bpf: allow BPF programs access 'protocol' and 'vlan_tci' fields
as a follow on to patch 70006af955 ("bpf: allow eBPF access skb fields")
this patch allows 'protocol' and 'vlan_tci' fields to be accessible
from extended BPF programs.
The usage of 'protocol', 'vlan_present' and 'vlan_tci' fields is the same as
corresponding SKF_AD_PROTOCOL, SKF_AD_VLAN_TAG_PRESENT and SKF_AD_VLAN_TAG
accesses in classic BPF.
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Alexei Starovoitov
David S. Miller
Родитель
9cf7867c24
Коммит
c249739579
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@ -178,6 +178,9 @@ struct __sk_buff {
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__u32 pkt_type;
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__u32 mark;
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__u32 queue_mapping;
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__u32 protocol;
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__u32 vlan_present;
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__u32 vlan_tci;
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};
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#endif /* _UAPI__LINUX_BPF_H__ */
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@ -177,6 +177,35 @@ static u32 convert_skb_access(int skb_field, int dst_reg, int src_reg,
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*insn++ = BPF_LDX_MEM(BPF_H, dst_reg, src_reg,
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offsetof(struct sk_buff, queue_mapping));
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break;
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case SKF_AD_PROTOCOL:
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BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, protocol) != 2);
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/* dst_reg = *(u16 *) (src_reg + offsetof(protocol)) */
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*insn++ = BPF_LDX_MEM(BPF_H, dst_reg, src_reg,
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offsetof(struct sk_buff, protocol));
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/* dst_reg = ntohs(dst_reg) [emitting a nop or swap16] */
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*insn++ = BPF_ENDIAN(BPF_FROM_BE, dst_reg, 16);
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break;
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case SKF_AD_VLAN_TAG:
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case SKF_AD_VLAN_TAG_PRESENT:
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BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, vlan_tci) != 2);
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BUILD_BUG_ON(VLAN_TAG_PRESENT != 0x1000);
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/* dst_reg = *(u16 *) (src_reg + offsetof(vlan_tci)) */
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*insn++ = BPF_LDX_MEM(BPF_H, dst_reg, src_reg,
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offsetof(struct sk_buff, vlan_tci));
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if (skb_field == SKF_AD_VLAN_TAG) {
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*insn++ = BPF_ALU32_IMM(BPF_AND, dst_reg,
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~VLAN_TAG_PRESENT);
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} else {
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/* dst_reg >>= 12 */
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*insn++ = BPF_ALU32_IMM(BPF_RSH, dst_reg, 12);
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/* dst_reg &= 1 */
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*insn++ = BPF_ALU32_IMM(BPF_AND, dst_reg, 1);
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}
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break;
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}
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return insn - insn_buf;
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@ -190,13 +219,8 @@ static bool convert_bpf_extensions(struct sock_filter *fp,
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switch (fp->k) {
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case SKF_AD_OFF + SKF_AD_PROTOCOL:
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BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, protocol) != 2);
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/* A = *(u16 *) (CTX + offsetof(protocol)) */
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*insn++ = BPF_LDX_MEM(BPF_H, BPF_REG_A, BPF_REG_CTX,
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offsetof(struct sk_buff, protocol));
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/* A = ntohs(A) [emitting a nop or swap16] */
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*insn = BPF_ENDIAN(BPF_FROM_BE, BPF_REG_A, 16);
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cnt = convert_skb_access(SKF_AD_PROTOCOL, BPF_REG_A, BPF_REG_CTX, insn);
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insn += cnt - 1;
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break;
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case SKF_AD_OFF + SKF_AD_PKTTYPE:
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@ -242,22 +266,15 @@ static bool convert_bpf_extensions(struct sock_filter *fp,
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break;
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case SKF_AD_OFF + SKF_AD_VLAN_TAG:
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case SKF_AD_OFF + SKF_AD_VLAN_TAG_PRESENT:
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BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, vlan_tci) != 2);
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BUILD_BUG_ON(VLAN_TAG_PRESENT != 0x1000);
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cnt = convert_skb_access(SKF_AD_VLAN_TAG,
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BPF_REG_A, BPF_REG_CTX, insn);
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insn += cnt - 1;
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break;
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/* A = *(u16 *) (CTX + offsetof(vlan_tci)) */
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*insn++ = BPF_LDX_MEM(BPF_H, BPF_REG_A, BPF_REG_CTX,
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offsetof(struct sk_buff, vlan_tci));
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if (fp->k == SKF_AD_OFF + SKF_AD_VLAN_TAG) {
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*insn = BPF_ALU32_IMM(BPF_AND, BPF_REG_A,
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~VLAN_TAG_PRESENT);
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} else {
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/* A >>= 12 */
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*insn++ = BPF_ALU32_IMM(BPF_RSH, BPF_REG_A, 12);
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/* A &= 1 */
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*insn = BPF_ALU32_IMM(BPF_AND, BPF_REG_A, 1);
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}
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case SKF_AD_OFF + SKF_AD_VLAN_TAG_PRESENT:
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cnt = convert_skb_access(SKF_AD_VLAN_TAG_PRESENT,
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BPF_REG_A, BPF_REG_CTX, insn);
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insn += cnt - 1;
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break;
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case SKF_AD_OFF + SKF_AD_PAY_OFFSET:
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@ -1215,6 +1232,17 @@ static u32 sk_filter_convert_ctx_access(int dst_reg, int src_reg, int ctx_off,
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case offsetof(struct __sk_buff, queue_mapping):
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return convert_skb_access(SKF_AD_QUEUE, dst_reg, src_reg, insn);
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case offsetof(struct __sk_buff, protocol):
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return convert_skb_access(SKF_AD_PROTOCOL, dst_reg, src_reg, insn);
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case offsetof(struct __sk_buff, vlan_present):
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return convert_skb_access(SKF_AD_VLAN_TAG_PRESENT,
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dst_reg, src_reg, insn);
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case offsetof(struct __sk_buff, vlan_tci):
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return convert_skb_access(SKF_AD_VLAN_TAG,
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dst_reg, src_reg, insn);
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}
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return insn - insn_buf;
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@ -658,6 +658,15 @@ static struct bpf_test tests[] = {
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BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_1,
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offsetof(struct __sk_buff, queue_mapping)),
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BPF_JMP_IMM(BPF_JGE, BPF_REG_0, 0, 0),
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BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_1,
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offsetof(struct __sk_buff, protocol)),
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BPF_JMP_IMM(BPF_JGE, BPF_REG_0, 0, 0),
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BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_1,
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offsetof(struct __sk_buff, vlan_present)),
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BPF_JMP_IMM(BPF_JGE, BPF_REG_0, 0, 0),
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BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_1,
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offsetof(struct __sk_buff, vlan_tci)),
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BPF_JMP_IMM(BPF_JGE, BPF_REG_0, 0, 0),
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BPF_EXIT_INSN(),
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},
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.result = ACCEPT,
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