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/b181acbe-caf8-502d-4b7b-7d96b9fc5d55@iogearbox.net/

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 <kafai@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20220309090509.3712315-1-kafai@fb.com

diff --git a/include/linux/filter.h b/include/linux/filter.h
index 9bf2630..05ed9bd 100644 (file)
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -573,7 +573,7 @@ struct bpf_prog {
                                enforce_expected_attach_type:1, /* Enforce expected_attach_type checking at attach time */
                                call_get_stack:1, /* Do we call bpf_get_stack() or bpf_get_stackid() */
                                call_get_func_ip:1, /* Do we call get_func_ip() */
-                               delivery_time_access:1; /* Accessed __sk_buff->delivery_time_type */
+                               tstamp_type_access:1; /* Accessed __sk_buff->tstamp_type */
        enum bpf_prog_type      type;           /* Type of BPF program */
        enum bpf_attach_type    expected_attach_type; /* For some prog types */
        u32                     len;            /* Number of filter blocks */

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index bc23020..d288a0a 100644 (file)
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -5090,23 +5090,22 @@ union bpf_attr {
  *             0 on success, or a negative error in case of failure. On error
  *             *dst* buffer is zeroed out.
  *
- * long bpf_skb_set_delivery_time(struct sk_buff *skb, u64 dtime, u32 dtime_type)
+ * long bpf_skb_set_tstamp(struct sk_buff *skb, u64 tstamp, u32 tstamp_type)
  *     Description
- *             Set a *dtime* (delivery time) to the __sk_buff->tstamp and also
- *             change the __sk_buff->delivery_time_type to *dtime_type*.
+ *             Change the __sk_buff->tstamp_type to *tstamp_type*
+ *             and set *tstamp* to the __sk_buff->tstamp together.
  *
- *             When setting a delivery time (non zero *dtime*) to
- *             __sk_buff->tstamp, only BPF_SKB_DELIVERY_TIME_MONO *dtime_type*
- *             is supported.  It is the only delivery_time_type that will be
- *             kept after bpf_redirect_*().
- *
- *             If there is no need to change the __sk_buff->delivery_time_type,
- *             the delivery time can be directly written to __sk_buff->tstamp
+ *             If there is no need to change the __sk_buff->tstamp_type,
+ *             the tstamp value can be directly written to __sk_buff->tstamp
  *             instead.
  *
- *             *dtime* 0 and *dtime_type* BPF_SKB_DELIVERY_TIME_NONE
- *             can be used to clear any delivery time stored in
- *             __sk_buff->tstamp.
+ *             BPF_SKB_TSTAMP_DELIVERY_MONO is the only tstamp that
+ *             will be kept during bpf_redirect_*().  A non zero
+ *             *tstamp* must be used with the BPF_SKB_TSTAMP_DELIVERY_MONO
+ *             *tstamp_type*.
+ *
+ *             A BPF_SKB_TSTAMP_UNSPEC *tstamp_type* can only be used
+ *             with a zero *tstamp*.
  *
  *             Only IPv4 and IPv6 skb->protocol are supported.
  *
@@ -5119,7 +5118,7 @@ union bpf_attr {
  *     Return
  *             0 on success.
  *             **-EINVAL** for invalid input
- *             **-EOPNOTSUPP** for unsupported delivery_time_type and protocol
+ *             **-EOPNOTSUPP** for unsupported protocol
  */
 #define __BPF_FUNC_MAPPER(FN)          \
        FN(unspec),                     \
@@ -5314,7 +5313,7 @@ union bpf_attr {
        FN(xdp_load_bytes),             \
        FN(xdp_store_bytes),            \
        FN(copy_from_user_task),        \
-       FN(skb_set_delivery_time),      \
+       FN(skb_set_tstamp),             \
        /* */
 
 /* integer value in 'imm' field of BPF_CALL instruction selects which helper
@@ -5505,9 +5504,12 @@ union {                                  \
 } __attribute__((aligned(8)))
 
 enum {
-       BPF_SKB_DELIVERY_TIME_NONE,
-       BPF_SKB_DELIVERY_TIME_UNSPEC,
-       BPF_SKB_DELIVERY_TIME_MONO,
+       BPF_SKB_TSTAMP_UNSPEC,
+       BPF_SKB_TSTAMP_DELIVERY_MONO,   /* tstamp has mono delivery time */
+       /* For any BPF_SKB_TSTAMP_* that the bpf prog cannot handle,
+        * the bpf prog should handle it like BPF_SKB_TSTAMP_UNSPEC
+        * and try to deduce it by ingress, egress or skb->sk->sk_clockid.
+        */
 };
 
 /* user accessible mirror of in-kernel sk_buff.
@@ -5550,7 +5552,7 @@ struct __sk_buff {
        __u32 gso_segs;
        __bpf_md_ptr(struct bpf_sock *, sk);
        __u32 gso_size;
-       __u8  delivery_time_type;
+       __u8  tstamp_type;
        __u32 :24;              /* Padding, future use. */
        __u64 hwtstamp;
 };

diff --git a/net/core/filter.c b/net/core/filter.c
index f914e4b..03655f2 100644 (file)
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -7388,36 +7388,36 @@ 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)
+BPF_CALL_3(bpf_skb_set_tstamp, struct sk_buff *, skb,
+          u64, tstamp, u32, tstamp_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)
+       switch (tstamp_type) {
+       case BPF_SKB_TSTAMP_DELIVERY_MONO:
+               if (!tstamp)
                        return -EINVAL;
-               skb->tstamp = dtime;
+               skb->tstamp = tstamp;
                skb->mono_delivery_time = 1;
                break;
-       case BPF_SKB_DELIVERY_TIME_NONE:
-               if (dtime)
+       case BPF_SKB_TSTAMP_UNSPEC:
+               if (tstamp)
                        return -EINVAL;
                skb->tstamp = 0;
                skb->mono_delivery_time = 0;
                break;
        default:
-               return -EOPNOTSUPP;
+               return -EINVAL;
        }
 
        return 0;
 }
 
-static const struct bpf_func_proto bpf_skb_set_delivery_time_proto = {
-       .func           = bpf_skb_set_delivery_time,
+static const struct bpf_func_proto bpf_skb_set_tstamp_proto = {
+       .func           = bpf_skb_set_tstamp,
        .gpl_only       = false,
        .ret_type       = RET_INTEGER,
        .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)
                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;
+       case BPF_FUNC_skb_set_tstamp:
+               return &bpf_skb_set_tstamp_proto;
 #endif
        default:
                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
                        return false;
                info->reg_type = PTR_TO_SOCK_COMMON_OR_NULL;
                break;
-       case offsetof(struct __sk_buff, delivery_time_type):
+       case offsetof(struct __sk_buff, tstamp_type):
                return false;
-       case offsetofend(struct __sk_buff, delivery_time_type) ... offsetof(struct __sk_buff, hwtstamp) - 1:
+       case offsetofend(struct __sk_buff, tstamp_type) ... offsetof(struct __sk_buff, hwtstamp) - 1:
                /* Explicitly prohibit access to padding in __sk_buff. */
                return false;
        default:
@@ -8484,14 +8484,14 @@ 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):
+       case offsetof(struct __sk_buff, tstamp_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
+                * has used __sk_buff->tstamp_type or not.
+                * Thus, we need to set prog->tstamp_type_access
                 * earlier during is_valid_access() here.
                 */
-               ((struct bpf_prog *)prog)->delivery_time_access = 1;
+               ((struct bpf_prog *)prog)->tstamp_type_access = 1;
                return size == sizeof(__u8);
        }
 
@@ -8888,42 +8888,22 @@ 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)
+static struct bpf_insn *bpf_convert_tstamp_type_read(const struct bpf_insn *si,
+                                                    struct bpf_insn *insn)
 {
        __u8 value_reg = si->dst_reg;
        __u8 skb_reg = si->src_reg;
+       /* AX is needed because src_reg and dst_reg could be the same */
        __u8 tmp_reg = BPF_REG_AX;
 
        *insn++ = BPF_LDX_MEM(BPF_B, tmp_reg, skb_reg,
                              PKT_VLAN_PRESENT_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, PKT_VLAN_PRESENT_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_JMP32_IMM(BPF_JSET, tmp_reg,
+                               SKB_MONO_DELIVERY_TIME_MASK, 2);
+       *insn++ = BPF_MOV32_IMM(value_reg, BPF_SKB_TSTAMP_UNSPEC);
        *insn++ = BPF_JMP_A(1);
-#endif
-
-       /* value_reg = BPF_SKB_DELIVERYT_TIME_UNSPEC */
-       *insn++ = BPF_MOV32_IMM(value_reg, BPF_SKB_DELIVERY_TIME_UNSPEC);
+       *insn++ = BPF_MOV32_IMM(value_reg, BPF_SKB_TSTAMP_DELIVERY_MONO);
 
-       /* 15 insns with CONFIG_NET_CLS_ACT */
        return insn;
 }
 
@@ -8956,11 +8936,11 @@ static struct bpf_insn *bpf_convert_tstamp_read(const struct bpf_prog *prog,
        __u8 skb_reg = si->src_reg;
 
 #ifdef CONFIG_NET_CLS_ACT
-       /* If the delivery_time_type is read,
+       /* If the tstamp_type is read,
         * the bpf prog is aware the tstamp could have delivery time.
-        * Thus, read skb->tstamp as is if delivery_time_access is true.
+        * Thus, read skb->tstamp as is if tstamp_type_access is true.
         */
-       if (!prog->delivery_time_access) {
+       if (!prog->tstamp_type_access) {
                /* AX is needed because src_reg and dst_reg could be the same */
                __u8 tmp_reg = BPF_REG_AX;
 
@@ -8990,13 +8970,13 @@ static struct bpf_insn *bpf_convert_tstamp_write(const struct bpf_prog *prog,
        __u8 skb_reg = si->dst_reg;
 
 #ifdef CONFIG_NET_CLS_ACT
-       /* If the delivery_time_type is read,
+       /* If the tstamp_type is read,
         * the bpf prog is aware the tstamp could have delivery time.
-        * Thus, write skb->tstamp as is if delivery_time_access is true.
+        * Thus, write skb->tstamp as is if tstamp_type_access is true.
         * Otherwise, writing at ingress will have to clear the
         * mono_delivery_time bit also.
         */
-       if (!prog->delivery_time_access) {
+       if (!prog->tstamp_type_access) {
                __u8 tmp_reg = BPF_REG_AX;
 
                *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,
                        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);
+       case offsetof(struct __sk_buff, tstamp_type):
+               insn = bpf_convert_tstamp_type_read(si, insn);
                break;
 
        case offsetof(struct __sk_buff, gso_segs):

diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index bc23020..d288a0a 100644 (file)
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -5090,23 +5090,22 @@ union bpf_attr {
  *             0 on success, or a negative error in case of failure. On error
  *             *dst* buffer is zeroed out.
  *
- * long bpf_skb_set_delivery_time(struct sk_buff *skb, u64 dtime, u32 dtime_type)
+ * long bpf_skb_set_tstamp(struct sk_buff *skb, u64 tstamp, u32 tstamp_type)
  *     Description
- *             Set a *dtime* (delivery time) to the __sk_buff->tstamp and also
- *             change the __sk_buff->delivery_time_type to *dtime_type*.
+ *             Change the __sk_buff->tstamp_type to *tstamp_type*
+ *             and set *tstamp* to the __sk_buff->tstamp together.
  *
- *             When setting a delivery time (non zero *dtime*) to
- *             __sk_buff->tstamp, only BPF_SKB_DELIVERY_TIME_MONO *dtime_type*
- *             is supported.  It is the only delivery_time_type that will be
- *             kept after bpf_redirect_*().
- *
- *             If there is no need to change the __sk_buff->delivery_time_type,
- *             the delivery time can be directly written to __sk_buff->tstamp
+ *             If there is no need to change the __sk_buff->tstamp_type,
+ *             the tstamp value can be directly written to __sk_buff->tstamp
  *             instead.
  *
- *             *dtime* 0 and *dtime_type* BPF_SKB_DELIVERY_TIME_NONE
- *             can be used to clear any delivery time stored in
- *             __sk_buff->tstamp.
+ *             BPF_SKB_TSTAMP_DELIVERY_MONO is the only tstamp that
+ *             will be kept during bpf_redirect_*().  A non zero
+ *             *tstamp* must be used with the BPF_SKB_TSTAMP_DELIVERY_MONO
+ *             *tstamp_type*.
+ *
+ *             A BPF_SKB_TSTAMP_UNSPEC *tstamp_type* can only be used
+ *             with a zero *tstamp*.
  *
  *             Only IPv4 and IPv6 skb->protocol are supported.
  *
@@ -5119,7 +5118,7 @@ union bpf_attr {
  *     Return
  *             0 on success.
  *             **-EINVAL** for invalid input
- *             **-EOPNOTSUPP** for unsupported delivery_time_type and protocol
+ *             **-EOPNOTSUPP** for unsupported protocol
  */
 #define __BPF_FUNC_MAPPER(FN)          \
        FN(unspec),                     \
@@ -5314,7 +5313,7 @@ union bpf_attr {
        FN(xdp_load_bytes),             \
        FN(xdp_store_bytes),            \
        FN(copy_from_user_task),        \
-       FN(skb_set_delivery_time),      \
+       FN(skb_set_tstamp),             \
        /* */
 
 /* integer value in 'imm' field of BPF_CALL instruction selects which helper
@@ -5505,9 +5504,12 @@ union {                                  \
 } __attribute__((aligned(8)))
 
 enum {
-       BPF_SKB_DELIVERY_TIME_NONE,
-       BPF_SKB_DELIVERY_TIME_UNSPEC,
-       BPF_SKB_DELIVERY_TIME_MONO,
+       BPF_SKB_TSTAMP_UNSPEC,
+       BPF_SKB_TSTAMP_DELIVERY_MONO,   /* tstamp has mono delivery time */
+       /* For any BPF_SKB_TSTAMP_* that the bpf prog cannot handle,
+        * the bpf prog should handle it like BPF_SKB_TSTAMP_UNSPEC
+        * and try to deduce it by ingress, egress or skb->sk->sk_clockid.
+        */
 };
 
 /* user accessible mirror of in-kernel sk_buff.
@@ -5550,7 +5552,7 @@ struct __sk_buff {
        __u32 gso_segs;
        __bpf_md_ptr(struct bpf_sock *, sk);
        __u32 gso_size;
-       __u8  delivery_time_type;
+       __u8  tstamp_type;
        __u32 :24;              /* Padding, future use. */
        __u64 hwtstamp;
 };