sk-filter: Add ability to get socket filter program (v2)
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>
This commit is contained in:
Pavel Emelyanov
David S. Miller
parent
96442e4242
commit
a8fc927780
19 changed files with 153 additions and 0 deletions
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@ -47,6 +47,7 @@
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/* Socket filtering */
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#define SO_ATTACH_FILTER 26
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#define SO_DETACH_FILTER 27
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#define SO_GET_FILTER SO_ATTACH_FILTER
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#define SO_PEERNAME 28
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#define SO_TIMESTAMP 29
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@ -40,6 +40,7 @@
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/* Socket filtering */
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#define SO_ATTACH_FILTER 26
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#define SO_DETACH_FILTER 27
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#define SO_GET_FILTER SO_ATTACH_FILTER
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#define SO_PEERNAME 28
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#define SO_TIMESTAMP 29
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@ -42,6 +42,7 @@
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/* Socket filtering */
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#define SO_ATTACH_FILTER 26
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#define SO_DETACH_FILTER 27
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#define SO_GET_FILTER SO_ATTACH_FILTER
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#define SO_PEERNAME 28
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#define SO_TIMESTAMP 29
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@ -40,6 +40,7 @@
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/* Socket filtering */
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#define SO_ATTACH_FILTER 26
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#define SO_DETACH_FILTER 27
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#define SO_GET_FILTER SO_ATTACH_FILTER
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#define SO_PEERNAME 28
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#define SO_TIMESTAMP 29
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@ -40,6 +40,7 @@
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/* Socket filtering */
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#define SO_ATTACH_FILTER 26
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#define SO_DETACH_FILTER 27
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#define SO_GET_FILTER SO_ATTACH_FILTER
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#define SO_PEERNAME 28
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#define SO_TIMESTAMP 29
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@ -49,6 +49,7 @@
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/* Socket filtering */
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#define SO_ATTACH_FILTER 26
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#define SO_DETACH_FILTER 27
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#define SO_GET_FILTER SO_ATTACH_FILTER
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#define SO_PEERNAME 28
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#define SO_TIMESTAMP 29
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@ -40,6 +40,7 @@
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/* Socket filtering */
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#define SO_ATTACH_FILTER 26
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#define SO_DETACH_FILTER 27
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#define SO_GET_FILTER SO_ATTACH_FILTER
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#define SO_PEERNAME 28
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#define SO_TIMESTAMP 29
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@ -40,6 +40,7 @@
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/* Socket filtering */
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#define SO_ATTACH_FILTER 26
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#define SO_DETACH_FILTER 27
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#define SO_GET_FILTER SO_ATTACH_FILTER
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#define SO_PEERNAME 28
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#define SO_TIMESTAMP 29
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@ -63,6 +63,7 @@ To add: #define SO_REUSEPORT 0x0200 /* Allow local address and port reuse. */
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/* Socket filtering */
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#define SO_ATTACH_FILTER 26
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#define SO_DETACH_FILTER 27
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#define SO_GET_FILTER SO_ATTACH_FILTER
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#define SO_PEERNAME 28
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#define SO_TIMESTAMP 29
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@ -40,6 +40,7 @@
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/* Socket filtering */
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#define SO_ATTACH_FILTER 26
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#define SO_DETACH_FILTER 27
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#define SO_GET_FILTER SO_ATTACH_FILTER
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#define SO_PEERNAME 28
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#define SO_TIMESTAMP 29
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@ -48,6 +48,7 @@
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/* Socket filtering */
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#define SO_ATTACH_FILTER 0x401a
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#define SO_DETACH_FILTER 0x401b
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#define SO_GET_FILTER SO_ATTACH_FILTER
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#define SO_ACCEPTCONN 0x401c
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@ -47,6 +47,7 @@
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/* Socket filtering */
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#define SO_ATTACH_FILTER 26
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#define SO_DETACH_FILTER 27
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#define SO_GET_FILTER SO_ATTACH_FILTER
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#define SO_PEERNAME 28
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#define SO_TIMESTAMP 29
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@ -46,6 +46,7 @@
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/* Socket filtering */
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#define SO_ATTACH_FILTER 26
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#define SO_DETACH_FILTER 27
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#define SO_GET_FILTER SO_ATTACH_FILTER
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#define SO_PEERNAME 28
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#define SO_TIMESTAMP 29
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@ -41,6 +41,7 @@
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#define SO_ATTACH_FILTER 0x001a
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#define SO_DETACH_FILTER 0x001b
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#define SO_GET_FILTER SO_ATTACH_FILTER
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#define SO_PEERNAME 0x001c
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#define SO_TIMESTAMP 0x001d
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@ -52,6 +52,7 @@
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#define SO_ATTACH_FILTER 26
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#define SO_DETACH_FILTER 27
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#define SO_GET_FILTER SO_ATTACH_FILTER
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#define SO_PEERNAME 28
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#define SO_TIMESTAMP 29
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@ -45,6 +45,7 @@ extern void sk_unattached_filter_destroy(struct sk_filter *fp);
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extern int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk);
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extern int sk_detach_filter(struct sock *sk);
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extern int sk_chk_filter(struct sock_filter *filter, unsigned int flen);
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extern int sk_get_filter(struct sock *sk, struct sock_filter __user *filter, unsigned len);
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#ifdef CONFIG_BPF_JIT
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extern void bpf_jit_compile(struct sk_filter *fp);
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@ -43,6 +43,7 @@
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/* Socket filtering */
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#define SO_ATTACH_FILTER 26
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#define SO_DETACH_FILTER 27
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#define SO_GET_FILTER SO_ATTACH_FILTER
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#define SO_PEERNAME 28
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#define SO_TIMESTAMP 29
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@ -760,3 +760,133 @@ int sk_detach_filter(struct sock *sk)
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return ret;
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}
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EXPORT_SYMBOL_GPL(sk_detach_filter);
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static void sk_decode_filter(struct sock_filter *filt, struct sock_filter *to)
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{
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static const u16 decodes[] = {
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[BPF_S_ALU_ADD_K] = BPF_ALU|BPF_ADD|BPF_K,
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[BPF_S_ALU_ADD_X] = BPF_ALU|BPF_ADD|BPF_X,
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[BPF_S_ALU_SUB_K] = BPF_ALU|BPF_SUB|BPF_K,
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[BPF_S_ALU_SUB_X] = BPF_ALU|BPF_SUB|BPF_X,
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[BPF_S_ALU_MUL_K] = BPF_ALU|BPF_MUL|BPF_K,
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[BPF_S_ALU_MUL_X] = BPF_ALU|BPF_MUL|BPF_X,
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[BPF_S_ALU_DIV_X] = BPF_ALU|BPF_DIV|BPF_X,
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[BPF_S_ALU_MOD_K] = BPF_ALU|BPF_MOD|BPF_K,
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[BPF_S_ALU_MOD_X] = BPF_ALU|BPF_MOD|BPF_X,
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[BPF_S_ALU_AND_K] = BPF_ALU|BPF_AND|BPF_K,
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[BPF_S_ALU_AND_X] = BPF_ALU|BPF_AND|BPF_X,
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[BPF_S_ALU_OR_K] = BPF_ALU|BPF_OR|BPF_K,
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[BPF_S_ALU_OR_X] = BPF_ALU|BPF_OR|BPF_X,
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[BPF_S_ALU_XOR_K] = BPF_ALU|BPF_XOR|BPF_K,
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[BPF_S_ALU_XOR_X] = BPF_ALU|BPF_XOR|BPF_X,
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[BPF_S_ALU_LSH_K] = BPF_ALU|BPF_LSH|BPF_K,
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[BPF_S_ALU_LSH_X] = BPF_ALU|BPF_LSH|BPF_X,
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[BPF_S_ALU_RSH_K] = BPF_ALU|BPF_RSH|BPF_K,
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[BPF_S_ALU_RSH_X] = BPF_ALU|BPF_RSH|BPF_X,
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[BPF_S_ALU_NEG] = BPF_ALU|BPF_NEG,
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[BPF_S_LD_W_ABS] = BPF_LD|BPF_W|BPF_ABS,
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[BPF_S_LD_H_ABS] = BPF_LD|BPF_H|BPF_ABS,
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[BPF_S_LD_B_ABS] = BPF_LD|BPF_B|BPF_ABS,
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[BPF_S_ANC_PROTOCOL] = BPF_LD|BPF_B|BPF_ABS,
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[BPF_S_ANC_PKTTYPE] = BPF_LD|BPF_B|BPF_ABS,
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[BPF_S_ANC_IFINDEX] = BPF_LD|BPF_B|BPF_ABS,
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[BPF_S_ANC_NLATTR] = BPF_LD|BPF_B|BPF_ABS,
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[BPF_S_ANC_NLATTR_NEST] = BPF_LD|BPF_B|BPF_ABS,
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[BPF_S_ANC_MARK] = BPF_LD|BPF_B|BPF_ABS,
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[BPF_S_ANC_QUEUE] = BPF_LD|BPF_B|BPF_ABS,
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[BPF_S_ANC_HATYPE] = BPF_LD|BPF_B|BPF_ABS,
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[BPF_S_ANC_RXHASH] = BPF_LD|BPF_B|BPF_ABS,
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[BPF_S_ANC_CPU] = BPF_LD|BPF_B|BPF_ABS,
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[BPF_S_ANC_ALU_XOR_X] = BPF_LD|BPF_B|BPF_ABS,
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[BPF_S_ANC_SECCOMP_LD_W] = BPF_LD|BPF_B|BPF_ABS,
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[BPF_S_ANC_VLAN_TAG] = BPF_LD|BPF_B|BPF_ABS,
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[BPF_S_ANC_VLAN_TAG_PRESENT] = BPF_LD|BPF_B|BPF_ABS,
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[BPF_S_LD_W_LEN] = BPF_LD|BPF_W|BPF_LEN,
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[BPF_S_LD_W_IND] = BPF_LD|BPF_W|BPF_IND,
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[BPF_S_LD_H_IND] = BPF_LD|BPF_H|BPF_IND,
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[BPF_S_LD_B_IND] = BPF_LD|BPF_B|BPF_IND,
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[BPF_S_LD_IMM] = BPF_LD|BPF_IMM,
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[BPF_S_LDX_W_LEN] = BPF_LDX|BPF_W|BPF_LEN,
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[BPF_S_LDX_B_MSH] = BPF_LDX|BPF_B|BPF_MSH,
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[BPF_S_LDX_IMM] = BPF_LDX|BPF_IMM,
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[BPF_S_MISC_TAX] = BPF_MISC|BPF_TAX,
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[BPF_S_MISC_TXA] = BPF_MISC|BPF_TXA,
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[BPF_S_RET_K] = BPF_RET|BPF_K,
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[BPF_S_RET_A] = BPF_RET|BPF_A,
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[BPF_S_ALU_DIV_K] = BPF_ALU|BPF_DIV|BPF_K,
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[BPF_S_LD_MEM] = BPF_LD|BPF_MEM,
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[BPF_S_LDX_MEM] = BPF_LDX|BPF_MEM,
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[BPF_S_ST] = BPF_ST,
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[BPF_S_STX] = BPF_STX,
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[BPF_S_JMP_JA] = BPF_JMP|BPF_JA,
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[BPF_S_JMP_JEQ_K] = BPF_JMP|BPF_JEQ|BPF_K,
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[BPF_S_JMP_JEQ_X] = BPF_JMP|BPF_JEQ|BPF_X,
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[BPF_S_JMP_JGE_K] = BPF_JMP|BPF_JGE|BPF_K,
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[BPF_S_JMP_JGE_X] = BPF_JMP|BPF_JGE|BPF_X,
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[BPF_S_JMP_JGT_K] = BPF_JMP|BPF_JGT|BPF_K,
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[BPF_S_JMP_JGT_X] = BPF_JMP|BPF_JGT|BPF_X,
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[BPF_S_JMP_JSET_K] = BPF_JMP|BPF_JSET|BPF_K,
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[BPF_S_JMP_JSET_X] = BPF_JMP|BPF_JSET|BPF_X,
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};
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u16 code;
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code = filt->code;
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to->code = decodes[code];
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to->jt = filt->jt;
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to->jf = filt->jf;
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if (code == BPF_S_ALU_DIV_K) {
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/*
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* When loaded this rule user gave us X, which was
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* translated into R = r(X). Now we calculate the
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* RR = r(R) and report it back. If next time this
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* value is loaded and RRR = r(RR) is calculated
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* then the R == RRR will be true.
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*
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* One exception. X == 1 translates into R == 0 and
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* we can't calculate RR out of it with r().
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*/
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if (filt->k == 0)
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to->k = 1;
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else
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to->k = reciprocal_value(filt->k);
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BUG_ON(reciprocal_value(to->k) != filt->k);
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} else
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to->k = filt->k;
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}
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int sk_get_filter(struct sock *sk, struct sock_filter __user *ubuf, unsigned int len)
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{
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struct sk_filter *filter;
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int i, ret;
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lock_sock(sk);
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filter = rcu_dereference_protected(sk->sk_filter,
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sock_owned_by_user(sk));
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ret = 0;
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if (!filter)
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goto out;
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ret = filter->len;
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if (!len)
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goto out;
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ret = -EINVAL;
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if (len < filter->len)
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goto out;
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ret = -EFAULT;
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for (i = 0; i < filter->len; i++) {
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struct sock_filter fb;
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sk_decode_filter(&filter->insns[i], &fb);
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if (copy_to_user(&ubuf[i], &fb, sizeof(fb)))
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goto out;
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}
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ret = filter->len;
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out:
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release_sock(sk);
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return ret;
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}
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@ -1077,6 +1077,12 @@ int sock_getsockopt(struct socket *sock, int level, int optname,
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case SO_BINDTODEVICE:
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v.val = sk->sk_bound_dev_if;
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break;
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case SO_GET_FILTER:
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len = sk_get_filter(sk, (struct sock_filter __user *)optval, len);
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if (len < 0)
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return len;
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goto lenout;
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default:
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return -ENOPROTOOPT;
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}
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