![Dmitry Kasatkin](/assets/img/avatar_default.png)
For each inode in the IMA policy, an iint is allocated. To support larger hash digests, the iint digest size changed from 20 bytes to the maximum supported hash digest size. Instead of allocating the maximum size, which most likely is not needed, this patch dynamically allocates the needed hash storage. Changelog: - fix krealloc bug Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com> Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
351 lines
8.3 KiB
C
351 lines
8.3 KiB
C
/*
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* Copyright (C) 2011 IBM Corporation
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*
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* Author:
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* Mimi Zohar <zohar@us.ibm.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, version 2 of the License.
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*/
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#include <linux/module.h>
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#include <linux/file.h>
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#include <linux/fs.h>
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#include <linux/xattr.h>
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#include <linux/magic.h>
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#include <linux/ima.h>
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#include <linux/evm.h>
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#include "ima.h"
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static int __init default_appraise_setup(char *str)
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{
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if (strncmp(str, "off", 3) == 0)
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ima_appraise = 0;
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else if (strncmp(str, "fix", 3) == 0)
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ima_appraise = IMA_APPRAISE_FIX;
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return 1;
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}
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__setup("ima_appraise=", default_appraise_setup);
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/*
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* ima_must_appraise - set appraise flag
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*
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* Return 1 to appraise
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*/
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int ima_must_appraise(struct inode *inode, int mask, enum ima_hooks func)
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{
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if (!ima_appraise)
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return 0;
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return ima_match_policy(inode, func, mask, IMA_APPRAISE);
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}
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static int ima_fix_xattr(struct dentry *dentry,
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struct integrity_iint_cache *iint)
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{
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iint->ima_hash->type = IMA_XATTR_DIGEST;
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return __vfs_setxattr_noperm(dentry, XATTR_NAME_IMA,
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&iint->ima_hash->type,
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1 + iint->ima_hash->length, 0);
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}
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/* Return specific func appraised cached result */
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enum integrity_status ima_get_cache_status(struct integrity_iint_cache *iint,
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int func)
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{
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switch (func) {
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case MMAP_CHECK:
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return iint->ima_mmap_status;
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case BPRM_CHECK:
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return iint->ima_bprm_status;
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case MODULE_CHECK:
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return iint->ima_module_status;
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case FILE_CHECK:
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default:
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return iint->ima_file_status;
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}
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}
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static void ima_set_cache_status(struct integrity_iint_cache *iint,
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int func, enum integrity_status status)
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{
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switch (func) {
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case MMAP_CHECK:
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iint->ima_mmap_status = status;
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break;
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case BPRM_CHECK:
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iint->ima_bprm_status = status;
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break;
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case MODULE_CHECK:
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iint->ima_module_status = status;
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break;
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case FILE_CHECK:
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default:
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iint->ima_file_status = status;
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break;
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}
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}
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static void ima_cache_flags(struct integrity_iint_cache *iint, int func)
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{
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switch (func) {
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case MMAP_CHECK:
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iint->flags |= (IMA_MMAP_APPRAISED | IMA_APPRAISED);
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break;
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case BPRM_CHECK:
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iint->flags |= (IMA_BPRM_APPRAISED | IMA_APPRAISED);
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break;
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case MODULE_CHECK:
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iint->flags |= (IMA_MODULE_APPRAISED | IMA_APPRAISED);
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break;
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case FILE_CHECK:
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default:
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iint->flags |= (IMA_FILE_APPRAISED | IMA_APPRAISED);
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break;
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}
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}
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void ima_get_hash_algo(struct evm_ima_xattr_data *xattr_value, int xattr_len,
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struct ima_digest_data *hash)
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{
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struct signature_v2_hdr *sig;
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if (!xattr_value || xattr_len < 0 || xattr_len <= 1 + sizeof(*sig))
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return;
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sig = (typeof(sig)) xattr_value->digest;
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if (xattr_value->type != EVM_IMA_XATTR_DIGSIG || sig->version != 2)
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return;
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hash->algo = sig->hash_algo;
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}
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int ima_read_xattr(struct dentry *dentry,
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struct evm_ima_xattr_data **xattr_value)
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{
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struct inode *inode = dentry->d_inode;
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if (!inode->i_op->getxattr)
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return 0;
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return vfs_getxattr_alloc(dentry, XATTR_NAME_IMA, (char **)xattr_value,
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0, GFP_NOFS);
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}
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/*
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* ima_appraise_measurement - appraise file measurement
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*
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* Call evm_verifyxattr() to verify the integrity of 'security.ima'.
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* Assuming success, compare the xattr hash with the collected measurement.
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*
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* Return 0 on success, error code otherwise
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*/
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int ima_appraise_measurement(int func, struct integrity_iint_cache *iint,
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struct file *file, const unsigned char *filename,
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struct evm_ima_xattr_data *xattr_value,
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int xattr_len)
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{
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struct dentry *dentry = file->f_dentry;
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struct inode *inode = dentry->d_inode;
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enum integrity_status status = INTEGRITY_UNKNOWN;
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const char *op = "appraise_data";
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char *cause = "unknown";
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int rc = xattr_len;
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if (!ima_appraise)
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return 0;
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if (!inode->i_op->getxattr)
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return INTEGRITY_UNKNOWN;
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if (rc <= 0) {
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if (rc && rc != -ENODATA)
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goto out;
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cause = "missing-hash";
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status =
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(inode->i_size == 0) ? INTEGRITY_PASS : INTEGRITY_NOLABEL;
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goto out;
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}
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status = evm_verifyxattr(dentry, XATTR_NAME_IMA, xattr_value, rc, iint);
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if ((status != INTEGRITY_PASS) && (status != INTEGRITY_UNKNOWN)) {
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if ((status == INTEGRITY_NOLABEL)
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|| (status == INTEGRITY_NOXATTRS))
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cause = "missing-HMAC";
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else if (status == INTEGRITY_FAIL)
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cause = "invalid-HMAC";
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goto out;
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}
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switch (xattr_value->type) {
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case IMA_XATTR_DIGEST:
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if (iint->flags & IMA_DIGSIG_REQUIRED) {
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cause = "IMA signature required";
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status = INTEGRITY_FAIL;
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break;
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}
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if (xattr_len - 1 >= iint->ima_hash->length)
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/* xattr length may be longer. md5 hash in previous
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version occupied 20 bytes in xattr, instead of 16
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*/
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rc = memcmp(xattr_value->digest,
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iint->ima_hash->digest,
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iint->ima_hash->length);
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else
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rc = -EINVAL;
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if (rc) {
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cause = "invalid-hash";
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status = INTEGRITY_FAIL;
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break;
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}
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status = INTEGRITY_PASS;
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break;
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case EVM_IMA_XATTR_DIGSIG:
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iint->flags |= IMA_DIGSIG;
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rc = integrity_digsig_verify(INTEGRITY_KEYRING_IMA,
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(const char *)xattr_value, rc,
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iint->ima_hash->digest,
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iint->ima_hash->length);
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if (rc == -EOPNOTSUPP) {
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status = INTEGRITY_UNKNOWN;
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} else if (rc) {
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cause = "invalid-signature";
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status = INTEGRITY_FAIL;
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} else {
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status = INTEGRITY_PASS;
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}
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break;
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default:
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status = INTEGRITY_UNKNOWN;
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cause = "unknown-ima-data";
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break;
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}
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out:
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if (status != INTEGRITY_PASS) {
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if ((ima_appraise & IMA_APPRAISE_FIX) &&
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(!xattr_value ||
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xattr_value->type != EVM_IMA_XATTR_DIGSIG)) {
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if (!ima_fix_xattr(dentry, iint))
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status = INTEGRITY_PASS;
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}
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integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode, filename,
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op, cause, rc, 0);
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} else {
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ima_cache_flags(iint, func);
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}
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ima_set_cache_status(iint, func, status);
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return status;
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}
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/*
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* ima_update_xattr - update 'security.ima' hash value
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*/
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void ima_update_xattr(struct integrity_iint_cache *iint, struct file *file)
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{
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struct dentry *dentry = file->f_dentry;
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int rc = 0;
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/* do not collect and update hash for digital signatures */
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if (iint->flags & IMA_DIGSIG)
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return;
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rc = ima_collect_measurement(iint, file, NULL, NULL);
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if (rc < 0)
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return;
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ima_fix_xattr(dentry, iint);
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}
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/**
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* ima_inode_post_setattr - reflect file metadata changes
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* @dentry: pointer to the affected dentry
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*
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* Changes to a dentry's metadata might result in needing to appraise.
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*
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* This function is called from notify_change(), which expects the caller
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* to lock the inode's i_mutex.
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*/
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void ima_inode_post_setattr(struct dentry *dentry)
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{
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struct inode *inode = dentry->d_inode;
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struct integrity_iint_cache *iint;
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int must_appraise, rc;
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if (!ima_initialized || !ima_appraise || !S_ISREG(inode->i_mode)
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|| !inode->i_op->removexattr)
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return;
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must_appraise = ima_must_appraise(inode, MAY_ACCESS, POST_SETATTR);
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iint = integrity_iint_find(inode);
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if (iint) {
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iint->flags &= ~(IMA_APPRAISE | IMA_APPRAISED |
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IMA_APPRAISE_SUBMASK | IMA_APPRAISED_SUBMASK |
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IMA_ACTION_FLAGS);
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if (must_appraise)
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iint->flags |= IMA_APPRAISE;
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}
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if (!must_appraise)
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rc = inode->i_op->removexattr(dentry, XATTR_NAME_IMA);
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return;
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}
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/*
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* ima_protect_xattr - protect 'security.ima'
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*
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* Ensure that not just anyone can modify or remove 'security.ima'.
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*/
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static int ima_protect_xattr(struct dentry *dentry, const char *xattr_name,
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const void *xattr_value, size_t xattr_value_len)
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{
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if (strcmp(xattr_name, XATTR_NAME_IMA) == 0) {
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if (!capable(CAP_SYS_ADMIN))
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return -EPERM;
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return 1;
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}
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return 0;
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}
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static void ima_reset_appraise_flags(struct inode *inode)
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{
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struct integrity_iint_cache *iint;
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if (!ima_initialized || !ima_appraise || !S_ISREG(inode->i_mode))
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return;
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iint = integrity_iint_find(inode);
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if (!iint)
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return;
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iint->flags &= ~IMA_DONE_MASK;
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return;
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}
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int ima_inode_setxattr(struct dentry *dentry, const char *xattr_name,
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const void *xattr_value, size_t xattr_value_len)
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{
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int result;
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result = ima_protect_xattr(dentry, xattr_name, xattr_value,
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xattr_value_len);
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if (result == 1) {
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ima_reset_appraise_flags(dentry->d_inode);
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result = 0;
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}
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return result;
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}
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int ima_inode_removexattr(struct dentry *dentry, const char *xattr_name)
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{
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int result;
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result = ima_protect_xattr(dentry, xattr_name, NULL, 0);
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if (result == 1) {
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ima_reset_appraise_flags(dentry->d_inode);
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result = 0;
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}
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return result;
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}
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