Re: [PATCH bpf-next v3 3/5] net/smc: bpf: register smc_ops info struct_ops

[Zhu Yanjun <yanjun.zhu@linux.dev>]

在 2024/12/18 3:44, D. Wythe 写道:
> To implement injection capability for smc via struct_ops, so that
> user can make their own smc_ops to modify the behavior of smc stack.
> 
> Currently, user can write their own implememtion to choose whether to
> use SMC or not before TCP 3rd handshake to be comleted. In the future,
> users can implement more complex functions on smc by expanding it.
> 
> Signed-off-by: D. Wythe <alibuda@linux.alibaba.com>
> ---
>   net/smc/af_smc.c  | 10 +++++
>   net/smc/smc_ops.c | 99 +++++++++++++++++++++++++++++++++++++++++++++++
>   net/smc/smc_ops.h |  2 +
>   3 files changed, 111 insertions(+)
> 
> diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
> index 9d76e902fd77..6adedae2986d 100644
> --- a/net/smc/af_smc.c
> +++ b/net/smc/af_smc.c
> @@ -55,6 +55,7 @@
>   #include "smc_sysctl.h"
>   #include "smc_loopback.h"
>   #include "smc_inet.h"
> +#include "smc_ops.h"
>   
>   static DEFINE_MUTEX(smc_server_lgr_pending);	/* serialize link group
>   						 * creation on server
> @@ -3576,8 +3577,17 @@ static int __init smc_init(void)
>   		pr_err("%s: smc_inet_init fails with %d\n", __func__, rc);
>   		goto out_ulp;
>   	}
> +
> +	rc = smc_bpf_struct_ops_init();
> +	if (rc) {
> +		pr_err("%s: smc_bpf_struct_ops_init fails with %d\n", __func__, rc);
> +		goto out_inet;
> +	}
> +
>   	static_branch_enable(&tcp_have_smc);
>   	return 0;
> +out_inet:
> +	smc_inet_exit();
>   out_ulp:
>   	tcp_unregister_ulp(&smc_ulp_ops);
>   out_lo:
> diff --git a/net/smc/smc_ops.c b/net/smc/smc_ops.c
> index 0fc19cadd760..0f07652f4837 100644
> --- a/net/smc/smc_ops.c
> +++ b/net/smc/smc_ops.c
> @@ -10,6 +10,10 @@
>    *  Author: D. Wythe <alibuda@linux.alibaba.com>
>    */
>   
> +#include <linux/bpf_verifier.h>
> +#include <linux/bpf.h>
> +#include <linux/btf.h>
> +
>   #include "smc_ops.h"
>   
>   static DEFINE_SPINLOCK(smc_ops_list_lock);
> @@ -49,3 +53,98 @@ struct smc_ops *smc_ops_find_by_name(const char *name)
>   	}
>   	return NULL;
>   }
> +
> +static int __bpf_smc_stub_set_tcp_option(struct tcp_sock *tp) { return 1; }
> +static int __bpf_smc_stub_set_tcp_option_cond(const struct tcp_sock *tp,
> +					      struct inet_request_sock *ireq)
> +{
> +	return 1;
> +}
> +
> +static struct smc_ops __bpf_smc_bpf_ops = {
> +	.set_option		= __bpf_smc_stub_set_tcp_option,
> +	.set_option_cond	= __bpf_smc_stub_set_tcp_option_cond,
> +};
> +
> +static int smc_bpf_ops_init(struct btf *btf) { return 0; }
> +
> +static int smc_bpf_ops_reg(void *kdata, struct bpf_link *link)
> +{
> +	return smc_ops_reg(kdata);
> +}
> +
> +static void smc_bpf_ops_unreg(void *kdata, struct bpf_link *link)
> +{
> +	smc_ops_unreg(kdata);
> +}
> +
> +static int smc_bpf_ops_init_member(const struct btf_type *t,
> +				   const struct btf_member *member,
> +				   void *kdata, const void *udata)
> +{
> +	const struct smc_ops *u_ops;
> +	struct smc_ops *k_ops;
> +	u32 moff;
> +
> +	u_ops = (const struct smc_ops *)udata;
> +	k_ops = (struct smc_ops *)kdata;
> +
> +	moff = __btf_member_bit_offset(t, member) / 8;
> +	switch (moff) {
> +	case offsetof(struct smc_ops, name):
> +		if (bpf_obj_name_cpy(k_ops->name, u_ops->name,
> +				     sizeof(u_ops->name)) <= 0)
> +			return -EINVAL;
> +		return 1;
> +	case offsetof(struct smc_ops, flags):
> +		if (u_ops->flags & ~SMC_OPS_ALL_FLAGS)
> +			return -EINVAL;
> +		k_ops->flags = u_ops->flags;
> +		return 1;
> +	default:
> +		break;
> +	}
> +
> +	return 0;
> +}
> +
> +static int smc_bpf_ops_check_member(const struct btf_type *t,
> +				    const struct btf_member *member,
> +				    const struct bpf_prog *prog)
> +{
> +	u32 moff = __btf_member_bit_offset(t, member) / 8;
> +
> +	switch (moff) {
> +	case offsetof(struct smc_ops, name):
> +	case offsetof(struct smc_ops, flags):
> +	case offsetof(struct smc_ops, set_option):
> +	case offsetof(struct smc_ops, set_option_cond):
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +
> +	return 0;
> +}
> +
> +static const struct bpf_verifier_ops smc_bpf_verifier_ops = {
> +	.get_func_proto		= bpf_base_func_proto,
> +	.is_valid_access	= bpf_tracing_btf_ctx_access,
> +};
> +
> +static struct bpf_struct_ops bpf_smc_bpf_ops = {
> +	.name		= "smc_ops",
> +	.init		= smc_bpf_ops_init,
> +	.reg		= smc_bpf_ops_reg,
> +	.unreg		= smc_bpf_ops_unreg,
> +	.cfi_stubs	= &__bpf_smc_bpf_ops,
> +	.verifier_ops	= &smc_bpf_verifier_ops,
> +	.init_member	= smc_bpf_ops_init_member,
> +	.check_member	= smc_bpf_ops_check_member,
> +	.owner		= THIS_MODULE,
> +};
> +
> +int smc_bpf_struct_ops_init(void)
> +{
> +	return register_bpf_struct_ops(&bpf_smc_bpf_ops, smc_ops);
> +}
> diff --git a/net/smc/smc_ops.h b/net/smc/smc_ops.h
> index 214f4c99efd4..f4e50eae13f6 100644
> --- a/net/smc/smc_ops.h
> +++ b/net/smc/smc_ops.h
> @@ -22,8 +22,10 @@
>    * Note: Caller MUST ensure it's was invoked under rcu_read_lock.
>    */
>   struct smc_ops *smc_ops_find_by_name(const char *name);
> +int smc_bpf_struct_ops_init(void);
>   #else
>   static inline struct smc_ops *smc_ops_find_by_name(const char *name) { return NULL; }
> +static inline int smc_bpf_struct_ops_init(void) { return 0; }

Both smc_ops_find_by_name and smc_bpf_struct_ops_init seem to be dead 
codes. Enabling/Disabling CONFIG_SMC_OPS, the above 2 inline functions 
will not be called. The 2 functions should be removed.

Zhu Yanjun

>   #endif /* CONFIG_SMC_OPS*/
>   
>   #endif /* __SMC_OPS */