1 /* 2 * security/tomoyo/realpath.c 3 * 4 * Get the canonicalized absolute pathnames. The basis for TOMOYO. 5 * 6 * Copyright (C) 2005-2009 NTT DATA CORPORATION 7 * 8 * Version: 2.2.0 2009/04/01 9 * 10 */ 11 12 #include <linux/types.h> 13 #include <linux/mount.h> 14 #include <linux/mnt_namespace.h> 15 #include <linux/fs_struct.h> 16 #include <linux/hash.h> 17 #include <linux/magic.h> 18 #include <linux/slab.h> 19 #include "common.h" 20 21 /** 22 * tomoyo_encode: Convert binary string to ascii string. 23 * 24 * @buffer: Buffer for ASCII string. 25 * @buflen: Size of @buffer. 26 * @str: Binary string. 27 * 28 * Returns 0 on success, -ENOMEM otherwise. 29 */ 30 int tomoyo_encode(char *buffer, int buflen, const char *str) 31 { 32 while (1) { 33 const unsigned char c = *(unsigned char *) str++; 34 35 if (tomoyo_is_valid(c)) { 36 if (--buflen <= 0) 37 break; 38 *buffer++ = (char) c; 39 if (c != '\\') 40 continue; 41 if (--buflen <= 0) 42 break; 43 *buffer++ = (char) c; 44 continue; 45 } 46 if (!c) { 47 if (--buflen <= 0) 48 break; 49 *buffer = '\0'; 50 return 0; 51 } 52 buflen -= 4; 53 if (buflen <= 0) 54 break; 55 *buffer++ = '\\'; 56 *buffer++ = (c >> 6) + '0'; 57 *buffer++ = ((c >> 3) & 7) + '0'; 58 *buffer++ = (c & 7) + '0'; 59 } 60 return -ENOMEM; 61 } 62 63 /** 64 * tomoyo_realpath_from_path2 - Returns realpath(3) of the given dentry but ignores chroot'ed root. 65 * 66 * @path: Pointer to "struct path". 67 * @newname: Pointer to buffer to return value in. 68 * @newname_len: Size of @newname. 69 * 70 * Returns 0 on success, negative value otherwise. 71 * 72 * If dentry is a directory, trailing '/' is appended. 73 * Characters out of 0x20 < c < 0x7F range are converted to 74 * \ooo style octal string. 75 * Character \ is converted to \\ string. 76 */ 77 int tomoyo_realpath_from_path2(struct path *path, char *newname, 78 int newname_len) 79 { 80 int error = -ENOMEM; 81 struct dentry *dentry = path->dentry; 82 char *sp; 83 84 if (!dentry || !path->mnt || !newname || newname_len <= 2048) 85 return -EINVAL; 86 if (dentry->d_op && dentry->d_op->d_dname) { 87 /* For "socket:[\$]" and "pipe:[\$]". */ 88 static const int offset = 1536; 89 sp = dentry->d_op->d_dname(dentry, newname + offset, 90 newname_len - offset); 91 } else { 92 struct path ns_root = {.mnt = NULL, .dentry = NULL}; 93 94 spin_lock(&dcache_lock); 95 /* go to whatever namespace root we are under */ 96 sp = __d_path(path, &ns_root, newname, newname_len); 97 spin_unlock(&dcache_lock); 98 /* Prepend "/proc" prefix if using internal proc vfs mount. */ 99 if (!IS_ERR(sp) && (path->mnt->mnt_flags & MNT_INTERNAL) && 100 (path->mnt->mnt_sb->s_magic == PROC_SUPER_MAGIC)) { 101 sp -= 5; 102 if (sp >= newname) 103 memcpy(sp, "/proc", 5); 104 else 105 sp = ERR_PTR(-ENOMEM); 106 } 107 } 108 if (IS_ERR(sp)) 109 error = PTR_ERR(sp); 110 else 111 error = tomoyo_encode(newname, sp - newname, sp); 112 /* Append trailing '/' if dentry is a directory. */ 113 if (!error && dentry->d_inode && S_ISDIR(dentry->d_inode->i_mode) 114 && *newname) { 115 sp = newname + strlen(newname); 116 if (*(sp - 1) != '/') { 117 if (sp < newname + newname_len - 4) { 118 *sp++ = '/'; 119 *sp = '\0'; 120 } else { 121 error = -ENOMEM; 122 } 123 } 124 } 125 if (error) 126 printk(KERN_WARNING "tomoyo_realpath: Pathname too long.\n"); 127 return error; 128 } 129 130 /** 131 * tomoyo_realpath_from_path - Returns realpath(3) of the given pathname but ignores chroot'ed root. 132 * 133 * @path: Pointer to "struct path". 134 * 135 * Returns the realpath of the given @path on success, NULL otherwise. 136 * 137 * These functions use kzalloc(), so the caller must call kfree() 138 * if these functions didn't return NULL. 139 */ 140 char *tomoyo_realpath_from_path(struct path *path) 141 { 142 char *buf = kzalloc(sizeof(struct tomoyo_page_buffer), GFP_KERNEL); 143 144 BUILD_BUG_ON(sizeof(struct tomoyo_page_buffer) 145 <= TOMOYO_MAX_PATHNAME_LEN - 1); 146 if (!buf) 147 return NULL; 148 if (tomoyo_realpath_from_path2(path, buf, 149 TOMOYO_MAX_PATHNAME_LEN - 1) == 0) 150 return buf; 151 kfree(buf); 152 return NULL; 153 } 154 155 /** 156 * tomoyo_realpath - Get realpath of a pathname. 157 * 158 * @pathname: The pathname to solve. 159 * 160 * Returns the realpath of @pathname on success, NULL otherwise. 161 */ 162 char *tomoyo_realpath(const char *pathname) 163 { 164 struct path path; 165 166 if (pathname && kern_path(pathname, LOOKUP_FOLLOW, &path) == 0) { 167 char *buf = tomoyo_realpath_from_path(&path); 168 path_put(&path); 169 return buf; 170 } 171 return NULL; 172 } 173 174 /** 175 * tomoyo_realpath_nofollow - Get realpath of a pathname. 176 * 177 * @pathname: The pathname to solve. 178 * 179 * Returns the realpath of @pathname on success, NULL otherwise. 180 */ 181 char *tomoyo_realpath_nofollow(const char *pathname) 182 { 183 struct path path; 184 185 if (pathname && kern_path(pathname, 0, &path) == 0) { 186 char *buf = tomoyo_realpath_from_path(&path); 187 path_put(&path); 188 return buf; 189 } 190 return NULL; 191 } 192 193 /* Memory allocated for non-string data. */ 194 static atomic_t tomoyo_policy_memory_size; 195 /* Quota for holding policy. */ 196 static unsigned int tomoyo_quota_for_policy; 197 198 /** 199 * tomoyo_memory_ok - Check memory quota. 200 * 201 * @ptr: Pointer to allocated memory. 202 * 203 * Returns true on success, false otherwise. 204 * 205 * Caller holds tomoyo_policy_lock. 206 * Memory pointed by @ptr will be zeroed on success. 207 */ 208 bool tomoyo_memory_ok(void *ptr) 209 { 210 int allocated_len = ptr ? ksize(ptr) : 0; 211 atomic_add(allocated_len, &tomoyo_policy_memory_size); 212 if (ptr && (!tomoyo_quota_for_policy || 213 atomic_read(&tomoyo_policy_memory_size) 214 <= tomoyo_quota_for_policy)) { 215 memset(ptr, 0, allocated_len); 216 return true; 217 } 218 printk(KERN_WARNING "ERROR: Out of memory " 219 "for tomoyo_alloc_element().\n"); 220 if (!tomoyo_policy_loaded) 221 panic("MAC Initialization failed.\n"); 222 return false; 223 } 224 225 /** 226 * tomoyo_memory_free - Free memory for elements. 227 * 228 * @ptr: Pointer to allocated memory. 229 */ 230 void tomoyo_memory_free(void *ptr) 231 { 232 atomic_sub(ksize(ptr), &tomoyo_policy_memory_size); 233 kfree(ptr); 234 } 235 236 /* 237 * tomoyo_name_list is used for holding string data used by TOMOYO. 238 * Since same string data is likely used for multiple times (e.g. 239 * "/lib/libc-2.5.so"), TOMOYO shares string data in the form of 240 * "const struct tomoyo_path_info *". 241 */ 242 struct list_head tomoyo_name_list[TOMOYO_MAX_HASH]; 243 /* Lock for protecting tomoyo_name_list . */ 244 DEFINE_MUTEX(tomoyo_name_list_lock); 245 246 /** 247 * tomoyo_get_name - Allocate permanent memory for string data. 248 * 249 * @name: The string to store into the permernent memory. 250 * 251 * Returns pointer to "struct tomoyo_path_info" on success, NULL otherwise. 252 */ 253 const struct tomoyo_path_info *tomoyo_get_name(const char *name) 254 { 255 struct tomoyo_name_entry *ptr; 256 unsigned int hash; 257 int len; 258 int allocated_len; 259 struct list_head *head; 260 261 if (!name) 262 return NULL; 263 len = strlen(name) + 1; 264 hash = full_name_hash((const unsigned char *) name, len - 1); 265 head = &tomoyo_name_list[hash_long(hash, TOMOYO_HASH_BITS)]; 266 mutex_lock(&tomoyo_name_list_lock); 267 list_for_each_entry(ptr, head, list) { 268 if (hash != ptr->entry.hash || strcmp(name, ptr->entry.name)) 269 continue; 270 atomic_inc(&ptr->users); 271 goto out; 272 } 273 ptr = kzalloc(sizeof(*ptr) + len, GFP_KERNEL); 274 allocated_len = ptr ? ksize(ptr) : 0; 275 if (!ptr || (tomoyo_quota_for_policy && 276 atomic_read(&tomoyo_policy_memory_size) + allocated_len 277 > tomoyo_quota_for_policy)) { 278 kfree(ptr); 279 printk(KERN_WARNING "ERROR: Out of memory " 280 "for tomoyo_get_name().\n"); 281 if (!tomoyo_policy_loaded) 282 panic("MAC Initialization failed.\n"); 283 ptr = NULL; 284 goto out; 285 } 286 atomic_add(allocated_len, &tomoyo_policy_memory_size); 287 ptr->entry.name = ((char *) ptr) + sizeof(*ptr); 288 memmove((char *) ptr->entry.name, name, len); 289 atomic_set(&ptr->users, 1); 290 tomoyo_fill_path_info(&ptr->entry); 291 list_add_tail(&ptr->list, head); 292 out: 293 mutex_unlock(&tomoyo_name_list_lock); 294 return ptr ? &ptr->entry : NULL; 295 } 296 297 /** 298 * tomoyo_realpath_init - Initialize realpath related code. 299 */ 300 void __init tomoyo_realpath_init(void) 301 { 302 int i; 303 304 BUILD_BUG_ON(TOMOYO_MAX_PATHNAME_LEN > PATH_MAX); 305 for (i = 0; i < TOMOYO_MAX_HASH; i++) 306 INIT_LIST_HEAD(&tomoyo_name_list[i]); 307 INIT_LIST_HEAD(&tomoyo_kernel_domain.acl_info_list); 308 tomoyo_kernel_domain.domainname = tomoyo_get_name(TOMOYO_ROOT_NAME); 309 /* 310 * tomoyo_read_lock() is not needed because this function is 311 * called before the first "delete" request. 312 */ 313 list_add_tail_rcu(&tomoyo_kernel_domain.list, &tomoyo_domain_list); 314 if (tomoyo_find_domain(TOMOYO_ROOT_NAME) != &tomoyo_kernel_domain) 315 panic("Can't register tomoyo_kernel_domain"); 316 } 317 318 /** 319 * tomoyo_read_memory_counter - Check for memory usage in bytes. 320 * 321 * @head: Pointer to "struct tomoyo_io_buffer". 322 * 323 * Returns memory usage. 324 */ 325 int tomoyo_read_memory_counter(struct tomoyo_io_buffer *head) 326 { 327 if (!head->read_eof) { 328 const unsigned int policy 329 = atomic_read(&tomoyo_policy_memory_size); 330 char buffer[64]; 331 332 memset(buffer, 0, sizeof(buffer)); 333 if (tomoyo_quota_for_policy) 334 snprintf(buffer, sizeof(buffer) - 1, 335 " (Quota: %10u)", 336 tomoyo_quota_for_policy); 337 else 338 buffer[0] = '\0'; 339 tomoyo_io_printf(head, "Policy: %10u%s\n", policy, buffer); 340 tomoyo_io_printf(head, "Total: %10u\n", policy); 341 head->read_eof = true; 342 } 343 return 0; 344 } 345 346 /** 347 * tomoyo_write_memory_quota - Set memory quota. 348 * 349 * @head: Pointer to "struct tomoyo_io_buffer". 350 * 351 * Returns 0. 352 */ 353 int tomoyo_write_memory_quota(struct tomoyo_io_buffer *head) 354 { 355 char *data = head->write_buf; 356 unsigned int size; 357 358 if (sscanf(data, "Policy: %u", &size) == 1) 359 tomoyo_quota_for_policy = size; 360 return 0; 361 } 362