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         &pidns_for_children_operations,
  27 #endif
  28 #ifdef CONFIG_USER_NS
  29         &userns_operations,
  30 #endif
  31         &mntns_operations,
  32 #ifdef CONFIG_CGROUPS
  33         &cgroupns_operations,
  34 #endif
  35 };
  36
  37 static const char *proc_ns_get_link(struct dentry *dentry,
  38                                     struct inode *inode,
  39                                     struct delayed_call *done)
  40 {
  41         const struct proc_ns_operations *ns_ops = PROC_I(inode)->ns_ops;
  42         struct task_struct *task;
  43         struct path ns_path;
  44         void *error = ERR_PTR(-EACCES);
  45
  46         if (!dentry)
  47                 return ERR_PTR(-ECHILD);
  48
  49         task = get_proc_task(inode);
  50         if (!task)
  51                 return error;
  52
  53         if (ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS)) {
  54                 error = ns_get_path(&ns_path, task, ns_ops);
  55                 if (!error)
  56                         nd_jump_link(&ns_path);
  57         }
  58         put_task_struct(task);
  59         return error;
  60 }
  61
  62 static int proc_ns_readlink(struct dentry *dentry, char __user *buffer, int buflen)
  63 {
  64         struct inode *inode = d_inode(dentry);
  65         const struct proc_ns_operations *ns_ops = PROC_I(inode)->ns_ops;
  66         struct task_struct *task;
  67         char name[50];
  68         int res = -EACCES;
  69
  70         task = get_proc_task(inode);
  71         if (!task)
  72                 return res;
  73
  74         if (ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS)) {
  75                 res = ns_get_name(name, sizeof(name), task, ns_ops);
  76                 if (res >= 0)
  77                         res = readlink_copy(buffer, buflen, name);
  78         }
  79         put_task_struct(task);
  80         return res;
  81 }
  82
  83 static const struct inode_operations proc_ns_link_inode_operations = {
  84         .readlink       = proc_ns_readlink,
  85         .get_link       = proc_ns_get_link,
  86         .setattr        = proc_setattr,
  87 };
  88
  89 static int proc_ns_instantiate(struct inode *dir,
  90         struct dentry *dentry, struct task_struct *task, const void *ptr)
  91 {
  92         const struct proc_ns_operations *ns_ops = ptr;
  93         struct inode *inode;
  94         struct proc_inode *ei;
  95
  96         inode = proc_pid_make_inode(dir->i_sb, task, S_IFLNK | S_IRWXUGO);
  97         if (!inode)
  98                 goto out;
  99
 100         ei = PROC_I(inode);
 101         inode->i_op = &proc_ns_link_inode_operations;
 102         ei->ns_ops = ns_ops;
 103
 104         d_set_d_op(dentry, &pid_dentry_operations);
 105         d_add(dentry, inode);
 106         /* Close the race of the process dying before we return the dentry */
 107         if (pid_revalidate(dentry, 0))
 108                 return 0;
 109 out:
 110         return -ENOENT;
 111 }
 112
 113 static int proc_ns_dir_readdir(struct file *file, struct dir_context *ctx)
 114 {
 115         struct task_struct *task = get_proc_task(file_inode(file));
 116         const struct proc_ns_operations **entry, **last;
 117
 118         if (!task)
 119                 return -ENOENT;
 120
 121         if (!dir_emit_dots(file, ctx))
 122                 goto out;
 123         if (ctx->pos >= 2 + ARRAY_SIZE(ns_entries))
 124                 goto out;
 125         entry = ns_entries + (ctx->pos - 2);
 126         last = &ns_entries[ARRAY_SIZE(ns_entries) - 1];
 127         while (entry <= last) {
 128                 const struct proc_ns_operations *ops = *entry;
 129                 if (!proc_fill_cache(file, ctx, ops->name, strlen(ops->name),
 130                                      proc_ns_instantiate, task, ops))
 131                         break;
 132                 ctx->pos++;
 133                 entry++;
 134         }
 135 out:
 136         put_task_struct(task);
 137         return 0;
 138 }
 139
 140 const struct file_operations proc_ns_dir_operations = {
 141         .read           = generic_read_dir,
 142         .iterate_shared = proc_ns_dir_readdir,
 143         .llseek         = generic_file_llseek,
 144 };
 145
 146 static struct dentry *proc_ns_dir_lookup(struct inode *dir,
 147                                 struct dentry *dentry, unsigned int flags)
 148 {
 149         int error;
 150         struct task_struct *task = get_proc_task(dir);
 151         const struct proc_ns_operations **entry, **last;
 152         unsigned int len = dentry->d_name.len;
 153
 154         error = -ENOENT;
 155
 156         if (!task)
 157                 goto out_no_task;
 158
 159         last = &ns_entries[ARRAY_SIZE(ns_entries)];
 160         for (entry = ns_entries; entry < last; entry++) {
 161                 if (strlen((*entry)->name) != len)
 162                         continue;
 163                 if (!memcmp(dentry->d_name.name, (*entry)->name, len))
 164                         break;
 165         }
 166         if (entry == last)
 167                 goto out;
 168
 169         error = proc_ns_instantiate(dir, dentry, task, *entry);
 170 out:
 171         put_task_struct(task);
 172 out_no_task:
 173         return ERR_PTR(error);
 174 }
 175
 176 const struct inode_operations proc_ns_dir_inode_operations = {
 177         .lookup         = proc_ns_dir_lookup,
 178         .getattr        = pid_getattr,
 179         .setattr        = proc_setattr,
 180 };