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