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/capability.h>
  11 #include <linux/mm.h>
  12 #include <linux/module.h>
  13 #include <linux/security.h>
  14 #include <linux/syscalls.h>
  15 #include <asm/uaccess.h>
  16
  17 unsigned securebits = SECUREBITS_DEFAULT; /* systemwide security settings */
  18 kernel_cap_t cap_bset = CAP_INIT_EFF_SET;
  19
  20 /*
  21  * This lock protects task->cap_* for all tasks including current.
  22  * Locking rule: acquire this prior to tasklist_lock.
  23  */
  24 static DEFINE_SPINLOCK(task_capability_lock);
  25
  26 /*
  27  * For sys_getproccap() and sys_setproccap(), any of the three
  28  * capability set pointers may be NULL -- indicating that that set is
  29  * uninteresting and/or not to be changed.
  30  */
  31
  32 /**
  33  * sys_capget - get the capabilities of a given process.
  34  * @header: pointer to struct that contains capability version and
  35  *      target pid data
  36  * @dataptr: pointer to struct that contains the effective, permitted,
  37  *      and inheritable capabilities that are returned
  38  *
  39  * Returns 0 on success and < 0 on error.
  40  */
  41 asmlinkage long sys_capget(cap_user_header_t header, cap_user_data_t dataptr)
  42 {
  43      int ret = 0;
  44      pid_t pid;
  45      __u32 version;
  46      struct task_struct *target;
  47      struct __user_cap_data_struct data;
  48
  49      if (get_user(version, &header->version))
  50              return -EFAULT;
  51
  52      if (version != _LINUX_CAPABILITY_VERSION) {
  53              if (put_user(_LINUX_CAPABILITY_VERSION, &header->version))
  54                      return -EFAULT;
  55              return -EINVAL;
  56      }
  57
  58      if (get_user(pid, &header->pid))
  59              return -EFAULT;
  60
  61      if (pid < 0)
  62              return -EINVAL;
  63
  64      spin_lock(&task_capability_lock);
  65      read_lock(&tasklist_lock);
  66
  67      if (pid && pid != current->pid) {
  68              target = find_task_by_pid(pid);
  69              if (!target) {
  70                   ret = -ESRCH;
  71                   goto out;
  72              }
  73      } else
  74              target = current;
  75
  76      ret = security_capget(target, &data.effective, &data.inheritable, &data.permitted);
  77
  78 out:
  79      read_unlock(&tasklist_lock);
  80      spin_unlock(&task_capability_lock);
  81
  82      if (!ret && copy_to_user(dataptr, &data, sizeof data))
  83           return -EFAULT;
  84
  85      return ret;
  86 }
  87
  88 /*
  89  * cap_set_pg - set capabilities for all processes in a given process
  90  * group.  We call this holding task_capability_lock and tasklist_lock.
  91  */
  92 static inline int cap_set_pg(int pgrp_nr, kernel_cap_t *effective,
  93                               kernel_cap_t *inheritable,
  94                               kernel_cap_t *permitted)
  95 {
  96         struct task_struct *g, *target;
  97         int ret = -EPERM;
  98         int found = 0;
  99         struct pid *pgrp;
 100
 101         pgrp = find_pid(pgrp_nr);
 102         do_each_pid_task(pgrp, PIDTYPE_PGID, g) {
 103                 target = g;
 104                 while_each_thread(g, target) {
 105                         if (!security_capset_check(target, effective,
 106                                                         inheritable,
 107                                                         permitted)) {
 108                                 security_capset_set(target, effective,
 109                                                         inheritable,
 110                                                         permitted);
 111                                 ret = 0;
 112                         }
 113                         found = 1;
 114                 }
 115         } while_each_pid_task(pgrp, PIDTYPE_PGID, g);
 116
 117         if (!found)
 118              ret = 0;
 119         return ret;
 120 }
 121
 122 /*
 123  * cap_set_all - set capabilities for all processes other than init
 124  * and self.  We call this holding task_capability_lock and tasklist_lock.
 125  */
 126 static inline int cap_set_all(kernel_cap_t *effective,
 127                                kernel_cap_t *inheritable,
 128                                kernel_cap_t *permitted)
 129 {
 130      struct task_struct *g, *target;
 131      int ret = -EPERM;
 132      int found = 0;
 133
 134      do_each_thread(g, target) {
 135              if (target == current || is_init(target))
 136                      continue;
 137              found = 1;
 138              if (security_capset_check(target, effective, inheritable,
 139                                                 permitted))
 140                      continue;
 141              ret = 0;
 142              security_capset_set(target, effective, inheritable, permitted);
 143      } while_each_thread(g, target);
 144
 145      if (!found)
 146              ret = 0;
 147      return ret;
 148 }
 149
 150 /**
 151  * sys_capset - set capabilities for a process or a group of processes
 152  * @header: pointer to struct that contains capability version and
 153  *      target pid data
 154  * @data: pointer to struct that contains the effective, permitted,
 155  *      and inheritable capabilities
 156  *
 157  * Set capabilities for a given process, all processes, or all
 158  * processes in a given process group.
 159  *
 160  * The restrictions on setting capabilities are specified as:
 161  *
 162  * [pid is for the 'target' task.  'current' is the calling task.]
 163  *
 164  * I: any raised capabilities must be a subset of the (old current) permitted
 165  * P: any raised capabilities must be a subset of the (old current) permitted
 166  * E: must be set to a subset of (new target) permitted
 167  *
 168  * Returns 0 on success and < 0 on error.
 169  */
 170 asmlinkage long sys_capset(cap_user_header_t header, const cap_user_data_t data)
 171 {
 172      kernel_cap_t inheritable, permitted, effective;
 173      __u32 version;
 174      struct task_struct *target;
 175      int ret;
 176      pid_t pid;
 177
 178      if (get_user(version, &header->version))
 179              return -EFAULT;
 180
 181      if (version != _LINUX_CAPABILITY_VERSION) {
 182              if (put_user(_LINUX_CAPABILITY_VERSION, &header->version))
 183                      return -EFAULT;
 184              return -EINVAL;
 185      }
 186
 187      if (get_user(pid, &header->pid))
 188              return -EFAULT;
 189
 190      if (pid && pid != current->pid && !capable(CAP_SETPCAP))
 191              return -EPERM;
 192
 193      if (copy_from_user(&effective, &data->effective, sizeof(effective)) ||
 194          copy_from_user(&inheritable, &data->inheritable, sizeof(inheritable)) ||
 195          copy_from_user(&permitted, &data->permitted, sizeof(permitted)))
 196              return -EFAULT;
 197
 198      spin_lock(&task_capability_lock);
 199      read_lock(&tasklist_lock);
 200
 201      if (pid > 0 && pid != current->pid) {
 202           target = find_task_by_pid(pid);
 203           if (!target) {
 204                ret = -ESRCH;
 205                goto out;
 206           }
 207      } else
 208                target = current;
 209
 210      ret = 0;
 211
 212      /* having verified that the proposed changes are legal,
 213            we now put them into effect. */
 214      if (pid < 0) {
 215              if (pid == -1)  /* all procs other than current and init */
 216                      ret = cap_set_all(&effective, &inheritable, &permitted);
 217
 218              else            /* all procs in process group */
 219                      ret = cap_set_pg(-pid, &effective, &inheritable,
 220                                                         &permitted);
 221      } else {
 222              ret = security_capset_check(target, &effective, &inheritable,
 223                                                         &permitted);
 224              if (!ret)
 225                      security_capset_set(target, &effective, &inheritable,
 226                                                         &permitted);
 227      }
 228
 229 out:
 230      read_unlock(&tasklist_lock);
 231      spin_unlock(&task_capability_lock);
 232
 233      return ret;
 234 }
 235
 236 int __capable(struct task_struct *t, int cap)
 237 {
 238         if (security_capable(t, cap) == 0) {
 239                 t->flags |= PF_SUPERPRIV;
 240                 return 1;
 241         }
 242         return 0;
 243 }
 244
 245 int capable(int cap)
 246 {
 247         return __capable(current, cap);
 248 }
 249 EXPORT_SYMBOL(capable);