tc: bpf: add checksum helpers

[mirror_ubuntu-artful-kernel.git] / net / core / filter.c

diff --git a/net/core/filter.c b/net/core/filter.c
index 955a7d77decdbfa19c08a908514bc2334e1cc049..b669e75d2b3624fb54935fc41b6d5df3d53aabe4 100644 (file)
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -1175,7 +1175,9 @@ int sk_attach_bpf(u32 ufd, struct sock *sk)
        return 0;
 }
 
-static u64 bpf_skb_store_bytes(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
+#define BPF_RECOMPUTE_CSUM(flags)      ((flags) & 1)
+
+static u64 bpf_skb_store_bytes(u64 r1, u64 r2, u64 r3, u64 r4, u64 flags)
 {
        struct sk_buff *skb = (struct sk_buff *) (long) r1;
        unsigned int offset = (unsigned int) r2;
@@ -1192,7 +1194,7 @@ static u64 bpf_skb_store_bytes(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
         *
         * so check for invalid 'offset' and too large 'len'
         */
-       if (offset > 0xffff || len > sizeof(buf))
+       if (unlikely(offset > 0xffff || len > sizeof(buf)))
                return -EFAULT;
 
        if (skb_cloned(skb) && !skb_clone_writable(skb, offset + len))
@@ -1202,7 +1204,8 @@ static u64 bpf_skb_store_bytes(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
        if (unlikely(!ptr))
                return -EFAULT;
 
-       skb_postpull_rcsum(skb, ptr, len);
+       if (BPF_RECOMPUTE_CSUM(flags))
+               skb_postpull_rcsum(skb, ptr, len);
 
        memcpy(ptr, from, len);
 
@@ -1210,7 +1213,7 @@ static u64 bpf_skb_store_bytes(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
                /* skb_store_bits cannot return -EFAULT here */
                skb_store_bits(skb, offset, ptr, len);
 
-       if (skb->ip_summed == CHECKSUM_COMPLETE)
+       if (BPF_RECOMPUTE_CSUM(flags) && skb->ip_summed == CHECKSUM_COMPLETE)
                skb->csum = csum_add(skb->csum, csum_partial(ptr, len, 0));
        return 0;
 }
@@ -1223,6 +1226,99 @@ const struct bpf_func_proto bpf_skb_store_bytes_proto = {
        .arg2_type      = ARG_ANYTHING,
        .arg3_type      = ARG_PTR_TO_STACK,
        .arg4_type      = ARG_CONST_STACK_SIZE,
+       .arg5_type      = ARG_ANYTHING,
+};
+
+#define BPF_HEADER_FIELD_SIZE(flags)   ((flags) & 0x0f)
+#define BPF_IS_PSEUDO_HEADER(flags)    ((flags) & 0x10)
+
+static u64 bpf_l3_csum_replace(u64 r1, u64 offset, u64 from, u64 to, u64 flags)
+{
+       struct sk_buff *skb = (struct sk_buff *) (long) r1;
+       __sum16 sum, *ptr;
+
+       if (unlikely(offset > 0xffff))
+               return -EFAULT;
+
+       if (skb_cloned(skb) && !skb_clone_writable(skb, offset + sizeof(sum)))
+               return -EFAULT;
+
+       ptr = skb_header_pointer(skb, offset, sizeof(sum), &sum);
+       if (unlikely(!ptr))
+               return -EFAULT;
+
+       switch (BPF_HEADER_FIELD_SIZE(flags)) {
+       case 2:
+               csum_replace2(ptr, from, to);
+               break;
+       case 4:
+               csum_replace4(ptr, from, to);
+               break;
+       default:
+               return -EINVAL;
+       }
+
+       if (ptr == &sum)
+               /* skb_store_bits guaranteed to not return -EFAULT here */
+               skb_store_bits(skb, offset, ptr, sizeof(sum));
+
+       return 0;
+}
+
+const struct bpf_func_proto bpf_l3_csum_replace_proto = {
+       .func           = bpf_l3_csum_replace,
+       .gpl_only       = false,
+       .ret_type       = RET_INTEGER,
+       .arg1_type      = ARG_PTR_TO_CTX,
+       .arg2_type      = ARG_ANYTHING,
+       .arg3_type      = ARG_ANYTHING,
+       .arg4_type      = ARG_ANYTHING,
+       .arg5_type      = ARG_ANYTHING,
+};
+
+static u64 bpf_l4_csum_replace(u64 r1, u64 offset, u64 from, u64 to, u64 flags)
+{
+       struct sk_buff *skb = (struct sk_buff *) (long) r1;
+       u32 is_pseudo = BPF_IS_PSEUDO_HEADER(flags);
+       __sum16 sum, *ptr;
+
+       if (unlikely(offset > 0xffff))
+               return -EFAULT;
+
+       if (skb_cloned(skb) && !skb_clone_writable(skb, offset + sizeof(sum)))
+               return -EFAULT;
+
+       ptr = skb_header_pointer(skb, offset, sizeof(sum), &sum);
+       if (unlikely(!ptr))
+               return -EFAULT;
+
+       switch (BPF_HEADER_FIELD_SIZE(flags)) {
+       case 2:
+               inet_proto_csum_replace2(ptr, skb, from, to, is_pseudo);
+               break;
+       case 4:
+               inet_proto_csum_replace4(ptr, skb, from, to, is_pseudo);
+               break;
+       default:
+               return -EINVAL;
+       }
+
+       if (ptr == &sum)
+               /* skb_store_bits guaranteed to not return -EFAULT here */
+               skb_store_bits(skb, offset, ptr, sizeof(sum));
+
+       return 0;
+}
+
+const struct bpf_func_proto bpf_l4_csum_replace_proto = {
+       .func           = bpf_l4_csum_replace,
+       .gpl_only       = false,
+       .ret_type       = RET_INTEGER,
+       .arg1_type      = ARG_PTR_TO_CTX,
+       .arg2_type      = ARG_ANYTHING,
+       .arg3_type      = ARG_ANYTHING,
+       .arg4_type      = ARG_ANYTHING,
+       .arg5_type      = ARG_ANYTHING,
 };
 
 static const struct bpf_func_proto *
@@ -1250,6 +1346,10 @@ tc_cls_act_func_proto(enum bpf_func_id func_id)
        switch (func_id) {
        case BPF_FUNC_skb_store_bytes:
                return &bpf_skb_store_bytes_proto;
+       case BPF_FUNC_l3_csum_replace:
+               return &bpf_l3_csum_replace_proto;
+       case BPF_FUNC_l4_csum_replace:
+               return &bpf_l4_csum_replace_proto;
        default:
                return sk_filter_func_proto(func_id);
        }