kernel/capability.c

   1 /*
   2  * linux/kernel/capability.c
   3  *
   4  * Copyright (C) 1997  Andrew Main <zefram@fysh.org>
   5  *
   6  * Integrated into 2.1.97+,  Andrew G. Morgan <morgan@transmeta.com>
   7  * 30 May 2002: Cleanup, Robert M. Love <rml@tech9.net>
   8  */
   9
  10 #include <linux/capability.h>
  11 #include <linux/mm.h>
  12 #include <linux/module.h>
  13 #include <linux/security.h>
  14 #include <linux/syscalls.h>
  15 #include <asm/uaccess.h>
  16
  17 unsigned securebits = SECUREBITS_DEFAULT; /* systemwide security settings */
  18 kernel_cap_t cap_bset = CAP_INIT_EFF_SET;
  19
  20 EXPORT_SYMBOL(securebits);
  21 EXPORT_SYMBOL(cap_bset);
  22
  23 /*
  24  * This lock protects task->cap_* for all tasks including current.
  25  * Locking rule: acquire this prior to tasklist_lock.
  26  */
  27 static DEFINE_SPINLOCK(task_capability_lock);
  28
  29 /*
  30  * For sys_getproccap() and sys_setproccap(), any of the three
  31  * capability set pointers may be NULL -- indicating that that set is
  32  * uninteresting and/or not to be changed.
  33  */
  34
  35 /**
  36  * sys_capget - get the capabilities of a given process.
  37  * @header: pointer to struct that contains capability version and
  38  *      target pid data
  39  * @dataptr: pointer to struct that contains the effective, permitted,
  40  *      and inheritable capabilities that are returned
  41  *
  42  * Returns 0 on success and < 0 on error.
  43  */
  44 asmlinkage long sys_capget(cap_user_header_t header, cap_user_data_t dataptr)
  45 {
  46      int ret = 0;
  47      pid_t pid;
  48      __u32 version;
  49      struct task_struct *target;
  50      struct __user_cap_data_struct data;
  51
  52      if (get_user(version, &header->version))
  53              return -EFAULT;
  54
  55      if (version != _LINUX_CAPABILITY_VERSION) {
  56              if (put_user(_LINUX_CAPABILITY_VERSION, &header->version))
  57                      return -EFAULT;
  58              return -EINVAL;
  59      }
  60
  61      if (get_user(pid, &header->pid))
  62              return -EFAULT;
  63
  64      if (pid < 0)
  65              return -EINVAL;
  66
  67      spin_lock(&task_capability_lock);
  68      read_lock(&tasklist_lock);
  69
  70      if (pid && pid != current->pid) {
  71              target = find_task_by_pid(pid);
  72              if (!target) {
  73                   ret = -ESRCH;
  74                   goto out;
  75              }
  76      } else
  77              target = current;
  78
  79      ret = security_capget(target, &data.effective, &data.inheritable, &data.permitted);
  80
  81 out:
  82      read_unlock(&tasklist_lock);
  83      spin_unlock(&task_capability_lock);
  84
  85      if (!ret && copy_to_user(dataptr, &data, sizeof data))
  86           return -EFAULT;
  87
  88      return ret;
  89 }
  90
  91 /*
  92  * cap_set_pg - set capabilities for all processes in a given process
  93  * group.  We call this holding task_capability_lock and tasklist_lock.
  94  */
  95 static inline int cap_set_pg(int pgrp, kernel_cap_t *effective,
  96                               kernel_cap_t *inheritable,
  97                               kernel_cap_t *permitted)
  98 {
  99         struct task_struct *g, *target;
 100         int ret = -EPERM;
 101         int found = 0;
 102
 103         do_each_task_pid(pgrp, PIDTYPE_PGID, g) {
 104                 target = g;
 105                 while_each_thread(g, target) {
 106                         if (!security_capset_check(target, effective,
 107                                                         inheritable,
 108                                                         permitted)) {
 109                                 security_capset_set(target, effective,
 110                                                         inheritable,
 111                                                         permitted);
 112                                 ret = 0;
 113                         }
 114                         found = 1;
 115                 }
 116         } while_each_task_pid(pgrp, PIDTYPE_PGID, g);
 117
 118         if (!found)
 119              ret = 0;
 120         return ret;
 121 }
 122
 123 /*
 124  * cap_set_all - set capabilities for all processes other than init
 125  * and self.  We call this holding task_capability_lock and tasklist_lock.
 126  */
 127 static inline int cap_set_all(kernel_cap_t *effective,
 128                                kernel_cap_t *inheritable,
 129                                kernel_cap_t *permitted)
 130 {
 131      struct task_struct *g, *target;
 132      int ret = -EPERM;
 133      int found = 0;
 134
 135      do_each_thread(g, target) {
 136              if (target == current || target->pid == 1)
 137                      continue;
 138              found = 1;
 139              if (security_capset_check(target, effective, inheritable,
 140                                                 permitted))
 141                      continue;
 142              ret = 0;
 143              security_capset_set(target, effective, inheritable, permitted);
 144      } while_each_thread(g, target);
 145
 146      if (!found)
 147              ret = 0;
 148      return ret;
 149 }
 150
 151 /**
 152  * sys_capset - set capabilities for a process or a group of processes
 153  * @header: pointer to struct that contains capability version and
 154  *      target pid data
 155  * @data: pointer to struct that contains the effective, permitted,
 156  *      and inheritable capabilities
 157  *
 158  * Set capabilities for a given process, all processes, or all
 159  * processes in a given process group.
 160  *
 161  * The restrictions on setting capabilities are specified as:
 162  *
 163  * [pid is for the 'target' task.  'current' is the calling task.]
 164  *
 165  * I: any raised capabilities must be a subset of the (old current) permitted
 166  * P: any raised capabilities must be a subset of the (old current) permitted
 167  * E: must be set to a subset of (new target) permitted
 168  *
 169  * Returns 0 on success and < 0 on error.
 170  */
 171 asmlinkage long sys_capset(cap_user_header_t header, const cap_user_data_t data)
 172 {
 173      kernel_cap_t inheritable, permitted, effective;
 174      __u32 version;
 175      struct task_struct *target;
 176      int ret;
 177      pid_t pid;
 178
 179      if (get_user(version, &header->version))
 180              return -EFAULT;
 181
 182      if (version != _LINUX_CAPABILITY_VERSION) {
 183              if (put_user(_LINUX_CAPABILITY_VERSION, &header->version))
 184                      return -EFAULT;
 185              return -EINVAL;
 186      }
 187
 188      if (get_user(pid, &header->pid))
 189              return -EFAULT;
 190
 191      if (pid && pid != current->pid && !capable(CAP_SETPCAP))
 192              return -EPERM;
 193
 194      if (copy_from_user(&effective, &data->effective, sizeof(effective)) ||
 195          copy_from_user(&inheritable, &data->inheritable, sizeof(inheritable)) ||
 196          copy_from_user(&permitted, &data->permitted, sizeof(permitted)))
 197              return -EFAULT;
 198
 199      spin_lock(&task_capability_lock);
 200      read_lock(&tasklist_lock);
 201
 202      if (pid > 0 && pid != current->pid) {
 203           target = find_task_by_pid(pid);
 204           if (!target) {
 205                ret = -ESRCH;
 206                goto out;
 207           }
 208      } else
 209                target = current;
 210
 211      ret = 0;
 212
 213      /* having verified that the proposed changes are legal,
 214            we now put them into effect. */
 215      if (pid < 0) {
 216              if (pid == -1)  /* all procs other than current and init */
 217                      ret = cap_set_all(&effective, &inheritable, &permitted);
 218
 219              else            /* all procs in process group */
 220                      ret = cap_set_pg(-pid, &effective, &inheritable,
 221                                                         &permitted);
 222      } else {
 223              ret = security_capset_check(target, &effective, &inheritable,
 224                                                         &permitted);
 225              if (!ret)
 226                      security_capset_set(target, &effective, &inheritable,
 227                                                         &permitted);
 228      }
 229
 230 out:
 231      read_unlock(&tasklist_lock);
 232      spin_unlock(&task_capability_lock);
 233
 234      return ret;
 235 }
 236
 237 int __capable(struct task_struct *t, int cap)
 238 {
 239         if (security_capable(t, cap) == 0) {
 240                 t->flags |= PF_SUPERPRIV;
 241                 return 1;
 242         }
 243         return 0;
 244 }
 245 EXPORT_SYMBOL(__capable);
 246
 247 int capable(int cap)
 248 {
 249         return __capable(current, cap);
 250 }
 251 EXPORT_SYMBOL(capable);