1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Copyright (c) 2019 Hammerspace Inc
4  */
5 
6 #include <linux/module.h>
7 #include <linux/kobject.h>
8 #include <linux/sysfs.h>
9 #include <linux/fs.h>
10 #include <linux/slab.h>
11 #include <linux/netdevice.h>
12 #include <linux/string.h>
13 #include <linux/nfs_fs.h>
14 #include <linux/rcupdate.h>
15 
16 #include "nfs4_fs.h"
17 #include "netns.h"
18 #include "sysfs.h"
19 
20 struct kobject *nfs_client_kobj;
21 static struct kset *nfs_client_kset;
22 
nfs_netns_object_release(struct kobject * kobj)23 static void nfs_netns_object_release(struct kobject *kobj)
24 {
25 	kfree(kobj);
26 }
27 
nfs_netns_object_child_ns_type(struct kobject * kobj)28 static const struct kobj_ns_type_operations *nfs_netns_object_child_ns_type(
29 		struct kobject *kobj)
30 {
31 	return &net_ns_type_operations;
32 }
33 
34 static struct kobj_type nfs_netns_object_type = {
35 	.release = nfs_netns_object_release,
36 	.sysfs_ops = &kobj_sysfs_ops,
37 	.child_ns_type = nfs_netns_object_child_ns_type,
38 };
39 
nfs_netns_object_alloc(const char * name,struct kset * kset,struct kobject * parent)40 static struct kobject *nfs_netns_object_alloc(const char *name,
41 		struct kset *kset, struct kobject *parent)
42 {
43 	struct kobject *kobj;
44 
45 	kobj = kzalloc(sizeof(*kobj), GFP_KERNEL);
46 	if (kobj) {
47 		kobj->kset = kset;
48 		if (kobject_init_and_add(kobj, &nfs_netns_object_type,
49 					parent, "%s", name) == 0)
50 			return kobj;
51 		kobject_put(kobj);
52 	}
53 	return NULL;
54 }
55 
nfs_sysfs_init(void)56 int nfs_sysfs_init(void)
57 {
58 	nfs_client_kset = kset_create_and_add("nfs", NULL, fs_kobj);
59 	if (!nfs_client_kset)
60 		return -ENOMEM;
61 	nfs_client_kobj = nfs_netns_object_alloc("net", nfs_client_kset, NULL);
62 	if  (!nfs_client_kobj) {
63 		kset_unregister(nfs_client_kset);
64 		nfs_client_kset = NULL;
65 		return -ENOMEM;
66 	}
67 	return 0;
68 }
69 
nfs_sysfs_exit(void)70 void nfs_sysfs_exit(void)
71 {
72 	kobject_put(nfs_client_kobj);
73 	kset_unregister(nfs_client_kset);
74 }
75 
nfs_netns_identifier_show(struct kobject * kobj,struct kobj_attribute * attr,char * buf)76 static ssize_t nfs_netns_identifier_show(struct kobject *kobj,
77 		struct kobj_attribute *attr, char *buf)
78 {
79 	struct nfs_netns_client *c = container_of(kobj,
80 			struct nfs_netns_client,
81 			kobject);
82 	ssize_t ret;
83 
84 	rcu_read_lock();
85 	ret = scnprintf(buf, PAGE_SIZE, "%s\n", rcu_dereference(c->identifier));
86 	rcu_read_unlock();
87 	return ret;
88 }
89 
90 /* Strip trailing '\n' */
nfs_string_strip(const char * c,size_t len)91 static size_t nfs_string_strip(const char *c, size_t len)
92 {
93 	while (len > 0 && c[len-1] == '\n')
94 		--len;
95 	return len;
96 }
97 
nfs_netns_identifier_store(struct kobject * kobj,struct kobj_attribute * attr,const char * buf,size_t count)98 static ssize_t nfs_netns_identifier_store(struct kobject *kobj,
99 		struct kobj_attribute *attr,
100 		const char *buf, size_t count)
101 {
102 	struct nfs_netns_client *c = container_of(kobj,
103 			struct nfs_netns_client,
104 			kobject);
105 	const char *old;
106 	char *p;
107 	size_t len;
108 
109 	len = nfs_string_strip(buf, min_t(size_t, count, CONTAINER_ID_MAXLEN));
110 	if (!len)
111 		return 0;
112 	p = kmemdup_nul(buf, len, GFP_KERNEL);
113 	if (!p)
114 		return -ENOMEM;
115 	old = rcu_dereference_protected(xchg(&c->identifier, (char __rcu *)p), 1);
116 	if (old) {
117 		synchronize_rcu();
118 		kfree(old);
119 	}
120 	return count;
121 }
122 
nfs_netns_client_release(struct kobject * kobj)123 static void nfs_netns_client_release(struct kobject *kobj)
124 {
125 	struct nfs_netns_client *c = container_of(kobj,
126 			struct nfs_netns_client,
127 			kobject);
128 
129 	kfree(rcu_dereference_raw(c->identifier));
130 	kfree(c);
131 }
132 
nfs_netns_client_namespace(struct kobject * kobj)133 static const void *nfs_netns_client_namespace(struct kobject *kobj)
134 {
135 	return container_of(kobj, struct nfs_netns_client, kobject)->net;
136 }
137 
138 static struct kobj_attribute nfs_netns_client_id = __ATTR(identifier,
139 		0644, nfs_netns_identifier_show, nfs_netns_identifier_store);
140 
141 static struct attribute *nfs_netns_client_attrs[] = {
142 	&nfs_netns_client_id.attr,
143 	NULL,
144 };
145 
146 static struct kobj_type nfs_netns_client_type = {
147 	.release = nfs_netns_client_release,
148 	.default_attrs = nfs_netns_client_attrs,
149 	.sysfs_ops = &kobj_sysfs_ops,
150 	.namespace = nfs_netns_client_namespace,
151 };
152 
nfs_netns_client_alloc(struct kobject * parent,struct net * net)153 static struct nfs_netns_client *nfs_netns_client_alloc(struct kobject *parent,
154 		struct net *net)
155 {
156 	struct nfs_netns_client *p;
157 
158 	p = kzalloc(sizeof(*p), GFP_KERNEL);
159 	if (p) {
160 		p->net = net;
161 		p->kobject.kset = nfs_client_kset;
162 		if (kobject_init_and_add(&p->kobject, &nfs_netns_client_type,
163 					parent, "nfs_client") == 0)
164 			return p;
165 		kobject_put(&p->kobject);
166 	}
167 	return NULL;
168 }
169 
nfs_netns_sysfs_setup(struct nfs_net * netns,struct net * net)170 void nfs_netns_sysfs_setup(struct nfs_net *netns, struct net *net)
171 {
172 	struct nfs_netns_client *clp;
173 
174 	clp = nfs_netns_client_alloc(nfs_client_kobj, net);
175 	if (clp) {
176 		netns->nfs_client = clp;
177 		kobject_uevent(&clp->kobject, KOBJ_ADD);
178 	}
179 }
180 
nfs_netns_sysfs_destroy(struct nfs_net * netns)181 void nfs_netns_sysfs_destroy(struct nfs_net *netns)
182 {
183 	struct nfs_netns_client *clp = netns->nfs_client;
184 
185 	if (clp) {
186 		kobject_uevent(&clp->kobject, KOBJ_REMOVE);
187 		kobject_del(&clp->kobject);
188 		kobject_put(&clp->kobject);
189 		netns->nfs_client = NULL;
190 	}
191 }
192