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@iogearbox.net>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Jiri Pirko <jpirko@redhat.com>

Signed-off-by: Michal Sekletar <msekleta@redhat.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@plumgrid.com>
Reviewed-by: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 12 insertions, 1 deletions

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 ']' {