Root/security/apparmor/apparmorfs.c

1/*
2 * AppArmor security module
3 *
4 * This file contains AppArmor /sys/kernel/security/apparmor interface functions
5 *
6 * Copyright (C) 1998-2008 Novell/SUSE
7 * Copyright 2009-2010 Canonical Ltd.
8 *
9 * This program is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU General Public License as
11 * published by the Free Software Foundation, version 2 of the
12 * License.
13 */
14
15#include <linux/security.h>
16#include <linux/vmalloc.h>
17#include <linux/module.h>
18#include <linux/seq_file.h>
19#include <linux/uaccess.h>
20#include <linux/namei.h>
21
22#include "include/apparmor.h"
23#include "include/apparmorfs.h"
24#include "include/audit.h"
25#include "include/context.h"
26#include "include/policy.h"
27
28/**
29 * aa_simple_write_to_buffer - common routine for getting policy from user
30 * @op: operation doing the user buffer copy
31 * @userbuf: user buffer to copy data from (NOT NULL)
32 * @alloc_size: size of user buffer
33 * @copy_size: size of data to copy from user buffer
34 * @pos: position write is at in the file (NOT NULL)
35 *
36 * Returns: kernel buffer containing copy of user buffer data or an
37 * ERR_PTR on failure.
38 */
39static char *aa_simple_write_to_buffer(int op, const char __user *userbuf,
40                       size_t alloc_size, size_t copy_size,
41                       loff_t *pos)
42{
43    char *data;
44
45    if (*pos != 0)
46        /* only writes from pos 0, that is complete writes */
47        return ERR_PTR(-ESPIPE);
48
49    /*
50     * Don't allow profile load/replace/remove from profiles that don't
51     * have CAP_MAC_ADMIN
52     */
53    if (!aa_may_manage_policy(op))
54        return ERR_PTR(-EACCES);
55
56    /* freed by caller to simple_write_to_buffer */
57    data = kvmalloc(alloc_size);
58    if (data == NULL)
59        return ERR_PTR(-ENOMEM);
60
61    if (copy_from_user(data, userbuf, copy_size)) {
62        kvfree(data);
63        return ERR_PTR(-EFAULT);
64    }
65
66    return data;
67}
68
69
70/* .load file hook fn to load policy */
71static ssize_t profile_load(struct file *f, const char __user *buf, size_t size,
72                loff_t *pos)
73{
74    char *data;
75    ssize_t error;
76
77    data = aa_simple_write_to_buffer(OP_PROF_LOAD, buf, size, size, pos);
78
79    error = PTR_ERR(data);
80    if (!IS_ERR(data)) {
81        error = aa_replace_profiles(data, size, PROF_ADD);
82        kvfree(data);
83    }
84
85    return error;
86}
87
88static const struct file_operations aa_fs_profile_load = {
89    .write = profile_load
90};
91
92/* .replace file hook fn to load and/or replace policy */
93static ssize_t profile_replace(struct file *f, const char __user *buf,
94                   size_t size, loff_t *pos)
95{
96    char *data;
97    ssize_t error;
98
99    data = aa_simple_write_to_buffer(OP_PROF_REPL, buf, size, size, pos);
100    error = PTR_ERR(data);
101    if (!IS_ERR(data)) {
102        error = aa_replace_profiles(data, size, PROF_REPLACE);
103        kvfree(data);
104    }
105
106    return error;
107}
108
109static const struct file_operations aa_fs_profile_replace = {
110    .write = profile_replace
111};
112
113/* .remove file hook fn to remove loaded policy */
114static ssize_t profile_remove(struct file *f, const char __user *buf,
115                  size_t size, loff_t *pos)
116{
117    char *data;
118    ssize_t error;
119
120    /*
121     * aa_remove_profile needs a null terminated string so 1 extra
122     * byte is allocated and the copied data is null terminated.
123     */
124    data = aa_simple_write_to_buffer(OP_PROF_RM, buf, size + 1, size, pos);
125
126    error = PTR_ERR(data);
127    if (!IS_ERR(data)) {
128        data[size] = 0;
129        error = aa_remove_profiles(data, size);
130        kvfree(data);
131    }
132
133    return error;
134}
135
136static const struct file_operations aa_fs_profile_remove = {
137    .write = profile_remove
138};
139
140/** Base file system setup **/
141
142static struct dentry *aa_fs_dentry __initdata;
143
144static void __init aafs_remove(const char *name)
145{
146    struct dentry *dentry;
147
148    dentry = lookup_one_len(name, aa_fs_dentry, strlen(name));
149    if (!IS_ERR(dentry)) {
150        securityfs_remove(dentry);
151        dput(dentry);
152    }
153}
154
155/**
156 * aafs_create - create an entry in the apparmor filesystem
157 * @name: name of the entry (NOT NULL)
158 * @mask: file permission mask of the file
159 * @fops: file operations for the file (NOT NULL)
160 *
161 * Used aafs_remove to remove entries created with this fn.
162 */
163static int __init aafs_create(const char *name, int mask,
164                  const struct file_operations *fops)
165{
166    struct dentry *dentry;
167
168    dentry = securityfs_create_file(name, S_IFREG | mask, aa_fs_dentry,
169                    NULL, fops);
170
171    return IS_ERR(dentry) ? PTR_ERR(dentry) : 0;
172}
173
174/**
175 * aa_destroy_aafs - cleanup and free aafs
176 *
177 * releases dentries allocated by aa_create_aafs
178 */
179void __init aa_destroy_aafs(void)
180{
181    if (aa_fs_dentry) {
182        aafs_remove(".remove");
183        aafs_remove(".replace");
184        aafs_remove(".load");
185
186        securityfs_remove(aa_fs_dentry);
187        aa_fs_dentry = NULL;
188    }
189}
190
191/**
192 * aa_create_aafs - create the apparmor security filesystem
193 *
194 * dentries created here are released by aa_destroy_aafs
195 *
196 * Returns: error on failure
197 */
198int __init aa_create_aafs(void)
199{
200    int error;
201
202    if (!apparmor_initialized)
203        return 0;
204
205    if (aa_fs_dentry) {
206        AA_ERROR("%s: AppArmor securityfs already exists\n", __func__);
207        return -EEXIST;
208    }
209
210    aa_fs_dentry = securityfs_create_dir("apparmor", NULL);
211    if (IS_ERR(aa_fs_dentry)) {
212        error = PTR_ERR(aa_fs_dentry);
213        aa_fs_dentry = NULL;
214        goto error;
215    }
216
217    error = aafs_create(".load", 0640, &aa_fs_profile_load);
218    if (error)
219        goto error;
220    error = aafs_create(".replace", 0640, &aa_fs_profile_replace);
221    if (error)
222        goto error;
223    error = aafs_create(".remove", 0640, &aa_fs_profile_remove);
224    if (error)
225        goto error;
226
227    /* TODO: add support for apparmorfs_null and apparmorfs_mnt */
228
229    /* Report that AppArmor fs is enabled */
230    aa_info_message("AppArmor Filesystem Enabled");
231    return 0;
232
233error:
234    aa_destroy_aafs();
235    AA_ERROR("Error creating AppArmor securityfs\n");
236    return error;
237}
238
239fs_initcall(aa_create_aafs);
240

Archive Download this file



interactive