mm: introduce follow_pte()
[sfrench/cifs-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   2009/04/01
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         int rc;
31
32         rc = cap_bprm_set_creds(bprm);
33         if (rc)
34                 return rc;
35
36         /*
37          * Do only if this function is called for the first time of an execve
38          * operation.
39          */
40         if (bprm->cred_prepared)
41                 return 0;
42         /*
43          * Load policy if /sbin/tomoyo-init exists and /sbin/init is requested
44          * for the first time.
45          */
46         if (!tomoyo_policy_loaded)
47                 tomoyo_load_policy(bprm->filename);
48         /*
49          * Tell tomoyo_bprm_check_security() is called for the first time of an
50          * execve operation.
51          */
52         bprm->cred->security = NULL;
53         return 0;
54 }
55
56 static int tomoyo_bprm_check_security(struct linux_binprm *bprm)
57 {
58         struct tomoyo_domain_info *domain = bprm->cred->security;
59
60         /*
61          * Execute permission is checked against pathname passed to do_execve()
62          * using current domain.
63          */
64         if (!domain) {
65                 struct tomoyo_domain_info *next_domain = NULL;
66                 int retval = tomoyo_find_next_domain(bprm, &next_domain);
67
68                 if (!retval)
69                         bprm->cred->security = next_domain;
70                 return retval;
71         }
72         /*
73          * Read permission is checked against interpreters using next domain.
74          * '1' is the result of open_to_namei_flags(O_RDONLY).
75          */
76         return tomoyo_check_open_permission(domain, &bprm->file->f_path, 1);
77 }
78
79 #ifdef CONFIG_SYSCTL
80
81 static int tomoyo_prepend(char **buffer, int *buflen, const char *str)
82 {
83         int namelen = strlen(str);
84
85         if (*buflen < namelen)
86                 return -ENOMEM;
87         *buflen -= namelen;
88         *buffer -= namelen;
89         memcpy(*buffer, str, namelen);
90         return 0;
91 }
92
93 /**
94  * tomoyo_sysctl_path - return the realpath of a ctl_table.
95  * @table: pointer to "struct ctl_table".
96  *
97  * Returns realpath(3) of the @table on success.
98  * Returns NULL on failure.
99  *
100  * This function uses tomoyo_alloc(), so the caller must call tomoyo_free()
101  * if this function didn't return NULL.
102  */
103 static char *tomoyo_sysctl_path(struct ctl_table *table)
104 {
105         int buflen = TOMOYO_MAX_PATHNAME_LEN;
106         char *buf = tomoyo_alloc(buflen);
107         char *end = buf + buflen;
108         int error = -ENOMEM;
109
110         if (!buf)
111                 return NULL;
112
113         *--end = '\0';
114         buflen--;
115         while (table) {
116                 char num[32];
117                 const char *sp = table->procname;
118
119                 if (!sp) {
120                         memset(num, 0, sizeof(num));
121                         snprintf(num, sizeof(num) - 1, "=%d=", table->ctl_name);
122                         sp = num;
123                 }
124                 if (tomoyo_prepend(&end, &buflen, sp) ||
125                     tomoyo_prepend(&end, &buflen, "/"))
126                         goto out;
127                 table = table->parent;
128         }
129         if (tomoyo_prepend(&end, &buflen, "/proc/sys"))
130                 goto out;
131         error = tomoyo_encode(buf, end - buf, end);
132  out:
133         if (!error)
134                 return buf;
135         tomoyo_free(buf);
136         return NULL;
137 }
138
139 static int tomoyo_sysctl(struct ctl_table *table, int op)
140 {
141         int error;
142         char *name;
143
144         op &= MAY_READ | MAY_WRITE;
145         if (!op)
146                 return 0;
147         name = tomoyo_sysctl_path(table);
148         if (!name)
149                 return -ENOMEM;
150         error = tomoyo_check_file_perm(tomoyo_domain(), name, op);
151         tomoyo_free(name);
152         return error;
153 }
154 #endif
155
156 static int tomoyo_path_truncate(struct path *path, loff_t length,
157                                 unsigned int time_attrs)
158 {
159         return tomoyo_check_1path_perm(tomoyo_domain(),
160                                        TOMOYO_TYPE_TRUNCATE_ACL,
161                                        path);
162 }
163
164 static int tomoyo_path_unlink(struct path *parent, struct dentry *dentry)
165 {
166         struct path path = { parent->mnt, dentry };
167         return tomoyo_check_1path_perm(tomoyo_domain(),
168                                        TOMOYO_TYPE_UNLINK_ACL,
169                                        &path);
170 }
171
172 static int tomoyo_path_mkdir(struct path *parent, struct dentry *dentry,
173                              int mode)
174 {
175         struct path path = { parent->mnt, dentry };
176         return tomoyo_check_1path_perm(tomoyo_domain(),
177                                        TOMOYO_TYPE_MKDIR_ACL,
178                                        &path);
179 }
180
181 static int tomoyo_path_rmdir(struct path *parent, struct dentry *dentry)
182 {
183         struct path path = { parent->mnt, dentry };
184         return tomoyo_check_1path_perm(tomoyo_domain(),
185                                        TOMOYO_TYPE_RMDIR_ACL,
186                                        &path);
187 }
188
189 static int tomoyo_path_symlink(struct path *parent, struct dentry *dentry,
190                                const char *old_name)
191 {
192         struct path path = { parent->mnt, dentry };
193         return tomoyo_check_1path_perm(tomoyo_domain(),
194                                        TOMOYO_TYPE_SYMLINK_ACL,
195                                        &path);
196 }
197
198 static int tomoyo_path_mknod(struct path *parent, struct dentry *dentry,
199                              int mode, unsigned int dev)
200 {
201         struct path path = { parent->mnt, dentry };
202         int type = TOMOYO_TYPE_CREATE_ACL;
203
204         switch (mode & S_IFMT) {
205         case S_IFCHR:
206                 type = TOMOYO_TYPE_MKCHAR_ACL;
207                 break;
208         case S_IFBLK:
209                 type = TOMOYO_TYPE_MKBLOCK_ACL;
210                 break;
211         case S_IFIFO:
212                 type = TOMOYO_TYPE_MKFIFO_ACL;
213                 break;
214         case S_IFSOCK:
215                 type = TOMOYO_TYPE_MKSOCK_ACL;
216                 break;
217         }
218         return tomoyo_check_1path_perm(tomoyo_domain(),
219                                        type, &path);
220 }
221
222 static int tomoyo_path_link(struct dentry *old_dentry, struct path *new_dir,
223                             struct dentry *new_dentry)
224 {
225         struct path path1 = { new_dir->mnt, old_dentry };
226         struct path path2 = { new_dir->mnt, new_dentry };
227         return tomoyo_check_2path_perm(tomoyo_domain(),
228                                        TOMOYO_TYPE_LINK_ACL,
229                                        &path1, &path2);
230 }
231
232 static int tomoyo_path_rename(struct path *old_parent,
233                               struct dentry *old_dentry,
234                               struct path *new_parent,
235                               struct dentry *new_dentry)
236 {
237         struct path path1 = { old_parent->mnt, old_dentry };
238         struct path path2 = { new_parent->mnt, new_dentry };
239         return tomoyo_check_2path_perm(tomoyo_domain(),
240                                        TOMOYO_TYPE_RENAME_ACL,
241                                        &path1, &path2);
242 }
243
244 static int tomoyo_file_fcntl(struct file *file, unsigned int cmd,
245                              unsigned long arg)
246 {
247         if (cmd == F_SETFL && ((arg ^ file->f_flags) & O_APPEND))
248                 return tomoyo_check_rewrite_permission(tomoyo_domain(), file);
249         return 0;
250 }
251
252 static int tomoyo_dentry_open(struct file *f, const struct cred *cred)
253 {
254         int flags = f->f_flags;
255
256         if ((flags + 1) & O_ACCMODE)
257                 flags++;
258         flags |= f->f_flags & (O_APPEND | O_TRUNC);
259         /* Don't check read permission here if called from do_execve(). */
260         if (current->in_execve)
261                 return 0;
262         return tomoyo_check_open_permission(tomoyo_domain(), &f->f_path, flags);
263 }
264
265 /*
266  * tomoyo_security_ops is a "struct security_operations" which is used for
267  * registering TOMOYO.
268  */
269 static struct security_operations tomoyo_security_ops = {
270         .name                = "tomoyo",
271         .cred_prepare        = tomoyo_cred_prepare,
272         .bprm_set_creds      = tomoyo_bprm_set_creds,
273         .bprm_check_security = tomoyo_bprm_check_security,
274 #ifdef CONFIG_SYSCTL
275         .sysctl              = tomoyo_sysctl,
276 #endif
277         .file_fcntl          = tomoyo_file_fcntl,
278         .dentry_open         = tomoyo_dentry_open,
279         .path_truncate       = tomoyo_path_truncate,
280         .path_unlink         = tomoyo_path_unlink,
281         .path_mkdir          = tomoyo_path_mkdir,
282         .path_rmdir          = tomoyo_path_rmdir,
283         .path_symlink        = tomoyo_path_symlink,
284         .path_mknod          = tomoyo_path_mknod,
285         .path_link           = tomoyo_path_link,
286         .path_rename         = tomoyo_path_rename,
287 };
288
289 static int __init tomoyo_init(void)
290 {
291         struct cred *cred = (struct cred *) current_cred();
292
293         if (!security_module_enable(&tomoyo_security_ops))
294                 return 0;
295         /* register ourselves with the security framework */
296         if (register_security(&tomoyo_security_ops))
297                 panic("Failure registering TOMOYO Linux");
298         printk(KERN_INFO "TOMOYO Linux initialized\n");
299         cred->security = &tomoyo_kernel_domain;
300         tomoyo_realpath_init();
301         return 0;
302 }
303
304 security_initcall(tomoyo_init);