security/ cleanups
[linux-2.6.git] / 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);