fs/nfs/sysfs.c

   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
  23 static void nfs_netns_object_release(struct kobject *kobj)
  24 {
  25         kfree(kobj);
  26 }
  27
  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
  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
  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
  70 void nfs_sysfs_exit(void)
  71 {
  72         kobject_put(nfs_client_kobj);
  73         kset_unregister(nfs_client_kset);
  74 }
  75
  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' */
  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
  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
 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
 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
 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
 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
 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 }