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 <linux/module.h>
  12 #include <linux/security.h>
  13 #include <linux/vs_cvirt.h>
  14 #include <linux/syscalls.h>
  15 #include <linux/vs_cvirt.h>
  16
  17 #include <asm/uaccess.h>
  18
  19 unsigned securebits = SECUREBITS_DEFAULT; /* systemwide security settings */
  20 kernel_cap_t cap_bset = CAP_INIT_EFF_SET;
  21
  22 EXPORT_SYMBOL(securebits);
  23 EXPORT_SYMBOL(cap_bset);
  24
  25 /*
  26  * This global lock protects task->cap_* for all tasks including current.
  27  * Locking rule: acquire this prior to tasklist_lock.
  28  */
  29 spinlock_t task_capability_lock = SPIN_LOCK_UNLOCKED;
  30
  31 /*
  32  * For sys_getproccap() and sys_setproccap(), any of the three
  33  * capability set pointers may be NULL -- indicating that that set is
  34  * uninteresting and/or not to be changed.
  35  */
  36
  37 /*
  38  * sys_capget - get the capabilities of a given process.
  39  */
  40 asmlinkage long sys_capget(cap_user_header_t header, cap_user_data_t dataptr)
  41 {
  42      int ret = 0;
  43      pid_t pid;
  44      __u32 version;
  45      task_t *target;
  46      struct __user_cap_data_struct data;
  47
  48      if (get_user(version, &header->version))
  49              return -EFAULT;
  50
  51      if (version != _LINUX_CAPABILITY_VERSION) {
  52              if (put_user(_LINUX_CAPABILITY_VERSION, &header->version))
  53                      return -EFAULT;
  54              return -EINVAL;
  55      }
  56
  57      if (get_user(pid, &header->pid))
  58              return -EFAULT;
  59
  60      if (pid < 0)
  61              return -EINVAL;
  62
  63      spin_lock(&task_capability_lock);
  64      read_lock(&tasklist_lock);
  65
  66      if (pid && pid != current->pid) {
  67              target = find_task_by_pid(pid);
  68              if (!target) {
  69                   ret = -ESRCH;
  70                   goto out;
  71              }
  72      } else
  73              target = current;
  74
  75      ret = security_capget(target, &data.effective, &data.inheritable, &data.permitted);
  76
  77 out:
  78      read_unlock(&tasklist_lock);
  79      spin_unlock(&task_capability_lock);
  80
  81      if (!ret && copy_to_user(dataptr, &data, sizeof data))
  82           return -EFAULT;
  83
  84      return ret;
  85 }
  86
  87 /*
  88  * cap_set_pg - set capabilities for all processes in a given process
  89  * group.  We call this holding task_capability_lock and tasklist_lock.
  90  */
  91 static inline void cap_set_pg(int pgrp, kernel_cap_t *effective,
  92                               kernel_cap_t *inheritable,
  93                               kernel_cap_t *permitted)
  94 {
  95         task_t *g, *target;
  96
  97         do_each_task_pid(pgrp, PIDTYPE_PGID, g) {
  98                 target = g;
  99                 while_each_thread(g, target)
 100                         security_capset_set(target, effective, inheritable, permitted);
 101         } while_each_task_pid(pgrp, PIDTYPE_PGID, g);
 102 }
 103
 104 /*
 105  * cap_set_all - set capabilities for all processes other than init
 106  * and self.  We call this holding task_capability_lock and tasklist_lock.
 107  */
 108 static inline void cap_set_all(kernel_cap_t *effective,
 109                                kernel_cap_t *inheritable,
 110                                kernel_cap_t *permitted)
 111 {
 112      task_t *g, *target;
 113
 114      do_each_thread(g, target) {
 115              if (target == current || target->pid == 1)
 116                      continue;
 117              security_capset_set(target, effective, inheritable, permitted);
 118      } while_each_thread(g, target);
 119 }
 120
 121 /*
 122  * sys_capset - set capabilities for a given process, all processes, or all
 123  * processes in a given process group.
 124  *
 125  * The restrictions on setting capabilities are specified as:
 126  *
 127  * [pid is for the 'target' task.  'current' is the calling task.]
 128  *
 129  * I: any raised capabilities must be a subset of the (old current) permitted
 130  * P: any raised capabilities must be a subset of the (old current) permitted
 131  * E: must be set to a subset of (new target) permitted
 132  */
 133 asmlinkage long sys_capset(cap_user_header_t header, const cap_user_data_t data)
 134 {
 135      kernel_cap_t inheritable, permitted, effective;
 136      __u32 version;
 137      task_t *target;
 138      int ret;
 139      pid_t pid;
 140
 141      if (get_user(version, &header->version))
 142              return -EFAULT;
 143
 144      if (version != _LINUX_CAPABILITY_VERSION) {
 145              if (put_user(_LINUX_CAPABILITY_VERSION, &header->version))
 146                      return -EFAULT;
 147              return -EINVAL;
 148      }
 149
 150      if (get_user(pid, &header->pid))
 151              return -EFAULT;
 152
 153      if (pid && !capable(CAP_SETPCAP))
 154              return -EPERM;
 155
 156      if (copy_from_user(&effective, &data->effective, sizeof(effective)) ||
 157          copy_from_user(&inheritable, &data->inheritable, sizeof(inheritable)) ||
 158          copy_from_user(&permitted, &data->permitted, sizeof(permitted)))
 159              return -EFAULT;
 160
 161      spin_lock(&task_capability_lock);
 162      read_lock(&tasklist_lock);
 163
 164      if (pid > 0 && pid != current->pid) {
 165           target = find_task_by_pid(pid);
 166           if (!target) {
 167                ret = -ESRCH;
 168                goto out;
 169           }
 170      } else
 171                target = current;
 172
 173      ret = -EPERM;
 174
 175      if (security_capset_check(target, &effective, &inheritable, &permitted))
 176              goto out;
 177
 178      if (!cap_issubset(inheritable, cap_combine(target->cap_inheritable,
 179                        current->cap_permitted)))
 180              goto out;
 181
 182      /* verify restrictions on target's new Permitted set */
 183      if (!cap_issubset(permitted, cap_combine(target->cap_permitted,
 184                        current->cap_permitted)))
 185              goto out;
 186
 187      /* verify the _new_Effective_ is a subset of the _new_Permitted_ */
 188      if (!cap_issubset(effective, permitted))
 189              goto out;
 190
 191      ret = 0;
 192
 193      /* having verified that the proposed changes are legal,
 194            we now put them into effect. */
 195      if (pid < 0) {
 196              if (pid == -1)  /* all procs other than current and init */
 197                      cap_set_all(&effective, &inheritable, &permitted);
 198
 199              else            /* all procs in process group */
 200                      cap_set_pg(-pid, &effective, &inheritable, &permitted);
 201      } else {
 202              security_capset_set(target, &effective, &inheritable, &permitted);
 203      }
 204
 205 out:
 206      read_unlock(&tasklist_lock);
 207      spin_unlock(&task_capability_lock);
 208
 209      return ret;
 210 }