* SK_RUN_FILTER. If pkt_len is 0 we toss packet. If skb->len is smaller
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* than pkt_len we keep whole skb->data. This is the socket level
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* wrapper to SK_RUN_FILTER. It returns 0 if the packet should
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* be accepted or -EPERM if the packet should be tossed.
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*
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*/
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int sk_filter(struct sock *sk, struct sk_buff *skb)
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{
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int err;
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struct sk_filter *filter;
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/*
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* If the skb was allocated from pfmemalloc reserves, only
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* allow SOCK_MEMALLOC sockets to use it as this socket is
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* helping free memory
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*/
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if (skb_pfmemalloc(skb) && !sock_flag(sk, SOCK_MEMALLOC))
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return -ENOMEM;
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err = security_sock_rcv_skb(sk, skb);
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if (err)
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return err;
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rcu_read_lock();
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filter = rcu_dereference(sk->sk_filter);
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if (filter) {
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unsigned int pkt_len = SK_RUN_FILTER(filter, skb);
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err = pkt_len ? pskb_trim(skb, pkt_len) : -EPERM;
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}
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rcu_read_unlock();
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return err;
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}
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EXPORT_SYMBOL(sk_filter);
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static u64 __skb_get_pay_offset(u64 ctx, u64 a, u64 x, u64 r4, u64 r5)
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{
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return skb_get_poff((struct sk_buff *)(unsigned long) ctx);
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}
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static u64 __skb_get_nlattr(u64 ctx, u64 a, u64 x, u64 r4, u64 r5)
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{
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struct sk_buff *skb = (struct sk_buff *)(unsigned long) ctx;
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struct nlattr *nla;
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if (skb_is_nonlinear(skb))
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return 0;
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if (skb->len < sizeof(struct nlattr))
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return 0;
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if (a > skb->len - sizeof(struct nlattr))
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return 0;
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nla = nla_find((struct nlattr *) &skb->data[a], skb->len - a, x);
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if (nla)
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return (void *) nla - (void *) skb->data;
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return 0;
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}
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static u64 __skb_get_nlattr_nest(u64 ctx, u64 a, u64 x, u64 r4, u64 r5)
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{
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struct sk_buff *skb = (struct sk_buff *)(unsigned long) ctx;
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struct nlattr *nla;
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if (skb_is_nonlinear(skb))
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return 0;
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if (skb->len < sizeof(struct nlattr))
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return 0;
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if (a > skb->len - sizeof(struct nlattr))
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return 0;
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nla = (struct nlattr *) &skb->data[a];
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if (nla->nla_len > skb->len - a)
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return 0;
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nla = nla_find_nested(nla, x);
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if (nla)
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return (void *) nla - (void *) skb->data;
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return 0;
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}
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static u64 __get_raw_cpu_id(u64 ctx, u64 a, u64 x, u64 r4, u64 r5)
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{
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return raw_smp_processor_id();
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}
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/* note that this only generates 32-bit random numbers */
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static u64 __get_random_u32(u64 ctx, u64 a, u64 x, u64 r4, u64 r5)
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{
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return prandom_u32();
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}
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static bool convert_bpf_extensions(struct sock_filter *fp,
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struct bpf_insn **insnp)
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{
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struct bpf_insn *insn = *insnp;
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switch (fp->k) {
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case SKF_AD_OFF + SKF_AD_PROTOCOL:
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BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, protocol) != 2);
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/* A = *(u16 *) (CTX + offsetof(protocol)) */
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*insn++ = BPF_LDX_MEM(BPF_H, BPF_REG_A, BPF_REG_CTX,
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offsetof(struct sk_buff, protocol));
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/* A = ntohs(A) [emitting a nop or swap16] */
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*insn = BPF_ENDIAN(BPF_FROM_BE, BPF_REG_A, 16);
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break;
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case SKF_AD_OFF + SKF_AD_PKTTYPE:
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*insn++ = BPF_LDX_MEM(BPF_B, BPF_REG_A, BPF_REG_CTX,
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PKT_TYPE_OFFSET());
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*insn = BPF_ALU32_IMM(BPF_AND, BPF_REG_A, PKT_TYPE_MAX);
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#ifdef __BIG_ENDIAN_BITFIELD
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insn++;
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*insn = BPF_ALU32_IMM(BPF_RSH, BPF_REG_A, 5);
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#endif
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break;
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case SKF_AD_OFF + SKF_AD_IFINDEX:
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case SKF_AD_OFF + SKF_AD_HATYPE:
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BUILD_BUG_ON(FIELD_SIZEOF(struct net_device, ifindex) != 4);
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BUILD_BUG_ON(FIELD_SIZEOF(struct net_device, type) != 2);
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BUILD_BUG_ON(bytes_to_bpf_size(FIELD_SIZEOF(struct sk_buff, dev)) < 0);
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*insn++ = BPF_LDX_MEM(bytes_to_bpf_size(FIELD_SIZEOF(struct sk_buff, dev)),
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BPF_REG_TMP, BPF_REG_CTX,
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offsetof(struct sk_buff, dev));
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/* if (tmp != 0) goto pc + 1 */
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*insn++ = BPF_JMP_IMM(BPF_JNE, BPF_REG_TMP, 0, 1);
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*insn++ = BPF_EXIT_INSN();
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if (fp->k == SKF_AD_OFF + SKF_AD_IFINDEX)
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*insn = BPF_LDX_MEM(BPF_W, BPF_REG_A, BPF_REG_TMP,
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offsetof(struct net_device, ifindex));
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else
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*insn = BPF_LDX_MEM(BPF_H, BPF_REG_A, BPF_REG_TMP,
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offsetof(struct net_device, type));
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break;
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case SKF_AD_OFF + SKF_AD_MARK:
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BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, mark) != 4);
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*insn = BPF_LDX_MEM(BPF_W, BPF_REG_A, BPF_REG_CTX,
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offsetof(struct sk_buff, mark));
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break;
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case SKF_AD_OFF + SKF_AD_RXHASH:
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BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, hash) != 4);
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*insn = BPF_LDX_MEM(BPF_W, BPF_REG_A, BPF_REG_CTX,
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offsetof(struct sk_buff, hash));
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break;
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case SKF_AD_OFF + SKF_AD_QUEUE:
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BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, queue_mapping) != 2);
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*insn = BPF_LDX_MEM(BPF_H, BPF_REG_A, BPF_REG_CTX,
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offsetof(struct sk_buff, queue_mapping));
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break;
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case SKF_AD_OFF + SKF_AD_VLAN_TAG:
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case SKF_AD_OFF + SKF_AD_VLAN_TAG_PRESENT:
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BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, vlan_tci) != 2);
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BUILD_BUG_ON(VLAN_TAG_PRESENT != 0x1000);
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/* A = *(u16 *) (CTX + offsetof(vlan_tci)) */
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*insn++ = BPF_LDX_MEM(BPF_H, BPF_REG_A, BPF_REG_CTX,
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offsetof(struct sk_buff, vlan_tci));
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if (fp->k == SKF_AD_OFF + SKF_AD_VLAN_TAG) {
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*insn = BPF_ALU32_IMM(BPF_AND, BPF_REG_A,
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~VLAN_TAG_PRESENT);
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} else {
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/* A >>= 12 */
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*insn++ = BPF_ALU32_IMM(BPF_RSH, BPF_REG_A, 12);
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/* A &= 1 */
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*insn = BPF_ALU32_IMM(BPF_AND, BPF_REG_A, 1);
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}
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break;
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case SKF_AD_OFF + SKF_AD_PAY_OFFSET:
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case SKF_AD_OFF + SKF_AD_NLATTR:
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case SKF_AD_OFF + SKF_AD_NLATTR_NEST:
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case SKF_AD_OFF + SKF_AD_CPU:
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case SKF_AD_OFF + SKF_AD_RANDOM:
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/* arg1 = CTX */
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*insn++ = BPF_MOV64_REG(BPF_REG_ARG1, BPF_REG_CTX);
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/* arg2 = A */
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*insn++ = BPF_MOV64_REG(BPF_REG_ARG2, BPF_REG_A);
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/* arg3 = X */
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*insn++ = BPF_MOV64_REG(BPF_REG_ARG3, BPF_REG_X);
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/* Emit call(arg1=CTX, arg2=A, arg3=X) */
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switch (fp->k) {
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case SKF_AD_OFF + SKF_AD_PAY_OFFSET:
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*insn = BPF_EMIT_CALL(__skb_get_pay_offset);
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break;
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case SKF_AD_OFF + SKF_AD_NLATTR:
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*insn = BPF_EMIT_CALL(__skb_get_nlattr);
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break;
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case SKF_AD_OFF + SKF_AD_NLATTR_NEST:
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*insn = BPF_EMIT_CALL(__skb_get_nlattr_nest);
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break;
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case SKF_AD_OFF + SKF_AD_CPU:
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*insn = BPF_EMIT_CALL(__get_raw_cpu_id);
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break;
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case SKF_AD_OFF + SKF_AD_RANDOM:
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*insn = BPF_EMIT_CALL(__get_random_u32);
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break;
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}
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break;
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case SKF_AD_OFF + SKF_AD_ALU_XOR_X:
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/* A ^= X */
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*insn = BPF_ALU32_REG(BPF_XOR, BPF_REG_A, BPF_REG_X);
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break;
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default:
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/* This is just a dummy call to avoid letting the compiler
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* evict __bpf_call_base() as an optimization. Placed here
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* where no-one bothers.
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*/
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BUG_ON(__bpf_call_base(0, 0, 0, 0, 0) != 0);
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return false;
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}
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*insnp = insn;
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return true;
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}
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/**
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* bpf_convert_filter - convert filter program
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* @prog: the user passed filter program
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* @len: the length of the user passed filter program
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* @new_prog: buffer where converted program will be stored
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* @new_len: pointer to store length of converted program
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*
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* Remap 'sock_filter' style BPF instruction set to 'sock_filter_ext' style.
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* Conversion workflow:
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*
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* 1) First pass for calculating the new program length:
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* bpf_convert_filter(old_prog, old_len, NULL, &new_len)
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*
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* 2) 2nd pass to remap in two passes: 1st pass finds new
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* jump offsets, 2nd pass remapping:
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* new_prog = kmalloc(sizeof(struct bpf_insn) * new_len);
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* bpf_convert_filter(old_prog, old_len, new_prog, &new_len);
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*
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* User BPF's register A is mapped to our BPF register 6, user BPF
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* register X is mapped to BPF register 7; frame pointer is always
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* register 10; Context 'void *ctx' is stored in register 1, that is,
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* for socket filters: ctx == 'struct sk_buff *', for seccomp:
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* ctx == 'struct seccomp_data *'.
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*/
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int bpf_convert_filter(struct sock_filter *prog, int len,
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struct bpf_insn *new_prog, int *new_len)
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{
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int new_flen = 0, pass = 0, target, i;
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struct bpf_insn *new_insn;
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struct sock_filter *fp;
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int *addrs = NULL;
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u8 bpf_src;
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BUILD_BUG_ON(BPF_MEMWORDS * sizeof(u32) > MAX_BPF_STACK);
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BUILD_BUG_ON(BPF_REG_FP + 1 != MAX_BPF_REG);
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if (len <= 0 || len > BPF_MAXINSNS)
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return -EINVAL;
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if (new_prog) {
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addrs = kcalloc(len, sizeof(*addrs), GFP_KERNEL);
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if (!addrs)
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return -ENOMEM;
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}
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do_pass:
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new_insn = new_prog;
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fp = prog;
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if (new_insn)
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*new_insn = BPF_MOV64_REG(BPF_REG_CTX, BPF_REG_ARG1);
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new_insn++;
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for (i = 0; i < len; fp++, i++) {
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struct bpf_insn tmp_insns[6] = { };
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struct bpf_insn *insn = tmp_insns;
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|
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if (addrs)
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addrs[i] = new_insn - new_prog;
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|
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switch (fp->code) {
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/* All arithmetic insns and skb loads map as-is. */
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case BPF_ALU | BPF_ADD | BPF_X:
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case BPF_ALU | BPF_ADD | BPF_K:
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case BPF_ALU | BPF_SUB | BPF_X:
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case BPF_ALU | BPF_SUB | BPF_K:
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case BPF_ALU | BPF_AND | BPF_X:
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case BPF_ALU | BPF_AND | BPF_K:
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case BPF_ALU | BPF_OR | BPF_X:
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case BPF_ALU | BPF_OR | BPF_K:
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case BPF_ALU | BPF_LSH | BPF_X:
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case BPF_ALU | BPF_LSH | BPF_K:
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case BPF_ALU | BPF_RSH | BPF_X:
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case BPF_ALU | BPF_RSH | BPF_K:
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case BPF_ALU | BPF_XOR | BPF_X:
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case BPF_ALU | BPF_XOR | BPF_K:
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case BPF_ALU | BPF_MUL | BPF_X:
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case BPF_ALU | BPF_MUL | BPF_K:
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case BPF_ALU | BPF_DIV | BPF_X:
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case BPF_ALU | BPF_DIV | BPF_K:
|
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case BPF_ALU | BPF_MOD | BPF_X:
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case BPF_ALU | BPF_MOD | BPF_K:
|
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case BPF_ALU | BPF_NEG:
|
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case BPF_LD | BPF_ABS | BPF_W:
|
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case BPF_LD | BPF_ABS | BPF_H:
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case BPF_LD | BPF_ABS | BPF_B:
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case BPF_LD | BPF_IND | BPF_W:
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case BPF_LD | BPF_IND | BPF_H:
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case BPF_LD | BPF_IND | BPF_B:
|
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/* Check for overloaded BPF extension and
|
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* directly convert it if found, otherwise
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* just move on with mapping.
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*/
|
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if (BPF_CLASS(fp->code) == BPF_LD &&
|
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BPF_MODE(fp->code) == BPF_ABS &&
|
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convert_bpf_extensions(fp, &insn))
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break;
|
|
|
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*insn = BPF_RAW_INSN(fp->code, BPF_REG_A, BPF_REG_X, 0, fp->k);
|
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break;
|
|
|
|
/* Jump transformation cannot use BPF block macros
|
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* everywhere as offset calculation and target updates
|
|
* require a bit more work than the rest, i.e. jump
|
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* opcodes map as-is, but offsets need adjustment.
|
|
*/
|
|
|
|
#define BPF_EMIT_JMP \
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do { \
|
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if (target >= len || target < 0) \
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goto err; \
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insn->off = addrs ? addrs[target] - addrs[i] - 1 : 0; \
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/* Adjust pc relative offset for 2nd or 3rd insn. */ \
|
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insn->off -= insn - tmp_insns; \
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|
} while (0)
|
|
|
|
case BPF_JMP | BPF_JA:
|
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target = i + fp->k + 1;
|
|
insn->code = fp->code;
|
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BPF_EMIT_JMP;
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break;
|
|
|
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case BPF_JMP | BPF_JEQ | BPF_K:
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case BPF_JMP | BPF_JEQ | BPF_X:
|
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case BPF_JMP | BPF_JSET | BPF_K:
|
|
case BPF_JMP | BPF_JSET | BPF_X:
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case BPF_JMP | BPF_JGT | BPF_K:
|
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case BPF_JMP | BPF_JGT | BPF_X:
|
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case BPF_JMP | BPF_JGE | BPF_K:
|
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case BPF_JMP | BPF_JGE | BPF_X:
|
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if (BPF_SRC(fp->code) == BPF_K && (int) fp->k < 0) {
|
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/* BPF immediates are signed, zero extend
|
|
* immediate into tmp register and use it
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* in compare insn.
|
|
*/
|
|
*insn++ = BPF_MOV32_IMM(BPF_REG_TMP, fp->k);
|
|
|
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insn->dst_reg = BPF_REG_A;
|
|
insn->src_reg = BPF_REG_TMP;
|
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bpf_src = BPF_X;
|
|
} else {
|
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insn->dst_reg = BPF_REG_A;
|
|
insn->src_reg = BPF_REG_X;
|
|
insn->imm = fp->k;
|
|
bpf_src = BPF_SRC(fp->code);
|
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}
|
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|
|
/* 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)
|
|
{
|
|
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);
|
|
|
|
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;
|
|
}
|