| /* |
| * Copyright (C) 2011 IBM Corporation |
| * |
| * Author: |
| * Mimi Zohar <zohar@us.ibm.com> |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License as published by |
| * the Free Software Foundation, version 2 of the License. |
| */ |
| #include <linux/module.h> |
| #include <linux/file.h> |
| #include <linux/fs.h> |
| #include <linux/xattr.h> |
| #include <linux/magic.h> |
| #include <linux/ima.h> |
| #include <linux/evm.h> |
| #include <crypto/hash_info.h> |
| |
| #include "ima.h" |
| |
| static int __init default_appraise_setup(char *str) |
| { |
| if (strncmp(str, "off", 3) == 0) |
| ima_appraise = 0; |
| else if (strncmp(str, "fix", 3) == 0) |
| ima_appraise = IMA_APPRAISE_FIX; |
| return 1; |
| } |
| |
| __setup("ima_appraise=", default_appraise_setup); |
| |
| /* |
| * ima_must_appraise - set appraise flag |
| * |
| * Return 1 to appraise |
| */ |
| int ima_must_appraise(struct inode *inode, int mask, enum ima_hooks func) |
| { |
| if (!ima_appraise) |
| return 0; |
| |
| return ima_match_policy(inode, func, mask, IMA_APPRAISE); |
| } |
| |
| static int ima_fix_xattr(struct dentry *dentry, |
| struct integrity_iint_cache *iint) |
| { |
| int rc, offset; |
| u8 algo = iint->ima_hash->algo; |
| |
| if (algo <= HASH_ALGO_SHA1) { |
| offset = 1; |
| iint->ima_hash->xattr.sha1.type = IMA_XATTR_DIGEST; |
| } else { |
| offset = 0; |
| iint->ima_hash->xattr.ng.type = IMA_XATTR_DIGEST_NG; |
| iint->ima_hash->xattr.ng.algo = algo; |
| } |
| rc = __vfs_setxattr_noperm(dentry, XATTR_NAME_IMA, |
| &iint->ima_hash->xattr.data[offset], |
| (sizeof(iint->ima_hash->xattr) - offset) + |
| iint->ima_hash->length, 0); |
| return rc; |
| } |
| |
| /* Return specific func appraised cached result */ |
| enum integrity_status ima_get_cache_status(struct integrity_iint_cache *iint, |
| int func) |
| { |
| switch (func) { |
| case MMAP_CHECK: |
| return iint->ima_mmap_status; |
| case BPRM_CHECK: |
| return iint->ima_bprm_status; |
| case MODULE_CHECK: |
| return iint->ima_module_status; |
| case FILE_CHECK: |
| default: |
| return iint->ima_file_status; |
| } |
| } |
| |
| static void ima_set_cache_status(struct integrity_iint_cache *iint, |
| int func, enum integrity_status status) |
| { |
| switch (func) { |
| case MMAP_CHECK: |
| iint->ima_mmap_status = status; |
| break; |
| case BPRM_CHECK: |
| iint->ima_bprm_status = status; |
| break; |
| case MODULE_CHECK: |
| iint->ima_module_status = status; |
| break; |
| case FILE_CHECK: |
| default: |
| iint->ima_file_status = status; |
| break; |
| } |
| } |
| |
| static void ima_cache_flags(struct integrity_iint_cache *iint, int func) |
| { |
| switch (func) { |
| case MMAP_CHECK: |
| iint->flags |= (IMA_MMAP_APPRAISED | IMA_APPRAISED); |
| break; |
| case BPRM_CHECK: |
| iint->flags |= (IMA_BPRM_APPRAISED | IMA_APPRAISED); |
| break; |
| case MODULE_CHECK: |
| iint->flags |= (IMA_MODULE_APPRAISED | IMA_APPRAISED); |
| break; |
| case FILE_CHECK: |
| default: |
| iint->flags |= (IMA_FILE_APPRAISED | IMA_APPRAISED); |
| break; |
| } |
| } |
| |
| void ima_get_hash_algo(struct evm_ima_xattr_data *xattr_value, int xattr_len, |
| struct ima_digest_data *hash) |
| { |
| struct signature_v2_hdr *sig; |
| |
| if (!xattr_value || xattr_len < 2) |
| return; |
| |
| switch (xattr_value->type) { |
| case EVM_IMA_XATTR_DIGSIG: |
| sig = (typeof(sig))xattr_value; |
| if (sig->version != 2 || xattr_len <= sizeof(*sig)) |
| return; |
| hash->algo = sig->hash_algo; |
| break; |
| case IMA_XATTR_DIGEST_NG: |
| hash->algo = xattr_value->digest[0]; |
| break; |
| case IMA_XATTR_DIGEST: |
| /* this is for backward compatibility */ |
| if (xattr_len == 21) { |
| unsigned int zero = 0; |
| if (!memcmp(&xattr_value->digest[16], &zero, 4)) |
| hash->algo = HASH_ALGO_MD5; |
| else |
| hash->algo = HASH_ALGO_SHA1; |
| } else if (xattr_len == 17) |
| hash->algo = HASH_ALGO_MD5; |
| break; |
| } |
| } |
| |
| int ima_read_xattr(struct dentry *dentry, |
| struct evm_ima_xattr_data **xattr_value) |
| { |
| struct inode *inode = dentry->d_inode; |
| |
| if (!inode->i_op->getxattr) |
| return 0; |
| |
| return vfs_getxattr_alloc(dentry, XATTR_NAME_IMA, (char **)xattr_value, |
| 0, GFP_NOFS); |
| } |
| |
| /* |
| * ima_appraise_measurement - appraise file measurement |
| * |
| * Call evm_verifyxattr() to verify the integrity of 'security.ima'. |
| * Assuming success, compare the xattr hash with the collected measurement. |
| * |
| * Return 0 on success, error code otherwise |
| */ |
| int ima_appraise_measurement(int func, struct integrity_iint_cache *iint, |
| struct file *file, const unsigned char *filename, |
| struct evm_ima_xattr_data *xattr_value, |
| int xattr_len) |
| { |
| struct dentry *dentry = file->f_dentry; |
| struct inode *inode = dentry->d_inode; |
| enum integrity_status status = INTEGRITY_UNKNOWN; |
| const char *op = "appraise_data"; |
| char *cause = "unknown"; |
| int rc = xattr_len, hash_start = 0; |
| |
| if (!ima_appraise) |
| return 0; |
| if (!inode->i_op->getxattr) |
| return INTEGRITY_UNKNOWN; |
| |
| if (rc <= 0) { |
| if (rc && rc != -ENODATA) |
| goto out; |
| |
| cause = "missing-hash"; |
| status = |
| (inode->i_size == 0) ? INTEGRITY_PASS : INTEGRITY_NOLABEL; |
| goto out; |
| } |
| |
| status = evm_verifyxattr(dentry, XATTR_NAME_IMA, xattr_value, rc, iint); |
| if ((status != INTEGRITY_PASS) && (status != INTEGRITY_UNKNOWN)) { |
| if ((status == INTEGRITY_NOLABEL) |
| || (status == INTEGRITY_NOXATTRS)) |
| cause = "missing-HMAC"; |
| else if (status == INTEGRITY_FAIL) |
| cause = "invalid-HMAC"; |
| goto out; |
| } |
| switch (xattr_value->type) { |
| case IMA_XATTR_DIGEST_NG: |
| /* first byte contains algorithm id */ |
| hash_start = 1; |
| case IMA_XATTR_DIGEST: |
| if (iint->flags & IMA_DIGSIG_REQUIRED) { |
| cause = "IMA signature required"; |
| status = INTEGRITY_FAIL; |
| break; |
| } |
| if (xattr_len - sizeof(xattr_value->type) - hash_start >= |
| iint->ima_hash->length) |
| /* xattr length may be longer. md5 hash in previous |
| version occupied 20 bytes in xattr, instead of 16 |
| */ |
| rc = memcmp(&xattr_value->digest[hash_start], |
| iint->ima_hash->digest, |
| iint->ima_hash->length); |
| else |
| rc = -EINVAL; |
| if (rc) { |
| cause = "invalid-hash"; |
| status = INTEGRITY_FAIL; |
| break; |
| } |
| status = INTEGRITY_PASS; |
| break; |
| case EVM_IMA_XATTR_DIGSIG: |
| iint->flags |= IMA_DIGSIG; |
| rc = integrity_digsig_verify(INTEGRITY_KEYRING_IMA, |
| (const char *)xattr_value, rc, |
| iint->ima_hash->digest, |
| iint->ima_hash->length); |
| if (rc == -EOPNOTSUPP) { |
| status = INTEGRITY_UNKNOWN; |
| } else if (rc) { |
| cause = "invalid-signature"; |
| status = INTEGRITY_FAIL; |
| } else { |
| status = INTEGRITY_PASS; |
| } |
| break; |
| default: |
| status = INTEGRITY_UNKNOWN; |
| cause = "unknown-ima-data"; |
| break; |
| } |
| |
| out: |
| if (status != INTEGRITY_PASS) { |
| if ((ima_appraise & IMA_APPRAISE_FIX) && |
| (!xattr_value || |
| xattr_value->type != EVM_IMA_XATTR_DIGSIG)) { |
| if (!ima_fix_xattr(dentry, iint)) |
| status = INTEGRITY_PASS; |
| } |
| integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode, filename, |
| op, cause, rc, 0); |
| } else { |
| ima_cache_flags(iint, func); |
| } |
| ima_set_cache_status(iint, func, status); |
| return status; |
| } |
| |
| /* |
| * ima_update_xattr - update 'security.ima' hash value |
| */ |
| void ima_update_xattr(struct integrity_iint_cache *iint, struct file *file) |
| { |
| struct dentry *dentry = file->f_dentry; |
| int rc = 0; |
| |
| /* do not collect and update hash for digital signatures */ |
| if (iint->flags & IMA_DIGSIG) |
| return; |
| |
| rc = ima_collect_measurement(iint, file, NULL, NULL); |
| if (rc < 0) |
| return; |
| |
| ima_fix_xattr(dentry, iint); |
| } |
| |
| /** |
| * ima_inode_post_setattr - reflect file metadata changes |
| * @dentry: pointer to the affected dentry |
| * |
| * Changes to a dentry's metadata might result in needing to appraise. |
| * |
| * This function is called from notify_change(), which expects the caller |
| * to lock the inode's i_mutex. |
| */ |
| void ima_inode_post_setattr(struct dentry *dentry) |
| { |
| struct inode *inode = dentry->d_inode; |
| struct integrity_iint_cache *iint; |
| int must_appraise, rc; |
| |
| if (!ima_initialized || !ima_appraise || !S_ISREG(inode->i_mode) |
| || !inode->i_op->removexattr) |
| return; |
| |
| must_appraise = ima_must_appraise(inode, MAY_ACCESS, POST_SETATTR); |
| iint = integrity_iint_find(inode); |
| if (iint) { |
| iint->flags &= ~(IMA_APPRAISE | IMA_APPRAISED | |
| IMA_APPRAISE_SUBMASK | IMA_APPRAISED_SUBMASK | |
| IMA_ACTION_FLAGS); |
| if (must_appraise) |
| iint->flags |= IMA_APPRAISE; |
| } |
| if (!must_appraise) |
| rc = inode->i_op->removexattr(dentry, XATTR_NAME_IMA); |
| return; |
| } |
| |
| /* |
| * ima_protect_xattr - protect 'security.ima' |
| * |
| * Ensure that not just anyone can modify or remove 'security.ima'. |
| */ |
| static int ima_protect_xattr(struct dentry *dentry, const char *xattr_name, |
| const void *xattr_value, size_t xattr_value_len) |
| { |
| if (strcmp(xattr_name, XATTR_NAME_IMA) == 0) { |
| if (!capable(CAP_SYS_ADMIN)) |
| return -EPERM; |
| return 1; |
| } |
| return 0; |
| } |
| |
| static void ima_reset_appraise_flags(struct inode *inode) |
| { |
| struct integrity_iint_cache *iint; |
| |
| if (!ima_initialized || !ima_appraise || !S_ISREG(inode->i_mode)) |
| return; |
| |
| iint = integrity_iint_find(inode); |
| if (!iint) |
| return; |
| |
| iint->flags &= ~IMA_DONE_MASK; |
| return; |
| } |
| |
| int ima_inode_setxattr(struct dentry *dentry, const char *xattr_name, |
| const void *xattr_value, size_t xattr_value_len) |
| { |
| int result; |
| |
| result = ima_protect_xattr(dentry, xattr_name, xattr_value, |
| xattr_value_len); |
| if (result == 1) { |
| ima_reset_appraise_flags(dentry->d_inode); |
| result = 0; |
| } |
| return result; |
| } |
| |
| int ima_inode_removexattr(struct dentry *dentry, const char *xattr_name) |
| { |
| int result; |
| |
| result = ima_protect_xattr(dentry, xattr_name, NULL, 0); |
| if (result == 1) { |
| ima_reset_appraise_flags(dentry->d_inode); |
| result = 0; |
| } |
| return result; |
| } |
| |
| #ifdef CONFIG_IMA_TRUSTED_KEYRING |
| static int __init init_ima_keyring(void) |
| { |
| int ret; |
| |
| ret = integrity_init_keyring(INTEGRITY_KEYRING_IMA); |
| return 0; |
| } |
| late_initcall(init_ima_keyring); |
| #endif |