1 files changed, 475 insertions, 0 deletions

diff --git a/net/sched/bpf_qdisc.c b/net/sched/bpf_qdisc.c
new file mode 100644
index 000000000000..7ea8b54b2ab1
--- /dev/null
+++ b/net/sched/bpf_qdisc.c
@@ -0,0 +1,475 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/types.h>
+#include <linux/bpf_verifier.h>
+#include <linux/bpf.h>
+#include <linux/btf.h>
+#include <linux/filter.h>
+#include <net/pkt_sched.h>
+#include <net/pkt_cls.h>
+
+#define QDISC_OP_IDX(op)	(offsetof(struct Qdisc_ops, op) / sizeof(void (*)(void)))
+#define QDISC_MOFF_IDX(moff)	(moff / sizeof(void (*)(void)))
+
+static struct bpf_struct_ops bpf_Qdisc_ops;
+
+struct bpf_sched_data {
+	struct qdisc_watchdog watchdog;
+};
+
+struct bpf_sk_buff_ptr {
+	struct sk_buff *skb;
+};
+
+static int bpf_qdisc_init(struct btf *btf)
+{
+	return 0;
+}
+
+BTF_ID_LIST_SINGLE(bpf_qdisc_ids, struct, Qdisc)
+BTF_ID_LIST_SINGLE(bpf_sk_buff_ids, struct, sk_buff)
+BTF_ID_LIST_SINGLE(bpf_sk_buff_ptr_ids, struct, bpf_sk_buff_ptr)
+
+static bool bpf_qdisc_is_valid_access(int off, int size,
+				      enum bpf_access_type type,
+				      const struct bpf_prog *prog,
+				      struct bpf_insn_access_aux *info)
+{
+	struct btf *btf = prog->aux->attach_btf;
+	u32 arg;
+
+	arg = btf_ctx_arg_idx(btf, prog->aux->attach_func_proto, off);
+	if (prog->aux->attach_st_ops_member_off == offsetof(struct Qdisc_ops, enqueue)) {
+		if (arg == 2 && type == BPF_READ) {
+			info->reg_type = PTR_TO_BTF_ID | PTR_TRUSTED;
+			info->btf = btf;
+			info->btf_id = bpf_sk_buff_ptr_ids[0];
+			return true;
+		}
+	}
+
+	return bpf_tracing_btf_ctx_access(off, size, type, prog, info);
+}
+
+static int bpf_qdisc_qdisc_access(struct bpf_verifier_log *log,
+				  const struct bpf_reg_state *reg,
+				  int off, size_t *end)
+{
+	switch (off) {
+	case offsetof(struct Qdisc, limit):
+		*end = offsetofend(struct Qdisc, limit);
+		break;
+	case offsetof(struct Qdisc, q) + offsetof(struct qdisc_skb_head, qlen):
+		*end = offsetof(struct Qdisc, q) + offsetofend(struct qdisc_skb_head, qlen);
+		break;
+	case offsetof(struct Qdisc, qstats) ... offsetofend(struct Qdisc, qstats) - 1:
+		*end = offsetofend(struct Qdisc, qstats);
+		break;
+	default:
+		return -EACCES;
+	}
+
+	return 0;
+}
+
+static int bpf_qdisc_sk_buff_access(struct bpf_verifier_log *log,
+				    const struct bpf_reg_state *reg,
+				    int off, size_t *end)
+{
+	switch (off) {
+	case offsetof(struct sk_buff, tstamp):
+		*end = offsetofend(struct sk_buff, tstamp);
+		break;
+	case offsetof(struct sk_buff, cb) + offsetof(struct qdisc_skb_cb, data[0]) ...
+	     offsetof(struct sk_buff, cb) + offsetof(struct qdisc_skb_cb,
+						     data[QDISC_CB_PRIV_LEN - 1]):
+		*end = offsetof(struct sk_buff, cb) +
+		       offsetofend(struct qdisc_skb_cb, data[QDISC_CB_PRIV_LEN - 1]);
+		break;
+	default:
+		return -EACCES;
+	}
+
+	return 0;
+}
+
+static int bpf_qdisc_btf_struct_access(struct bpf_verifier_log *log,
+				       const struct bpf_reg_state *reg,
+				       int off, int size)
+{
+	const struct btf_type *t, *skbt, *qdisct;
+	size_t end;
+	int err;
+
+	skbt = btf_type_by_id(reg->btf, bpf_sk_buff_ids[0]);
+	qdisct = btf_type_by_id(reg->btf, bpf_qdisc_ids[0]);
+	t = btf_type_by_id(reg->btf, reg->btf_id);
+
+	if (t == skbt) {
+		err = bpf_qdisc_sk_buff_access(log, reg, off, &end);
+	} else if (t == qdisct) {
+		err = bpf_qdisc_qdisc_access(log, reg, off, &end);
+	} else {
+		bpf_log(log, "only read is supported\n");
+		return -EACCES;
+	}
+
+	if (err) {
+		bpf_log(log, "no write support to %s at off %d\n",
+			btf_name_by_offset(reg->btf, t->name_off), off);
+		return -EACCES;
+	}
+
+	if (off + size > end) {
+		bpf_log(log,
+			"write access at off %d with size %d beyond the member of %s ended at %zu\n",
+			off, size, btf_name_by_offset(reg->btf, t->name_off), end);
+		return -EACCES;
+	}
+
+	return 0;
+}
+
+BTF_ID_LIST(bpf_qdisc_init_prologue_ids)
+BTF_ID(func, bpf_qdisc_init_prologue)
+
+static int bpf_qdisc_gen_prologue(struct bpf_insn *insn_buf, bool direct_write,
+				  const struct bpf_prog *prog)
+{
+	struct bpf_insn *insn = insn_buf;
+
+	if (prog->aux->attach_st_ops_member_off != offsetof(struct Qdisc_ops, init))
+		return 0;
+
+	/* r6 = r1; // r6 will be "u64 *ctx". r1 is "u64 *ctx".
+	 * r2 = r1[16]; // r2 will be "struct netlink_ext_ack *extack"
+	 * r1 = r1[0]; // r1 will be "struct Qdisc *sch"
+	 * r0 = bpf_qdisc_init_prologue(r1, r2);
+	 * if r0 == 0 goto pc+1;
+	 * BPF_EXIT;
+	 * r1 = r6; // r1 will be "u64 *ctx".
+	 */
+	*insn++ = BPF_MOV64_REG(BPF_REG_6, BPF_REG_1);
+	*insn++ = BPF_LDX_MEM(BPF_DW, BPF_REG_2, BPF_REG_1, 16);
+	*insn++ = BPF_LDX_MEM(BPF_DW, BPF_REG_1, BPF_REG_1, 0);
+	*insn++ = BPF_CALL_KFUNC(0, bpf_qdisc_init_prologue_ids[0]);
+	*insn++ = BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 1);
+	*insn++ = BPF_EXIT_INSN();
+	*insn++ = BPF_MOV64_REG(BPF_REG_1, BPF_REG_6);
+	*insn++ = prog->insnsi[0];
+
+	return insn - insn_buf;
+}
+
+BTF_ID_LIST(bpf_qdisc_reset_destroy_epilogue_ids)
+BTF_ID(func, bpf_qdisc_reset_destroy_epilogue)
+
+static int bpf_qdisc_gen_epilogue(struct bpf_insn *insn_buf, const struct bpf_prog *prog,
+				  s16 ctx_stack_off)
+{
+	struct bpf_insn *insn = insn_buf;
+
+	if (prog->aux->attach_st_ops_member_off != offsetof(struct Qdisc_ops, reset) &&
+	    prog->aux->attach_st_ops_member_off != offsetof(struct Qdisc_ops, destroy))
+		return 0;
+
+	/* r1 = stack[ctx_stack_off]; // r1 will be "u64 *ctx"
+	 * r1 = r1[0]; // r1 will be "struct Qdisc *sch"
+	 * r0 = bpf_qdisc_reset_destroy_epilogue(r1);
+	 * BPF_EXIT;
+	 */
+	*insn++ = BPF_LDX_MEM(BPF_DW, BPF_REG_1, BPF_REG_FP, ctx_stack_off);
+	*insn++ = BPF_LDX_MEM(BPF_DW, BPF_REG_1, BPF_REG_1, 0);
+	*insn++ = BPF_CALL_KFUNC(0, bpf_qdisc_reset_destroy_epilogue_ids[0]);
+	*insn++ = BPF_EXIT_INSN();
+
+	return insn - insn_buf;
+}
+
+__bpf_kfunc_start_defs();
+
+/* bpf_skb_get_hash - Get the flow hash of an skb.
+ * @skb: The skb to get the flow hash from.
+ */
+__bpf_kfunc u32 bpf_skb_get_hash(struct sk_buff *skb)
+{
+	return skb_get_hash(skb);
+}
+
+/* bpf_kfree_skb - Release an skb's reference and drop it immediately.
+ * @skb: The skb whose reference to be released and dropped.
+ */
+__bpf_kfunc void bpf_kfree_skb(struct sk_buff *skb)
+{
+	kfree_skb(skb);
+}
+
+/* bpf_qdisc_skb_drop - Drop an skb by adding it to a deferred free list.
+ * @skb: The skb whose reference to be released and dropped.
+ * @to_free_list: The list of skbs to be dropped.
+ */
+__bpf_kfunc void bpf_qdisc_skb_drop(struct sk_buff *skb,
+				    struct bpf_sk_buff_ptr *to_free_list)
+{
+	__qdisc_drop(skb, (struct sk_buff **)to_free_list);
+}
+
+/* bpf_qdisc_watchdog_schedule - Schedule a qdisc to a later time using a timer.
+ * @sch: The qdisc to be scheduled.
+ * @expire: The expiry time of the timer.
+ * @delta_ns: The slack range of the timer.
+ */
+__bpf_kfunc void bpf_qdisc_watchdog_schedule(struct Qdisc *sch, u64 expire, u64 delta_ns)
+{
+	struct bpf_sched_data *q = qdisc_priv(sch);
+
+	qdisc_watchdog_schedule_range_ns(&q->watchdog, expire, delta_ns);
+}
+
+/* bpf_qdisc_init_prologue - Hidden kfunc called in prologue of .init. */
+__bpf_kfunc int bpf_qdisc_init_prologue(struct Qdisc *sch,
+					struct netlink_ext_ack *extack)
+{
+	struct bpf_sched_data *q = qdisc_priv(sch);
+	struct net_device *dev = qdisc_dev(sch);
+	struct Qdisc *p;
+
+	qdisc_watchdog_init(&q->watchdog, sch);
+
+	if (sch->parent != TC_H_ROOT) {
+		/* If qdisc_lookup() returns NULL, it means .init is called by
+		 * qdisc_create_dflt() in mq/mqprio_init and the parent qdisc
+		 * has not been added to qdisc_hash yet.
+		 */
+		p = qdisc_lookup(dev, TC_H_MAJ(sch->parent));
+		if (p && !(p->flags & TCQ_F_MQROOT)) {
+			NL_SET_ERR_MSG(extack, "BPF qdisc only supported on root or mq");
+			return -EINVAL;
+		}
+	}
+
+	return 0;
+}
+
+/* bpf_qdisc_reset_destroy_epilogue - Hidden kfunc called in epilogue of .reset
+ * and .destroy
+ */
+__bpf_kfunc void bpf_qdisc_reset_destroy_epilogue(struct Qdisc *sch)
+{
+	struct bpf_sched_data *q = qdisc_priv(sch);
+
+	qdisc_watchdog_cancel(&q->watchdog);
+}
+
+/* bpf_qdisc_bstats_update - Update Qdisc basic statistics
+ * @sch: The qdisc from which an skb is dequeued.
+ * @skb: The skb to be dequeued.
+ */
+__bpf_kfunc void bpf_qdisc_bstats_update(struct Qdisc *sch, const struct sk_buff *skb)
+{
+	bstats_update(&sch->bstats, skb);
+}
+
+__bpf_kfunc_end_defs();
+
+BTF_KFUNCS_START(qdisc_kfunc_ids)
+BTF_ID_FLAGS(func, bpf_skb_get_hash, KF_TRUSTED_ARGS)
+BTF_ID_FLAGS(func, bpf_kfree_skb, KF_RELEASE)
+BTF_ID_FLAGS(func, bpf_qdisc_skb_drop, KF_RELEASE)
+BTF_ID_FLAGS(func, bpf_dynptr_from_skb, KF_TRUSTED_ARGS)
+BTF_ID_FLAGS(func, bpf_qdisc_watchdog_schedule, KF_TRUSTED_ARGS)
+BTF_ID_FLAGS(func, bpf_qdisc_init_prologue, KF_TRUSTED_ARGS)
+BTF_ID_FLAGS(func, bpf_qdisc_reset_destroy_epilogue, KF_TRUSTED_ARGS)
+BTF_ID_FLAGS(func, bpf_qdisc_bstats_update, KF_TRUSTED_ARGS)
+BTF_KFUNCS_END(qdisc_kfunc_ids)
+
+BTF_SET_START(qdisc_common_kfunc_set)
+BTF_ID(func, bpf_skb_get_hash)
+BTF_ID(func, bpf_kfree_skb)
+BTF_ID(func, bpf_dynptr_from_skb)
+BTF_SET_END(qdisc_common_kfunc_set)
+
+BTF_SET_START(qdisc_enqueue_kfunc_set)
+BTF_ID(func, bpf_qdisc_skb_drop)
+BTF_ID(func, bpf_qdisc_watchdog_schedule)
+BTF_SET_END(qdisc_enqueue_kfunc_set)
+
+BTF_SET_START(qdisc_dequeue_kfunc_set)
+BTF_ID(func, bpf_qdisc_watchdog_schedule)
+BTF_ID(func, bpf_qdisc_bstats_update)
+BTF_SET_END(qdisc_dequeue_kfunc_set)
+
+enum qdisc_ops_kf_flags {
+	QDISC_OPS_KF_COMMON		= 0,
+	QDISC_OPS_KF_ENQUEUE		= 1 << 0,
+	QDISC_OPS_KF_DEQUEUE		= 1 << 1,
+};
+
+static const u32 qdisc_ops_context_flags[] = {
+	[QDISC_OP_IDX(enqueue)]		= QDISC_OPS_KF_ENQUEUE,
+	[QDISC_OP_IDX(dequeue)]		= QDISC_OPS_KF_DEQUEUE,
+	[QDISC_OP_IDX(init)]		= QDISC_OPS_KF_COMMON,
+	[QDISC_OP_IDX(reset)]		= QDISC_OPS_KF_COMMON,
+	[QDISC_OP_IDX(destroy)]		= QDISC_OPS_KF_COMMON,
+};
+
+static int bpf_qdisc_kfunc_filter(const struct bpf_prog *prog, u32 kfunc_id)
+{
+	u32 moff, flags;
+
+	if (!btf_id_set8_contains(&qdisc_kfunc_ids, kfunc_id))
+		return 0;
+
+	if (prog->aux->st_ops != &bpf_Qdisc_ops)
+		return -EACCES;
+
+	moff = prog->aux->attach_st_ops_member_off;
+	flags = qdisc_ops_context_flags[QDISC_MOFF_IDX(moff)];
+
+	if ((flags & QDISC_OPS_KF_ENQUEUE) &&
+	    btf_id_set_contains(&qdisc_enqueue_kfunc_set, kfunc_id))
+		return 0;
+
+	if ((flags & QDISC_OPS_KF_DEQUEUE) &&
+	    btf_id_set_contains(&qdisc_dequeue_kfunc_set, kfunc_id))
+		return 0;
+
+	if (btf_id_set_contains(&qdisc_common_kfunc_set, kfunc_id))
+		return 0;
+
+	return -EACCES;
+}
+
+static const struct btf_kfunc_id_set bpf_qdisc_kfunc_set = {
+	.owner = THIS_MODULE,
+	.set   = &qdisc_kfunc_ids,
+	.filter = bpf_qdisc_kfunc_filter,
+};
+
+static const struct bpf_verifier_ops bpf_qdisc_verifier_ops = {
+	.get_func_proto		= bpf_base_func_proto,
+	.is_valid_access	= bpf_qdisc_is_valid_access,
+	.btf_struct_access	= bpf_qdisc_btf_struct_access,
+	.gen_prologue		= bpf_qdisc_gen_prologue,
+	.gen_epilogue		= bpf_qdisc_gen_epilogue,
+};
+
+static int bpf_qdisc_init_member(const struct btf_type *t,
+				 const struct btf_member *member,
+				 void *kdata, const void *udata)
+{
+	const struct Qdisc_ops *uqdisc_ops;
+	struct Qdisc_ops *qdisc_ops;
+	u32 moff;
+
+	uqdisc_ops = (const struct Qdisc_ops *)udata;
+	qdisc_ops = (struct Qdisc_ops *)kdata;
+
+	moff = __btf_member_bit_offset(t, member) / 8;
+	switch (moff) {
+	case offsetof(struct Qdisc_ops, priv_size):
+		if (uqdisc_ops->priv_size)
+			return -EINVAL;
+		qdisc_ops->priv_size = sizeof(struct bpf_sched_data);
+		return 1;
+	case offsetof(struct Qdisc_ops, peek):
+		qdisc_ops->peek = qdisc_peek_dequeued;
+		return 0;
+	case offsetof(struct Qdisc_ops, id):
+		if (bpf_obj_name_cpy(qdisc_ops->id, uqdisc_ops->id,
+				     sizeof(qdisc_ops->id)) <= 0)
+			return -EINVAL;
+		return 1;
+	}
+
+	return 0;
+}
+
+static int bpf_qdisc_reg(void *kdata, struct bpf_link *link)
+{
+	return register_qdisc(kdata);
+}
+
+static void bpf_qdisc_unreg(void *kdata, struct bpf_link *link)
+{
+	return unregister_qdisc(kdata);
+}
+
+static int bpf_qdisc_validate(void *kdata)
+{
+	struct Qdisc_ops *ops = (struct Qdisc_ops *)kdata;
+
+	if (!ops->enqueue || !ops->dequeue || !ops->init ||
+	    !ops->reset || !ops->destroy)
+		return -EINVAL;
+
+	return 0;
+}
+
+static int Qdisc_ops__enqueue(struct sk_buff *skb__ref, struct Qdisc *sch,
+			      struct sk_buff **to_free)
+{
+	return 0;
+}
+
+static struct sk_buff *Qdisc_ops__dequeue(struct Qdisc *sch)
+{
+	return NULL;
+}
+
+static int Qdisc_ops__init(struct Qdisc *sch, struct nlattr *arg,
+			   struct netlink_ext_ack *extack)
+{
+	return 0;
+}
+
+static void Qdisc_ops__reset(struct Qdisc *sch)
+{
+}
+
+static void Qdisc_ops__destroy(struct Qdisc *sch)
+{
+}
+
+static struct Qdisc_ops __bpf_ops_qdisc_ops = {
+	.enqueue = Qdisc_ops__enqueue,
+	.dequeue = Qdisc_ops__dequeue,
+	.init = Qdisc_ops__init,
+	.reset = Qdisc_ops__reset,
+	.destroy = Qdisc_ops__destroy,
+};
+
+static struct bpf_struct_ops bpf_Qdisc_ops = {
+	.verifier_ops = &bpf_qdisc_verifier_ops,
+	.reg = bpf_qdisc_reg,
+	.unreg = bpf_qdisc_unreg,
+	.validate = bpf_qdisc_validate,
+	.init_member = bpf_qdisc_init_member,
+	.init = bpf_qdisc_init,
+	.name = "Qdisc_ops",
+	.cfi_stubs = &__bpf_ops_qdisc_ops,
+	.owner = THIS_MODULE,
+};
+
+BTF_ID_LIST(bpf_sk_buff_dtor_ids)
+BTF_ID(func, bpf_kfree_skb)
+
+static int __init bpf_qdisc_kfunc_init(void)
+{
+	int ret;
+	const struct btf_id_dtor_kfunc skb_kfunc_dtors[] = {
+		{
+			.btf_id       = bpf_sk_buff_ids[0],
+			.kfunc_btf_id = bpf_sk_buff_dtor_ids[0]
+		},
+	};
+
+	ret = register_btf_kfunc_id_set(BPF_PROG_TYPE_STRUCT_OPS, &bpf_qdisc_kfunc_set);
+	ret = ret ?: register_btf_id_dtor_kfuncs(skb_kfunc_dtors,
+						 ARRAY_SIZE(skb_kfunc_dtors),
+						 THIS_MODULE);
+	ret = ret ?: register_bpf_struct_ops(&bpf_Qdisc_ops, Qdisc_ops);
+
+	return ret;
+}
+late_initcall(bpf_qdisc_kfunc_init);