security/integrity/ima/ima_fs.c

   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 #include <linux/vmalloc.h>
  26
  27 #include "ima.h"
  28
  29 static DEFINE_MUTEX(ima_write_mutex);
  30
  31 bool ima_canonical_fmt;
  32 static int __init default_canonical_fmt_setup(char *str)
  33 {
  34 #ifdef __BIG_ENDIAN
  35         ima_canonical_fmt = 1;
  36 #endif
  37         return 1;
  38 }
  39 __setup("ima_canonical_fmt", default_canonical_fmt_setup);
  40
  41 static int valid_policy = 1;
  42 #define TMPBUFLEN 12
  43 static ssize_t ima_show_htable_value(char __user *buf, size_t count,
  44                                      loff_t *ppos, atomic_long_t *val)
  45 {
  46         char tmpbuf[TMPBUFLEN];
  47         ssize_t len;
  48
  49         len = scnprintf(tmpbuf, TMPBUFLEN, "%li\n", atomic_long_read(val));
  50         return simple_read_from_buffer(buf, count, ppos, tmpbuf, len);
  51 }
  52
  53 static ssize_t ima_show_htable_violations(struct file *filp,
  54                                           char __user *buf,
  55                                           size_t count, loff_t *ppos)
  56 {
  57         return ima_show_htable_value(buf, count, ppos, &ima_htable.violations);
  58 }
  59
  60 static const struct file_operations ima_htable_violations_ops = {
  61         .read = ima_show_htable_violations,
  62         .llseek = generic_file_llseek,
  63 };
  64
  65 static ssize_t ima_show_measurements_count(struct file *filp,
  66                                            char __user *buf,
  67                                            size_t count, loff_t *ppos)
  68 {
  69         return ima_show_htable_value(buf, count, ppos, &ima_htable.len);
  70
  71 }
  72
  73 static const struct file_operations ima_measurements_count_ops = {
  74         .read = ima_show_measurements_count,
  75         .llseek = generic_file_llseek,
  76 };
  77
  78 /* returns pointer to hlist_node */
  79 static void *ima_measurements_start(struct seq_file *m, loff_t *pos)
  80 {
  81         loff_t l = *pos;
  82         struct ima_queue_entry *qe;
  83
  84         /* we need a lock since pos could point beyond last element */
  85         rcu_read_lock();
  86         list_for_each_entry_rcu(qe, &ima_measurements, later) {
  87                 if (!l--) {
  88                         rcu_read_unlock();
  89                         return qe;
  90                 }
  91         }
  92         rcu_read_unlock();
  93         return NULL;
  94 }
  95
  96 static void *ima_measurements_next(struct seq_file *m, void *v, loff_t *pos)
  97 {
  98         struct ima_queue_entry *qe = v;
  99
 100         /* lock protects when reading beyond last element
 101          * against concurrent list-extension
 102          */
 103         rcu_read_lock();
 104         qe = list_entry_rcu(qe->later.next, struct ima_queue_entry, later);
 105         rcu_read_unlock();
 106         (*pos)++;
 107
 108         return (&qe->later == &ima_measurements) ? NULL : qe;
 109 }
 110
 111 static void ima_measurements_stop(struct seq_file *m, void *v)
 112 {
 113 }
 114
 115 void ima_putc(struct seq_file *m, void *data, int datalen)
 116 {
 117         while (datalen--)
 118                 seq_putc(m, *(char *)data++);
 119 }
 120
 121 /* print format:
 122  *       32bit-le=pcr#
 123  *       char[20]=template digest
 124  *       32bit-le=template name size
 125  *       char[n]=template name
 126  *       [eventdata length]
 127  *       eventdata[n]=template specific data
 128  */
 129 int ima_measurements_show(struct seq_file *m, void *v)
 130 {
 131         /* the list never shrinks, so we don't need a lock here */
 132         struct ima_queue_entry *qe = v;
 133         struct ima_template_entry *e;
 134         char *template_name;
 135         u32 pcr, namelen, template_data_len; /* temporary fields */
 136         bool is_ima_template = false;
 137         int i;
 138
 139         /* get entry */
 140         e = qe->entry;
 141         if (e == NULL)
 142                 return -1;
 143
 144         template_name = (e->template_desc->name[0] != '\0') ?
 145             e->template_desc->name : e->template_desc->fmt;
 146
 147         /*
 148          * 1st: PCRIndex
 149          * PCR used defaults to the same (config option) in
 150          * little-endian format, unless set in policy
 151          */
 152         pcr = !ima_canonical_fmt ? e->pcr : cpu_to_le32(e->pcr);
 153         ima_putc(m, &pcr, sizeof(e->pcr));
 154
 155         /* 2nd: template digest */
 156         ima_putc(m, e->digest, TPM_DIGEST_SIZE);
 157
 158         /* 3rd: template name size */
 159         namelen = !ima_canonical_fmt ? strlen(template_name) :
 160                 cpu_to_le32(strlen(template_name));
 161         ima_putc(m, &namelen, sizeof(namelen));
 162
 163         /* 4th:  template name */
 164         ima_putc(m, template_name, strlen(template_name));
 165
 166         /* 5th:  template length (except for 'ima' template) */
 167         if (strcmp(template_name, IMA_TEMPLATE_IMA_NAME) == 0)
 168                 is_ima_template = true;
 169
 170         if (!is_ima_template) {
 171                 template_data_len = !ima_canonical_fmt ? e->template_data_len :
 172                         cpu_to_le32(e->template_data_len);
 173                 ima_putc(m, &template_data_len, sizeof(e->template_data_len));
 174         }
 175
 176         /* 6th:  template specific data */
 177         for (i = 0; i < e->template_desc->num_fields; i++) {
 178                 enum ima_show_type show = IMA_SHOW_BINARY;
 179                 struct ima_template_field *field = e->template_desc->fields[i];
 180
 181                 if (is_ima_template && strcmp(field->field_id, "d") == 0)
 182                         show = IMA_SHOW_BINARY_NO_FIELD_LEN;
 183                 if (is_ima_template && strcmp(field->field_id, "n") == 0)
 184                         show = IMA_SHOW_BINARY_OLD_STRING_FMT;
 185                 field->field_show(m, show, &e->template_data[i]);
 186         }
 187         return 0;
 188 }
 189
 190 static const struct seq_operations ima_measurments_seqops = {
 191         .start = ima_measurements_start,
 192         .next = ima_measurements_next,
 193         .stop = ima_measurements_stop,
 194         .show = ima_measurements_show
 195 };
 196
 197 static int ima_measurements_open(struct inode *inode, struct file *file)
 198 {
 199         return seq_open(file, &ima_measurments_seqops);
 200 }
 201
 202 static const struct file_operations ima_measurements_ops = {
 203         .open = ima_measurements_open,
 204         .read = seq_read,
 205         .llseek = seq_lseek,
 206         .release = seq_release,
 207 };
 208
 209 void ima_print_digest(struct seq_file *m, u8 *digest, u32 size)
 210 {
 211         u32 i;
 212
 213         for (i = 0; i < size; i++)
 214                 seq_printf(m, "%02x", *(digest + i));
 215 }
 216
 217 /* print in ascii */
 218 static int ima_ascii_measurements_show(struct seq_file *m, void *v)
 219 {
 220         /* the list never shrinks, so we don't need a lock here */
 221         struct ima_queue_entry *qe = v;
 222         struct ima_template_entry *e;
 223         char *template_name;
 224         int i;
 225
 226         /* get entry */
 227         e = qe->entry;
 228         if (e == NULL)
 229                 return -1;
 230
 231         template_name = (e->template_desc->name[0] != '\0') ?
 232             e->template_desc->name : e->template_desc->fmt;
 233
 234         /* 1st: PCR used (config option) */
 235         seq_printf(m, "%2d ", e->pcr);
 236
 237         /* 2nd: SHA1 template hash */
 238         ima_print_digest(m, e->digest, TPM_DIGEST_SIZE);
 239
 240         /* 3th:  template name */
 241         seq_printf(m, " %s", template_name);
 242
 243         /* 4th:  template specific data */
 244         for (i = 0; i < e->template_desc->num_fields; i++) {
 245                 seq_puts(m, " ");
 246                 if (e->template_data[i].len == 0)
 247                         continue;
 248
 249                 e->template_desc->fields[i]->field_show(m, IMA_SHOW_ASCII,
 250                                                         &e->template_data[i]);
 251         }
 252         seq_puts(m, "\n");
 253         return 0;
 254 }
 255
 256 static const struct seq_operations ima_ascii_measurements_seqops = {
 257         .start = ima_measurements_start,
 258         .next = ima_measurements_next,
 259         .stop = ima_measurements_stop,
 260         .show = ima_ascii_measurements_show
 261 };
 262
 263 static int ima_ascii_measurements_open(struct inode *inode, struct file *file)
 264 {
 265         return seq_open(file, &ima_ascii_measurements_seqops);
 266 }
 267
 268 static const struct file_operations ima_ascii_measurements_ops = {
 269         .open = ima_ascii_measurements_open,
 270         .read = seq_read,
 271         .llseek = seq_lseek,
 272         .release = seq_release,
 273 };
 274
 275 static ssize_t ima_read_policy(char *path)
 276 {
 277         void *data;
 278         char *datap;
 279         loff_t size;
 280         int rc, pathlen = strlen(path);
 281
 282         char *p;
 283
 284         /* remove \n */
 285         datap = path;
 286         strsep(&datap, "\n");
 287
 288         rc = kernel_read_file_from_path(path, &data, &size, 0, READING_POLICY);
 289         if (rc < 0) {
 290                 pr_err("Unable to open file: %s (%d)", path, rc);
 291                 return rc;
 292         }
 293
 294         datap = data;
 295         while (size > 0 && (p = strsep(&datap, "\n"))) {
 296                 pr_debug("rule: %s\n", p);
 297                 rc = ima_parse_add_rule(p);
 298                 if (rc < 0)
 299                         break;
 300                 size -= rc;
 301         }
 302
 303         vfree(data);
 304         if (rc < 0)
 305                 return rc;
 306         else if (size)
 307                 return -EINVAL;
 308         else
 309                 return pathlen;
 310 }
 311
 312 static ssize_t ima_write_policy(struct file *file, const char __user *buf,
 313                                 size_t datalen, loff_t *ppos)
 314 {
 315         char *data;
 316         ssize_t result;
 317
 318         if (datalen >= PAGE_SIZE)
 319                 datalen = PAGE_SIZE - 1;
 320
 321         /* No partial writes. */
 322         result = -EINVAL;
 323         if (*ppos != 0)
 324                 goto out;
 325
 326         result = -ENOMEM;
 327         data = kmalloc(datalen + 1, GFP_KERNEL);
 328         if (!data)
 329                 goto out;
 330
 331         *(data + datalen) = '\0';
 332
 333         result = -EFAULT;
 334         if (copy_from_user(data, buf, datalen))
 335                 goto out_free;
 336
 337         result = mutex_lock_interruptible(&ima_write_mutex);
 338         if (result < 0)
 339                 goto out_free;
 340
 341         if (data[0] == '/') {
 342                 result = ima_read_policy(data);
 343         } else if (ima_appraise & IMA_APPRAISE_POLICY) {
 344                 pr_err("IMA: signed policy file (specified as an absolute pathname) required\n");
 345                 integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL, NULL,
 346                                     "policy_update", "signed policy required",
 347                                     1, 0);
 348                 if (ima_appraise & IMA_APPRAISE_ENFORCE)
 349                         result = -EACCES;
 350         } else {
 351                 result = ima_parse_add_rule(data);
 352         }
 353         mutex_unlock(&ima_write_mutex);
 354 out_free:
 355         kfree(data);
 356 out:
 357         if (result < 0)
 358                 valid_policy = 0;
 359
 360         return result;
 361 }
 362
 363 static struct dentry *ima_dir;
 364 static struct dentry *binary_runtime_measurements;
 365 static struct dentry *ascii_runtime_measurements;
 366 static struct dentry *runtime_measurements_count;
 367 static struct dentry *violations;
 368 static struct dentry *ima_policy;
 369
 370 enum ima_fs_flags {
 371         IMA_FS_BUSY,
 372 };
 373
 374 static unsigned long ima_fs_flags;
 375
 376 #ifdef  CONFIG_IMA_READ_POLICY
 377 static const struct seq_operations ima_policy_seqops = {
 378                 .start = ima_policy_start,
 379                 .next = ima_policy_next,
 380                 .stop = ima_policy_stop,
 381                 .show = ima_policy_show,
 382 };
 383 #endif
 384
 385 /*
 386  * ima_open_policy: sequentialize access to the policy file
 387  */
 388 static int ima_open_policy(struct inode *inode, struct file *filp)
 389 {
 390         if (!(filp->f_flags & O_WRONLY)) {
 391 #ifndef CONFIG_IMA_READ_POLICY
 392                 return -EACCES;
 393 #else
 394                 if ((filp->f_flags & O_ACCMODE) != O_RDONLY)
 395                         return -EACCES;
 396                 if (!capable(CAP_SYS_ADMIN))
 397                         return -EPERM;
 398                 return seq_open(filp, &ima_policy_seqops);
 399 #endif
 400         }
 401         if (test_and_set_bit(IMA_FS_BUSY, &ima_fs_flags))
 402                 return -EBUSY;
 403         return 0;
 404 }
 405
 406 /*
 407  * ima_release_policy - start using the new measure policy rules.
 408  *
 409  * Initially, ima_measure points to the default policy rules, now
 410  * point to the new policy rules, and remove the securityfs policy file,
 411  * assuming a valid policy.
 412  */
 413 static int ima_release_policy(struct inode *inode, struct file *file)
 414 {
 415         const char *cause = valid_policy ? "completed" : "failed";
 416
 417         if ((file->f_flags & O_ACCMODE) == O_RDONLY)
 418                 return seq_release(inode, file);
 419
 420         if (valid_policy && ima_check_policy() < 0) {
 421                 cause = "failed";
 422                 valid_policy = 0;
 423         }
 424
 425         pr_info("IMA: policy update %s\n", cause);
 426         integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL, NULL,
 427                             "policy_update", cause, !valid_policy, 0);
 428
 429         if (!valid_policy) {
 430                 ima_delete_rules();
 431                 valid_policy = 1;
 432                 clear_bit(IMA_FS_BUSY, &ima_fs_flags);
 433                 return 0;
 434         }
 435
 436         ima_update_policy();
 437 #ifndef CONFIG_IMA_WRITE_POLICY
 438         securityfs_remove(ima_policy);
 439         ima_policy = NULL;
 440 #else
 441         clear_bit(IMA_FS_BUSY, &ima_fs_flags);
 442 #endif
 443         return 0;
 444 }
 445
 446 static const struct file_operations ima_measure_policy_ops = {
 447         .open = ima_open_policy,
 448         .write = ima_write_policy,
 449         .read = seq_read,
 450         .release = ima_release_policy,
 451         .llseek = generic_file_llseek,
 452 };
 453
 454 int __init ima_fs_init(void)
 455 {
 456         ima_dir = securityfs_create_dir("ima", NULL);
 457         if (IS_ERR(ima_dir))
 458                 return -1;
 459
 460         binary_runtime_measurements =
 461             securityfs_create_file("binary_runtime_measurements",
 462                                    S_IRUSR | S_IRGRP, ima_dir, NULL,
 463                                    &ima_measurements_ops);
 464         if (IS_ERR(binary_runtime_measurements))
 465                 goto out;
 466
 467         ascii_runtime_measurements =
 468             securityfs_create_file("ascii_runtime_measurements",
 469                                    S_IRUSR | S_IRGRP, ima_dir, NULL,
 470                                    &ima_ascii_measurements_ops);
 471         if (IS_ERR(ascii_runtime_measurements))
 472                 goto out;
 473
 474         runtime_measurements_count =
 475             securityfs_create_file("runtime_measurements_count",
 476                                    S_IRUSR | S_IRGRP, ima_dir, NULL,
 477                                    &ima_measurements_count_ops);
 478         if (IS_ERR(runtime_measurements_count))
 479                 goto out;
 480
 481         violations =
 482             securityfs_create_file("violations", S_IRUSR | S_IRGRP,
 483                                    ima_dir, NULL, &ima_htable_violations_ops);
 484         if (IS_ERR(violations))
 485                 goto out;
 486
 487         ima_policy = securityfs_create_file("policy", POLICY_FILE_FLAGS,
 488                                             ima_dir, NULL,
 489                                             &ima_measure_policy_ops);
 490         if (IS_ERR(ima_policy))
 491                 goto out;
 492
 493         return 0;
 494 out:
 495         securityfs_remove(violations);
 496         securityfs_remove(runtime_measurements_count);
 497         securityfs_remove(ascii_runtime_measurements);
 498         securityfs_remove(binary_runtime_measurements);
 499         securityfs_remove(ima_dir);
 500         securityfs_remove(ima_policy);
 501         return -1;
 502 }