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Message-ID: <509264AC.5090802@parallels.com>
Date: Thu, 01 Nov 2012 16:01:48 +0400
From: Pavel Emelyanov <xemul@...allels.com>
To: David Miller <davem@...emloft.net>,
Linux Netdev List <netdev@...r.kernel.org>
Subject: [PATCH net-next] 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@...allels.com>
---
diff --git a/arch/alpha/include/asm/socket.h b/arch/alpha/include/asm/socket.h
index 7d2f75b..0087d05 100644
--- a/arch/alpha/include/asm/socket.h
+++ b/arch/alpha/include/asm/socket.h
@@ -47,6 +47,7 @@
/* Socket filtering */
#define SO_ATTACH_FILTER 26
#define SO_DETACH_FILTER 27
+#define SO_GET_FILTER SO_ATTACH_FILTER
#define SO_PEERNAME 28
#define SO_TIMESTAMP 29
diff --git a/arch/avr32/include/uapi/asm/socket.h b/arch/avr32/include/uapi/asm/socket.h
index a473f8c..486df68 100644
--- a/arch/avr32/include/uapi/asm/socket.h
+++ b/arch/avr32/include/uapi/asm/socket.h
@@ -40,6 +40,7 @@
/* Socket filtering */
#define SO_ATTACH_FILTER 26
#define SO_DETACH_FILTER 27
+#define SO_GET_FILTER SO_ATTACH_FILTER
#define SO_PEERNAME 28
#define SO_TIMESTAMP 29
diff --git a/arch/cris/include/asm/socket.h b/arch/cris/include/asm/socket.h
index ae52825..b681b04 100644
--- a/arch/cris/include/asm/socket.h
+++ b/arch/cris/include/asm/socket.h
@@ -42,6 +42,7 @@
/* Socket filtering */
#define SO_ATTACH_FILTER 26
#define SO_DETACH_FILTER 27
+#define SO_GET_FILTER SO_ATTACH_FILTER
#define SO_PEERNAME 28
#define SO_TIMESTAMP 29
diff --git a/arch/frv/include/uapi/asm/socket.h b/arch/frv/include/uapi/asm/socket.h
index a5b1d7d..871f89b 100644
--- a/arch/frv/include/uapi/asm/socket.h
+++ b/arch/frv/include/uapi/asm/socket.h
@@ -40,6 +40,7 @@
/* Socket filtering */
#define SO_ATTACH_FILTER 26
#define SO_DETACH_FILTER 27
+#define SO_GET_FILTER SO_ATTACH_FILTER
#define SO_PEERNAME 28
#define SO_TIMESTAMP 29
diff --git a/arch/h8300/include/asm/socket.h b/arch/h8300/include/asm/socket.h
index ec4554e..90a2e57 100644
--- a/arch/h8300/include/asm/socket.h
+++ b/arch/h8300/include/asm/socket.h
@@ -40,6 +40,7 @@
/* Socket filtering */
#define SO_ATTACH_FILTER 26
#define SO_DETACH_FILTER 27
+#define SO_GET_FILTER SO_ATTACH_FILTER
#define SO_PEERNAME 28
#define SO_TIMESTAMP 29
diff --git a/arch/ia64/include/uapi/asm/socket.h b/arch/ia64/include/uapi/asm/socket.h
index 41fc28a..23d6759 100644
--- a/arch/ia64/include/uapi/asm/socket.h
+++ b/arch/ia64/include/uapi/asm/socket.h
@@ -49,6 +49,7 @@
/* Socket filtering */
#define SO_ATTACH_FILTER 26
#define SO_DETACH_FILTER 27
+#define SO_GET_FILTER SO_ATTACH_FILTER
#define SO_PEERNAME 28
#define SO_TIMESTAMP 29
diff --git a/arch/m32r/include/asm/socket.h b/arch/m32r/include/asm/socket.h
index a15f40b..5e7088a 100644
--- a/arch/m32r/include/asm/socket.h
+++ b/arch/m32r/include/asm/socket.h
@@ -40,6 +40,7 @@
/* Socket filtering */
#define SO_ATTACH_FILTER 26
#define SO_DETACH_FILTER 27
+#define SO_GET_FILTER SO_ATTACH_FILTER
#define SO_PEERNAME 28
#define SO_TIMESTAMP 29
diff --git a/arch/m68k/include/asm/socket.h b/arch/m68k/include/asm/socket.h
index d1be684..285da3b 100644
--- a/arch/m68k/include/asm/socket.h
+++ b/arch/m68k/include/asm/socket.h
@@ -40,6 +40,7 @@
/* Socket filtering */
#define SO_ATTACH_FILTER 26
#define SO_DETACH_FILTER 27
+#define SO_GET_FILTER SO_ATTACH_FILTER
#define SO_PEERNAME 28
#define SO_TIMESTAMP 29
diff --git a/arch/mips/include/uapi/asm/socket.h b/arch/mips/include/uapi/asm/socket.h
index c5ed595..17307ab 100644
--- a/arch/mips/include/uapi/asm/socket.h
+++ b/arch/mips/include/uapi/asm/socket.h
@@ -63,6 +63,7 @@ To add: #define SO_REUSEPORT 0x0200 /* Allow local address and port reuse. */
/* Socket filtering */
#define SO_ATTACH_FILTER 26
#define SO_DETACH_FILTER 27
+#define SO_GET_FILTER SO_ATTACH_FILTER
#define SO_PEERNAME 28
#define SO_TIMESTAMP 29
diff --git a/arch/mn10300/include/uapi/asm/socket.h b/arch/mn10300/include/uapi/asm/socket.h
index 820463a..af5366b 100644
--- a/arch/mn10300/include/uapi/asm/socket.h
+++ b/arch/mn10300/include/uapi/asm/socket.h
@@ -40,6 +40,7 @@
/* Socket filtering */
#define SO_ATTACH_FILTER 26
#define SO_DETACH_FILTER 27
+#define SO_GET_FILTER SO_ATTACH_FILTER
#define SO_PEERNAME 28
#define SO_TIMESTAMP 29
diff --git a/arch/parisc/include/asm/socket.h b/arch/parisc/include/asm/socket.h
index 1b52c2c..d9ff473 100644
--- a/arch/parisc/include/asm/socket.h
+++ b/arch/parisc/include/asm/socket.h
@@ -48,6 +48,7 @@
/* Socket filtering */
#define SO_ATTACH_FILTER 0x401a
#define SO_DETACH_FILTER 0x401b
+#define SO_GET_FILTER SO_ATTACH_FILTER
#define SO_ACCEPTCONN 0x401c
diff --git a/arch/powerpc/include/uapi/asm/socket.h b/arch/powerpc/include/uapi/asm/socket.h
index 3d5179b..eb0b186 100644
--- a/arch/powerpc/include/uapi/asm/socket.h
+++ b/arch/powerpc/include/uapi/asm/socket.h
@@ -47,6 +47,7 @@
/* Socket filtering */
#define SO_ATTACH_FILTER 26
#define SO_DETACH_FILTER 27
+#define SO_GET_FILTER SO_ATTACH_FILTER
#define SO_PEERNAME 28
#define SO_TIMESTAMP 29
diff --git a/arch/s390/include/uapi/asm/socket.h b/arch/s390/include/uapi/asm/socket.h
index 69718cd..436d07c 100644
--- a/arch/s390/include/uapi/asm/socket.h
+++ b/arch/s390/include/uapi/asm/socket.h
@@ -46,6 +46,7 @@
/* Socket filtering */
#define SO_ATTACH_FILTER 26
#define SO_DETACH_FILTER 27
+#define SO_GET_FILTER SO_ATTACH_FILTER
#define SO_PEERNAME 28
#define SO_TIMESTAMP 29
diff --git a/arch/sparc/include/uapi/asm/socket.h b/arch/sparc/include/uapi/asm/socket.h
index bea1568..c83a937 100644
--- a/arch/sparc/include/uapi/asm/socket.h
+++ b/arch/sparc/include/uapi/asm/socket.h
@@ -41,6 +41,7 @@
#define SO_ATTACH_FILTER 0x001a
#define SO_DETACH_FILTER 0x001b
+#define SO_GET_FILTER SO_ATTACH_FILTER
#define SO_PEERNAME 0x001c
#define SO_TIMESTAMP 0x001d
diff --git a/arch/xtensa/include/asm/socket.h b/arch/xtensa/include/asm/socket.h
index e36c681..38079be 100644
--- a/arch/xtensa/include/asm/socket.h
+++ b/arch/xtensa/include/asm/socket.h
@@ -52,6 +52,7 @@
#define SO_ATTACH_FILTER 26
#define SO_DETACH_FILTER 27
+#define SO_GET_FILTER SO_ATTACH_FILTER
#define SO_PEERNAME 28
#define SO_TIMESTAMP 29
diff --git a/include/linux/filter.h b/include/linux/filter.h
index c9f0005..c45eabc 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -45,6 +45,7 @@ extern void sk_unattached_filter_destroy(struct sk_filter *fp);
extern int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk);
extern int sk_detach_filter(struct sock *sk);
extern int sk_chk_filter(struct sock_filter *filter, unsigned int flen);
+extern int sk_get_filter(struct sock *sk, struct sock_filter __user *filter, unsigned len);
#ifdef CONFIG_BPF_JIT
extern void bpf_jit_compile(struct sk_filter *fp);
diff --git a/include/uapi/asm-generic/socket.h b/include/uapi/asm-generic/socket.h
index b1bea03..2d32d07 100644
--- a/include/uapi/asm-generic/socket.h
+++ b/include/uapi/asm-generic/socket.h
@@ -43,6 +43,7 @@
/* Socket filtering */
#define SO_ATTACH_FILTER 26
#define SO_DETACH_FILTER 27
+#define SO_GET_FILTER SO_ATTACH_FILTER
#define SO_PEERNAME 28
#define SO_TIMESTAMP 29
diff --git a/net/core/filter.c b/net/core/filter.c
index 5a114d4..c23543c 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -760,3 +760,133 @@ int sk_detach_filter(struct sock *sk)
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;
+}
diff --git a/net/core/sock.c b/net/core/sock.c
index 0a023b8..0628600 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -1077,6 +1077,12 @@ int sock_getsockopt(struct socket *sock, int level, int optname,
case SO_BINDTODEVICE:
v.val = sk->sk_bound_dev_if;
break;
+ case SO_GET_FILTER:
+ len = sk_get_filter(sk, (struct sock_filter __user *)optval, len);
+ if (len < 0)
+ return len;
+
+ goto lenout;
default:
return -ENOPROTOOPT;
}
--
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