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