Pileus Git - ~andy/linux/blob - 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
  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         .llseek = generic_file_llseek,
  50 };
  51
  52 static ssize_t ima_show_measurements_count(struct file *filp,
  53                                            char __user *buf,
  54                                            size_t count, loff_t *ppos)
  55 {
  56         return ima_show_htable_value(buf, count, ppos, &ima_htable.len);
  57
  58 }
  59
  60 static const struct file_operations ima_measurements_count_ops = {
  61         .read = ima_show_measurements_count,
  62         .llseek = generic_file_llseek,
  63 };
  64
  65 /* returns pointer to hlist_node */
  66 static void *ima_measurements_start(struct seq_file *m, loff_t *pos)
  67 {
  68         loff_t l = *pos;
  69         struct ima_queue_entry *qe;
  70
  71         /* we need a lock since pos could point beyond last element */
  72         rcu_read_lock();
  73         list_for_each_entry_rcu(qe, &ima_measurements, later) {
  74                 if (!l--) {
  75                         rcu_read_unlock();
  76                         return qe;
  77                 }
  78         }
  79         rcu_read_unlock();
  80         return NULL;
  81 }
  82
  83 static void *ima_measurements_next(struct seq_file *m, void *v, loff_t *pos)
  84 {
  85         struct ima_queue_entry *qe = v;
  86
  87         /* lock protects when reading beyond last element
  88          * against concurrent list-extension
  89          */
  90         rcu_read_lock();
  91         qe = list_entry_rcu(qe->later.next, struct ima_queue_entry, later);
  92         rcu_read_unlock();
  93         (*pos)++;
  94
  95         return (&qe->later == &ima_measurements) ? NULL : qe;
  96 }
  97
  98 static void ima_measurements_stop(struct seq_file *m, void *v)
  99 {
 100 }
 101
 102 void ima_putc(struct seq_file *m, void *data, int datalen)
 103 {
 104         while (datalen--)
 105                 seq_putc(m, *(char *)data++);
 106 }
 107
 108 /* print format:
 109  *       32bit-le=pcr#
 110  *       char[20]=template digest
 111  *       32bit-le=template name size
 112  *       char[n]=template name
 113  *       [eventdata length]
 114  *       eventdata[n]=template specific data
 115  */
 116 static int ima_measurements_show(struct seq_file *m, void *v)
 117 {
 118         /* the list never shrinks, so we don't need a lock here */
 119         struct ima_queue_entry *qe = v;
 120         struct ima_template_entry *e;
 121         int namelen;
 122         u32 pcr = CONFIG_IMA_MEASURE_PCR_IDX;
 123         int i;
 124
 125         /* get entry */
 126         e = qe->entry;
 127         if (e == NULL)
 128                 return -1;
 129
 130         /*
 131          * 1st: PCRIndex
 132          * PCR used is always the same (config option) in
 133          * little-endian format
 134          */
 135         ima_putc(m, &pcr, sizeof pcr);
 136
 137         /* 2nd: template digest */
 138         ima_putc(m, e->digest, TPM_DIGEST_SIZE);
 139
 140         /* 3rd: template name size */
 141         namelen = strlen(e->template_desc->name);
 142         ima_putc(m, &namelen, sizeof namelen);
 143
 144         /* 4th:  template name */
 145         ima_putc(m, e->template_desc->name, namelen);
 146
 147         /* 5th:  template length (except for 'ima' template) */
 148         if (strcmp(e->template_desc->name, IMA_TEMPLATE_IMA_NAME) != 0)
 149                 ima_putc(m, &e->template_data_len,
 150                          sizeof(e->template_data_len));
 151
 152         /* 6th:  template specific data */
 153         for (i = 0; i < e->template_desc->num_fields; i++) {
 154                 e->template_desc->fields[i]->field_show(m, IMA_SHOW_BINARY,
 155                                                         &e->template_data[i]);
 156         }
 157         return 0;
 158 }
 159
 160 static const struct seq_operations ima_measurments_seqops = {
 161         .start = ima_measurements_start,
 162         .next = ima_measurements_next,
 163         .stop = ima_measurements_stop,
 164         .show = ima_measurements_show
 165 };
 166
 167 static int ima_measurements_open(struct inode *inode, struct file *file)
 168 {
 169         return seq_open(file, &ima_measurments_seqops);
 170 }
 171
 172 static const struct file_operations ima_measurements_ops = {
 173         .open = ima_measurements_open,
 174         .read = seq_read,
 175         .llseek = seq_lseek,
 176         .release = seq_release,
 177 };
 178
 179 void ima_print_digest(struct seq_file *m, u8 *digest, int size)
 180 {
 181         int i;
 182
 183         for (i = 0; i < size; i++)
 184                 seq_printf(m, "%02x", *(digest + i));
 185 }
 186
 187 /* print in ascii */
 188 static int ima_ascii_measurements_show(struct seq_file *m, void *v)
 189 {
 190         /* the list never shrinks, so we don't need a lock here */
 191         struct ima_queue_entry *qe = v;
 192         struct ima_template_entry *e;
 193         int i;
 194
 195         /* get entry */
 196         e = qe->entry;
 197         if (e == NULL)
 198                 return -1;
 199
 200         /* 1st: PCR used (config option) */
 201         seq_printf(m, "%2d ", CONFIG_IMA_MEASURE_PCR_IDX);
 202
 203         /* 2nd: SHA1 template hash */
 204         ima_print_digest(m, e->digest, TPM_DIGEST_SIZE);
 205
 206         /* 3th:  template name */
 207         seq_printf(m, " %s", e->template_desc->name);
 208
 209         /* 4th:  template specific data */
 210         for (i = 0; i < e->template_desc->num_fields; i++) {
 211                 seq_puts(m, " ");
 212                 if (e->template_data[i].len == 0)
 213                         continue;
 214
 215                 e->template_desc->fields[i]->field_show(m, IMA_SHOW_ASCII,
 216                                                         &e->template_data[i]);
 217         }
 218         seq_puts(m, "\n");
 219         return 0;
 220 }
 221
 222 static const struct seq_operations ima_ascii_measurements_seqops = {
 223         .start = ima_measurements_start,
 224         .next = ima_measurements_next,
 225         .stop = ima_measurements_stop,
 226         .show = ima_ascii_measurements_show
 227 };
 228
 229 static int ima_ascii_measurements_open(struct inode *inode, struct file *file)
 230 {
 231         return seq_open(file, &ima_ascii_measurements_seqops);
 232 }
 233
 234 static const struct file_operations ima_ascii_measurements_ops = {
 235         .open = ima_ascii_measurements_open,
 236         .read = seq_read,
 237         .llseek = seq_lseek,
 238         .release = seq_release,
 239 };
 240
 241 static ssize_t ima_write_policy(struct file *file, const char __user *buf,
 242                                 size_t datalen, loff_t *ppos)
 243 {
 244         char *data = NULL;
 245         ssize_t result;
 246
 247         if (datalen >= PAGE_SIZE)
 248                 datalen = PAGE_SIZE - 1;
 249
 250         /* No partial writes. */
 251         result = -EINVAL;
 252         if (*ppos != 0)
 253                 goto out;
 254
 255         result = -ENOMEM;
 256         data = kmalloc(datalen + 1, GFP_KERNEL);
 257         if (!data)
 258                 goto out;
 259
 260         *(data + datalen) = '\0';
 261
 262         result = -EFAULT;
 263         if (copy_from_user(data, buf, datalen))
 264                 goto out;
 265
 266         result = ima_parse_add_rule(data);
 267 out:
 268         if (result < 0)
 269                 valid_policy = 0;
 270         kfree(data);
 271         return result;
 272 }
 273
 274 static struct dentry *ima_dir;
 275 static struct dentry *binary_runtime_measurements;
 276 static struct dentry *ascii_runtime_measurements;
 277 static struct dentry *runtime_measurements_count;
 278 static struct dentry *violations;
 279 static struct dentry *ima_policy;
 280
 281 static atomic_t policy_opencount = ATOMIC_INIT(1);
 282 /*
 283  * ima_open_policy: sequentialize access to the policy file
 284  */
 285 static int ima_open_policy(struct inode * inode, struct file * filp)
 286 {
 287         /* No point in being allowed to open it if you aren't going to write */
 288         if (!(filp->f_flags & O_WRONLY))
 289                 return -EACCES;
 290         if (atomic_dec_and_test(&policy_opencount))
 291                 return 0;
 292         return -EBUSY;
 293 }
 294
 295 /*
 296  * ima_release_policy - start using the new measure policy rules.
 297  *
 298  * Initially, ima_measure points to the default policy rules, now
 299  * point to the new policy rules, and remove the securityfs policy file,
 300  * assuming a valid policy.
 301  */
 302 static int ima_release_policy(struct inode *inode, struct file *file)
 303 {
 304         if (!valid_policy) {
 305                 ima_delete_rules();
 306                 valid_policy = 1;
 307                 atomic_set(&policy_opencount, 1);
 308                 return 0;
 309         }
 310         ima_update_policy();
 311         securityfs_remove(ima_policy);
 312         ima_policy = NULL;
 313         return 0;
 314 }
 315
 316 static const struct file_operations ima_measure_policy_ops = {
 317         .open = ima_open_policy,
 318         .write = ima_write_policy,
 319         .release = ima_release_policy,
 320         .llseek = generic_file_llseek,
 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(violations);
 366         securityfs_remove(runtime_measurements_count);
 367         securityfs_remove(ascii_runtime_measurements);
 368         securityfs_remove(binary_runtime_measurements);
 369         securityfs_remove(ima_dir);
 370         securityfs_remove(ima_policy);
 371         return -1;
 372 }