1 /* 2 * Copyright (C) 2005,2006,2007,2008 IBM Corporation 3 * 4 * Authors: 5 * Kylene Hall <kjhall@us.ibm.com> 6 * Reiner Sailer <sailer@us.ibm.com> 7 * Mimi Zohar <zohar@us.ibm.com> 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 * File: ima_fs.c 15 * implemenents security file system for reporting 16 * current measurement list and IMA statistics 17 */ 18 #include <linux/fcntl.h> 19 #include <linux/slab.h> 20 #include <linux/module.h> 21 #include <linux/seq_file.h> 22 #include <linux/rculist.h> 23 #include <linux/rcupdate.h> 24 #include <linux/parser.h> 25 26 #include "ima.h" 27 28 static int valid_policy = 1; 29 #define TMPBUFLEN 12 30 static ssize_t ima_show_htable_value(char __user *buf, size_t count, 31 loff_t *ppos, atomic_long_t *val) 32 { 33 char tmpbuf[TMPBUFLEN]; 34 ssize_t len; 35 36 len = scnprintf(tmpbuf, TMPBUFLEN, "%li\n", atomic_long_read(val)); 37 return simple_read_from_buffer(buf, count, ppos, tmpbuf, len); 38 } 39 40 static ssize_t ima_show_htable_violations(struct file *filp, 41 char __user *buf, 42 size_t count, loff_t *ppos) 43 { 44 return ima_show_htable_value(buf, count, ppos, &ima_htable.violations); 45 } 46 47 static const struct file_operations ima_htable_violations_ops = { 48 .read = ima_show_htable_violations 49 }; 50 51 static ssize_t ima_show_measurements_count(struct file *filp, 52 char __user *buf, 53 size_t count, loff_t *ppos) 54 { 55 return ima_show_htable_value(buf, count, ppos, &ima_htable.len); 56 57 } 58 59 static const struct file_operations ima_measurements_count_ops = { 60 .read = ima_show_measurements_count 61 }; 62 63 /* returns pointer to hlist_node */ 64 static void *ima_measurements_start(struct seq_file *m, loff_t *pos) 65 { 66 loff_t l = *pos; 67 struct ima_queue_entry *qe; 68 69 /* we need a lock since pos could point beyond last element */ 70 rcu_read_lock(); 71 list_for_each_entry_rcu(qe, &ima_measurements, later) { 72 if (!l--) { 73 rcu_read_unlock(); 74 return qe; 75 } 76 } 77 rcu_read_unlock(); 78 return NULL; 79 } 80 81 static void *ima_measurements_next(struct seq_file *m, void *v, loff_t *pos) 82 { 83 struct ima_queue_entry *qe = v; 84 85 /* lock protects when reading beyond last element 86 * against concurrent list-extension 87 */ 88 rcu_read_lock(); 89 qe = list_entry_rcu(qe->later.next, 90 struct ima_queue_entry, later); 91 rcu_read_unlock(); 92 (*pos)++; 93 94 return (&qe->later == &ima_measurements) ? NULL : qe; 95 } 96 97 static void ima_measurements_stop(struct seq_file *m, void *v) 98 { 99 } 100 101 static void ima_putc(struct seq_file *m, void *data, int datalen) 102 { 103 while (datalen--) 104 seq_putc(m, *(char *)data++); 105 } 106 107 /* print format: 108 * 32bit-le=pcr# 109 * char[20]=template digest 110 * 32bit-le=template name size 111 * char[n]=template name 112 * eventdata[n]=template specific data 113 */ 114 static int ima_measurements_show(struct seq_file *m, void *v) 115 { 116 /* the list never shrinks, so we don't need a lock here */ 117 struct ima_queue_entry *qe = v; 118 struct ima_template_entry *e; 119 int namelen; 120 u32 pcr = CONFIG_IMA_MEASURE_PCR_IDX; 121 122 /* get entry */ 123 e = qe->entry; 124 if (e == NULL) 125 return -1; 126 127 /* 128 * 1st: PCRIndex 129 * PCR used is always the same (config option) in 130 * little-endian format 131 */ 132 ima_putc(m, &pcr, sizeof pcr); 133 134 /* 2nd: template digest */ 135 ima_putc(m, e->digest, IMA_DIGEST_SIZE); 136 137 /* 3rd: template name size */ 138 namelen = strlen(e->template_name); 139 ima_putc(m, &namelen, sizeof namelen); 140 141 /* 4th: template name */ 142 ima_putc(m, (void *)e->template_name, namelen); 143 144 /* 5th: template specific data */ 145 ima_template_show(m, (struct ima_template_data *)&e->template, 146 IMA_SHOW_BINARY); 147 return 0; 148 } 149 150 static const struct seq_operations ima_measurments_seqops = { 151 .start = ima_measurements_start, 152 .next = ima_measurements_next, 153 .stop = ima_measurements_stop, 154 .show = ima_measurements_show 155 }; 156 157 static int ima_measurements_open(struct inode *inode, struct file *file) 158 { 159 return seq_open(file, &ima_measurments_seqops); 160 } 161 162 static const struct file_operations ima_measurements_ops = { 163 .open = ima_measurements_open, 164 .read = seq_read, 165 .llseek = seq_lseek, 166 .release = seq_release, 167 }; 168 169 static void ima_print_digest(struct seq_file *m, u8 *digest) 170 { 171 int i; 172 173 for (i = 0; i < IMA_DIGEST_SIZE; i++) 174 seq_printf(m, "%02x", *(digest + i)); 175 } 176 177 void ima_template_show(struct seq_file *m, void *e, enum ima_show_type show) 178 { 179 struct ima_template_data *entry = e; 180 int namelen; 181 182 switch (show) { 183 case IMA_SHOW_ASCII: 184 ima_print_digest(m, entry->digest); 185 seq_printf(m, " %s\n", entry->file_name); 186 break; 187 case IMA_SHOW_BINARY: 188 ima_putc(m, entry->digest, IMA_DIGEST_SIZE); 189 190 namelen = strlen(entry->file_name); 191 ima_putc(m, &namelen, sizeof namelen); 192 ima_putc(m, entry->file_name, namelen); 193 default: 194 break; 195 } 196 } 197 198 /* print in ascii */ 199 static int ima_ascii_measurements_show(struct seq_file *m, void *v) 200 { 201 /* the list never shrinks, so we don't need a lock here */ 202 struct ima_queue_entry *qe = v; 203 struct ima_template_entry *e; 204 205 /* get entry */ 206 e = qe->entry; 207 if (e == NULL) 208 return -1; 209 210 /* 1st: PCR used (config option) */ 211 seq_printf(m, "%2d ", CONFIG_IMA_MEASURE_PCR_IDX); 212 213 /* 2nd: SHA1 template hash */ 214 ima_print_digest(m, e->digest); 215 216 /* 3th: template name */ 217 seq_printf(m, " %s ", e->template_name); 218 219 /* 4th: template specific data */ 220 ima_template_show(m, (struct ima_template_data *)&e->template, 221 IMA_SHOW_ASCII); 222 return 0; 223 } 224 225 static const struct seq_operations ima_ascii_measurements_seqops = { 226 .start = ima_measurements_start, 227 .next = ima_measurements_next, 228 .stop = ima_measurements_stop, 229 .show = ima_ascii_measurements_show 230 }; 231 232 static int ima_ascii_measurements_open(struct inode *inode, struct file *file) 233 { 234 return seq_open(file, &ima_ascii_measurements_seqops); 235 } 236 237 static const struct file_operations ima_ascii_measurements_ops = { 238 .open = ima_ascii_measurements_open, 239 .read = seq_read, 240 .llseek = seq_lseek, 241 .release = seq_release, 242 }; 243 244 static ssize_t ima_write_policy(struct file *file, const char __user *buf, 245 size_t datalen, loff_t *ppos) 246 { 247 char *data; 248 int rc; 249 250 if (datalen >= PAGE_SIZE) 251 return -ENOMEM; 252 if (*ppos != 0) { 253 /* No partial writes. */ 254 return -EINVAL; 255 } 256 data = kmalloc(datalen + 1, GFP_KERNEL); 257 if (!data) 258 return -ENOMEM; 259 260 if (copy_from_user(data, buf, datalen)) { 261 kfree(data); 262 return -EFAULT; 263 } 264 *(data + datalen) = '\0'; 265 rc = ima_parse_add_rule(data); 266 if (rc < 0) { 267 datalen = -EINVAL; 268 valid_policy = 0; 269 } 270 271 kfree(data); 272 return datalen; 273 } 274 275 static struct dentry *ima_dir; 276 static struct dentry *binary_runtime_measurements; 277 static struct dentry *ascii_runtime_measurements; 278 static struct dentry *runtime_measurements_count; 279 static struct dentry *violations; 280 static struct dentry *ima_policy; 281 282 static atomic_t policy_opencount = ATOMIC_INIT(1); 283 /* 284 * ima_open_policy: sequentialize access to the policy file 285 */ 286 int ima_open_policy(struct inode * inode, struct file * filp) 287 { 288 /* No point in being allowed to open it if you aren't going to write */ 289 if (!(filp->f_flags & O_WRONLY)) 290 return -EACCES; 291 if (atomic_dec_and_test(&policy_opencount)) 292 return 0; 293 return -EBUSY; 294 } 295 296 /* 297 * ima_release_policy - start using the new measure policy rules. 298 * 299 * Initially, ima_measure points to the default policy rules, now 300 * point to the new policy rules, and remove the securityfs policy file, 301 * assuming a valid policy. 302 */ 303 static int ima_release_policy(struct inode *inode, struct file *file) 304 { 305 if (!valid_policy) { 306 ima_delete_rules(); 307 valid_policy = 1; 308 atomic_set(&policy_opencount, 1); 309 return 0; 310 } 311 ima_update_policy(); 312 securityfs_remove(ima_policy); 313 ima_policy = NULL; 314 return 0; 315 } 316 317 static const struct file_operations ima_measure_policy_ops = { 318 .open = ima_open_policy, 319 .write = ima_write_policy, 320 .release = ima_release_policy 321 }; 322 323 int __init ima_fs_init(void) 324 { 325 ima_dir = securityfs_create_dir("ima", NULL); 326 if (IS_ERR(ima_dir)) 327 return -1; 328 329 binary_runtime_measurements = 330 securityfs_create_file("binary_runtime_measurements", 331 S_IRUSR | S_IRGRP, ima_dir, NULL, 332 &ima_measurements_ops); 333 if (IS_ERR(binary_runtime_measurements)) 334 goto out; 335 336 ascii_runtime_measurements = 337 securityfs_create_file("ascii_runtime_measurements", 338 S_IRUSR | S_IRGRP, ima_dir, NULL, 339 &ima_ascii_measurements_ops); 340 if (IS_ERR(ascii_runtime_measurements)) 341 goto out; 342 343 runtime_measurements_count = 344 securityfs_create_file("runtime_measurements_count", 345 S_IRUSR | S_IRGRP, ima_dir, NULL, 346 &ima_measurements_count_ops); 347 if (IS_ERR(runtime_measurements_count)) 348 goto out; 349 350 violations = 351 securityfs_create_file("violations", S_IRUSR | S_IRGRP, 352 ima_dir, NULL, &ima_htable_violations_ops); 353 if (IS_ERR(violations)) 354 goto out; 355 356 ima_policy = securityfs_create_file("policy", 357 S_IWUSR, 358 ima_dir, NULL, 359 &ima_measure_policy_ops); 360 if (IS_ERR(ima_policy)) 361 goto out; 362 363 return 0; 364 out: 365 securityfs_remove(runtime_measurements_count); 366 securityfs_remove(ascii_runtime_measurements); 367 securityfs_remove(binary_runtime_measurements); 368 securityfs_remove(ima_dir); 369 securityfs_remove(ima_policy); 370 return -1; 371 } 372 373 void __exit ima_fs_cleanup(void) 374 { 375 securityfs_remove(violations); 376 securityfs_remove(runtime_measurements_count); 377 securityfs_remove(ascii_runtime_measurements); 378 securityfs_remove(binary_runtime_measurements); 379 securityfs_remove(ima_dir); 380 securityfs_remove(ima_policy); 381 } 382