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