diff options
| -rw-r--r-- | include/net/strparser.h | 4 | ||||
| -rw-r--r-- | net/core/filter.c | 36 |
2 files changed, 34 insertions, 6 deletions
diff --git a/include/net/strparser.h b/include/net/strparser.h index bec1439bd3be..732b7097d78e 100644 --- a/include/net/strparser.h +++ b/include/net/strparser.h @@ -66,6 +66,10 @@ struct sk_skb_cb { #define SK_SKB_CB_PRIV_LEN 20 unsigned char data[SK_SKB_CB_PRIV_LEN]; struct _strp_msg strp; + /* temp_reg is a temporary register used for bpf_convert_data_end_access + * when dst_reg == src_reg. + */ + u64 temp_reg; }; static inline struct strp_msg *strp_msg(struct sk_buff *skb) diff --git a/net/core/filter.c b/net/core/filter.c index c3936d0724b8..e471c9b09670 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -9756,22 +9756,46 @@ static u32 sock_ops_convert_ctx_access(enum bpf_access_type type, static struct bpf_insn *bpf_convert_data_end_access(const struct bpf_insn *si, struct bpf_insn *insn) { - /* si->dst_reg = skb->data */ + int reg; + int temp_reg_off = offsetof(struct sk_buff, cb) + + offsetof(struct sk_skb_cb, temp_reg); + + if (si->src_reg == si->dst_reg) { + /* We need an extra register, choose and save a register. */ + reg = BPF_REG_9; + if (si->src_reg == reg || si->dst_reg == reg) + reg--; + if (si->src_reg == reg || si->dst_reg == reg) + reg--; + *insn++ = BPF_STX_MEM(BPF_DW, si->src_reg, reg, temp_reg_off); + } else { + reg = si->dst_reg; + } + + /* reg = skb->data */ *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct sk_buff, data), - si->dst_reg, si->src_reg, + reg, si->src_reg, offsetof(struct sk_buff, data)); /* AX = skb->len */ *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct sk_buff, len), BPF_REG_AX, si->src_reg, offsetof(struct sk_buff, len)); - /* si->dst_reg = skb->data + skb->len */ - *insn++ = BPF_ALU64_REG(BPF_ADD, si->dst_reg, BPF_REG_AX); + /* reg = skb->data + skb->len */ + *insn++ = BPF_ALU64_REG(BPF_ADD, reg, BPF_REG_AX); /* AX = skb->data_len */ *insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct sk_buff, data_len), BPF_REG_AX, si->src_reg, offsetof(struct sk_buff, data_len)); - /* si->dst_reg = skb->data + skb->len - skb->data_len */ - *insn++ = BPF_ALU64_REG(BPF_SUB, si->dst_reg, BPF_REG_AX); + + /* reg = skb->data + skb->len - skb->data_len */ + *insn++ = BPF_ALU64_REG(BPF_SUB, reg, BPF_REG_AX); + + if (si->src_reg == si->dst_reg) { + /* Restore the saved register */ + *insn++ = BPF_MOV64_REG(BPF_REG_AX, si->src_reg); + *insn++ = BPF_MOV64_REG(si->dst_reg, reg); + *insn++ = BPF_LDX_MEM(BPF_DW, reg, BPF_REG_AX, temp_reg_off); + } return insn; } |