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