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iamkafai
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borkmann
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bpf: Remove BPF_SKB_DELIVERY_TIME_NONE and rename s/delivery_time_/tstamp_/
This patch is to simplify the uapi bpf.h regarding to the tstamp type and use a similar way as the kernel to describe the value stored in __sk_buff->tstamp. My earlier thought was to avoid describing the semantic and clock base for the rcv timestamp until there is more clarity on the use case, so the __sk_buff->delivery_time_type naming instead of __sk_buff->tstamp_type. With some thoughts, it can reuse the UNSPEC naming. This patch first removes BPF_SKB_DELIVERY_TIME_NONE and also rename BPF_SKB_DELIVERY_TIME_UNSPEC to BPF_SKB_TSTAMP_UNSPEC and BPF_SKB_DELIVERY_TIME_MONO to BPF_SKB_TSTAMP_DELIVERY_MONO. The semantic of BPF_SKB_TSTAMP_DELIVERY_MONO is the same: __sk_buff->tstamp has delivery time in mono clock base. BPF_SKB_TSTAMP_UNSPEC means __sk_buff->tstamp has the (rcv) tstamp at ingress and the delivery time at egress. At egress, the clock base could be found from skb->sk->sk_clockid. __sk_buff->tstamp == 0 naturally means NONE, so NONE is not needed. With BPF_SKB_TSTAMP_UNSPEC for the rcv tstamp at ingress, the __sk_buff->delivery_time_type is also renamed to __sk_buff->tstamp_type which was also suggested in the earlier discussion: https://lore.kernel.org/bpf/[email protected]/ The above will then make __sk_buff->tstamp and __sk_buff->tstamp_type the same as its kernel skb->tstamp and skb->mono_delivery_time counter part. The internal kernel function bpf_skb_convert_dtime_type_read() is then renamed to bpf_skb_convert_tstamp_type_read() and it can be simplified with the BPF_SKB_DELIVERY_TIME_NONE gone. A BPF_ALU32_IMM(BPF_AND) insn is also saved by using BPF_JMP32_IMM(BPF_JSET). The bpf helper bpf_skb_set_delivery_time() is also renamed to bpf_skb_set_tstamp(). The arg name is changed from dtime to tstamp also. It only allows setting tstamp 0 for BPF_SKB_TSTAMP_UNSPEC and it could be relaxed later if there is use case to change mono delivery time to non mono. prog->delivery_time_access is also renamed to prog->tstamp_type_access. Signed-off-by: Martin KaFai Lau <[email protected]> Signed-off-by: Daniel Borkmann <[email protected]> Link: https://lore.kernel.org/bpf/[email protected]
1 parent 9d90db9 commit 9bb984f

4 files changed

Lines changed: 77 additions & 93 deletions

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‎include/linux/filter.h‎

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -573,7 +573,7 @@ struct bpf_prog {
573573
enforce_expected_attach_type:1, /* Enforce expected_attach_type checking at attach time */
574574
call_get_stack:1, /* Do we call bpf_get_stack() or bpf_get_stackid() */
575575
call_get_func_ip:1, /* Do we call get_func_ip() */
576-
delivery_time_access:1; /* Accessed __sk_buff->delivery_time_type */
576+
tstamp_type_access:1; /* Accessed __sk_buff->tstamp_type */
577577
enum bpf_prog_type type; /* Type of BPF program */
578578
enum bpf_attach_type expected_attach_type; /* For some prog types */
579579
u32 len; /* Number of filter blocks */

‎include/uapi/linux/bpf.h‎

Lines changed: 21 additions & 19 deletions
Original file line numberDiff line numberDiff line change
@@ -5090,23 +5090,22 @@ union bpf_attr {
50905090
* 0 on success, or a negative error in case of failure. On error
50915091
* *dst* buffer is zeroed out.
50925092
*
5093-
* long bpf_skb_set_delivery_time(struct sk_buff *skb, u64 dtime, u32 dtime_type)
5093+
* long bpf_skb_set_tstamp(struct sk_buff *skb, u64 tstamp, u32 tstamp_type)
50945094
* Description
5095-
* Set a *dtime* (delivery time) to the __sk_buff->tstamp and also
5096-
* change the __sk_buff->delivery_time_type to *dtime_type*.
5095+
* Change the __sk_buff->tstamp_type to *tstamp_type*
5096+
* and set *tstamp* to the __sk_buff->tstamp together.
50975097
*
5098-
* When setting a delivery time (non zero *dtime*) to
5099-
* __sk_buff->tstamp, only BPF_SKB_DELIVERY_TIME_MONO *dtime_type*
5100-
* is supported. It is the only delivery_time_type that will be
5101-
* kept after bpf_redirect_*().
5102-
*
5103-
* If there is no need to change the __sk_buff->delivery_time_type,
5104-
* the delivery time can be directly written to __sk_buff->tstamp
5098+
* If there is no need to change the __sk_buff->tstamp_type,
5099+
* the tstamp value can be directly written to __sk_buff->tstamp
51055100
* instead.
51065101
*
5107-
* *dtime* 0 and *dtime_type* BPF_SKB_DELIVERY_TIME_NONE
5108-
* can be used to clear any delivery time stored in
5109-
* __sk_buff->tstamp.
5102+
* BPF_SKB_TSTAMP_DELIVERY_MONO is the only tstamp that
5103+
* will be kept during bpf_redirect_*(). A non zero
5104+
* *tstamp* must be used with the BPF_SKB_TSTAMP_DELIVERY_MONO
5105+
* *tstamp_type*.
5106+
*
5107+
* A BPF_SKB_TSTAMP_UNSPEC *tstamp_type* can only be used
5108+
* with a zero *tstamp*.
51105109
*
51115110
* Only IPv4 and IPv6 skb->protocol are supported.
51125111
*
@@ -5119,7 +5118,7 @@ union bpf_attr {
51195118
* Return
51205119
* 0 on success.
51215120
* **-EINVAL** for invalid input
5122-
* **-EOPNOTSUPP** for unsupported delivery_time_type and protocol
5121+
* **-EOPNOTSUPP** for unsupported protocol
51235122
*/
51245123
#define __BPF_FUNC_MAPPER(FN) \
51255124
FN(unspec), \
@@ -5314,7 +5313,7 @@ union bpf_attr {
53145313
FN(xdp_load_bytes), \
53155314
FN(xdp_store_bytes), \
53165315
FN(copy_from_user_task), \
5317-
FN(skb_set_delivery_time), \
5316+
FN(skb_set_tstamp), \
53185317
/* */
53195318

53205319
/* integer value in 'imm' field of BPF_CALL instruction selects which helper
@@ -5505,9 +5504,12 @@ union { \
55055504
} __attribute__((aligned(8)))
55065505

55075506
enum {
5508-
BPF_SKB_DELIVERY_TIME_NONE,
5509-
BPF_SKB_DELIVERY_TIME_UNSPEC,
5510-
BPF_SKB_DELIVERY_TIME_MONO,
5507+
BPF_SKB_TSTAMP_UNSPEC,
5508+
BPF_SKB_TSTAMP_DELIVERY_MONO, /* tstamp has mono delivery time */
5509+
/* For any BPF_SKB_TSTAMP_* that the bpf prog cannot handle,
5510+
* the bpf prog should handle it like BPF_SKB_TSTAMP_UNSPEC
5511+
* and try to deduce it by ingress, egress or skb->sk->sk_clockid.
5512+
*/
55115513
};
55125514

55135515
/* user accessible mirror of in-kernel sk_buff.
@@ -5550,7 +5552,7 @@ struct __sk_buff {
55505552
__u32 gso_segs;
55515553
__bpf_md_ptr(struct bpf_sock *, sk);
55525554
__u32 gso_size;
5553-
__u8 delivery_time_type;
5555+
__u8 tstamp_type;
55545556
__u32 :24; /* Padding, future use. */
55555557
__u64 hwtstamp;
55565558
};

‎net/core/filter.c‎

Lines changed: 34 additions & 54 deletions
Original file line numberDiff line numberDiff line change
@@ -7388,36 +7388,36 @@ static const struct bpf_func_proto bpf_sock_ops_reserve_hdr_opt_proto = {
73887388
.arg3_type = ARG_ANYTHING,
73897389
};
73907390

7391-
BPF_CALL_3(bpf_skb_set_delivery_time, struct sk_buff *, skb,
7392-
u64, dtime, u32, dtime_type)
7391+
BPF_CALL_3(bpf_skb_set_tstamp, struct sk_buff *, skb,
7392+
u64, tstamp, u32, tstamp_type)
73937393
{
73947394
/* skb_clear_delivery_time() is done for inet protocol */
73957395
if (skb->protocol != htons(ETH_P_IP) &&
73967396
skb->protocol != htons(ETH_P_IPV6))
73977397
return -EOPNOTSUPP;
73987398

7399-
switch (dtime_type) {
7400-
case BPF_SKB_DELIVERY_TIME_MONO:
7401-
if (!dtime)
7399+
switch (tstamp_type) {
7400+
case BPF_SKB_TSTAMP_DELIVERY_MONO:
7401+
if (!tstamp)
74027402
return -EINVAL;
7403-
skb->tstamp = dtime;
7403+
skb->tstamp = tstamp;
74047404
skb->mono_delivery_time = 1;
74057405
break;
7406-
case BPF_SKB_DELIVERY_TIME_NONE:
7407-
if (dtime)
7406+
case BPF_SKB_TSTAMP_UNSPEC:
7407+
if (tstamp)
74087408
return -EINVAL;
74097409
skb->tstamp = 0;
74107410
skb->mono_delivery_time = 0;
74117411
break;
74127412
default:
7413-
return -EOPNOTSUPP;
7413+
return -EINVAL;
74147414
}
74157415

74167416
return 0;
74177417
}
74187418

7419-
static const struct bpf_func_proto bpf_skb_set_delivery_time_proto = {
7420-
.func = bpf_skb_set_delivery_time,
7419+
static const struct bpf_func_proto bpf_skb_set_tstamp_proto = {
7420+
.func = bpf_skb_set_tstamp,
74217421
.gpl_only = false,
74227422
.ret_type = RET_INTEGER,
74237423
.arg1_type = ARG_PTR_TO_CTX,
@@ -7786,8 +7786,8 @@ tc_cls_act_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
77867786
return &bpf_tcp_gen_syncookie_proto;
77877787
case BPF_FUNC_sk_assign:
77887788
return &bpf_sk_assign_proto;
7789-
case BPF_FUNC_skb_set_delivery_time:
7790-
return &bpf_skb_set_delivery_time_proto;
7789+
case BPF_FUNC_skb_set_tstamp:
7790+
return &bpf_skb_set_tstamp_proto;
77917791
#endif
77927792
default:
77937793
return bpf_sk_base_func_proto(func_id);
@@ -8127,9 +8127,9 @@ static bool bpf_skb_is_valid_access(int off, int size, enum bpf_access_type type
81278127
return false;
81288128
info->reg_type = PTR_TO_SOCK_COMMON_OR_NULL;
81298129
break;
8130-
case offsetof(struct __sk_buff, delivery_time_type):
8130+
case offsetof(struct __sk_buff, tstamp_type):
81318131
return false;
8132-
case offsetofend(struct __sk_buff, delivery_time_type) ... offsetof(struct __sk_buff, hwtstamp) - 1:
8132+
case offsetofend(struct __sk_buff, tstamp_type) ... offsetof(struct __sk_buff, hwtstamp) - 1:
81338133
/* Explicitly prohibit access to padding in __sk_buff. */
81348134
return false;
81358135
default:
@@ -8484,14 +8484,14 @@ static bool tc_cls_act_is_valid_access(int off, int size,
84848484
break;
84858485
case bpf_ctx_range_till(struct __sk_buff, family, local_port):
84868486
return false;
8487-
case offsetof(struct __sk_buff, delivery_time_type):
8487+
case offsetof(struct __sk_buff, tstamp_type):
84888488
/* The convert_ctx_access() on reading and writing
84898489
* __sk_buff->tstamp depends on whether the bpf prog
8490-
* has used __sk_buff->delivery_time_type or not.
8491-
* Thus, we need to set prog->delivery_time_access
8490+
* has used __sk_buff->tstamp_type or not.
8491+
* Thus, we need to set prog->tstamp_type_access
84928492
* earlier during is_valid_access() here.
84938493
*/
8494-
((struct bpf_prog *)prog)->delivery_time_access = 1;
8494+
((struct bpf_prog *)prog)->tstamp_type_access = 1;
84958495
return size == sizeof(__u8);
84968496
}
84978497

@@ -8888,42 +8888,22 @@ static u32 flow_dissector_convert_ctx_access(enum bpf_access_type type,
88888888
return insn - insn_buf;
88898889
}
88908890

8891-
static struct bpf_insn *bpf_convert_dtime_type_read(const struct bpf_insn *si,
8892-
struct bpf_insn *insn)
8891+
static struct bpf_insn *bpf_convert_tstamp_type_read(const struct bpf_insn *si,
8892+
struct bpf_insn *insn)
88938893
{
88948894
__u8 value_reg = si->dst_reg;
88958895
__u8 skb_reg = si->src_reg;
8896+
/* AX is needed because src_reg and dst_reg could be the same */
88968897
__u8 tmp_reg = BPF_REG_AX;
88978898

88988899
*insn++ = BPF_LDX_MEM(BPF_B, tmp_reg, skb_reg,
88998900
PKT_VLAN_PRESENT_OFFSET);
8900-
*insn++ = BPF_ALU32_IMM(BPF_AND, tmp_reg,
8901-
SKB_MONO_DELIVERY_TIME_MASK);
8902-
*insn++ = BPF_JMP32_IMM(BPF_JEQ, tmp_reg, 0, 2);
8903-
/* value_reg = BPF_SKB_DELIVERY_TIME_MONO */
8904-
*insn++ = BPF_MOV32_IMM(value_reg, BPF_SKB_DELIVERY_TIME_MONO);
8905-
*insn++ = BPF_JMP_A(IS_ENABLED(CONFIG_NET_CLS_ACT) ? 10 : 5);
8906-
8907-
*insn++ = BPF_LDX_MEM(BPF_DW, tmp_reg, skb_reg,
8908-
offsetof(struct sk_buff, tstamp));
8909-
*insn++ = BPF_JMP_IMM(BPF_JNE, tmp_reg, 0, 2);
8910-
/* value_reg = BPF_SKB_DELIVERY_TIME_NONE */
8911-
*insn++ = BPF_MOV32_IMM(value_reg, BPF_SKB_DELIVERY_TIME_NONE);
8912-
*insn++ = BPF_JMP_A(IS_ENABLED(CONFIG_NET_CLS_ACT) ? 6 : 1);
8913-
8914-
#ifdef CONFIG_NET_CLS_ACT
8915-
*insn++ = BPF_LDX_MEM(BPF_B, tmp_reg, skb_reg, PKT_VLAN_PRESENT_OFFSET);
8916-
*insn++ = BPF_ALU32_IMM(BPF_AND, tmp_reg, TC_AT_INGRESS_MASK);
8917-
*insn++ = BPF_JMP32_IMM(BPF_JEQ, tmp_reg, 0, 2);
8918-
/* At ingress, value_reg = 0 */
8919-
*insn++ = BPF_MOV32_IMM(value_reg, 0);
8901+
*insn++ = BPF_JMP32_IMM(BPF_JSET, tmp_reg,
8902+
SKB_MONO_DELIVERY_TIME_MASK, 2);
8903+
*insn++ = BPF_MOV32_IMM(value_reg, BPF_SKB_TSTAMP_UNSPEC);
89208904
*insn++ = BPF_JMP_A(1);
8921-
#endif
8922-
8923-
/* value_reg = BPF_SKB_DELIVERYT_TIME_UNSPEC */
8924-
*insn++ = BPF_MOV32_IMM(value_reg, BPF_SKB_DELIVERY_TIME_UNSPEC);
8905+
*insn++ = BPF_MOV32_IMM(value_reg, BPF_SKB_TSTAMP_DELIVERY_MONO);
89258906

8926-
/* 15 insns with CONFIG_NET_CLS_ACT */
89278907
return insn;
89288908
}
89298909

@@ -8956,11 +8936,11 @@ static struct bpf_insn *bpf_convert_tstamp_read(const struct bpf_prog *prog,
89568936
__u8 skb_reg = si->src_reg;
89578937

89588938
#ifdef CONFIG_NET_CLS_ACT
8959-
/* If the delivery_time_type is read,
8939+
/* If the tstamp_type is read,
89608940
* the bpf prog is aware the tstamp could have delivery time.
8961-
* Thus, read skb->tstamp as is if delivery_time_access is true.
8941+
* Thus, read skb->tstamp as is if tstamp_type_access is true.
89628942
*/
8963-
if (!prog->delivery_time_access) {
8943+
if (!prog->tstamp_type_access) {
89648944
/* AX is needed because src_reg and dst_reg could be the same */
89658945
__u8 tmp_reg = BPF_REG_AX;
89668946

@@ -8990,13 +8970,13 @@ static struct bpf_insn *bpf_convert_tstamp_write(const struct bpf_prog *prog,
89908970
__u8 skb_reg = si->dst_reg;
89918971

89928972
#ifdef CONFIG_NET_CLS_ACT
8993-
/* If the delivery_time_type is read,
8973+
/* If the tstamp_type is read,
89948974
* the bpf prog is aware the tstamp could have delivery time.
8995-
* Thus, write skb->tstamp as is if delivery_time_access is true.
8975+
* Thus, write skb->tstamp as is if tstamp_type_access is true.
89968976
* Otherwise, writing at ingress will have to clear the
89978977
* mono_delivery_time bit also.
89988978
*/
8999-
if (!prog->delivery_time_access) {
8979+
if (!prog->tstamp_type_access) {
90008980
__u8 tmp_reg = BPF_REG_AX;
90018981

90028982
*insn++ = BPF_LDX_MEM(BPF_B, tmp_reg, skb_reg, PKT_VLAN_PRESENT_OFFSET);
@@ -9329,8 +9309,8 @@ static u32 bpf_convert_ctx_access(enum bpf_access_type type,
93299309
insn = bpf_convert_tstamp_read(prog, si, insn);
93309310
break;
93319311

9332-
case offsetof(struct __sk_buff, delivery_time_type):
9333-
insn = bpf_convert_dtime_type_read(si, insn);
9312+
case offsetof(struct __sk_buff, tstamp_type):
9313+
insn = bpf_convert_tstamp_type_read(si, insn);
93349314
break;
93359315

93369316
case offsetof(struct __sk_buff, gso_segs):

‎tools/include/uapi/linux/bpf.h‎

Lines changed: 21 additions & 19 deletions
Original file line numberDiff line numberDiff line change
@@ -5090,23 +5090,22 @@ union bpf_attr {
50905090
* 0 on success, or a negative error in case of failure. On error
50915091
* *dst* buffer is zeroed out.
50925092
*
5093-
* long bpf_skb_set_delivery_time(struct sk_buff *skb, u64 dtime, u32 dtime_type)
5093+
* long bpf_skb_set_tstamp(struct sk_buff *skb, u64 tstamp, u32 tstamp_type)
50945094
* Description
5095-
* Set a *dtime* (delivery time) to the __sk_buff->tstamp and also
5096-
* change the __sk_buff->delivery_time_type to *dtime_type*.
5095+
* Change the __sk_buff->tstamp_type to *tstamp_type*
5096+
* and set *tstamp* to the __sk_buff->tstamp together.
50975097
*
5098-
* When setting a delivery time (non zero *dtime*) to
5099-
* __sk_buff->tstamp, only BPF_SKB_DELIVERY_TIME_MONO *dtime_type*
5100-
* is supported. It is the only delivery_time_type that will be
5101-
* kept after bpf_redirect_*().
5102-
*
5103-
* If there is no need to change the __sk_buff->delivery_time_type,
5104-
* the delivery time can be directly written to __sk_buff->tstamp
5098+
* If there is no need to change the __sk_buff->tstamp_type,
5099+
* the tstamp value can be directly written to __sk_buff->tstamp
51055100
* instead.
51065101
*
5107-
* *dtime* 0 and *dtime_type* BPF_SKB_DELIVERY_TIME_NONE
5108-
* can be used to clear any delivery time stored in
5109-
* __sk_buff->tstamp.
5102+
* BPF_SKB_TSTAMP_DELIVERY_MONO is the only tstamp that
5103+
* will be kept during bpf_redirect_*(). A non zero
5104+
* *tstamp* must be used with the BPF_SKB_TSTAMP_DELIVERY_MONO
5105+
* *tstamp_type*.
5106+
*
5107+
* A BPF_SKB_TSTAMP_UNSPEC *tstamp_type* can only be used
5108+
* with a zero *tstamp*.
51105109
*
51115110
* Only IPv4 and IPv6 skb->protocol are supported.
51125111
*
@@ -5119,7 +5118,7 @@ union bpf_attr {
51195118
* Return
51205119
* 0 on success.
51215120
* **-EINVAL** for invalid input
5122-
* **-EOPNOTSUPP** for unsupported delivery_time_type and protocol
5121+
* **-EOPNOTSUPP** for unsupported protocol
51235122
*/
51245123
#define __BPF_FUNC_MAPPER(FN) \
51255124
FN(unspec), \
@@ -5314,7 +5313,7 @@ union bpf_attr {
53145313
FN(xdp_load_bytes), \
53155314
FN(xdp_store_bytes), \
53165315
FN(copy_from_user_task), \
5317-
FN(skb_set_delivery_time), \
5316+
FN(skb_set_tstamp), \
53185317
/* */
53195318

53205319
/* integer value in 'imm' field of BPF_CALL instruction selects which helper
@@ -5505,9 +5504,12 @@ union { \
55055504
} __attribute__((aligned(8)))
55065505

55075506
enum {
5508-
BPF_SKB_DELIVERY_TIME_NONE,
5509-
BPF_SKB_DELIVERY_TIME_UNSPEC,
5510-
BPF_SKB_DELIVERY_TIME_MONO,
5507+
BPF_SKB_TSTAMP_UNSPEC,
5508+
BPF_SKB_TSTAMP_DELIVERY_MONO, /* tstamp has mono delivery time */
5509+
/* For any BPF_SKB_TSTAMP_* that the bpf prog cannot handle,
5510+
* the bpf prog should handle it like BPF_SKB_TSTAMP_UNSPEC
5511+
* and try to deduce it by ingress, egress or skb->sk->sk_clockid.
5512+
*/
55115513
};
55125514

55135515
/* user accessible mirror of in-kernel sk_buff.
@@ -5550,7 +5552,7 @@ struct __sk_buff {
55505552
__u32 gso_segs;
55515553
__bpf_md_ptr(struct bpf_sock *, sk);
55525554
__u32 gso_size;
5553-
__u8 delivery_time_type;
5555+
__u8 tstamp_type;
55545556
__u32 :24; /* Padding, future use. */
55555557
__u64 hwtstamp;
55565558
};

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