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 <linux/vs_context.h>
  16 #include <asm/uaccess.h>
  17
  18 unsigned securebits = SECUREBITS_DEFAULT; /* systemwide security settings */
  19 kernel_cap_t cap_bset = CAP_INIT_EFF_SET;
  20
  21 EXPORT_SYMBOL(securebits);
  22 EXPORT_SYMBOL(cap_bset);
  23
  24 /*
  25  * This lock protects task->cap_* for all tasks including current.
  26  * Locking rule: acquire this prior to tasklist_lock.
  27  */
  28 static DEFINE_SPINLOCK(task_capability_lock);
  29
  30 /*
  31  * For sys_getproccap() and sys_setproccap(), any of the three
  32  * capability set pointers may be NULL -- indicating that that set is
  33  * uninteresting and/or not to be changed.
  34  */
  35
  36 /**
  37  * sys_capget - get the capabilities of a given process.
  38  * @header: pointer to struct that contains capability version and
  39  *      target pid data
  40  * @dataptr: pointer to struct that contains the effective, permitted,
  41  *      and inheritable capabilities that are returned
  42  *
  43  * Returns 0 on success and < 0 on error.
  44  */
  45 asmlinkage long sys_capget(cap_user_header_t header, cap_user_data_t dataptr)
  46 {
  47      int ret = 0;
  48      pid_t pid;
  49      __u32 version;
  50      struct task_struct *target;
  51      struct __user_cap_data_struct data;
  52
  53      if (get_user(version, &header->version))
  54              return -EFAULT;
  55
  56      if (version != _LINUX_CAPABILITY_VERSION) {
  57              if (put_user(_LINUX_CAPABILITY_VERSION, &header->version))
  58                      return -EFAULT;
  59              return -EINVAL;
  60      }
  61
  62      if (get_user(pid, &header->pid))
  63              return -EFAULT;
  64
  65      if (pid < 0)
  66              return -EINVAL;
  67
  68      spin_lock(&task_capability_lock);
  69      read_lock(&tasklist_lock);
  70
  71      if (pid && pid != current->pid) {
  72              target = find_task_by_pid(pid);
  73              if (!target) {
  74                   ret = -ESRCH;
  75                   goto out;
  76              }
  77      } else
  78              target = current;
  79
  80      ret = security_capget(target, &data.effective, &data.inheritable, &data.permitted);
  81
  82 out:
  83      read_unlock(&tasklist_lock);
  84      spin_unlock(&task_capability_lock);
  85
  86      if (!ret && copy_to_user(dataptr, &data, sizeof data))
  87           return -EFAULT;
  88
  89      return ret;
  90 }
  91
  92 /*
  93  * cap_set_pg - set capabilities for all processes in a given process
  94  * group.  We call this holding task_capability_lock and tasklist_lock.
  95  */
  96 static inline int cap_set_pg(int pgrp, kernel_cap_t *effective,
  97                               kernel_cap_t *inheritable,
  98                               kernel_cap_t *permitted)
  99 {
 100         struct task_struct *g, *target;
 101         int ret = -EPERM;
 102         int found = 0;
 103
 104         do_each_task_pid(pgrp, PIDTYPE_PGID, g) {
 105                 if (!vx_check(g->xid, VS_ADMIN_P | VS_IDENT))
 106                         continue;
 107                 target = g;
 108                 while_each_thread(g, target) {
 109                         if (!security_capset_check(target, effective,
 110                                                         inheritable,
 111                                                         permitted)) {
 112                                 security_capset_set(target, effective,
 113                                                         inheritable,
 114                                                         permitted);
 115                                 ret = 0;
 116                         }
 117                         found = 1;
 118                 }
 119         } while_each_task_pid(pgrp, PIDTYPE_PGID, g);
 120
 121         if (!found)
 122              ret = 0;
 123         return ret;
 124 }
 125
 126 /*
 127  * cap_set_all - set capabilities for all processes other than init
 128  * and self.  We call this holding task_capability_lock and tasklist_lock.
 129  */
 130 static inline int cap_set_all(kernel_cap_t *effective,
 131                                kernel_cap_t *inheritable,
 132                                kernel_cap_t *permitted)
 133 {
 134      struct task_struct *g, *target;
 135      int ret = -EPERM;
 136      int found = 0;
 137
 138      do_each_thread(g, target) {
 139              if (target == current || is_init(target))
 140                      continue;
 141              found = 1;
 142              if (security_capset_check(target, effective, inheritable,
 143                                                 permitted))
 144                      continue;
 145              ret = 0;
 146              security_capset_set(target, effective, inheritable, permitted);
 147      } while_each_thread(g, target);
 148
 149      if (!found)
 150              ret = 0;
 151      return ret;
 152 }
 153
 154 /**
 155  * sys_capset - set capabilities for a process or a group of processes
 156  * @header: pointer to struct that contains capability version and
 157  *      target pid data
 158  * @data: pointer to struct that contains the effective, permitted,
 159  *      and inheritable capabilities
 160  *
 161  * Set capabilities for a given process, all processes, or all
 162  * processes in a given process group.
 163  *
 164  * The restrictions on setting capabilities are specified as:
 165  *
 166  * [pid is for the 'target' task.  'current' is the calling task.]
 167  *
 168  * I: any raised capabilities must be a subset of the (old current) permitted
 169  * P: any raised capabilities must be a subset of the (old current) permitted
 170  * E: must be set to a subset of (new target) permitted
 171  *
 172  * Returns 0 on success and < 0 on error.
 173  */
 174 asmlinkage long sys_capset(cap_user_header_t header, const cap_user_data_t data)
 175 {
 176      kernel_cap_t inheritable, permitted, effective;
 177      __u32 version;
 178      struct task_struct *target;
 179      int ret;
 180      pid_t pid;
 181
 182      if (get_user(version, &header->version))
 183              return -EFAULT;
 184
 185      if (version != _LINUX_CAPABILITY_VERSION) {
 186              if (put_user(_LINUX_CAPABILITY_VERSION, &header->version))
 187                      return -EFAULT;
 188              return -EINVAL;
 189      }
 190
 191      if (get_user(pid, &header->pid))
 192              return -EFAULT;
 193
 194      if (pid && pid != current->pid && !capable(CAP_SETPCAP))
 195              return -EPERM;
 196
 197      if (copy_from_user(&effective, &data->effective, sizeof(effective)) ||
 198          copy_from_user(&inheritable, &data->inheritable, sizeof(inheritable)) ||
 199          copy_from_user(&permitted, &data->permitted, sizeof(permitted)))
 200              return -EFAULT;
 201
 202      spin_lock(&task_capability_lock);
 203      read_lock(&tasklist_lock);
 204
 205      if (pid > 0 && pid != current->pid) {
 206           target = find_task_by_pid(pid);
 207           if (!target) {
 208                ret = -ESRCH;
 209                goto out;
 210           }
 211      } else
 212                target = current;
 213
 214      ret = 0;
 215
 216      /* having verified that the proposed changes are legal,
 217            we now put them into effect. */
 218      if (pid < 0) {
 219              if (pid == -1)  /* all procs other than current and init */
 220                      ret = cap_set_all(&effective, &inheritable, &permitted);
 221
 222              else            /* all procs in process group */
 223                      ret = cap_set_pg(-pid, &effective, &inheritable,
 224                                                         &permitted);
 225      } else {
 226              ret = security_capset_check(target, &effective, &inheritable,
 227                                                         &permitted);
 228              if (!ret)
 229                      security_capset_set(target, &effective, &inheritable,
 230                                                         &permitted);
 231      }
 232
 233 out:
 234      read_unlock(&tasklist_lock);
 235      spin_unlock(&task_capability_lock);
 236
 237      return ret;
 238 }
 239
 240 int __capable(struct task_struct *t, int cap)
 241 {
 242         if (security_capable(t, cap) == 0) {
 243                 t->flags |= PF_SUPERPRIV;
 244                 return 1;
 245         }
 246         return 0;
 247 }
 248 EXPORT_SYMBOL(__capable);
 249
 250 #include <linux/vserver/base.h>
 251 int capable(int cap)
 252 {
 253         /* here for now so we don't require task locking */
 254         if (vs_check_bit(VXC_CAP_MASK, cap) && !vx_mcaps(1L << cap))
 255                 return 0;
 256         return __capable(current, cap);
 257 }
 258 EXPORT_SYMBOL(capable);