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