[PATCH] kernel/capability.c: add kerneldoc
[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/mm.h>
11 #include <linux/module.h>
12 #include <linux/security.h>
13 #include <linux/syscalls.h>
14 #include <asm/uaccess.h>
15
16 unsigned securebits = SECUREBITS_DEFAULT; /* systemwide security settings */
17 kernel_cap_t cap_bset = CAP_INIT_EFF_SET;
18
19 EXPORT_SYMBOL(securebits);
20 EXPORT_SYMBOL(cap_bset);
21
22 /*
23  * This lock protects task->cap_* for all tasks including current.
24  * Locking rule: acquire this prior to tasklist_lock.
25  */
26 static DEFINE_SPINLOCK(task_capability_lock);
27
28 /*
29  * For sys_getproccap() and sys_setproccap(), any of the three
30  * capability set pointers may be NULL -- indicating that that set is
31  * uninteresting and/or not to be changed.
32  */
33
34 /**
35  * sys_capget - get the capabilities of a given process.
36  * @header: pointer to struct that contains capability version and
37  *      target pid data
38  * @dataptr: pointer to struct that contains the effective, permitted,
39  *      and inheritable capabilities that are returned
40  *
41  * Returns 0 on success and < 0 on error.
42  */
43 asmlinkage long sys_capget(cap_user_header_t header, cap_user_data_t dataptr)
44 {
45      int ret = 0;
46      pid_t pid;
47      __u32 version;
48      task_t *target;
49      struct __user_cap_data_struct data;
50
51      if (get_user(version, &header->version))
52              return -EFAULT;
53
54      if (version != _LINUX_CAPABILITY_VERSION) {
55              if (put_user(_LINUX_CAPABILITY_VERSION, &header->version))
56                      return -EFAULT; 
57              return -EINVAL;
58      }
59
60      if (get_user(pid, &header->pid))
61              return -EFAULT;
62
63      if (pid < 0) 
64              return -EINVAL;
65
66      spin_lock(&task_capability_lock);
67      read_lock(&tasklist_lock); 
68
69      if (pid && pid != current->pid) {
70              target = find_task_by_pid(pid);
71              if (!target) {
72                   ret = -ESRCH;
73                   goto out;
74              }
75      } else
76              target = current;
77
78      ret = security_capget(target, &data.effective, &data.inheritable, &data.permitted);
79
80 out:
81      read_unlock(&tasklist_lock); 
82      spin_unlock(&task_capability_lock);
83
84      if (!ret && copy_to_user(dataptr, &data, sizeof data))
85           return -EFAULT; 
86
87      return ret;
88 }
89
90 /*
91  * cap_set_pg - set capabilities for all processes in a given process
92  * group.  We call this holding task_capability_lock and tasklist_lock.
93  */
94 static inline int cap_set_pg(int pgrp, kernel_cap_t *effective,
95                               kernel_cap_t *inheritable,
96                               kernel_cap_t *permitted)
97 {
98         task_t *g, *target;
99         int ret = -EPERM;
100         int found = 0;
101
102         do_each_task_pid(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_task_pid(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      task_t *g, *target;
131      int ret = -EPERM;
132      int found = 0;
133
134      do_each_thread(g, target) {
135              if (target == current || target->pid == 1)
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      task_t *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 }