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Message-Id: <20180328162715.113-2-shrijeetoss@gmail.com>
Date: Wed, 28 Mar 2018 09:27:15 -0700
From: Shrijeet Mukherjee <shrijeetoss@...il.com>
To: daniel@...earbox.net
Cc: netdev@...r.kernel.org, roopa@...ulusnetworks.com,
dsa@...ulusnetworks.com, ast@...com
Subject: [PATCH bpf-next RFC 2/2] Add MPLS label push/pop functions for EBPF
From: Shrijeet Mukherjee <shrijeet@...il.com>
Push: takes an array/size of labels and encaps
Pop : Takes a number and pops the top "n" labels
Signed-off-by: Shrijeet Mukherjee <shm@...ulusnetworks.com>
PS: Will be adding tests as well, refactoring my test into something
smaller.
---
include/linux/bpf.h | 2 +
include/net/mpls.h | 38 +++++++++++++-
include/uapi/linux/bpf.h | 11 +++-
net/core/filter.c | 127 ++++++++++++++++++++++++++++++++++++++++++++++-
4 files changed, 175 insertions(+), 3 deletions(-)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 819229c80eca..b38bfabc1fb5 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -672,6 +672,8 @@ extern const struct bpf_func_proto bpf_get_current_uid_gid_proto;
extern const struct bpf_func_proto bpf_get_current_comm_proto;
extern const struct bpf_func_proto bpf_skb_vlan_push_proto;
extern const struct bpf_func_proto bpf_skb_vlan_pop_proto;
+extern const struct bpf_func_proto bpf_skb_mpls_push_proto;
+extern const struct bpf_func_proto bpf_skb_mpls_pop_proto;
extern const struct bpf_func_proto bpf_get_stackid_proto;
extern const struct bpf_func_proto bpf_sock_map_update_proto;
diff --git a/include/net/mpls.h b/include/net/mpls.h
index 2583dbc689b8..3a5b8c00823d 100644
--- a/include/net/mpls.h
+++ b/include/net/mpls.h
@@ -24,14 +24,50 @@ struct mpls_shim_hdr {
__be32 label_stack_entry;
};
+struct mpls_entry_decoded {
+ u32 label;
+ u8 ttl;
+ u8 tc;
+ u8 bos;
+};
+
static inline bool eth_p_mpls(__be16 eth_type)
{
return eth_type == htons(ETH_P_MPLS_UC) ||
eth_type == htons(ETH_P_MPLS_MC);
}
-static inline struct mpls_shim_hdr *mpls_hdr(const struct sk_buff *skb)
+static inline struct mpls_shim_hdr *skb_mpls_hdr(const struct sk_buff *skb)
{
return (struct mpls_shim_hdr *)skb_network_header(skb);
}
+
+static inline struct mpls_shim_hdr
+mpls_entry_encode(u32 label, unsigned int ttl, unsigned int tc, bool bos)
+{
+ struct mpls_shim_hdr result;
+
+ result.label_stack_entry =
+ cpu_to_be32((label << MPLS_LS_LABEL_SHIFT)
+ | (tc << MPLS_LS_TC_SHIFT)
+ | (bos ? (1 << MPLS_LS_S_SHIFT) : 0)
+ | (ttl << MPLS_LS_TTL_SHIFT));
+
+ return result;
+}
+
+static inline
+struct mpls_entry_decoded mpls_entry_decode(struct mpls_shim_hdr *hdr)
+{
+ struct mpls_entry_decoded result;
+ unsigned int entry = be32_to_cpu(hdr->label_stack_entry);
+
+ result.label = (entry & MPLS_LS_LABEL_MASK) >> MPLS_LS_LABEL_SHIFT;
+ result.ttl = (entry & MPLS_LS_TTL_MASK) >> MPLS_LS_TTL_SHIFT;
+ result.tc = (entry & MPLS_LS_TC_MASK) >> MPLS_LS_TC_SHIFT;
+ result.bos = (entry & MPLS_LS_S_MASK) >> MPLS_LS_S_SHIFT;
+
+ return result;
+}
+
#endif
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 18b7c510c511..2278548e1f8f 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -439,6 +439,12 @@ union bpf_attr {
* int bpf_skb_vlan_pop(skb)
* Return: 0 on success or negative error
*
+ * int bpf_skb_mpls_push(skb, num_lbls, lbls[])
+ * Return 0 on success or negative error
+ *
+ * int bpf_skb_mpls_pop(skb, num_lbls)
+ * Return number of popped labels, 0 is no-op, deliver packet to current dst
+ *
* int bpf_skb_get_tunnel_key(skb, key, size, flags)
* int bpf_skb_set_tunnel_key(skb, key, size, flags)
* retrieve or populate tunnel metadata
@@ -794,7 +800,10 @@ union bpf_attr {
FN(msg_redirect_map), \
FN(msg_apply_bytes), \
FN(msg_cork_bytes), \
- FN(msg_pull_data),
+ FN(msg_pull_data), \
+ FN(skb_mpls_push), \
+ FN(skb_mpls_pop),
+
/* integer value in 'imm' field of BPF_CALL instruction selects which helper
* function eBPF program intends to call
diff --git a/net/core/filter.c b/net/core/filter.c
index 00f62fafc788..c96ae8ef423d 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -2522,7 +2522,7 @@ static int bpf_skb_adjust_net(struct sk_buff *skb, s32 len_diff)
}
BPF_CALL_4(bpf_skb_adjust_room, struct sk_buff *, skb, s32, len_diff,
- u32, mode, u64, flags)
+ u32, mode, u64, flags)
{
if (unlikely(flags))
return -EINVAL;
@@ -2542,6 +2542,125 @@ static const struct bpf_func_proto bpf_skb_adjust_room_proto = {
.arg4_type = ARG_ANYTHING,
};
+static int bpf_skb_mpls_net_grow(struct sk_buff *skb, int len_diff)
+{
+ u32 off = skb_mac_header_len(skb); /*LL_RESERVED_SPACE ?? */
+ int ret;
+
+ ret = skb_cow(skb, len_diff);
+ if (unlikely(ret < 0))
+ return ret;
+
+ skb_set_inner_protocol(skb, skb->protocol);
+ skb_reset_inner_network_header(skb);
+
+ ret = bpf_skb_generic_push(skb, off, len_diff);
+ if (unlikely(ret < 0))
+ return ret;
+
+ skb_reset_mac_header(skb);
+ skb_set_network_header(skb, ETH_HLEN);
+ skb->protocol = eth_hdr(skb)->h_proto = htons(ETH_P_MPLS_UC);
+
+ if (skb_is_gso(skb)) {
+/* Due to header grow, MSS needs to be downgraded. */
+ skb_shinfo(skb)->gso_size -= len_diff;
+/* Header must be checked, and gso_segs recomputed. */
+ skb_shinfo(skb)->gso_type |= SKB_GSO_DODGY;
+ skb_shinfo(skb)->gso_segs = 0;
+ }
+
+ bpf_compute_data_pointers(skb);
+ return 0;
+}
+
+BPF_CALL_2(bpf_skb_mpls_pop, struct sk_buff*, skb, u32, num_lbls)
+{
+ u32 i = 0;
+ struct mpls_shim_hdr *hdr;
+ unsigned char *cursor;
+ struct mpls_entry_decoded dec;
+
+ if (num_lbls == 0)
+ return 0;
+
+ cursor = skb_network_header(skb);
+ do {
+ hdr = (struct mpls_shim_hdr *)cursor;
+ dec = mpls_entry_decode(hdr);
+ i++; cursor = cursor + sizeof(struct mpls_shim_hdr);
+ } while (dec.bos != 1 && i < num_lbls);
+
+ bpf_push_mac_rcsum(skb);
+ skb_pull(skb, i * sizeof(struct mpls_shim_hdr));
+ skb_reset_network_header(skb);
+
+ skb->protocol = eth_hdr(skb)->h_proto = htons(ETH_P_MPLS_UC);
+ bpf_pull_mac_rcsum(skb);
+ bpf_compute_data_pointers(skb);
+
+ return i;
+}
+
+const struct bpf_func_proto bpf_skb_mpls_pop_proto = {
+ .func = bpf_skb_mpls_pop,
+ .gpl_only = false,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_PTR_TO_CTX,
+ .arg2_type = ARG_ANYTHING,
+};
+EXPORT_SYMBOL_GPL(bpf_skb_mpls_pop_proto);
+
+BPF_CALL_3(bpf_skb_mpls_push, struct sk_buff*, skb,
+ __be32*, lbls, u32, num_lbls)
+{
+ int ret, i;
+ unsigned int new_header_size = num_lbls * sizeof(__be32);
+ unsigned int ttl = 255;
+ struct dst_entry *dst = skb_dst(skb);
+ struct net_device *out_dev = dst->dev;
+ struct mpls_shim_hdr *hdr;
+ bool bos;
+
+ /* Ensure there is enough space for the headers in the skb */
+ ret = bpf_skb_mpls_net_grow(skb, new_header_size);
+ if (ret < 0) {
+ trace_printk("COW was killed\n");
+ bpf_compute_data_pointers(skb);
+ return -ENOMEM;
+ }
+
+ skb->dev = out_dev;
+/* XXX this may need finesse to integrate with
+ * global TTL values for MPLS
+ */
+ if (dst->ops->family == AF_INET)
+ ttl = ip_hdr(skb)->ttl;
+ else if (dst->ops->family == AF_INET6)
+ ttl = ipv6_hdr(skb)->hop_limit;
+
+ /* Push the new labels */
+ hdr = skb_mpls_hdr(skb);
+ bos = true;
+ for (i = num_lbls - 1; i >= 0; i--) {
+ hdr[i] = mpls_entry_encode(lbls[i], ttl, 0, bos);
+ bos = false;
+ }
+
+ bpf_compute_data_pointers(skb);
+ return 0;
+}
+
+const struct bpf_func_proto bpf_skb_mpls_push_proto = {
+ .func = bpf_skb_mpls_push,
+ .gpl_only = false,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_PTR_TO_CTX,
+ .arg2_type = ARG_PTR_TO_MEM,
+ .arg3_type = ARG_CONST_SIZE,
+};
+EXPORT_SYMBOL_GPL(bpf_skb_mpls_push_proto);
+
static u32 __bpf_skb_min_len(const struct sk_buff *skb)
{
u32 min_len = skb_network_offset(skb);
@@ -3019,6 +3138,8 @@ bool bpf_helper_changes_pkt_data(void *func)
{
if (func == bpf_skb_vlan_push ||
func == bpf_skb_vlan_pop ||
+ func == bpf_skb_mpls_push ||
+ func == bpf_skb_mpls_pop ||
func == bpf_skb_store_bytes ||
func == bpf_skb_change_proto ||
func == bpf_skb_change_head ||
@@ -3682,6 +3803,10 @@ tc_cls_act_func_proto(enum bpf_func_id func_id)
return &bpf_skb_vlan_push_proto;
case BPF_FUNC_skb_vlan_pop:
return &bpf_skb_vlan_pop_proto;
+ case BPF_FUNC_skb_mpls_push:
+ return &bpf_skb_mpls_push_proto;
+ case BPF_FUNC_skb_mpls_pop:
+ return &bpf_skb_mpls_pop_proto;
case BPF_FUNC_skb_change_proto:
return &bpf_skb_change_proto_proto;
case BPF_FUNC_skb_change_type:
--
2.16.2.windows.1
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