bpf: Refactor to provide aux info to bpf_iter_init_seq_priv_t

This patch refactored target bpf_iter_init_seq_priv_t callback
function to accept additional information. This will be needed
in later patches for map element targets since a particular
map should be passed to traverse elements for that particular
map. In the future, other information may be passed to target
as well, e.g., pid, cgroup id, etc. to customize the iterator.
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200723184110.590156-1-yhs@fb.com

fs/proc/proc_net.c

@@ -98,7 +98,7 @@ static const struct proc_ops proc_net_seq_ops = {
 	.proc_release	= seq_release_net,
 };
 
-int bpf_iter_init_seq_net(void *priv_data)
+int bpf_iter_init_seq_net(void *priv_data, struct bpf_iter_aux_info *aux)
 {
 #ifdef CONFIG_NET_NS
 	struct seq_net_private *p = priv_data;

include/linux/bpf.h

@@ -33,11 +33,13 @@ struct btf;
 struct btf_type;
 struct exception_table_entry;
 struct seq_operations;
+struct bpf_iter_aux_info;
 
 extern struct idr btf_idr;
 extern spinlock_t btf_idr_lock;
 
-typedef int (*bpf_iter_init_seq_priv_t)(void *private_data);
+typedef int (*bpf_iter_init_seq_priv_t)(void *private_data,
+					struct bpf_iter_aux_info *aux);
 typedef void (*bpf_iter_fini_seq_priv_t)(void *private_data);
 struct bpf_iter_seq_info {
 	const struct seq_operations *seq_ops;
@@ -1198,6 +1200,9 @@ int bpf_obj_get_user(const char __user *pathname, int flags);
 	extern int bpf_iter_ ## target(args);			\
 	int __init bpf_iter_ ## target(args) { return 0; }
 
+struct bpf_iter_aux_info {
+};
+
 #define BPF_ITER_CTX_ARG_MAX 2
 struct bpf_iter_reg {
 	const char *target;

include/linux/proc_fs.h

@@ -133,7 +133,8 @@ struct proc_dir_entry *proc_create_net_single_write(const char *name, umode_t mo
 						    void *data);
 extern struct pid *tgid_pidfd_to_pid(const struct file *file);
 
-extern int bpf_iter_init_seq_net(void *priv_data);
+struct bpf_iter_aux_info;
+extern int bpf_iter_init_seq_net(void *priv_data, struct bpf_iter_aux_info *aux);
 extern void bpf_iter_fini_seq_net(void *priv_data);
 
 #ifdef CONFIG_PROC_PID_ARCH_STATUS

kernel/bpf/bpf_iter.c

@@ -442,7 +442,7 @@ static int prepare_seq_file(struct file *file, struct bpf_iter_link *link)
 	}
 
 	if (tinfo->reg_info->seq_info->init_seq_private) {
-		err = tinfo->reg_info->seq_info->init_seq_private(priv_data->target_private);
+		err = tinfo->reg_info->seq_info->init_seq_private(priv_data->target_private, NULL);
 		if (err)
 			goto release_seq_file;
 	}

kernel/bpf/task_iter.c

@@ -293,7 +293,7 @@ static void task_file_seq_stop(struct seq_file *seq, void *v)
 	}
 }
 
-static int init_seq_pidns(void *priv_data)
+static int init_seq_pidns(void *priv_data, struct bpf_iter_aux_info *aux)
 {
 	struct bpf_iter_seq_task_common *common = priv_data;
 

net/ipv4/tcp_ipv4.c

@@ -2921,7 +2921,7 @@ static struct pernet_operations __net_initdata tcp_sk_ops = {
 DEFINE_BPF_ITER_FUNC(tcp, struct bpf_iter_meta *meta,
 		     struct sock_common *sk_common, uid_t uid)
 
-static int bpf_iter_init_tcp(void *priv_data)
+static int bpf_iter_init_tcp(void *priv_data, struct bpf_iter_aux_info *aux)
 {
 	struct tcp_iter_state *st = priv_data;
 	struct tcp_seq_afinfo *afinfo;
@@ -2933,7 +2933,7 @@ static int bpf_iter_init_tcp(void *priv_data)
 
 	afinfo->family = AF_UNSPEC;
 	st->bpf_seq_afinfo = afinfo;
-	ret = bpf_iter_init_seq_net(priv_data);
+	ret = bpf_iter_init_seq_net(priv_data, aux);
 	if (ret)
 		kfree(afinfo);
 	return ret;

net/ipv4/udp.c

@@ -3181,7 +3181,7 @@ static struct pernet_operations __net_initdata udp_sysctl_ops = {
 DEFINE_BPF_ITER_FUNC(udp, struct bpf_iter_meta *meta,
 		     struct udp_sock *udp_sk, uid_t uid, int bucket)
 
-static int bpf_iter_init_udp(void *priv_data)
+static int bpf_iter_init_udp(void *priv_data, struct bpf_iter_aux_info *aux)
 {
 	struct udp_iter_state *st = priv_data;
 	struct udp_seq_afinfo *afinfo;
@@ -3194,7 +3194,7 @@ static int bpf_iter_init_udp(void *priv_data)
 	afinfo->family = AF_UNSPEC;
 	afinfo->udp_table = &udp_table;
 	st->bpf_seq_afinfo = afinfo;
-	ret = bpf_iter_init_seq_net(priv_data);
+	ret = bpf_iter_init_seq_net(priv_data, aux);
 	if (ret)
 		kfree(afinfo);
 	return ret;