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/mm.h>
  11 #include <asm/uaccess.h>
  12
  13 unsigned securebits = SECUREBITS_DEFAULT; /* systemwide security settings */
  14 kernel_cap_t cap_bset = CAP_INIT_EFF_SET;
  15
  16 /*
  17  * This global lock protects task->cap_* for all tasks including current.
  18  * Locking rule: acquire this prior to tasklist_lock.
  19  */
  20 spinlock_t task_capability_lock = SPIN_LOCK_UNLOCKED;
  21
  22 /*
  23  * For sys_getproccap() and sys_setproccap(), any of the three
  24  * capability set pointers may be NULL -- indicating that that set is
  25  * uninteresting and/or not to be changed.
  26  */
  27
  28 /*
  29  * sys_capget - get the capabilities of a given process.
  30  */
  31 asmlinkage long sys_capget(cap_user_header_t header, cap_user_data_t dataptr)
  32 {
  33      int ret = 0;
  34      pid_t pid;
  35      __u32 version;
  36      task_t *target;
  37      struct __user_cap_data_struct data;
  38
  39      if (get_user(version, &header->version))
  40              return -EFAULT;
  41
  42      if (version != _LINUX_CAPABILITY_VERSION) {
  43              if (put_user(_LINUX_CAPABILITY_VERSION, &header->version))
  44                      return -EFAULT;
  45              return -EINVAL;
  46      }
  47
  48      if (get_user(pid, &header->pid))
  49              return -EFAULT;
  50
  51      if (pid < 0)
  52              return -EINVAL;
  53
  54      spin_lock(&task_capability_lock);
  55      read_lock(&tasklist_lock);
  56
  57      target = find_task_by_pid(pid);
  58      if (!target) {
  59           ret = -ESRCH;
  60           goto out;
  61      }
  62
  63      data.permitted = cap_t(target->cap_permitted);
  64      data.inheritable = cap_t(target->cap_inheritable);
  65      data.effective = cap_t(target->cap_effective);
  66      ret = security_ops->capget(target, &data.effective, &data.inheritable, &data.permitted);
  67
  68 out:
  69      read_unlock(&tasklist_lock);
  70      spin_unlock(&task_capability_lock);
  71
  72      if (!ret && copy_to_user(dataptr, &data, sizeof data))
  73           return -EFAULT;
  74
  75      return ret;
  76 }
  77
  78 /*
  79  * cap_set_pg - set capabilities for all processes in a given process
  80  * group.  We call this holding task_capability_lock and tasklist_lock.
  81  */
  82 static inline void cap_set_pg(int pgrp, kernel_cap_t *effective,
  83                               kernel_cap_t *inheritable,
  84                               kernel_cap_t *permitted)
  85 {
  86      task_t *g, *target;
  87
  88      do_each_thread(g, target) {
  89              if (target->pgrp != pgrp)
  90                      continue;
  91              security_ops->capset_set(target, effective, inheritable, permitted);
  92      } while_each_thread(g, target);
  93 }
  94
  95 /*
  96  * cap_set_all - set capabilities for all processes other than init
  97  * and self.  We call this holding task_capability_lock and tasklist_lock.
  98  */
  99 static inline void cap_set_all(kernel_cap_t *effective,
 100                                kernel_cap_t *inheritable,
 101                                kernel_cap_t *permitted)
 102 {
 103      task_t *g, *target;
 104
 105      do_each_thread(g, target) {
 106              if (target == current || target->pid == 1)
 107                      continue;
 108              security_ops->capset_set(target, effective, inheritable, permitted);
 109      } while_each_thread(g, target);
 110 }
 111
 112 /*
 113  * sys_capset - set capabilities for a given process, all processes, or all
 114  * processes in a given process group.
 115  *
 116  * The restrictions on setting capabilities are specified as:
 117  *
 118  * [pid is for the 'target' task.  'current' is the calling task.]
 119  *
 120  * I: any raised capabilities must be a subset of the (old current) permitted
 121  * P: any raised capabilities must be a subset of the (old current) permitted
 122  * E: must be set to a subset of (new target) permitted
 123  */
 124 asmlinkage long sys_capset(cap_user_header_t header, const cap_user_data_t data)
 125 {
 126      kernel_cap_t inheritable, permitted, effective;
 127      __u32 version;
 128      task_t *target;
 129      int ret;
 130      pid_t pid;
 131
 132      if (get_user(version, &header->version))
 133              return -EFAULT;
 134
 135      if (version != _LINUX_CAPABILITY_VERSION) {
 136              if (put_user(_LINUX_CAPABILITY_VERSION, &header->version))
 137                      return -EFAULT;
 138              return -EINVAL;
 139      }
 140
 141      if (get_user(pid, &header->pid))
 142              return -EFAULT;
 143
 144      if (pid && !capable(CAP_SETPCAP))
 145              return -EPERM;
 146
 147      if (copy_from_user(&effective, &data->effective, sizeof(effective)) ||
 148          copy_from_user(&inheritable, &data->inheritable, sizeof(inheritable)) ||
 149          copy_from_user(&permitted, &data->permitted, sizeof(permitted)))
 150              return -EFAULT;
 151
 152      spin_lock(&task_capability_lock);
 153      read_lock(&tasklist_lock);
 154
 155      if (pid > 0 && pid != current->pid) {
 156           target = find_task_by_pid(pid);
 157           if (!target) {
 158                ret = -ESRCH;
 159                goto out;
 160           }
 161      } else
 162                target = current;
 163
 164      ret = -EPERM;
 165
 166      if (security_ops->capset_check(target, &effective, &inheritable, &permitted))
 167              goto out;
 168
 169      if (!cap_issubset(inheritable, cap_combine(target->cap_inheritable,
 170                        current->cap_permitted)))
 171              goto out;
 172
 173      /* verify restrictions on target's new Permitted set */
 174      if (!cap_issubset(permitted, cap_combine(target->cap_permitted,
 175                        current->cap_permitted)))
 176              goto out;
 177
 178      /* verify the _new_Effective_ is a subset of the _new_Permitted_ */
 179      if (!cap_issubset(effective, permitted))
 180              goto out;
 181
 182      ret = 0;
 183
 184      /* having verified that the proposed changes are legal,
 185            we now put them into effect. */
 186      if (pid < 0) {
 187              if (pid == -1)  /* all procs other than current and init */
 188                      cap_set_all(&effective, &inheritable, &permitted);
 189
 190              else            /* all procs in process group */
 191                      cap_set_pg(-pid, &effective, &inheritable, &permitted);
 192      } else {
 193              security_ops->capset_set(target, &effective, &inheritable, &permitted);
 194      }
 195
 196 out:
 197      read_unlock(&tasklist_lock);
 198      spin_unlock(&task_capability_lock);
 199
 200      return ret;
 201 }