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![Pavel Emelyanov](/assets/img/avatar_default.png)
The SO_ATTACH_FILTER option is set only. I propose to add the get ability by using SO_ATTACH_FILTER in getsockopt. To be less irritating to eyes the SO_GET_FILTER alias to it is declared. This ability is required by checkpoint-restore project to be able to save full state of a socket. There are two issues with getting filter back. First, kernel modifies the sock_filter->code on filter load, thus in order to return the filter element back to user we have to decode it into user-visible constants. Fortunately the modification in question is interconvertible. Second, the BPF_S_ALU_DIV_K code modifies the command argument k to speed up the run-time division by doing kernel_k = reciprocal(user_k). Bad news is that different user_k may result in same kernel_k, so we can't get the original user_k back. Good news is that we don't have to do it. What we need to is calculate a user2_k so, that reciprocal(user2_k) == reciprocal(user_k) == kernel_k i.e. if it's re-loaded back the compiled again value will be exactly the same as it was. That said, the user2_k can be calculated like this user2_k = reciprocal(kernel_k) with an exception, that if kernel_k == 0, then user2_k == 1. The optlen argument is treated like this -- when zero, kernel returns the amount of sock_fprog elements in filter, otherwise it should be large enough for the sock_fprog array. changes since v1: * Declared SO_GET_FILTER in all arch headers * Added decode of vlan-tag codes Signed-off-by: Pavel Emelyanov <xemul@parallels.com> Signed-off-by: David S. Miller <davem@davemloft.net>
892 lines
22 KiB
C
892 lines
22 KiB
C
/*
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* Linux Socket Filter - Kernel level socket filtering
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*
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* Author:
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* Jay Schulist <jschlst@samba.org>
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*
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* Based on the design of:
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* - The Berkeley Packet Filter
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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 sk_chk_filter()
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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/reciprocal_div.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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/* No hurry in this branch
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*
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* Exported for the bpf jit load helper.
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*/
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void *bpf_internal_load_pointer_neg_helper(const struct sk_buff *skb, int k, unsigned int size)
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{
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u8 *ptr = NULL;
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if (k >= SKF_NET_OFF)
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ptr = skb_network_header(skb) + k - SKF_NET_OFF;
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else if (k >= SKF_LL_OFF)
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ptr = skb_mac_header(skb) + k - SKF_LL_OFF;
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if (ptr >= skb->head && ptr + size <= skb_tail_pointer(skb))
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return ptr;
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return NULL;
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}
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static inline void *load_pointer(const struct sk_buff *skb, int k,
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unsigned int size, void *buffer)
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{
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if (k >= 0)
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return skb_header_pointer(skb, k, size, buffer);
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return bpf_internal_load_pointer_neg_helper(skb, k, size);
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}
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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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/**
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* sk_run_filter - run a filter on a socket
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* @skb: buffer to run the filter on
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* @fentry: filter to apply
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*
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* Decode and apply filter instructions to the skb->data.
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* Return length to keep, 0 for none. @skb is the data we are
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* filtering, @filter is the array of filter instructions.
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* Because all jumps are guaranteed to be before last instruction,
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* and last instruction guaranteed to be a RET, we dont need to check
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* flen. (We used to pass to this function the length of filter)
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*/
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unsigned int sk_run_filter(const struct sk_buff *skb,
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const struct sock_filter *fentry)
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{
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void *ptr;
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u32 A = 0; /* Accumulator */
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u32 X = 0; /* Index Register */
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u32 mem[BPF_MEMWORDS]; /* Scratch Memory Store */
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u32 tmp;
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int k;
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/*
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* Process array of filter instructions.
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*/
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for (;; fentry++) {
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#if defined(CONFIG_X86_32)
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#define K (fentry->k)
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#else
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const u32 K = fentry->k;
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#endif
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switch (fentry->code) {
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case BPF_S_ALU_ADD_X:
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A += X;
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continue;
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case BPF_S_ALU_ADD_K:
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A += K;
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continue;
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case BPF_S_ALU_SUB_X:
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A -= X;
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continue;
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case BPF_S_ALU_SUB_K:
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A -= K;
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continue;
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case BPF_S_ALU_MUL_X:
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A *= X;
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continue;
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case BPF_S_ALU_MUL_K:
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A *= K;
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continue;
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case BPF_S_ALU_DIV_X:
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if (X == 0)
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return 0;
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A /= X;
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continue;
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case BPF_S_ALU_DIV_K:
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A = reciprocal_divide(A, K);
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continue;
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case BPF_S_ALU_MOD_X:
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if (X == 0)
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return 0;
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A %= X;
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continue;
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case BPF_S_ALU_MOD_K:
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A %= K;
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continue;
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case BPF_S_ALU_AND_X:
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A &= X;
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continue;
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case BPF_S_ALU_AND_K:
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A &= K;
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continue;
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case BPF_S_ALU_OR_X:
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A |= X;
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continue;
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case BPF_S_ALU_OR_K:
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A |= K;
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continue;
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case BPF_S_ANC_ALU_XOR_X:
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case BPF_S_ALU_XOR_X:
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A ^= X;
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continue;
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case BPF_S_ALU_XOR_K:
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A ^= K;
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continue;
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case BPF_S_ALU_LSH_X:
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A <<= X;
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continue;
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case BPF_S_ALU_LSH_K:
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A <<= K;
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continue;
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case BPF_S_ALU_RSH_X:
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A >>= X;
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continue;
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case BPF_S_ALU_RSH_K:
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A >>= K;
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continue;
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case BPF_S_ALU_NEG:
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A = -A;
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continue;
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case BPF_S_JMP_JA:
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fentry += K;
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continue;
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case BPF_S_JMP_JGT_K:
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fentry += (A > K) ? fentry->jt : fentry->jf;
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continue;
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case BPF_S_JMP_JGE_K:
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fentry += (A >= K) ? fentry->jt : fentry->jf;
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continue;
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case BPF_S_JMP_JEQ_K:
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fentry += (A == K) ? fentry->jt : fentry->jf;
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continue;
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case BPF_S_JMP_JSET_K:
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fentry += (A & K) ? fentry->jt : fentry->jf;
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continue;
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case BPF_S_JMP_JGT_X:
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fentry += (A > X) ? fentry->jt : fentry->jf;
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continue;
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case BPF_S_JMP_JGE_X:
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fentry += (A >= X) ? fentry->jt : fentry->jf;
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continue;
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case BPF_S_JMP_JEQ_X:
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fentry += (A == X) ? fentry->jt : fentry->jf;
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continue;
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case BPF_S_JMP_JSET_X:
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fentry += (A & X) ? fentry->jt : fentry->jf;
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continue;
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case BPF_S_LD_W_ABS:
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k = K;
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load_w:
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ptr = load_pointer(skb, k, 4, &tmp);
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if (ptr != NULL) {
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A = get_unaligned_be32(ptr);
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continue;
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}
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return 0;
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case BPF_S_LD_H_ABS:
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k = K;
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load_h:
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ptr = load_pointer(skb, k, 2, &tmp);
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if (ptr != NULL) {
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A = get_unaligned_be16(ptr);
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continue;
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}
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return 0;
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case BPF_S_LD_B_ABS:
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k = K;
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load_b:
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ptr = load_pointer(skb, k, 1, &tmp);
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if (ptr != NULL) {
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A = *(u8 *)ptr;
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continue;
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}
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return 0;
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case BPF_S_LD_W_LEN:
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A = skb->len;
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continue;
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case BPF_S_LDX_W_LEN:
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X = skb->len;
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continue;
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case BPF_S_LD_W_IND:
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k = X + K;
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goto load_w;
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case BPF_S_LD_H_IND:
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k = X + K;
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goto load_h;
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case BPF_S_LD_B_IND:
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k = X + K;
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goto load_b;
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case BPF_S_LDX_B_MSH:
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ptr = load_pointer(skb, K, 1, &tmp);
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if (ptr != NULL) {
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X = (*(u8 *)ptr & 0xf) << 2;
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continue;
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}
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return 0;
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case BPF_S_LD_IMM:
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A = K;
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continue;
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case BPF_S_LDX_IMM:
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X = K;
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continue;
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case BPF_S_LD_MEM:
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A = mem[K];
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continue;
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case BPF_S_LDX_MEM:
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X = mem[K];
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continue;
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case BPF_S_MISC_TAX:
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X = A;
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continue;
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case BPF_S_MISC_TXA:
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A = X;
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continue;
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case BPF_S_RET_K:
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return K;
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case BPF_S_RET_A:
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return A;
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case BPF_S_ST:
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mem[K] = A;
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continue;
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case BPF_S_STX:
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mem[K] = X;
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continue;
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case BPF_S_ANC_PROTOCOL:
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A = ntohs(skb->protocol);
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continue;
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case BPF_S_ANC_PKTTYPE:
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A = skb->pkt_type;
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continue;
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case BPF_S_ANC_IFINDEX:
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if (!skb->dev)
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return 0;
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A = skb->dev->ifindex;
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continue;
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case BPF_S_ANC_MARK:
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A = skb->mark;
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continue;
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case BPF_S_ANC_QUEUE:
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A = skb->queue_mapping;
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continue;
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case BPF_S_ANC_HATYPE:
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if (!skb->dev)
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return 0;
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A = skb->dev->type;
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continue;
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case BPF_S_ANC_RXHASH:
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A = skb->rxhash;
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continue;
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case BPF_S_ANC_CPU:
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A = raw_smp_processor_id();
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continue;
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case BPF_S_ANC_VLAN_TAG:
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A = vlan_tx_tag_get(skb);
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continue;
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case BPF_S_ANC_VLAN_TAG_PRESENT:
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A = !!vlan_tx_tag_present(skb);
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continue;
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case BPF_S_ANC_NLATTR: {
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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 (A > skb->len - sizeof(struct nlattr))
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return 0;
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nla = nla_find((struct nlattr *)&skb->data[A],
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skb->len - A, X);
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if (nla)
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A = (void *)nla - (void *)skb->data;
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else
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A = 0;
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continue;
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}
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case BPF_S_ANC_NLATTR_NEST: {
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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 (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 > A - skb->len)
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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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A = (void *)nla - (void *)skb->data;
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else
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A = 0;
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continue;
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}
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#ifdef CONFIG_SECCOMP_FILTER
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case BPF_S_ANC_SECCOMP_LD_W:
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A = seccomp_bpf_load(fentry->k);
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continue;
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#endif
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default:
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WARN_RATELIMIT(1, "Unknown code:%u jt:%u tf:%u k:%u\n",
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fentry->code, fentry->jt,
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fentry->jf, fentry->k);
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return 0;
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}
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}
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return 0;
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}
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EXPORT_SYMBOL(sk_run_filter);
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/*
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* Security :
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* A BPF program is able to use 16 cells of memory to store intermediate
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* values (check u32 mem[BPF_MEMWORDS] in sk_run_filter())
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* As we dont want to clear mem[] array for each packet going through
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* sk_run_filter(), we check that filter loaded by user never try to read
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* a cell if not previously written, and we check all branches to be sure
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* a malicious user doesn't try to abuse us.
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*/
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static int check_load_and_stores(struct sock_filter *filter, int flen)
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{
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u16 *masks, memvalid = 0; /* one bit per cell, 16 cells */
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int pc, ret = 0;
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BUILD_BUG_ON(BPF_MEMWORDS > 16);
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masks = kmalloc(flen * sizeof(*masks), GFP_KERNEL);
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if (!masks)
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return -ENOMEM;
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memset(masks, 0xff, flen * sizeof(*masks));
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for (pc = 0; pc < flen; pc++) {
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memvalid &= masks[pc];
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switch (filter[pc].code) {
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case BPF_S_ST:
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case BPF_S_STX:
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memvalid |= (1 << filter[pc].k);
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break;
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case BPF_S_LD_MEM:
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case BPF_S_LDX_MEM:
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if (!(memvalid & (1 << filter[pc].k))) {
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ret = -EINVAL;
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goto error;
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}
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break;
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case BPF_S_JMP_JA:
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/* a jump must set masks on target */
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masks[pc + 1 + filter[pc].k] &= memvalid;
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memvalid = ~0;
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break;
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case BPF_S_JMP_JEQ_K:
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case BPF_S_JMP_JEQ_X:
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case BPF_S_JMP_JGE_K:
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case BPF_S_JMP_JGE_X:
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case BPF_S_JMP_JGT_K:
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case BPF_S_JMP_JGT_X:
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case BPF_S_JMP_JSET_X:
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case BPF_S_JMP_JSET_K:
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/* a jump must set masks on targets */
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masks[pc + 1 + filter[pc].jt] &= memvalid;
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masks[pc + 1 + filter[pc].jf] &= memvalid;
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memvalid = ~0;
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break;
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}
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}
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error:
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kfree(masks);
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return ret;
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}
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|
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/**
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* sk_chk_filter - verify socket filter code
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* @filter: filter to verify
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* @flen: length of filter
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*
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* Check the user's filter code. If we let some ugly
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* filter code slip through kaboom! The filter must contain
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* no references or jumps that are out of range, no illegal
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* instructions, and must end with a RET instruction.
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*
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* All jumps are forward as they are not signed.
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*
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* Returns 0 if the rule set is legal or -EINVAL if not.
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*/
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int sk_chk_filter(struct sock_filter *filter, unsigned int flen)
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{
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/*
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* Valid instructions are initialized to non-0.
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* Invalid instructions are initialized to 0.
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*/
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static const u8 codes[] = {
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[BPF_ALU|BPF_ADD|BPF_K] = BPF_S_ALU_ADD_K,
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[BPF_ALU|BPF_ADD|BPF_X] = BPF_S_ALU_ADD_X,
|
|
[BPF_ALU|BPF_SUB|BPF_K] = BPF_S_ALU_SUB_K,
|
|
[BPF_ALU|BPF_SUB|BPF_X] = BPF_S_ALU_SUB_X,
|
|
[BPF_ALU|BPF_MUL|BPF_K] = BPF_S_ALU_MUL_K,
|
|
[BPF_ALU|BPF_MUL|BPF_X] = BPF_S_ALU_MUL_X,
|
|
[BPF_ALU|BPF_DIV|BPF_X] = BPF_S_ALU_DIV_X,
|
|
[BPF_ALU|BPF_MOD|BPF_K] = BPF_S_ALU_MOD_K,
|
|
[BPF_ALU|BPF_MOD|BPF_X] = BPF_S_ALU_MOD_X,
|
|
[BPF_ALU|BPF_AND|BPF_K] = BPF_S_ALU_AND_K,
|
|
[BPF_ALU|BPF_AND|BPF_X] = BPF_S_ALU_AND_X,
|
|
[BPF_ALU|BPF_OR|BPF_K] = BPF_S_ALU_OR_K,
|
|
[BPF_ALU|BPF_OR|BPF_X] = BPF_S_ALU_OR_X,
|
|
[BPF_ALU|BPF_XOR|BPF_K] = BPF_S_ALU_XOR_K,
|
|
[BPF_ALU|BPF_XOR|BPF_X] = BPF_S_ALU_XOR_X,
|
|
[BPF_ALU|BPF_LSH|BPF_K] = BPF_S_ALU_LSH_K,
|
|
[BPF_ALU|BPF_LSH|BPF_X] = BPF_S_ALU_LSH_X,
|
|
[BPF_ALU|BPF_RSH|BPF_K] = BPF_S_ALU_RSH_K,
|
|
[BPF_ALU|BPF_RSH|BPF_X] = BPF_S_ALU_RSH_X,
|
|
[BPF_ALU|BPF_NEG] = BPF_S_ALU_NEG,
|
|
[BPF_LD|BPF_W|BPF_ABS] = BPF_S_LD_W_ABS,
|
|
[BPF_LD|BPF_H|BPF_ABS] = BPF_S_LD_H_ABS,
|
|
[BPF_LD|BPF_B|BPF_ABS] = BPF_S_LD_B_ABS,
|
|
[BPF_LD|BPF_W|BPF_LEN] = BPF_S_LD_W_LEN,
|
|
[BPF_LD|BPF_W|BPF_IND] = BPF_S_LD_W_IND,
|
|
[BPF_LD|BPF_H|BPF_IND] = BPF_S_LD_H_IND,
|
|
[BPF_LD|BPF_B|BPF_IND] = BPF_S_LD_B_IND,
|
|
[BPF_LD|BPF_IMM] = BPF_S_LD_IMM,
|
|
[BPF_LDX|BPF_W|BPF_LEN] = BPF_S_LDX_W_LEN,
|
|
[BPF_LDX|BPF_B|BPF_MSH] = BPF_S_LDX_B_MSH,
|
|
[BPF_LDX|BPF_IMM] = BPF_S_LDX_IMM,
|
|
[BPF_MISC|BPF_TAX] = BPF_S_MISC_TAX,
|
|
[BPF_MISC|BPF_TXA] = BPF_S_MISC_TXA,
|
|
[BPF_RET|BPF_K] = BPF_S_RET_K,
|
|
[BPF_RET|BPF_A] = BPF_S_RET_A,
|
|
[BPF_ALU|BPF_DIV|BPF_K] = BPF_S_ALU_DIV_K,
|
|
[BPF_LD|BPF_MEM] = BPF_S_LD_MEM,
|
|
[BPF_LDX|BPF_MEM] = BPF_S_LDX_MEM,
|
|
[BPF_ST] = BPF_S_ST,
|
|
[BPF_STX] = BPF_S_STX,
|
|
[BPF_JMP|BPF_JA] = BPF_S_JMP_JA,
|
|
[BPF_JMP|BPF_JEQ|BPF_K] = BPF_S_JMP_JEQ_K,
|
|
[BPF_JMP|BPF_JEQ|BPF_X] = BPF_S_JMP_JEQ_X,
|
|
[BPF_JMP|BPF_JGE|BPF_K] = BPF_S_JMP_JGE_K,
|
|
[BPF_JMP|BPF_JGE|BPF_X] = BPF_S_JMP_JGE_X,
|
|
[BPF_JMP|BPF_JGT|BPF_K] = BPF_S_JMP_JGT_K,
|
|
[BPF_JMP|BPF_JGT|BPF_X] = BPF_S_JMP_JGT_X,
|
|
[BPF_JMP|BPF_JSET|BPF_K] = BPF_S_JMP_JSET_K,
|
|
[BPF_JMP|BPF_JSET|BPF_X] = BPF_S_JMP_JSET_X,
|
|
};
|
|
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];
|
|
u16 code = ftest->code;
|
|
|
|
if (code >= ARRAY_SIZE(codes))
|
|
return -EINVAL;
|
|
code = codes[code];
|
|
if (!code)
|
|
return -EINVAL;
|
|
/* Some instructions need special checks */
|
|
switch (code) {
|
|
case BPF_S_ALU_DIV_K:
|
|
/* check for division by zero */
|
|
if (ftest->k == 0)
|
|
return -EINVAL;
|
|
ftest->k = reciprocal_value(ftest->k);
|
|
break;
|
|
case BPF_S_ALU_MOD_K:
|
|
/* check for division by zero */
|
|
if (ftest->k == 0)
|
|
return -EINVAL;
|
|
break;
|
|
case BPF_S_LD_MEM:
|
|
case BPF_S_LDX_MEM:
|
|
case BPF_S_ST:
|
|
case BPF_S_STX:
|
|
/* check for invalid memory addresses */
|
|
if (ftest->k >= BPF_MEMWORDS)
|
|
return -EINVAL;
|
|
break;
|
|
case BPF_S_JMP_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_S_JMP_JEQ_K:
|
|
case BPF_S_JMP_JEQ_X:
|
|
case BPF_S_JMP_JGE_K:
|
|
case BPF_S_JMP_JGE_X:
|
|
case BPF_S_JMP_JGT_K:
|
|
case BPF_S_JMP_JGT_X:
|
|
case BPF_S_JMP_JSET_X:
|
|
case BPF_S_JMP_JSET_K:
|
|
/* for conditionals both must be safe */
|
|
if (pc + ftest->jt + 1 >= flen ||
|
|
pc + ftest->jf + 1 >= flen)
|
|
return -EINVAL;
|
|
break;
|
|
case BPF_S_LD_W_ABS:
|
|
case BPF_S_LD_H_ABS:
|
|
case BPF_S_LD_B_ABS:
|
|
#define ANCILLARY(CODE) case SKF_AD_OFF + SKF_AD_##CODE: \
|
|
code = BPF_S_ANC_##CODE; \
|
|
break
|
|
switch (ftest->k) {
|
|
ANCILLARY(PROTOCOL);
|
|
ANCILLARY(PKTTYPE);
|
|
ANCILLARY(IFINDEX);
|
|
ANCILLARY(NLATTR);
|
|
ANCILLARY(NLATTR_NEST);
|
|
ANCILLARY(MARK);
|
|
ANCILLARY(QUEUE);
|
|
ANCILLARY(HATYPE);
|
|
ANCILLARY(RXHASH);
|
|
ANCILLARY(CPU);
|
|
ANCILLARY(ALU_XOR_X);
|
|
ANCILLARY(VLAN_TAG);
|
|
ANCILLARY(VLAN_TAG_PRESENT);
|
|
}
|
|
}
|
|
ftest->code = code;
|
|
}
|
|
|
|
/* last instruction must be a RET code */
|
|
switch (filter[flen - 1].code) {
|
|
case BPF_S_RET_K:
|
|
case BPF_S_RET_A:
|
|
return check_load_and_stores(filter, flen);
|
|
}
|
|
return -EINVAL;
|
|
}
|
|
EXPORT_SYMBOL(sk_chk_filter);
|
|
|
|
/**
|
|
* sk_filter_release_rcu - Release a socket filter by rcu_head
|
|
* @rcu: rcu_head that contains the sk_filter to free
|
|
*/
|
|
void sk_filter_release_rcu(struct rcu_head *rcu)
|
|
{
|
|
struct sk_filter *fp = container_of(rcu, struct sk_filter, rcu);
|
|
|
|
bpf_jit_free(fp);
|
|
kfree(fp);
|
|
}
|
|
EXPORT_SYMBOL(sk_filter_release_rcu);
|
|
|
|
static int __sk_prepare_filter(struct sk_filter *fp)
|
|
{
|
|
int err;
|
|
|
|
fp->bpf_func = sk_run_filter;
|
|
|
|
err = sk_chk_filter(fp->insns, fp->len);
|
|
if (err)
|
|
return err;
|
|
|
|
bpf_jit_compile(fp);
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* sk_unattached_filter_create - create an unattached filter
|
|
* @fprog: the filter program
|
|
* @pfp: the unattached filter that is created
|
|
*
|
|
* 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 *fprog)
|
|
{
|
|
struct sk_filter *fp;
|
|
unsigned int fsize = sizeof(struct sock_filter) * fprog->len;
|
|
int err;
|
|
|
|
/* Make sure new filter is there and in the right amounts. */
|
|
if (fprog->filter == NULL)
|
|
return -EINVAL;
|
|
|
|
fp = kmalloc(fsize + sizeof(*fp), GFP_KERNEL);
|
|
if (!fp)
|
|
return -ENOMEM;
|
|
memcpy(fp->insns, fprog->filter, fsize);
|
|
|
|
atomic_set(&fp->refcnt, 1);
|
|
fp->len = fprog->len;
|
|
|
|
err = __sk_prepare_filter(fp);
|
|
if (err)
|
|
goto free_mem;
|
|
|
|
*pfp = fp;
|
|
return 0;
|
|
free_mem:
|
|
kfree(fp);
|
|
return err;
|
|
}
|
|
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 = sizeof(struct sock_filter) * fprog->len;
|
|
int err;
|
|
|
|
/* Make sure new filter is there and in the right amounts. */
|
|
if (fprog->filter == NULL)
|
|
return -EINVAL;
|
|
|
|
fp = sock_kmalloc(sk, fsize+sizeof(*fp), GFP_KERNEL);
|
|
if (!fp)
|
|
return -ENOMEM;
|
|
if (copy_from_user(fp->insns, fprog->filter, fsize)) {
|
|
sock_kfree_s(sk, fp, fsize+sizeof(*fp));
|
|
return -EFAULT;
|
|
}
|
|
|
|
atomic_set(&fp->refcnt, 1);
|
|
fp->len = fprog->len;
|
|
|
|
err = __sk_prepare_filter(fp);
|
|
if (err) {
|
|
sk_filter_uncharge(sk, fp);
|
|
return err;
|
|
}
|
|
|
|
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;
|
|
|
|
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);
|
|
|
|
static void sk_decode_filter(struct sock_filter *filt, struct sock_filter *to)
|
|
{
|
|
static const u16 decodes[] = {
|
|
[BPF_S_ALU_ADD_K] = BPF_ALU|BPF_ADD|BPF_K,
|
|
[BPF_S_ALU_ADD_X] = BPF_ALU|BPF_ADD|BPF_X,
|
|
[BPF_S_ALU_SUB_K] = BPF_ALU|BPF_SUB|BPF_K,
|
|
[BPF_S_ALU_SUB_X] = BPF_ALU|BPF_SUB|BPF_X,
|
|
[BPF_S_ALU_MUL_K] = BPF_ALU|BPF_MUL|BPF_K,
|
|
[BPF_S_ALU_MUL_X] = BPF_ALU|BPF_MUL|BPF_X,
|
|
[BPF_S_ALU_DIV_X] = BPF_ALU|BPF_DIV|BPF_X,
|
|
[BPF_S_ALU_MOD_K] = BPF_ALU|BPF_MOD|BPF_K,
|
|
[BPF_S_ALU_MOD_X] = BPF_ALU|BPF_MOD|BPF_X,
|
|
[BPF_S_ALU_AND_K] = BPF_ALU|BPF_AND|BPF_K,
|
|
[BPF_S_ALU_AND_X] = BPF_ALU|BPF_AND|BPF_X,
|
|
[BPF_S_ALU_OR_K] = BPF_ALU|BPF_OR|BPF_K,
|
|
[BPF_S_ALU_OR_X] = BPF_ALU|BPF_OR|BPF_X,
|
|
[BPF_S_ALU_XOR_K] = BPF_ALU|BPF_XOR|BPF_K,
|
|
[BPF_S_ALU_XOR_X] = BPF_ALU|BPF_XOR|BPF_X,
|
|
[BPF_S_ALU_LSH_K] = BPF_ALU|BPF_LSH|BPF_K,
|
|
[BPF_S_ALU_LSH_X] = BPF_ALU|BPF_LSH|BPF_X,
|
|
[BPF_S_ALU_RSH_K] = BPF_ALU|BPF_RSH|BPF_K,
|
|
[BPF_S_ALU_RSH_X] = BPF_ALU|BPF_RSH|BPF_X,
|
|
[BPF_S_ALU_NEG] = BPF_ALU|BPF_NEG,
|
|
[BPF_S_LD_W_ABS] = BPF_LD|BPF_W|BPF_ABS,
|
|
[BPF_S_LD_H_ABS] = BPF_LD|BPF_H|BPF_ABS,
|
|
[BPF_S_LD_B_ABS] = BPF_LD|BPF_B|BPF_ABS,
|
|
[BPF_S_ANC_PROTOCOL] = BPF_LD|BPF_B|BPF_ABS,
|
|
[BPF_S_ANC_PKTTYPE] = BPF_LD|BPF_B|BPF_ABS,
|
|
[BPF_S_ANC_IFINDEX] = BPF_LD|BPF_B|BPF_ABS,
|
|
[BPF_S_ANC_NLATTR] = BPF_LD|BPF_B|BPF_ABS,
|
|
[BPF_S_ANC_NLATTR_NEST] = BPF_LD|BPF_B|BPF_ABS,
|
|
[BPF_S_ANC_MARK] = BPF_LD|BPF_B|BPF_ABS,
|
|
[BPF_S_ANC_QUEUE] = BPF_LD|BPF_B|BPF_ABS,
|
|
[BPF_S_ANC_HATYPE] = BPF_LD|BPF_B|BPF_ABS,
|
|
[BPF_S_ANC_RXHASH] = BPF_LD|BPF_B|BPF_ABS,
|
|
[BPF_S_ANC_CPU] = BPF_LD|BPF_B|BPF_ABS,
|
|
[BPF_S_ANC_ALU_XOR_X] = BPF_LD|BPF_B|BPF_ABS,
|
|
[BPF_S_ANC_SECCOMP_LD_W] = BPF_LD|BPF_B|BPF_ABS,
|
|
[BPF_S_ANC_VLAN_TAG] = BPF_LD|BPF_B|BPF_ABS,
|
|
[BPF_S_ANC_VLAN_TAG_PRESENT] = BPF_LD|BPF_B|BPF_ABS,
|
|
[BPF_S_LD_W_LEN] = BPF_LD|BPF_W|BPF_LEN,
|
|
[BPF_S_LD_W_IND] = BPF_LD|BPF_W|BPF_IND,
|
|
[BPF_S_LD_H_IND] = BPF_LD|BPF_H|BPF_IND,
|
|
[BPF_S_LD_B_IND] = BPF_LD|BPF_B|BPF_IND,
|
|
[BPF_S_LD_IMM] = BPF_LD|BPF_IMM,
|
|
[BPF_S_LDX_W_LEN] = BPF_LDX|BPF_W|BPF_LEN,
|
|
[BPF_S_LDX_B_MSH] = BPF_LDX|BPF_B|BPF_MSH,
|
|
[BPF_S_LDX_IMM] = BPF_LDX|BPF_IMM,
|
|
[BPF_S_MISC_TAX] = BPF_MISC|BPF_TAX,
|
|
[BPF_S_MISC_TXA] = BPF_MISC|BPF_TXA,
|
|
[BPF_S_RET_K] = BPF_RET|BPF_K,
|
|
[BPF_S_RET_A] = BPF_RET|BPF_A,
|
|
[BPF_S_ALU_DIV_K] = BPF_ALU|BPF_DIV|BPF_K,
|
|
[BPF_S_LD_MEM] = BPF_LD|BPF_MEM,
|
|
[BPF_S_LDX_MEM] = BPF_LDX|BPF_MEM,
|
|
[BPF_S_ST] = BPF_ST,
|
|
[BPF_S_STX] = BPF_STX,
|
|
[BPF_S_JMP_JA] = BPF_JMP|BPF_JA,
|
|
[BPF_S_JMP_JEQ_K] = BPF_JMP|BPF_JEQ|BPF_K,
|
|
[BPF_S_JMP_JEQ_X] = BPF_JMP|BPF_JEQ|BPF_X,
|
|
[BPF_S_JMP_JGE_K] = BPF_JMP|BPF_JGE|BPF_K,
|
|
[BPF_S_JMP_JGE_X] = BPF_JMP|BPF_JGE|BPF_X,
|
|
[BPF_S_JMP_JGT_K] = BPF_JMP|BPF_JGT|BPF_K,
|
|
[BPF_S_JMP_JGT_X] = BPF_JMP|BPF_JGT|BPF_X,
|
|
[BPF_S_JMP_JSET_K] = BPF_JMP|BPF_JSET|BPF_K,
|
|
[BPF_S_JMP_JSET_X] = BPF_JMP|BPF_JSET|BPF_X,
|
|
};
|
|
u16 code;
|
|
|
|
code = filt->code;
|
|
|
|
to->code = decodes[code];
|
|
to->jt = filt->jt;
|
|
to->jf = filt->jf;
|
|
|
|
if (code == BPF_S_ALU_DIV_K) {
|
|
/*
|
|
* When loaded this rule user gave us X, which was
|
|
* translated into R = r(X). Now we calculate the
|
|
* RR = r(R) and report it back. If next time this
|
|
* value is loaded and RRR = r(RR) is calculated
|
|
* then the R == RRR will be true.
|
|
*
|
|
* One exception. X == 1 translates into R == 0 and
|
|
* we can't calculate RR out of it with r().
|
|
*/
|
|
|
|
if (filt->k == 0)
|
|
to->k = 1;
|
|
else
|
|
to->k = reciprocal_value(filt->k);
|
|
|
|
BUG_ON(reciprocal_value(to->k) != filt->k);
|
|
} else
|
|
to->k = filt->k;
|
|
}
|
|
|
|
int sk_get_filter(struct sock *sk, struct sock_filter __user *ubuf, unsigned int len)
|
|
{
|
|
struct sk_filter *filter;
|
|
int i, ret;
|
|
|
|
lock_sock(sk);
|
|
filter = rcu_dereference_protected(sk->sk_filter,
|
|
sock_owned_by_user(sk));
|
|
ret = 0;
|
|
if (!filter)
|
|
goto out;
|
|
ret = filter->len;
|
|
if (!len)
|
|
goto out;
|
|
ret = -EINVAL;
|
|
if (len < filter->len)
|
|
goto out;
|
|
|
|
ret = -EFAULT;
|
|
for (i = 0; i < filter->len; i++) {
|
|
struct sock_filter fb;
|
|
|
|
sk_decode_filter(&filter->insns[i], &fb);
|
|
if (copy_to_user(&ubuf[i], &fb, sizeof(fb)))
|
|
goto out;
|
|
}
|
|
|
|
ret = filter->len;
|
|
out:
|
|
release_sock(sk);
|
|
return ret;
|
|
}
|