tc: bpf: generalize pedit action
existing TC action 'pedit' can munge any bits of the packet.
Generalize it for use in bpf programs attached as cls_bpf and act_bpf via
bpf_skb_store_bytes() helper function.
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Reviewed-by: Jiri Pirko <jiri@resnulli.us>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 280a315..d5cda06 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -59,6 +59,7 @@
ARG_PTR_TO_STACK, /* any pointer to eBPF program stack */
ARG_CONST_STACK_SIZE, /* number of bytes accessed from stack */
+ ARG_PTR_TO_CTX, /* pointer to context */
ARG_ANYTHING, /* any (initialized) argument is ok */
};
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 27dc4ec..74aab6e 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -168,6 +168,7 @@
BPF_FUNC_map_delete_elem, /* int map_delete_elem(&map, &key) */
BPF_FUNC_get_prandom_u32, /* u32 prandom_u32(void) */
BPF_FUNC_get_smp_processor_id, /* u32 raw_smp_processor_id(void) */
+ BPF_FUNC_skb_store_bytes, /* int skb_store_bytes(skb, offset, from, len) */
__BPF_FUNC_MAX_ID,
};
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 0e714f7..630a7ba 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -773,6 +773,8 @@
expected_type = CONST_IMM;
} else if (arg_type == ARG_CONST_MAP_PTR) {
expected_type = CONST_PTR_TO_MAP;
+ } else if (arg_type == ARG_PTR_TO_CTX) {
+ expected_type = PTR_TO_CTX;
} else {
verbose("unsupported arg_type %d\n", arg_type);
return -EFAULT;
diff --git a/net/core/filter.c b/net/core/filter.c
index 32f43c5..444a07e 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -1175,6 +1175,56 @@
return 0;
}
+static u64 bpf_skb_store_bytes(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
+{
+ struct sk_buff *skb = (struct sk_buff *) (long) r1;
+ unsigned int offset = (unsigned int) r2;
+ void *from = (void *) (long) r3;
+ unsigned int len = (unsigned int) r4;
+ char buf[16];
+ void *ptr;
+
+ /* bpf verifier guarantees that:
+ * 'from' pointer points to bpf program stack
+ * 'len' bytes of it were initialized
+ * 'len' > 0
+ * 'skb' is a valid pointer to 'struct sk_buff'
+ *
+ * so check for invalid 'offset' and too large 'len'
+ */
+ if (offset > 0xffff || len > sizeof(buf))
+ return -EFAULT;
+
+ if (skb_cloned(skb) && !skb_clone_writable(skb, offset + len))
+ return -EFAULT;
+
+ ptr = skb_header_pointer(skb, offset, len, buf);
+ if (unlikely(!ptr))
+ return -EFAULT;
+
+ skb_postpull_rcsum(skb, ptr, len);
+
+ memcpy(ptr, from, len);
+
+ if (ptr == buf)
+ /* skb_store_bits cannot return -EFAULT here */
+ skb_store_bits(skb, offset, ptr, len);
+
+ if (skb->ip_summed == CHECKSUM_COMPLETE)
+ skb->csum = csum_add(skb->csum, csum_partial(ptr, len, 0));
+ return 0;
+}
+
+const struct bpf_func_proto bpf_skb_store_bytes_proto = {
+ .func = bpf_skb_store_bytes,
+ .gpl_only = false,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_PTR_TO_CTX,
+ .arg2_type = ARG_ANYTHING,
+ .arg3_type = ARG_PTR_TO_STACK,
+ .arg4_type = ARG_CONST_STACK_SIZE,
+};
+
static const struct bpf_func_proto *
sk_filter_func_proto(enum bpf_func_id func_id)
{
@@ -1194,6 +1244,17 @@
}
}
+static const struct bpf_func_proto *
+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;
+ default:
+ return sk_filter_func_proto(func_id);
+ }
+}
+
static bool sk_filter_is_valid_access(int off, int size,
enum bpf_access_type type)
{
@@ -1270,18 +1331,24 @@
.convert_ctx_access = sk_filter_convert_ctx_access,
};
+static const struct bpf_verifier_ops tc_cls_act_ops = {
+ .get_func_proto = tc_cls_act_func_proto,
+ .is_valid_access = sk_filter_is_valid_access,
+ .convert_ctx_access = sk_filter_convert_ctx_access,
+};
+
static struct bpf_prog_type_list sk_filter_type __read_mostly = {
.ops = &sk_filter_ops,
.type = BPF_PROG_TYPE_SOCKET_FILTER,
};
static struct bpf_prog_type_list sched_cls_type __read_mostly = {
- .ops = &sk_filter_ops,
+ .ops = &tc_cls_act_ops,
.type = BPF_PROG_TYPE_SCHED_CLS,
};
static struct bpf_prog_type_list sched_act_type __read_mostly = {
- .ops = &sk_filter_ops,
+ .ops = &tc_cls_act_ops,
.type = BPF_PROG_TYPE_SCHED_ACT,
};