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Date: Tue, 24 Mar 2015 14:48:41 +0100
From: Michal Sekletar <msekleta@...hat.com>
To: netdev@...r.kernel.org
Cc: Michal Sekletar <msekleta@...hat.com>,
Daniel Borkmann <daniel@...earbox.net>,
Alexei Starovoitov <ast@...mgrid.com>,
Jiri Pirko <jpirko@...hat.com>
Subject: [PATCH net-next v3] filter: introduce SKF_AD_VLAN_TPID BPF extension
If vlan offloading takes place then vlan header is removed from frame
and its contents, both vlan_tci and vlan_proto, is available to user
space via TPACKET interface. However, only vlan_tci can be used in BPF
filters.
This commit introduces a new BPF extension. It makes possible to load
the value of vlan_proto (vlan TPID) to register A. Support for classic
BPF and eBPF is being added, analogous to skb->protocol.
Cc: Daniel Borkmann <daniel@...earbox.net>
Cc: Alexei Starovoitov <ast@...mgrid.com>
Cc: Jiri Pirko <jpirko@...hat.com>
Signed-off-by: Michal Sekletar <msekleta@...hat.com>
---
* Changes in v3:
- changes for JIT implementations are left out
- support for eBPF was added
- polish, whitespace fixes
Documentation/networking/filter.txt | 3 ++-
include/linux/filter.h | 1 +
include/uapi/linux/bpf.h | 1 +
include/uapi/linux/filter.h | 3 ++-
net/core/filter.c | 17 +++++++++++++++++
tools/net/bpf_exp.l | 2 ++
tools/net/bpf_exp.y | 11 ++++++++++-
7 files changed, 35 insertions(+), 3 deletions(-)
diff --git a/Documentation/networking/filter.txt b/Documentation/networking/filter.txt
index 9930ecfb..135581f 100644
--- a/Documentation/networking/filter.txt
+++ b/Documentation/networking/filter.txt
@@ -280,7 +280,8 @@ Possible BPF extensions are shown in the following table:
rxhash skb->hash
cpu raw_smp_processor_id()
vlan_tci skb_vlan_tag_get(skb)
- vlan_pr skb_vlan_tag_present(skb)
+ vlan_avail skb_vlan_tag_present(skb)
+ vlan_tpid skb->vlan_proto
rand prandom_u32()
These extensions can also be prefixed with '#'.
diff --git a/include/linux/filter.h b/include/linux/filter.h
index 9ee8c67..fa11b3a 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -454,6 +454,7 @@ static inline u16 bpf_anc_helper(const struct sock_filter *ftest)
BPF_ANCILLARY(VLAN_TAG_PRESENT);
BPF_ANCILLARY(PAY_OFFSET);
BPF_ANCILLARY(RANDOM);
+ BPF_ANCILLARY(VLAN_TPID);
}
/* Fallthrough. */
default:
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 3dd314a..27dc4ec 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -182,6 +182,7 @@ struct __sk_buff {
__u32 protocol;
__u32 vlan_present;
__u32 vlan_tci;
+ __u32 vlan_proto;
};
#endif /* _UAPI__LINUX_BPF_H__ */
diff --git a/include/uapi/linux/filter.h b/include/uapi/linux/filter.h
index 47785d5..34c7936 100644
--- a/include/uapi/linux/filter.h
+++ b/include/uapi/linux/filter.h
@@ -77,7 +77,8 @@ struct sock_fprog { /* Required for SO_ATTACH_FILTER. */
#define SKF_AD_VLAN_TAG_PRESENT 48
#define SKF_AD_PAY_OFFSET 52
#define SKF_AD_RANDOM 56
-#define SKF_AD_MAX 60
+#define SKF_AD_VLAN_TPID 60
+#define SKF_AD_MAX 64
#define SKF_NET_OFF (-0x100000)
#define SKF_LL_OFF (-0x200000)
diff --git a/net/core/filter.c b/net/core/filter.c
index 084eacc..32f43c5 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -272,6 +272,16 @@ static bool convert_bpf_extensions(struct sock_filter *fp,
insn += cnt - 1;
break;
+ case SKF_AD_OFF + SKF_AD_VLAN_TPID:
+ BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, vlan_proto) != 2);
+
+ /* A = *(u16 *) (CTX + offsetof(vlan_proto)) */
+ *insn++ = BPF_LDX_MEM(BPF_H, BPF_REG_A, BPF_REG_CTX,
+ offsetof(struct sk_buff, vlan_proto));
+ /* A = ntohs(A) [emitting a nop or swap16] */
+ *insn = BPF_ENDIAN(BPF_FROM_BE, BPF_REG_A, 16);
+ break;
+
case SKF_AD_OFF + SKF_AD_PAY_OFFSET:
case SKF_AD_OFF + SKF_AD_NLATTR:
case SKF_AD_OFF + SKF_AD_NLATTR_NEST:
@@ -1226,6 +1236,13 @@ static u32 sk_filter_convert_ctx_access(int dst_reg, int src_reg, int ctx_off,
offsetof(struct sk_buff, protocol));
break;
+ case offsetof(struct __sk_buff, vlan_proto):
+ BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, vlan_proto) != 2);
+
+ *insn++ = BPF_LDX_MEM(BPF_H, dst_reg, src_reg,
+ offsetof(struct sk_buff, vlan_proto));
+ break;
+
case offsetof(struct __sk_buff, mark):
return convert_skb_access(SKF_AD_MARK, dst_reg, src_reg, insn);
diff --git a/tools/net/bpf_exp.l b/tools/net/bpf_exp.l
index 833a966..c83af3f 100644
--- a/tools/net/bpf_exp.l
+++ b/tools/net/bpf_exp.l
@@ -92,6 +92,8 @@ extern void yyerror(const char *str);
"#"?("cpu") { return K_CPU; }
"#"?("vlan_tci") { return K_VLANT; }
"#"?("vlan_pr") { return K_VLANP; }
+"#"?("vlan_avail") { return K_VLANP; }
+"#"?("vlan_tpid") { return K_VLANTPID; }
"#"?("rand") { return K_RAND; }
":" { return ':'; }
diff --git a/tools/net/bpf_exp.y b/tools/net/bpf_exp.y
index e6306c5..f833274 100644
--- a/tools/net/bpf_exp.y
+++ b/tools/net/bpf_exp.y
@@ -56,7 +56,7 @@ static void bpf_set_jmp_label(char *label, enum jmp_type type);
%token OP_LDXI
%token K_PKT_LEN K_PROTO K_TYPE K_NLATTR K_NLATTR_NEST K_MARK K_QUEUE K_HATYPE
-%token K_RXHASH K_CPU K_IFIDX K_VLANT K_VLANP K_POFF K_RAND
+%token K_RXHASH K_CPU K_IFIDX K_VLANT K_VLANP K_VLANTPID K_POFF K_RAND
%token ':' ',' '[' ']' '(' ')' 'x' 'a' '+' 'M' '*' '&' '#' '%'
@@ -167,6 +167,9 @@ ldb
| OP_LDB K_RAND {
bpf_set_curr_instr(BPF_LD | BPF_B | BPF_ABS, 0, 0,
SKF_AD_OFF + SKF_AD_RANDOM); }
+ | OP_LDB K_VLANTPID {
+ bpf_set_curr_instr(BPF_LD | BPF_B | BPF_ABS, 0, 0,
+ SKF_AD_OFF + SKF_AD_VLAN_TPID); }
;
ldh
@@ -218,6 +221,9 @@ ldh
| OP_LDH K_RAND {
bpf_set_curr_instr(BPF_LD | BPF_H | BPF_ABS, 0, 0,
SKF_AD_OFF + SKF_AD_RANDOM); }
+ | OP_LDH K_VLANTPID {
+ bpf_set_curr_instr(BPF_LD | BPF_H | BPF_ABS, 0, 0,
+ SKF_AD_OFF + SKF_AD_VLAN_TPID); }
;
ldi
@@ -274,6 +280,9 @@ ld
| OP_LD K_RAND {
bpf_set_curr_instr(BPF_LD | BPF_W | BPF_ABS, 0, 0,
SKF_AD_OFF + SKF_AD_RANDOM); }
+ | OP_LD K_VLANTPID {
+ bpf_set_curr_instr(BPF_LD | BPF_W | BPF_ABS, 0, 0,
+ SKF_AD_OFF + SKF_AD_VLAN_TPID); }
| OP_LD 'M' '[' number ']' {
bpf_set_curr_instr(BPF_LD | BPF_MEM, 0, 0, $4); }
| OP_LD '[' 'x' '+' number ']' {
--
2.3.4
--
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