diff mbox

[v4,net-next,1/4] bpf: xdp: Allow head adjustment in XDP prog

Message ID 1481154794-2311034-2-git-send-email-kafai@fb.com
State Accepted, archived
Delegated to: David Miller
Headers show

Commit Message

Martin KaFai Lau Dec. 7, 2016, 11:53 p.m. UTC 
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.

This patch adds one "xdp_adjust_head" bit to bpf_prog for the
XDP-capable driver to check if the XDP prog requires
bpf_xdp_adjust_head() support.  The driver can then decide
to error out during XDP_SETUP_PROG.

Signed-off-by: Martin KaFai Lau <kafai@fb.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 +-
 drivers/net/ethernet/mellanox/mlx4/en_netdev.c     |  5 ++++
 drivers/net/ethernet/mellanox/mlx5/core/en_main.c  |  5 ++++
 .../net/ethernet/netronome/nfp/nfp_net_common.c    |  4 ++++
 drivers/net/ethernet/qlogic/qede/qede_main.c       |  5 ++++
 include/linux/filter.h                             |  6 +++--
 include/uapi/linux/bpf.h                           | 11 ++++++++-
 kernel/bpf/core.c                                  |  2 +-
 kernel/bpf/syscall.c                               |  2 ++
 kernel/bpf/verifier.c                              |  2 +-
 net/core/filter.c                                  | 28 ++++++++++++++++++++--
 13 files changed, 67 insertions(+), 11 deletions(-)

Comments

Daniel Borkmann Dec. 8, 2016, 9:02 a.m. UTC | #1 
On 12/08/2016 12:53 AM, Martin KaFai Lau wrote:
> 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.
>
> This patch adds one "xdp_adjust_head" bit to bpf_prog for the
> XDP-capable driver to check if the XDP prog requires
> bpf_xdp_adjust_head() support.  The driver can then decide
> to error out during XDP_SETUP_PROG.
>
> Signed-off-by: Martin KaFai Lau <kafai@fb.com>

Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Alexei Starovoitov Dec. 8, 2016, 4:55 p.m. UTC | #2 
On Thu, Dec 08, 2016 at 10:02:37AM +0100, Daniel Borkmann wrote:
> On 12/08/2016 12:53 AM, Martin KaFai Lau wrote:
> >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.
> >
> >This patch adds one "xdp_adjust_head" bit to bpf_prog for the
> >XDP-capable driver to check if the XDP prog requires
> >bpf_xdp_adjust_head() support.  The driver can then decide
> >to error out during XDP_SETUP_PROG.
> >
> >Signed-off-by: Martin KaFai Lau <kafai@fb.com>
> 
> Acked-by: Daniel Borkmann <daniel@iogearbox.net>

Acked-by: Alexei Starovoitov <ast@kernel.org>
John Fastabend Dec. 8, 2016, 5 p.m. UTC | #3 
On 16-12-08 08:55 AM, Alexei Starovoitov wrote:
> On Thu, Dec 08, 2016 at 10:02:37AM +0100, Daniel Borkmann wrote:
>> On 12/08/2016 12:53 AM, Martin KaFai Lau wrote:
>>> 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.
>>>
>>> This patch adds one "xdp_adjust_head" bit to bpf_prog for the
>>> XDP-capable driver to check if the XDP prog requires
>>> bpf_xdp_adjust_head() support.  The driver can then decide
>>> to error out during XDP_SETUP_PROG.
>>>
>>> Signed-off-by: Martin KaFai Lau <kafai@fb.com>
>>
>> Acked-by: Daniel Borkmann <daniel@iogearbox.net>
> 
> Acked-by: Alexei Starovoitov <ast@kernel.org>
> 

Thanks for fixing up the xdp_buff struct. And for good measure,

Acked-by: John Fastabend <john.r.fastabend@intel.com>
diff mbox

Patch

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/drivers/net/ethernet/mellanox/mlx4/en_netdev.c b/drivers/net/ethernet/mellanox/mlx4/en_netdev.c
index 49a81f1fc1d6..f441eda63bec 100644
--- a/drivers/net/ethernet/mellanox/mlx4/en_netdev.c
+++ b/drivers/net/ethernet/mellanox/mlx4/en_netdev.c
@@ -2686,6 +2686,11 @@  static int mlx4_xdp_set(struct net_device *dev, struct bpf_prog *prog)
 	int err;
 	int i;
 
+	if (prog && prog->xdp_adjust_head) {
+		en_err(priv, "Does not support bpf_xdp_adjust_head()\n");
+		return -EOPNOTSUPP;
+	}
+
 	xdp_ring_num = prog ? priv->rx_ring_num : 0;
 
 	/* No need to reconfigure buffers when simply swapping the
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
index 9def5cc378a3..504ca130f88d 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
@@ -3180,6 +3180,11 @@  static int mlx5e_xdp_set(struct net_device *netdev, struct bpf_prog *prog)
 	bool reset, was_opened;
 	int i;
 
+	if (prog && prog->xdp_adjust_head) {
+		netdev_err(netdev, "Does not support bpf_xdp_adjust_head()\n");
+		return -EOPNOTSUPP;
+	}
+
 	mutex_lock(&priv->state_lock);
 
 	if ((netdev->features & NETIF_F_LRO) && prog) {
diff --git a/drivers/net/ethernet/netronome/nfp/nfp_net_common.c b/drivers/net/ethernet/netronome/nfp/nfp_net_common.c
index 00d9a03be31d..e8d448109e03 100644
--- a/drivers/net/ethernet/netronome/nfp/nfp_net_common.c
+++ b/drivers/net/ethernet/netronome/nfp/nfp_net_common.c
@@ -2946,6 +2946,10 @@  static int nfp_net_xdp_setup(struct nfp_net *nn, struct bpf_prog *prog)
 	};
 	int err;
 
+	if (prog && prog->xdp_adjust_head) {
+		nn_err(nn, "Does not support bpf_xdp_adjust_head()\n");
+		return -EOPNOTSUPP;
+	}
 	if (!prog && !nn->xdp_prog)
 		return 0;
 	if (prog && nn->xdp_prog) {
diff --git a/drivers/net/ethernet/qlogic/qede/qede_main.c b/drivers/net/ethernet/qlogic/qede/qede_main.c
index cf1dd1436d93..aecdd1c5c0ea 100644
--- a/drivers/net/ethernet/qlogic/qede/qede_main.c
+++ b/drivers/net/ethernet/qlogic/qede/qede_main.c
@@ -2507,6 +2507,11 @@  static int qede_xdp_set(struct qede_dev *edev, struct bpf_prog *prog)
 {
 	struct qede_reload_args args;
 
+	if (prog && prog->xdp_adjust_head) {
+		DP_ERR(edev, "Does not support bpf_xdp_adjust_head()\n");
+		return -EOPNOTSUPP;
+	}
+
 	/* If we're called, there was already a bpf reference increment */
 	args.func = &qede_xdp_reload_func;
 	args.u.new_prog = prog;
diff --git a/include/linux/filter.h b/include/linux/filter.h
index f078d2b1cff6..6a1658308612 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -406,7 +406,8 @@  struct bpf_prog {
 	u16			jited:1,	/* Is our filter JIT'ed? */
 				gpl_compatible:1, /* Is filter GPL compatible? */
 				cb_access:1,	/* Is control block accessed? */
-				dst_needed:1;	/* Do we need dst entry? */
+				dst_needed:1,	/* Do we need dst entry? */
+				xdp_adjust_head:1; /* Adjusting pkt head? */
 	kmemcheck_bitfield_end(meta);
 	enum bpf_prog_type	type;		/* Type of BPF program */
 	u32			len;		/* Number of filter blocks */
@@ -440,6 +441,7 @@  struct bpf_skb_data_end {
 struct xdp_buff {
 	void *data;
 	void *data_end;
+	void *data_hard_start;
 };
 
 /* compute the linear packet data range [data, data_end) which
@@ -595,7 +597,7 @@  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 bdcc9f4ba767..83e0d153b0b4 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -1143,7 +1143,7 @@  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/syscall.c b/kernel/bpf/syscall.c
index c0d2b423ce93..add93ecd7e69 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -579,6 +579,8 @@  static void fixup_bpf_calls(struct bpf_prog *prog)
 				prog->dst_needed = 1;
 			if (insn->imm == BPF_FUNC_get_prandom_u32)
 				bpf_user_rnd_init_once();
+			if (insn->imm == BPF_FUNC_xdp_adjust_head)
+				prog->xdp_adjust_head = 1;
 			if (insn->imm == BPF_FUNC_tail_call) {
 				/* mark bpf_tail_call as different opcode
 				 * to avoid conditional branch in
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index cb37339ca0da..f5fa326518c9 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 b751202e12f8..b1461708a977 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -2234,7 +2234,28 @@  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)
+{
+	void *data = xdp->data + offset;
+
+	if (unlikely(data < xdp->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 +2265,8 @@  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 +2692,8 @@  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);
 	}