kernel/fs/proc/namespaces.c

   1 #include <linux/proc_fs.h>
   2 #include <linux/nsproxy.h>
   3 #include <linux/ptrace.h>
   4 #include <linux/namei.h>
   5 #include <linux/file.h>
   6 #include <linux/utsname.h>
   7 #include <net/net_namespace.h>
   8 #include <linux/ipc_namespace.h>
   9 #include <linux/pid_namespace.h>
  10 #include <linux/user_namespace.h>
  11 #include "internal.h"
  12
  13
  14 static const struct proc_ns_operations *ns_entries[] = {
  15 #ifdef CONFIG_NET_NS
  16         &netns_operations,
  17 #endif
  18 #ifdef CONFIG_UTS_NS
  19         &utsns_operations,
  20 #endif
  21 #ifdef CONFIG_IPC_NS
  22         &ipcns_operations,
  23 #endif
  24 #ifdef CONFIG_PID_NS
  25         &pidns_operations,
  26 #endif
  27 #ifdef CONFIG_USER_NS
  28         &userns_operations,
  29 #endif
  30         &mntns_operations,
  31 };
  32
  33 static void *proc_ns_follow_link(struct dentry *dentry, struct nameidata *nd)
  34 {
  35         struct inode *inode = d_inode(dentry);
  36         const struct proc_ns_operations *ns_ops = PROC_I(inode)->ns_ops;
  37         struct task_struct *task;
  38         struct path ns_path;
  39         void *error = ERR_PTR(-EACCES);
  40
  41         task = get_proc_task(inode);
  42         if (!task)
  43                 return error;
  44
  45         if (ptrace_may_access(task, PTRACE_MODE_READ)) {
  46                 error = ns_get_path(&ns_path, task, ns_ops);
  47                 if (!error)
  48                         nd_jump_link(nd, &ns_path);
  49         }
  50         put_task_struct(task);
  51         return error;
  52 }
  53
  54 static int proc_ns_readlink(struct dentry *dentry, char __user *buffer, int buflen)
  55 {
  56         struct inode *inode = d_inode(dentry);
  57         const struct proc_ns_operations *ns_ops = PROC_I(inode)->ns_ops;
  58         struct task_struct *task;
  59         char name[50];
  60         int res = -EACCES;
  61
  62         task = get_proc_task(inode);
  63         if (!task)
  64                 return res;
  65
  66         if (ptrace_may_access(task, PTRACE_MODE_READ)) {
  67                 res = ns_get_name(name, sizeof(name), task, ns_ops);
  68                 if (res >= 0)
  69                         res = readlink_copy(buffer, buflen, name);
  70         }
  71         put_task_struct(task);
  72         return res;
  73 }
  74
  75 static const struct inode_operations proc_ns_link_inode_operations = {
  76         .readlink       = proc_ns_readlink,
  77         .follow_link    = proc_ns_follow_link,
  78         .setattr        = proc_setattr,
  79 };
  80
  81 static int proc_ns_instantiate(struct inode *dir,
  82         struct dentry *dentry, struct task_struct *task, const void *ptr)
  83 {
  84         const struct proc_ns_operations *ns_ops = ptr;
  85         struct inode *inode;
  86         struct proc_inode *ei;
  87
  88         inode = proc_pid_make_inode(dir->i_sb, task);
  89         if (!inode)
  90                 goto out;
  91
  92         ei = PROC_I(inode);
  93         inode->i_mode = S_IFLNK|S_IRWXUGO;
  94         inode->i_op = &proc_ns_link_inode_operations;
  95         ei->ns_ops = ns_ops;
  96
  97         d_set_d_op(dentry, &pid_dentry_operations);
  98         d_add(dentry, inode);
  99         /* Close the race of the process dying before we return the dentry */
 100         if (pid_revalidate(dentry, 0))
 101                 return 0;
 102 out:
 103         return -ENOENT;
 104 }
 105
 106 static int proc_ns_dir_readdir(struct file *file, struct dir_context *ctx)
 107 {
 108         struct task_struct *task = get_proc_task(file_inode(file));
 109         const struct proc_ns_operations **entry, **last;
 110
 111         if (!task)
 112                 return -ENOENT;
 113
 114         if (!dir_emit_dots(file, ctx))
 115                 goto out;
 116         if (ctx->pos >= 2 + ARRAY_SIZE(ns_entries))
 117                 goto out;
 118         entry = ns_entries + (ctx->pos - 2);
 119         last = &ns_entries[ARRAY_SIZE(ns_entries) - 1];
 120         while (entry <= last) {
 121                 const struct proc_ns_operations *ops = *entry;
 122                 if (!proc_fill_cache(file, ctx, ops->name, strlen(ops->name),
 123                                      proc_ns_instantiate, task, ops))
 124                         break;
 125                 ctx->pos++;
 126                 entry++;
 127         }
 128 out:
 129         put_task_struct(task);
 130         return 0;
 131 }
 132
 133 const struct file_operations proc_ns_dir_operations = {
 134         .read           = generic_read_dir,
 135         .iterate        = proc_ns_dir_readdir,
 136 };
 137
 138 static struct dentry *proc_ns_dir_lookup(struct inode *dir,
 139                                 struct dentry *dentry, unsigned int flags)
 140 {
 141         int error;
 142         struct task_struct *task = get_proc_task(dir);
 143         const struct proc_ns_operations **entry, **last;
 144         unsigned int len = dentry->d_name.len;
 145
 146         error = -ENOENT;
 147
 148         if (!task)
 149                 goto out_no_task;
 150
 151         last = &ns_entries[ARRAY_SIZE(ns_entries)];
 152         for (entry = ns_entries; entry < last; entry++) {
 153                 if (strlen((*entry)->name) != len)
 154                         continue;
 155                 if (!memcmp(dentry->d_name.name, (*entry)->name, len))
 156                         break;
 157         }
 158         if (entry == last)
 159                 goto out;
 160
 161         error = proc_ns_instantiate(dir, dentry, task, *entry);
 162 out:
 163         put_task_struct(task);
 164 out_no_task:
 165         return ERR_PTR(error);
 166 }
 167
 168 const struct inode_operations proc_ns_dir_inode_operations = {
 169         .lookup         = proc_ns_dir_lookup,
 170         .getattr        = pid_getattr,
 171         .setattr        = proc_setattr,
 172 };