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TOMOYO Linux Cross Reference
Linux/fs/nsfs.c

Version: ~ [ linux-5.4-rc3 ] ~ [ linux-5.3.6 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.79 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.149 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.196 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.196 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.140 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.75 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-3.9.11 ] ~ [ linux-3.8.13 ] ~ [ linux-3.7.10 ] ~ [ linux-3.6.11 ] ~ [ linux-3.5.7 ] ~ [ linux-3.4.113 ] ~ [ linux-3.3.8 ] ~ [ linux-3.2.102 ] ~ [ linux-3.1.10 ] ~ [ linux-3.0.101 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
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  1 #include <linux/mount.h>
  2 #include <linux/file.h>
  3 #include <linux/fs.h>
  4 #include <linux/proc_ns.h>
  5 #include <linux/magic.h>
  6 #include <linux/ktime.h>
  7 #include <linux/seq_file.h>
  8 
  9 static struct vfsmount *nsfs_mnt;
 10 
 11 static const struct file_operations ns_file_operations = {
 12         .llseek         = no_llseek,
 13 };
 14 
 15 static char *ns_dname(struct dentry *dentry, char *buffer, int buflen)
 16 {
 17         struct inode *inode = d_inode(dentry);
 18         const struct proc_ns_operations *ns_ops = dentry->d_fsdata;
 19 
 20         return dynamic_dname(dentry, buffer, buflen, "%s:[%lu]",
 21                 ns_ops->name, inode->i_ino);
 22 }
 23 
 24 static void ns_prune_dentry(struct dentry *dentry)
 25 {
 26         struct inode *inode = d_inode(dentry);
 27         if (inode) {
 28                 struct ns_common *ns = inode->i_private;
 29                 atomic_long_set(&ns->stashed, 0);
 30         }
 31 }
 32 
 33 const struct dentry_operations ns_dentry_operations =
 34 {
 35         .d_prune        = ns_prune_dentry,
 36         .d_delete       = always_delete_dentry,
 37         .d_dname        = ns_dname,
 38 };
 39 
 40 static void nsfs_evict(struct inode *inode)
 41 {
 42         struct ns_common *ns = inode->i_private;
 43         clear_inode(inode);
 44         ns->ops->put(ns);
 45 }
 46 
 47 void *ns_get_path(struct path *path, struct task_struct *task,
 48                         const struct proc_ns_operations *ns_ops)
 49 {
 50         struct vfsmount *mnt = mntget(nsfs_mnt);
 51         struct qstr qname = { .name = "", };
 52         struct dentry *dentry;
 53         struct inode *inode;
 54         struct ns_common *ns;
 55         unsigned long d;
 56 
 57 again:
 58         ns = ns_ops->get(task);
 59         if (!ns) {
 60                 mntput(mnt);
 61                 return ERR_PTR(-ENOENT);
 62         }
 63         rcu_read_lock();
 64         d = atomic_long_read(&ns->stashed);
 65         if (!d)
 66                 goto slow;
 67         dentry = (struct dentry *)d;
 68         if (!lockref_get_not_dead(&dentry->d_lockref))
 69                 goto slow;
 70         rcu_read_unlock();
 71         ns_ops->put(ns);
 72 got_it:
 73         path->mnt = mnt;
 74         path->dentry = dentry;
 75         return NULL;
 76 slow:
 77         rcu_read_unlock();
 78         inode = new_inode_pseudo(mnt->mnt_sb);
 79         if (!inode) {
 80                 ns_ops->put(ns);
 81                 mntput(mnt);
 82                 return ERR_PTR(-ENOMEM);
 83         }
 84         inode->i_ino = ns->inum;
 85         inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
 86         inode->i_flags |= S_IMMUTABLE;
 87         inode->i_mode = S_IFREG | S_IRUGO;
 88         inode->i_fop = &ns_file_operations;
 89         inode->i_private = ns;
 90 
 91         dentry = d_alloc_pseudo(mnt->mnt_sb, &qname);
 92         if (!dentry) {
 93                 iput(inode);
 94                 mntput(mnt);
 95                 return ERR_PTR(-ENOMEM);
 96         }
 97         d_instantiate(dentry, inode);
 98         dentry->d_fsdata = (void *)ns_ops;
 99         d = atomic_long_cmpxchg(&ns->stashed, 0, (unsigned long)dentry);
100         if (d) {
101                 d_delete(dentry);       /* make sure ->d_prune() does nothing */
102                 dput(dentry);
103                 cpu_relax();
104                 goto again;
105         }
106         goto got_it;
107 }
108 
109 int ns_get_name(char *buf, size_t size, struct task_struct *task,
110                         const struct proc_ns_operations *ns_ops)
111 {
112         struct ns_common *ns;
113         int res = -ENOENT;
114         ns = ns_ops->get(task);
115         if (ns) {
116                 res = snprintf(buf, size, "%s:[%u]", ns_ops->name, ns->inum);
117                 ns_ops->put(ns);
118         }
119         return res;
120 }
121 
122 struct file *proc_ns_fget(int fd)
123 {
124         struct file *file;
125 
126         file = fget(fd);
127         if (!file)
128                 return ERR_PTR(-EBADF);
129 
130         if (file->f_op != &ns_file_operations)
131                 goto out_invalid;
132 
133         return file;
134 
135 out_invalid:
136         fput(file);
137         return ERR_PTR(-EINVAL);
138 }
139 
140 static int nsfs_show_path(struct seq_file *seq, struct dentry *dentry)
141 {
142         struct inode *inode = d_inode(dentry);
143         const struct proc_ns_operations *ns_ops = dentry->d_fsdata;
144 
145         seq_printf(seq, "%s:[%lu]", ns_ops->name, inode->i_ino);
146         return 0;
147 }
148 
149 static const struct super_operations nsfs_ops = {
150         .statfs = simple_statfs,
151         .evict_inode = nsfs_evict,
152         .show_path = nsfs_show_path,
153 };
154 static struct dentry *nsfs_mount(struct file_system_type *fs_type,
155                         int flags, const char *dev_name, void *data)
156 {
157         return mount_pseudo(fs_type, "nsfs:", &nsfs_ops,
158                         &ns_dentry_operations, NSFS_MAGIC);
159 }
160 static struct file_system_type nsfs = {
161         .name = "nsfs",
162         .mount = nsfs_mount,
163         .kill_sb = kill_anon_super,
164 };
165 
166 void __init nsfs_init(void)
167 {
168         nsfs_mnt = kern_mount(&nsfs);
169         if (IS_ERR(nsfs_mnt))
170                 panic("can't set nsfs up\n");
171         nsfs_mnt->mnt_sb->s_flags &= ~MS_NOUSER;
172 }
173 

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