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e0751257a6
Asymmetric keys were introduced in linux-3.7 to verify the signature on signed kernel modules. The asymmetric keys infrastructure abstracts the signature verification from the crypto details. This patch adds IMA/EVM signature verification using asymmetric keys. Support for additional signature verification methods can now be delegated to the asymmetric key infrastructure. Although the module signature header and the IMA/EVM signature header could use the same format, to minimize the signature length and save space in the extended attribute, this patch defines a new IMA/EVM header format. The main difference is that the key identifier is a sha1[12 - 19] hash of the key modulus and exponent, similar to the current implementation. The only purpose of the key identifier is to identify the corresponding key in the kernel keyring. ima-evm-utils was updated to support the new signature format. While asymmetric signature verification functionality supports many different hash algorithms, the hash used in this patch is calculated during the IMA collection phase, based on the configured algorithm. The default algorithm is sha1, but for backwards compatibility md5 is supported. Due to this current limitation, signatures should be generated using a sha1 hash algorithm. Changes in this patch: - Functionality has been moved to separate source file in order to get rid of in source #ifdefs. - keyid is derived according to the RFC 3280. It does not require to assign IMA/EVM specific "description" when loading X509 certificate. Kernel asymmetric key subsystem automatically generate the description. Also loading a certificate does not require using of ima-evm-utils and can be done using keyctl only. - keyid size is reduced to 32 bits to save xattr space. Key search is done using partial match functionality of asymmetric_key_match(). - Kconfig option title was changed Signed-off-by: Dmitry Kasatkin <dmitry.kasatkin@intel.com> Acked-by: David Howells <dhowells@redhat.com> Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
118 lines
3.4 KiB
C
118 lines
3.4 KiB
C
/*
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* Copyright (C) 2009-2010 IBM Corporation
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*
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* Authors:
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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
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation, version 2 of the
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* License.
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*
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*/
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#include <linux/types.h>
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#include <linux/integrity.h>
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#include <crypto/sha.h>
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#include <linux/key.h>
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/* iint action cache flags */
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#define IMA_MEASURE 0x00000001
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#define IMA_MEASURED 0x00000002
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#define IMA_APPRAISE 0x00000004
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#define IMA_APPRAISED 0x00000008
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/*#define IMA_COLLECT 0x00000010 do not use this flag */
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#define IMA_COLLECTED 0x00000020
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#define IMA_AUDIT 0x00000040
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#define IMA_AUDITED 0x00000080
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/* iint cache flags */
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#define IMA_ACTION_FLAGS 0xff000000
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#define IMA_DIGSIG 0x01000000
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#define IMA_DIGSIG_REQUIRED 0x02000000
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#define IMA_DO_MASK (IMA_MEASURE | IMA_APPRAISE | IMA_AUDIT | \
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IMA_APPRAISE_SUBMASK)
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#define IMA_DONE_MASK (IMA_MEASURED | IMA_APPRAISED | IMA_AUDITED | \
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IMA_COLLECTED | IMA_APPRAISED_SUBMASK)
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/* iint subaction appraise cache flags */
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#define IMA_FILE_APPRAISE 0x00000100
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#define IMA_FILE_APPRAISED 0x00000200
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#define IMA_MMAP_APPRAISE 0x00000400
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#define IMA_MMAP_APPRAISED 0x00000800
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#define IMA_BPRM_APPRAISE 0x00001000
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#define IMA_BPRM_APPRAISED 0x00002000
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#define IMA_MODULE_APPRAISE 0x00004000
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#define IMA_MODULE_APPRAISED 0x00008000
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#define IMA_APPRAISE_SUBMASK (IMA_FILE_APPRAISE | IMA_MMAP_APPRAISE | \
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IMA_BPRM_APPRAISE | IMA_MODULE_APPRAISE)
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#define IMA_APPRAISED_SUBMASK (IMA_FILE_APPRAISED | IMA_MMAP_APPRAISED | \
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IMA_BPRM_APPRAISED | IMA_MODULE_APPRAISED)
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enum evm_ima_xattr_type {
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IMA_XATTR_DIGEST = 0x01,
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EVM_XATTR_HMAC,
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EVM_IMA_XATTR_DIGSIG,
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};
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struct evm_ima_xattr_data {
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u8 type;
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u8 digest[SHA1_DIGEST_SIZE];
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} __attribute__((packed));
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/* integrity data associated with an inode */
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struct integrity_iint_cache {
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struct rb_node rb_node; /* rooted in integrity_iint_tree */
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struct inode *inode; /* back pointer to inode in question */
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u64 version; /* track inode changes */
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unsigned long flags;
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struct evm_ima_xattr_data ima_xattr;
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enum integrity_status ima_file_status:4;
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enum integrity_status ima_mmap_status:4;
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enum integrity_status ima_bprm_status:4;
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enum integrity_status ima_module_status:4;
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enum integrity_status evm_status:4;
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};
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/* rbtree tree calls to lookup, insert, delete
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* integrity data associated with an inode.
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*/
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struct integrity_iint_cache *integrity_iint_insert(struct inode *inode);
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struct integrity_iint_cache *integrity_iint_find(struct inode *inode);
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#define INTEGRITY_KEYRING_EVM 0
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#define INTEGRITY_KEYRING_MODULE 1
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#define INTEGRITY_KEYRING_IMA 2
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#define INTEGRITY_KEYRING_MAX 3
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#ifdef CONFIG_INTEGRITY_SIGNATURE
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int integrity_digsig_verify(const unsigned int id, const char *sig, int siglen,
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const char *digest, int digestlen);
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#else
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static inline int integrity_digsig_verify(const unsigned int id,
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const char *sig, int siglen,
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const char *digest, int digestlen)
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{
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return -EOPNOTSUPP;
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}
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#endif /* CONFIG_INTEGRITY_SIGNATURE */
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#ifdef CONFIG_INTEGRITY_ASYMMETRIC_KEYS
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int asymmetric_verify(struct key *keyring, const char *sig,
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int siglen, const char *data, int datalen);
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#else
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static inline int asymmetric_verify(struct key *keyring, const char *sig,
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int siglen, const char *data, int datalen)
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{
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return -EOPNOTSUPP;
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}
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#endif
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/* set during initialization */
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extern int iint_initialized;
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