From 27cd5452476978283decb19e429e81fc6c71e74b Mon Sep 17 00:00:00 2001 From: Michal Sekletar Date: Tue, 24 Mar 2015 14:48:41 +0100 Subject: 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 Cc: Alexei Starovoitov Cc: Jiri Pirko Signed-off-by: Michal Sekletar Acked-by: Daniel Borkmann Acked-by: Alexei Starovoitov Reviewed-by: Jiri Pirko Signed-off-by: David S. Miller --- 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 9930ecfbb465..135581f015e1 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 9ee8c67ea249..fa11b3a367be 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 3dd314a45d0d..27dc4ec58840 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 47785d5ecf17..34c7936ca114 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 084eacc4d1d4..32f43c59908c 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 833a96611da6..c83af3fb77de 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 e6306c51c26f..f8332749b44c 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 ']' { -- cgit v1.2.3-59-g8ed1b