From 8d21ec0e46ed6e39994accff8eb4f2be3d2e76b5 Mon Sep 17 00:00:00 2001 From: Martin KaFai Lau Date: Wed, 2 Mar 2022 11:56:34 -0800 Subject: bpf: Add __sk_buff->delivery_time_type and bpf_skb_set_skb_delivery_time() * __sk_buff->delivery_time_type: This patch adds __sk_buff->delivery_time_type. It tells if the delivery_time is stored in __sk_buff->tstamp or not. It will be most useful for ingress to tell if the __sk_buff->tstamp has the (rcv) timestamp or delivery_time. If delivery_time_type is 0 (BPF_SKB_DELIVERY_TIME_NONE), it has the (rcv) timestamp. Two non-zero types are defined for the delivery_time_type, BPF_SKB_DELIVERY_TIME_MONO and BPF_SKB_DELIVERY_TIME_UNSPEC. For UNSPEC, it can only happen in egress because only mono delivery_time can be forwarded to ingress now. The clock of UNSPEC delivery_time can be deduced from the skb->sk->sk_clockid which is how the sch_etf doing it also. * Provide forwarded delivery_time to tc-bpf@ingress: With the help of the new delivery_time_type, the tc-bpf has a way to tell if the __sk_buff->tstamp has the (rcv) timestamp or the delivery_time. During bpf load time, the verifier will learn if the bpf prog has accessed the new __sk_buff->delivery_time_type. If it does, it means the tc-bpf@ingress is expecting the skb->tstamp could have the delivery_time. The kernel will then read the skb->tstamp as-is during bpf insn rewrite without checking the skb->mono_delivery_time. This is done by adding a new prog->delivery_time_access bit. The same goes for writing skb->tstamp. * bpf_skb_set_delivery_time(): The bpf_skb_set_delivery_time() helper is added to allow setting both delivery_time and the delivery_time_type at the same time. If the tc-bpf does not need to change the delivery_time_type, it can directly write to the __sk_buff->tstamp as the existing tc-bpf has already been doing. It will be most useful at ingress to change the __sk_buff->tstamp from the (rcv) timestamp to a mono delivery_time and then bpf_redirect_*(). bpf only has mono clock helper (bpf_ktime_get_ns), and the current known use case is the mono EDT for fq, and only mono delivery time can be kept during forward now, so bpf_skb_set_delivery_time() only supports setting BPF_SKB_DELIVERY_TIME_MONO. It can be extended later when use cases come up and the forwarding path also supports other clock bases. Signed-off-by: Martin KaFai Lau Signed-off-by: David S. Miller --- net/core/filter.c | 169 +++++++++++++++++++++++++++++++++++++++++++----------- 1 file changed, 134 insertions(+), 35 deletions(-) (limited to 'net') diff --git a/net/core/filter.c b/net/core/filter.c index 5072733743e9..88767f7da150 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -7388,6 +7388,43 @@ static const struct bpf_func_proto bpf_sock_ops_reserve_hdr_opt_proto = { .arg3_type = ARG_ANYTHING, }; +BPF_CALL_3(bpf_skb_set_delivery_time, struct sk_buff *, skb, + u64, dtime, u32, dtime_type) +{ + /* skb_clear_delivery_time() is done for inet protocol */ + if (skb->protocol != htons(ETH_P_IP) && + skb->protocol != htons(ETH_P_IPV6)) + return -EOPNOTSUPP; + + switch (dtime_type) { + case BPF_SKB_DELIVERY_TIME_MONO: + if (!dtime) + return -EINVAL; + skb->tstamp = dtime; + skb->mono_delivery_time = 1; + break; + case BPF_SKB_DELIVERY_TIME_NONE: + if (dtime) + return -EINVAL; + skb->tstamp = 0; + skb->mono_delivery_time = 0; + break; + default: + return -EOPNOTSUPP; + } + + return 0; +} + +static const struct bpf_func_proto bpf_skb_set_delivery_time_proto = { + .func = bpf_skb_set_delivery_time, + .gpl_only = false, + .ret_type = RET_INTEGER, + .arg1_type = ARG_PTR_TO_CTX, + .arg2_type = ARG_ANYTHING, + .arg3_type = ARG_ANYTHING, +}; + #endif /* CONFIG_INET */ bool bpf_helper_changes_pkt_data(void *func) @@ -7749,6 +7786,8 @@ tc_cls_act_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) return &bpf_tcp_gen_syncookie_proto; case BPF_FUNC_sk_assign: return &bpf_sk_assign_proto; + case BPF_FUNC_skb_set_delivery_time: + return &bpf_skb_set_delivery_time_proto; #endif default: return bpf_sk_base_func_proto(func_id); @@ -8088,7 +8127,9 @@ static bool bpf_skb_is_valid_access(int off, int size, enum bpf_access_type type return false; info->reg_type = PTR_TO_SOCK_COMMON_OR_NULL; break; - case offsetofend(struct __sk_buff, gso_size) ... offsetof(struct __sk_buff, hwtstamp) - 1: + case offsetof(struct __sk_buff, delivery_time_type): + return false; + case offsetofend(struct __sk_buff, delivery_time_type) ... offsetof(struct __sk_buff, hwtstamp) - 1: /* Explicitly prohibit access to padding in __sk_buff. */ return false; default: @@ -8443,6 +8484,15 @@ static bool tc_cls_act_is_valid_access(int off, int size, break; case bpf_ctx_range_till(struct __sk_buff, family, local_port): return false; + case offsetof(struct __sk_buff, delivery_time_type): + /* The convert_ctx_access() on reading and writing + * __sk_buff->tstamp depends on whether the bpf prog + * has used __sk_buff->delivery_time_type or not. + * Thus, we need to set prog->delivery_time_access + * earlier during is_valid_access() here. + */ + ((struct bpf_prog *)prog)->delivery_time_access = 1; + return size == sizeof(__u8); } return bpf_skb_is_valid_access(off, size, type, prog, info); @@ -8838,6 +8888,45 @@ static u32 flow_dissector_convert_ctx_access(enum bpf_access_type type, return insn - insn_buf; } +static struct bpf_insn *bpf_convert_dtime_type_read(const struct bpf_insn *si, + struct bpf_insn *insn) +{ + __u8 value_reg = si->dst_reg; + __u8 skb_reg = si->src_reg; + __u8 tmp_reg = BPF_REG_AX; + + *insn++ = BPF_LDX_MEM(BPF_B, tmp_reg, skb_reg, + SKB_MONO_DELIVERY_TIME_OFFSET); + *insn++ = BPF_ALU32_IMM(BPF_AND, tmp_reg, + SKB_MONO_DELIVERY_TIME_MASK); + *insn++ = BPF_JMP32_IMM(BPF_JEQ, tmp_reg, 0, 2); + /* value_reg = BPF_SKB_DELIVERY_TIME_MONO */ + *insn++ = BPF_MOV32_IMM(value_reg, BPF_SKB_DELIVERY_TIME_MONO); + *insn++ = BPF_JMP_A(IS_ENABLED(CONFIG_NET_CLS_ACT) ? 10 : 5); + + *insn++ = BPF_LDX_MEM(BPF_DW, tmp_reg, skb_reg, + offsetof(struct sk_buff, tstamp)); + *insn++ = BPF_JMP_IMM(BPF_JNE, tmp_reg, 0, 2); + /* value_reg = BPF_SKB_DELIVERY_TIME_NONE */ + *insn++ = BPF_MOV32_IMM(value_reg, BPF_SKB_DELIVERY_TIME_NONE); + *insn++ = BPF_JMP_A(IS_ENABLED(CONFIG_NET_CLS_ACT) ? 6 : 1); + +#ifdef CONFIG_NET_CLS_ACT + *insn++ = BPF_LDX_MEM(BPF_B, tmp_reg, skb_reg, TC_AT_INGRESS_OFFSET); + *insn++ = BPF_ALU32_IMM(BPF_AND, tmp_reg, TC_AT_INGRESS_MASK); + *insn++ = BPF_JMP32_IMM(BPF_JEQ, tmp_reg, 0, 2); + /* At ingress, value_reg = 0 */ + *insn++ = BPF_MOV32_IMM(value_reg, 0); + *insn++ = BPF_JMP_A(1); +#endif + + /* value_reg = BPF_SKB_DELIVERYT_TIME_UNSPEC */ + *insn++ = BPF_MOV32_IMM(value_reg, BPF_SKB_DELIVERY_TIME_UNSPEC); + + /* 15 insns with CONFIG_NET_CLS_ACT */ + return insn; +} + static struct bpf_insn *bpf_convert_shinfo_access(const struct bpf_insn *si, struct bpf_insn *insn) { @@ -8859,29 +8948,32 @@ static struct bpf_insn *bpf_convert_shinfo_access(const struct bpf_insn *si, return insn; } -static struct bpf_insn *bpf_convert_tstamp_read(const struct bpf_insn *si, +static struct bpf_insn *bpf_convert_tstamp_read(const struct bpf_prog *prog, + const struct bpf_insn *si, struct bpf_insn *insn) { __u8 value_reg = si->dst_reg; __u8 skb_reg = si->src_reg; #ifdef CONFIG_NET_CLS_ACT - __u8 tmp_reg = BPF_REG_AX; - - *insn++ = BPF_LDX_MEM(BPF_B, tmp_reg, skb_reg, TC_AT_INGRESS_OFFSET); - *insn++ = BPF_ALU32_IMM(BPF_AND, tmp_reg, TC_AT_INGRESS_MASK); - *insn++ = BPF_JMP32_IMM(BPF_JEQ, tmp_reg, 0, 5); - /* @ingress, read __sk_buff->tstamp as the (rcv) timestamp, - * so check the skb->mono_delivery_time. - */ - *insn++ = BPF_LDX_MEM(BPF_B, tmp_reg, skb_reg, - SKB_MONO_DELIVERY_TIME_OFFSET); - *insn++ = BPF_ALU32_IMM(BPF_AND, tmp_reg, - SKB_MONO_DELIVERY_TIME_MASK); - *insn++ = BPF_JMP32_IMM(BPF_JEQ, tmp_reg, 0, 2); - /* skb->mono_delivery_time is set, read 0 as the (rcv) timestamp. */ - *insn++ = BPF_MOV64_IMM(value_reg, 0); - *insn++ = BPF_JMP_A(1); + if (!prog->delivery_time_access) { + __u8 tmp_reg = BPF_REG_AX; + + *insn++ = BPF_LDX_MEM(BPF_B, tmp_reg, skb_reg, TC_AT_INGRESS_OFFSET); + *insn++ = BPF_ALU32_IMM(BPF_AND, tmp_reg, TC_AT_INGRESS_MASK); + *insn++ = BPF_JMP32_IMM(BPF_JEQ, tmp_reg, 0, 5); + /* @ingress, read __sk_buff->tstamp as the (rcv) timestamp, + * so check the skb->mono_delivery_time. + */ + *insn++ = BPF_LDX_MEM(BPF_B, tmp_reg, skb_reg, + SKB_MONO_DELIVERY_TIME_OFFSET); + *insn++ = BPF_ALU32_IMM(BPF_AND, tmp_reg, + SKB_MONO_DELIVERY_TIME_MASK); + *insn++ = BPF_JMP32_IMM(BPF_JEQ, tmp_reg, 0, 2); + /* skb->mono_delivery_time is set, read 0 as the (rcv) timestamp. */ + *insn++ = BPF_MOV64_IMM(value_reg, 0); + *insn++ = BPF_JMP_A(1); + } #endif *insn++ = BPF_LDX_MEM(BPF_DW, value_reg, skb_reg, @@ -8889,27 +8981,30 @@ static struct bpf_insn *bpf_convert_tstamp_read(const struct bpf_insn *si, return insn; } -static struct bpf_insn *bpf_convert_tstamp_write(const struct bpf_insn *si, +static struct bpf_insn *bpf_convert_tstamp_write(const struct bpf_prog *prog, + const struct bpf_insn *si, struct bpf_insn *insn) { __u8 value_reg = si->src_reg; __u8 skb_reg = si->dst_reg; #ifdef CONFIG_NET_CLS_ACT - __u8 tmp_reg = BPF_REG_AX; - - *insn++ = BPF_LDX_MEM(BPF_B, tmp_reg, skb_reg, TC_AT_INGRESS_OFFSET); - *insn++ = BPF_ALU32_IMM(BPF_AND, tmp_reg, TC_AT_INGRESS_MASK); - *insn++ = BPF_JMP32_IMM(BPF_JEQ, tmp_reg, 0, 3); - /* Writing __sk_buff->tstamp at ingress as the (rcv) timestamp. - * Clear the skb->mono_delivery_time. - */ - *insn++ = BPF_LDX_MEM(BPF_B, tmp_reg, skb_reg, - SKB_MONO_DELIVERY_TIME_OFFSET); - *insn++ = BPF_ALU32_IMM(BPF_AND, tmp_reg, - ~SKB_MONO_DELIVERY_TIME_MASK); - *insn++ = BPF_STX_MEM(BPF_B, skb_reg, tmp_reg, - SKB_MONO_DELIVERY_TIME_OFFSET); + if (!prog->delivery_time_access) { + __u8 tmp_reg = BPF_REG_AX; + + *insn++ = BPF_LDX_MEM(BPF_B, tmp_reg, skb_reg, TC_AT_INGRESS_OFFSET); + *insn++ = BPF_ALU32_IMM(BPF_AND, tmp_reg, TC_AT_INGRESS_MASK); + *insn++ = BPF_JMP32_IMM(BPF_JEQ, tmp_reg, 0, 3); + /* Writing __sk_buff->tstamp at ingress as the (rcv) timestamp. + * Clear the skb->mono_delivery_time. + */ + *insn++ = BPF_LDX_MEM(BPF_B, tmp_reg, skb_reg, + SKB_MONO_DELIVERY_TIME_OFFSET); + *insn++ = BPF_ALU32_IMM(BPF_AND, tmp_reg, + ~SKB_MONO_DELIVERY_TIME_MASK); + *insn++ = BPF_STX_MEM(BPF_B, skb_reg, tmp_reg, + SKB_MONO_DELIVERY_TIME_OFFSET); + } #endif /* skb->tstamp = tstamp */ @@ -9226,9 +9321,13 @@ static u32 bpf_convert_ctx_access(enum bpf_access_type type, BUILD_BUG_ON(sizeof_field(struct sk_buff, tstamp) != 8); if (type == BPF_WRITE) - insn = bpf_convert_tstamp_write(si, insn); + insn = bpf_convert_tstamp_write(prog, si, insn); else - insn = bpf_convert_tstamp_read(si, insn); + insn = bpf_convert_tstamp_read(prog, si, insn); + break; + + case offsetof(struct __sk_buff, delivery_time_type): + insn = bpf_convert_dtime_type_read(si, insn); break; case offsetof(struct __sk_buff, gso_segs): -- cgit