3eeeae12c4dcde1569e9b809bc97aa6dbf07d464
[linux-2.6.git] / security / tomoyo / tomoyo.c
1 /*
2  * security/tomoyo/tomoyo.c
3  *
4  * LSM hooks for TOMOYO Linux.
5  *
6  * Copyright (C) 2005-2009  NTT DATA CORPORATION
7  *
8  * Version: 2.2.0-pre   2009/02/01
9  *
10  */
11
12 #include <linux/security.h>
13 #include "common.h"
14 #include "tomoyo.h"
15 #include "realpath.h"
16
17 static int tomoyo_cred_prepare(struct cred *new, const struct cred *old,
18                                gfp_t gfp)
19 {
20         /*
21          * Since "struct tomoyo_domain_info *" is a sharable pointer,
22          * we don't need to duplicate.
23          */
24         new->security = old->security;
25         return 0;
26 }
27
28 static int tomoyo_bprm_set_creds(struct linux_binprm *bprm)
29 {
30         /*
31          * Do only if this function is called for the first time of an execve
32          * operation.
33          */
34         if (bprm->cred_prepared)
35                 return 0;
36         /*
37          * Load policy if /sbin/tomoyo-init exists and /sbin/init is requested
38          * for the first time.
39          */
40         if (!tomoyo_policy_loaded)
41                 tomoyo_load_policy(bprm->filename);
42         /*
43          * Tell tomoyo_bprm_check_security() is called for the first time of an
44          * execve operation.
45          */
46         bprm->cred->security = NULL;
47         return 0;
48 }
49
50 static int tomoyo_bprm_check_security(struct linux_binprm *bprm)
51 {
52         struct tomoyo_domain_info *domain = bprm->cred->security;
53
54         /*
55          * Execute permission is checked against pathname passed to do_execve()
56          * using current domain.
57          */
58         if (!domain) {
59                 struct tomoyo_domain_info *next_domain = NULL;
60                 int retval = tomoyo_find_next_domain(bprm, &next_domain);
61
62                 if (!retval)
63                         bprm->cred->security = next_domain;
64                 return retval;
65         }
66         /*
67          * Read permission is checked against interpreters using next domain.
68          * '1' is the result of open_to_namei_flags(O_RDONLY).
69          */
70         return tomoyo_check_open_permission(domain, &bprm->file->f_path, 1);
71 }
72
73 #ifdef CONFIG_SYSCTL
74
75 static int tomoyo_prepend(char **buffer, int *buflen, const char *str)
76 {
77         int namelen = strlen(str);
78
79         if (*buflen < namelen)
80                 return -ENOMEM;
81         *buflen -= namelen;
82         *buffer -= namelen;
83         memcpy(*buffer, str, namelen);
84         return 0;
85 }
86
87 /**
88  * tomoyo_sysctl_path - return the realpath of a ctl_table.
89  * @table: pointer to "struct ctl_table".
90  *
91  * Returns realpath(3) of the @table on success.
92  * Returns NULL on failure.
93  *
94  * This function uses tomoyo_alloc(), so the caller must call tomoyo_free()
95  * if this function didn't return NULL.
96  */
97 static char *tomoyo_sysctl_path(struct ctl_table *table)
98 {
99         int buflen = TOMOYO_MAX_PATHNAME_LEN;
100         char *buf = tomoyo_alloc(buflen);
101         char *end = buf + buflen;
102         int error = -ENOMEM;
103
104         if (!buf)
105                 return NULL;
106
107         *--end = '\0';
108         buflen--;
109         while (table) {
110                 char num[32];
111                 const char *sp = table->procname;
112
113                 if (!sp) {
114                         memset(num, 0, sizeof(num));
115                         snprintf(num, sizeof(num) - 1, "=%d=", table->ctl_name);
116                         sp = num;
117                 }
118                 if (tomoyo_prepend(&end, &buflen, sp) ||
119                     tomoyo_prepend(&end, &buflen, "/"))
120                         goto out;
121                 table = table->parent;
122         }
123         if (tomoyo_prepend(&end, &buflen, "/proc/sys"))
124                 goto out;
125         error = tomoyo_encode(buf, end - buf, end);
126  out:
127         if (!error)
128                 return buf;
129         tomoyo_free(buf);
130         return NULL;
131 }
132
133 static int tomoyo_sysctl(struct ctl_table *table, int op)
134 {
135         int error;
136         char *name;
137
138         op &= MAY_READ | MAY_WRITE;
139         if (!op)
140                 return 0;
141         name = tomoyo_sysctl_path(table);
142         if (!name)
143                 return -ENOMEM;
144         error = tomoyo_check_file_perm(tomoyo_domain(), name, op);
145         tomoyo_free(name);
146         return error;
147 }
148 #endif
149
150 static int tomoyo_path_truncate(struct path *path, loff_t length,
151                                 unsigned int time_attrs)
152 {
153         return tomoyo_check_1path_perm(tomoyo_domain(),
154                                        TOMOYO_TYPE_TRUNCATE_ACL,
155                                        path);
156 }
157
158 static int tomoyo_path_unlink(struct path *parent, struct dentry *dentry)
159 {
160         struct path path = { parent->mnt, dentry };
161         return tomoyo_check_1path_perm(tomoyo_domain(),
162                                        TOMOYO_TYPE_UNLINK_ACL,
163                                        &path);
164 }
165
166 static int tomoyo_path_mkdir(struct path *parent, struct dentry *dentry,
167                              int mode)
168 {
169         struct path path = { parent->mnt, dentry };
170         return tomoyo_check_1path_perm(tomoyo_domain(),
171                                        TOMOYO_TYPE_MKDIR_ACL,
172                                        &path);
173 }
174
175 static int tomoyo_path_rmdir(struct path *parent, struct dentry *dentry)
176 {
177         struct path path = { parent->mnt, dentry };
178         return tomoyo_check_1path_perm(tomoyo_domain(),
179                                        TOMOYO_TYPE_RMDIR_ACL,
180                                        &path);
181 }
182
183 static int tomoyo_path_symlink(struct path *parent, struct dentry *dentry,
184                                const char *old_name)
185 {
186         struct path path = { parent->mnt, dentry };
187         return tomoyo_check_1path_perm(tomoyo_domain(),
188                                        TOMOYO_TYPE_SYMLINK_ACL,
189                                        &path);
190 }
191
192 static int tomoyo_path_mknod(struct path *parent, struct dentry *dentry,
193                              int mode, unsigned int dev)
194 {
195         struct path path = { parent->mnt, dentry };
196         int type = TOMOYO_TYPE_CREATE_ACL;
197
198         switch (mode & S_IFMT) {
199         case S_IFCHR:
200                 type = TOMOYO_TYPE_MKCHAR_ACL;
201                 break;
202         case S_IFBLK:
203                 type = TOMOYO_TYPE_MKBLOCK_ACL;
204                 break;
205         case S_IFIFO:
206                 type = TOMOYO_TYPE_MKFIFO_ACL;
207                 break;
208         case S_IFSOCK:
209                 type = TOMOYO_TYPE_MKSOCK_ACL;
210                 break;
211         }
212         return tomoyo_check_1path_perm(tomoyo_domain(),
213                                        type, &path);
214 }
215
216 static int tomoyo_path_link(struct dentry *old_dentry, struct path *new_dir,
217                             struct dentry *new_dentry)
218 {
219         struct path path1 = { new_dir->mnt, old_dentry };
220         struct path path2 = { new_dir->mnt, new_dentry };
221         return tomoyo_check_2path_perm(tomoyo_domain(),
222                                        TOMOYO_TYPE_LINK_ACL,
223                                        &path1, &path2);
224 }
225
226 static int tomoyo_path_rename(struct path *old_parent,
227                               struct dentry *old_dentry,
228                               struct path *new_parent,
229                               struct dentry *new_dentry)
230 {
231         struct path path1 = { old_parent->mnt, old_dentry };
232         struct path path2 = { new_parent->mnt, new_dentry };
233         return tomoyo_check_2path_perm(tomoyo_domain(),
234                                        TOMOYO_TYPE_RENAME_ACL,
235                                        &path1, &path2);
236 }
237
238 static int tomoyo_file_fcntl(struct file *file, unsigned int cmd,
239                              unsigned long arg)
240 {
241         if (cmd == F_SETFL && ((arg ^ file->f_flags) & O_APPEND))
242                 return tomoyo_check_rewrite_permission(tomoyo_domain(), file);
243         return 0;
244 }
245
246 static int tomoyo_dentry_open(struct file *f, const struct cred *cred)
247 {
248         int flags = f->f_flags;
249
250         if ((flags + 1) & O_ACCMODE)
251                 flags++;
252         flags |= f->f_flags & (O_APPEND | O_TRUNC);
253         /* Don't check read permission here if called from do_execve(). */
254         if (current->in_execve)
255                 return 0;
256         return tomoyo_check_open_permission(tomoyo_domain(), &f->f_path, flags);
257 }
258
259 static struct security_operations tomoyo_security_ops = {
260         .name                = "tomoyo",
261         .cred_prepare        = tomoyo_cred_prepare,
262         .bprm_set_creds      = tomoyo_bprm_set_creds,
263         .bprm_check_security = tomoyo_bprm_check_security,
264 #ifdef CONFIG_SYSCTL
265         .sysctl              = tomoyo_sysctl,
266 #endif
267         .file_fcntl          = tomoyo_file_fcntl,
268         .dentry_open         = tomoyo_dentry_open,
269         .path_truncate       = tomoyo_path_truncate,
270         .path_unlink         = tomoyo_path_unlink,
271         .path_mkdir          = tomoyo_path_mkdir,
272         .path_rmdir          = tomoyo_path_rmdir,
273         .path_symlink        = tomoyo_path_symlink,
274         .path_mknod          = tomoyo_path_mknod,
275         .path_link           = tomoyo_path_link,
276         .path_rename         = tomoyo_path_rename,
277 };
278
279 static int __init tomoyo_init(void)
280 {
281         struct cred *cred = (struct cred *) current_cred();
282
283         if (!security_module_enable(&tomoyo_security_ops))
284                 return 0;
285         /* register ourselves with the security framework */
286         if (register_security(&tomoyo_security_ops))
287                 panic("Failure registering TOMOYO Linux");
288         printk(KERN_INFO "TOMOYO Linux initialized\n");
289         cred->security = &tomoyo_kernel_domain;
290         tomoyo_realpath_init();
291         return 0;
292 }
293
294 security_initcall(tomoyo_init);