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Date: Sat, 3 Dec 2016 19:17:23 -0800
From: Martin KaFai Lau <kafai@...com>
To: <netdev@...r.kernel.org>
CC: Alexei Starovoitov <ast@...com>,
Brenden Blanco <bblanco@...mgrid.com>,
Daniel Borkmann <daniel@...earbox.net>,
David Miller <davem@...emloft.net>,
Jesper Dangaard Brouer <brouer@...hat.com>,
Saeed Mahameed <saeedm@...lanox.com>,
Tariq Toukan <tariqt@...lanox.com>,
Kernel Team <kernel-team@...com>
Subject: [PATCH v2 net-next 1/4] bpf: xdp: Allow head adjustment in XDP prog
This patch allows XDP prog to extend/remove the packet
data at the head (like adding or removing header). It is
done by adding a new XDP helper bpf_xdp_adjust_head().
It also renames bpf_helper_changes_skb_data() to
bpf_helper_changes_pkt_data() to better reflect
that XDP prog does not work on skb.
Acked-by: Alexei Starovoitov <ast@...nel.org>
Signed-off-by: Martin KaFai Lau <kafai@...com>
---
arch/powerpc/net/bpf_jit_comp64.c | 4 ++--
arch/s390/net/bpf_jit_comp.c | 2 +-
arch/x86/net/bpf_jit_comp.c | 2 +-
include/linux/filter.h | 2 +-
include/uapi/linux/bpf.h | 11 ++++++++++-
kernel/bpf/core.c | 2 +-
kernel/bpf/verifier.c | 2 +-
net/core/filter.c | 34 ++++++++++++++++++++++++++++++++--
8 files changed, 49 insertions(+), 10 deletions(-)
diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c
index 0fe98a567125..73a5cf18fd84 100644
--- a/arch/powerpc/net/bpf_jit_comp64.c
+++ b/arch/powerpc/net/bpf_jit_comp64.c
@@ -766,7 +766,7 @@ static int bpf_jit_build_body(struct bpf_prog *fp, u32 *image,
func = (u8 *) __bpf_call_base + imm;
/* Save skb pointer if we need to re-cache skb data */
- if (bpf_helper_changes_skb_data(func))
+ if (bpf_helper_changes_pkt_data(func))
PPC_BPF_STL(3, 1, bpf_jit_stack_local(ctx));
bpf_jit_emit_func_call(image, ctx, (u64)func);
@@ -775,7 +775,7 @@ static int bpf_jit_build_body(struct bpf_prog *fp, u32 *image,
PPC_MR(b2p[BPF_REG_0], 3);
/* refresh skb cache */
- if (bpf_helper_changes_skb_data(func)) {
+ if (bpf_helper_changes_pkt_data(func)) {
/* reload skb pointer to r3 */
PPC_BPF_LL(3, 1, bpf_jit_stack_local(ctx));
bpf_jit_emit_skb_loads(image, ctx);
diff --git a/arch/s390/net/bpf_jit_comp.c b/arch/s390/net/bpf_jit_comp.c
index bee281f3163d..167b31b186c1 100644
--- a/arch/s390/net/bpf_jit_comp.c
+++ b/arch/s390/net/bpf_jit_comp.c
@@ -981,7 +981,7 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, int i
EMIT2(0x0d00, REG_14, REG_W1);
/* lgr %b0,%r2: load return value into %b0 */
EMIT4(0xb9040000, BPF_REG_0, REG_2);
- if (bpf_helper_changes_skb_data((void *)func)) {
+ if (bpf_helper_changes_pkt_data((void *)func)) {
jit->seen |= SEEN_SKB_CHANGE;
/* lg %b1,ST_OFF_SKBP(%r15) */
EMIT6_DISP_LH(0xe3000000, 0x0004, BPF_REG_1, REG_0,
diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index fe04a04dab8e..e76d1af60f7a 100644
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -853,7 +853,7 @@ xadd: if (is_imm8(insn->off))
func = (u8 *) __bpf_call_base + imm32;
jmp_offset = func - (image + addrs[i]);
if (seen_ld_abs) {
- reload_skb_data = bpf_helper_changes_skb_data(func);
+ reload_skb_data = bpf_helper_changes_pkt_data(func);
if (reload_skb_data) {
EMIT1(0x57); /* push %rdi */
jmp_offset += 22; /* pop, mov, sub, mov */
diff --git a/include/linux/filter.h b/include/linux/filter.h
index 97338134398f..3c02de77ad6a 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -590,7 +590,7 @@ void sk_filter_uncharge(struct sock *sk, struct sk_filter *fp);
u64 __bpf_call_base(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);
struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog);
-bool bpf_helper_changes_skb_data(void *func);
+bool bpf_helper_changes_pkt_data(void *func);
struct bpf_prog *bpf_patch_insn_single(struct bpf_prog *prog, u32 off,
const struct bpf_insn *patch, u32 len);
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 6123d9b8e828..0eb0e87dbe9f 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -424,6 +424,12 @@ union bpf_attr {
* @len: length of header to be pushed in front
* @flags: Flags (unused for now)
* Return: 0 on success or negative error
+ *
+ * int bpf_xdp_adjust_head(xdp_md, delta)
+ * Adjust the xdp_md.data by delta
+ * @xdp_md: pointer to xdp_md
+ * @delta: An positive/negative integer to be added to xdp_md.data
+ * Return: 0 on success or negative on error
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@@ -469,7 +475,8 @@ union bpf_attr {
FN(csum_update), \
FN(set_hash_invalid), \
FN(get_numa_node_id), \
- FN(skb_change_head),
+ FN(skb_change_head), \
+ FN(xdp_adjust_head),
/* integer value in 'imm' field of BPF_CALL instruction selects which helper
* function eBPF program intends to call
@@ -576,6 +583,8 @@ struct bpf_sock {
__u32 protocol;
};
+#define XDP_PACKET_HEADROOM 256
+
/* User return codes for XDP prog type.
* A valid XDP program must return one of these defined values. All other
* return codes are reserved for future use. Unknown return codes will result
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 82a04143368e..871e2f398cf5 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -1078,7 +1078,7 @@ struct bpf_prog * __weak bpf_int_jit_compile(struct bpf_prog *prog)
return prog;
}
-bool __weak bpf_helper_changes_skb_data(void *func)
+bool __weak bpf_helper_changes_pkt_data(void *func)
{
return false;
}
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 0e742210750e..e6ce4d664521 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -1216,7 +1216,7 @@ static int check_call(struct bpf_verifier_env *env, int func_id)
return -EINVAL;
}
- changes_data = bpf_helper_changes_skb_data(fn->func);
+ changes_data = bpf_helper_changes_pkt_data(fn->func);
memset(&meta, 0, sizeof(meta));
meta.pkt_access = fn->pkt_access;
diff --git a/net/core/filter.c b/net/core/filter.c
index 56b43587d200..ccef948cf58a 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -2234,7 +2234,34 @@ static const struct bpf_func_proto bpf_skb_change_head_proto = {
.arg3_type = ARG_ANYTHING,
};
-bool bpf_helper_changes_skb_data(void *func)
+BPF_CALL_2(bpf_xdp_adjust_head, struct xdp_buff *, xdp, int, offset)
+{
+ /* Both mlx4 and mlx5 driver align each packet to PAGE_SIZE when
+ * XDP prog is set.
+ * If the above is not true for the other drivers to support
+ * bpf_xdp_adjust_head, struct xdp_buff can be extended.
+ */
+ unsigned long addr = (unsigned long)xdp->data & PAGE_MASK;
+ void *data_hard_start = (void *)addr;
+ void *data = xdp->data + offset;
+
+ if (unlikely(data < data_hard_start || data > xdp->data_end - ETH_HLEN))
+ return -EINVAL;
+
+ xdp->data = data;
+
+ return 0;
+}
+
+static const struct bpf_func_proto bpf_xdp_adjust_head_proto = {
+ .func = bpf_xdp_adjust_head,
+ .gpl_only = false,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_PTR_TO_CTX,
+ .arg2_type = ARG_ANYTHING,
+};
+
+bool bpf_helper_changes_pkt_data(void *func)
{
if (func == bpf_skb_vlan_push ||
func == bpf_skb_vlan_pop ||
@@ -2244,7 +2271,8 @@ bool bpf_helper_changes_skb_data(void *func)
func == bpf_skb_change_tail ||
func == bpf_skb_pull_data ||
func == bpf_l3_csum_replace ||
- func == bpf_l4_csum_replace)
+ func == bpf_l4_csum_replace ||
+ func == bpf_xdp_adjust_head)
return true;
return false;
@@ -2670,6 +2698,8 @@ xdp_func_proto(enum bpf_func_id func_id)
return &bpf_xdp_event_output_proto;
case BPF_FUNC_get_smp_processor_id:
return &bpf_get_smp_processor_id_proto;
+ case BPF_FUNC_xdp_adjust_head:
+ return &bpf_xdp_adjust_head_proto;
default:
return sk_filter_func_proto(func_id);
}
--
2.5.1
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