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b836c4d29f
Commit 18b44bc5a6 ("ovl: Always reevaluate the file signature for
IMA") forced signature re-evaulation on every file access.
Instead of always re-evaluating the file's integrity, detect a change
to the backing file, by comparing the cached file metadata with the
backing file's metadata. Verifying just the i_version has not changed
is insufficient. In addition save and compare the i_ino and s_dev
as well.
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Tested-by: Eric Snowberg <eric.snowberg@oracle.com>
Tested-by: Raul E Rangel <rrangel@chromium.org>
Cc: stable@vger.kernel.org
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
337 lines
8.9 KiB
C
337 lines
8.9 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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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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#ifdef pr_fmt
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#undef pr_fmt
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#endif
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/types.h>
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#include <linux/integrity.h>
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#include <crypto/sha1.h>
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#include <crypto/hash.h>
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#include <linux/key.h>
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#include <linux/audit.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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#define IMA_HASH 0x00000100
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#define IMA_HASHED 0x00000200
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/* iint policy rule cache flags */
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#define IMA_NONACTION_FLAGS 0xff000000
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#define IMA_DIGSIG_REQUIRED 0x01000000
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#define IMA_PERMIT_DIRECTIO 0x02000000
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#define IMA_NEW_FILE 0x04000000
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#define EVM_IMMUTABLE_DIGSIG 0x08000000
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#define IMA_FAIL_UNVERIFIABLE_SIGS 0x10000000
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#define IMA_MODSIG_ALLOWED 0x20000000
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#define IMA_CHECK_BLACKLIST 0x40000000
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#define IMA_VERITY_REQUIRED 0x80000000
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#define IMA_DO_MASK (IMA_MEASURE | IMA_APPRAISE | IMA_AUDIT | \
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IMA_HASH | IMA_APPRAISE_SUBMASK)
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#define IMA_DONE_MASK (IMA_MEASURED | IMA_APPRAISED | IMA_AUDITED | \
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IMA_HASHED | IMA_COLLECTED | \
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IMA_APPRAISED_SUBMASK)
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/* iint subaction appraise cache flags */
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#define IMA_FILE_APPRAISE 0x00001000
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#define IMA_FILE_APPRAISED 0x00002000
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#define IMA_MMAP_APPRAISE 0x00004000
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#define IMA_MMAP_APPRAISED 0x00008000
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#define IMA_BPRM_APPRAISE 0x00010000
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#define IMA_BPRM_APPRAISED 0x00020000
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#define IMA_READ_APPRAISE 0x00040000
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#define IMA_READ_APPRAISED 0x00080000
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#define IMA_CREDS_APPRAISE 0x00100000
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#define IMA_CREDS_APPRAISED 0x00200000
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#define IMA_APPRAISE_SUBMASK (IMA_FILE_APPRAISE | IMA_MMAP_APPRAISE | \
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IMA_BPRM_APPRAISE | IMA_READ_APPRAISE | \
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IMA_CREDS_APPRAISE)
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#define IMA_APPRAISED_SUBMASK (IMA_FILE_APPRAISED | IMA_MMAP_APPRAISED | \
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IMA_BPRM_APPRAISED | IMA_READ_APPRAISED | \
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IMA_CREDS_APPRAISED)
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/* iint cache atomic_flags */
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#define IMA_CHANGE_XATTR 0
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#define IMA_UPDATE_XATTR 1
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#define IMA_CHANGE_ATTR 2
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#define IMA_DIGSIG 3
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#define IMA_MUST_MEASURE 4
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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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IMA_XATTR_DIGEST_NG,
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EVM_XATTR_PORTABLE_DIGSIG,
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IMA_VERITY_DIGSIG,
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IMA_XATTR_LAST
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};
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struct evm_ima_xattr_data {
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u8 type;
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u8 data[];
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} __packed;
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/* Only used in the EVM HMAC code. */
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struct evm_xattr {
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struct evm_ima_xattr_data data;
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u8 digest[SHA1_DIGEST_SIZE];
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} __packed;
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#define IMA_MAX_DIGEST_SIZE HASH_MAX_DIGESTSIZE
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struct ima_digest_data {
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u8 algo;
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u8 length;
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union {
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struct {
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u8 unused;
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u8 type;
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} sha1;
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struct {
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u8 type;
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u8 algo;
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} ng;
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u8 data[2];
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} xattr;
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u8 digest[];
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} __packed;
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/*
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* Instead of wrapping the ima_digest_data struct inside a local structure
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* with the maximum hash size, define ima_max_digest_data struct.
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*/
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struct ima_max_digest_data {
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struct ima_digest_data hdr;
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u8 digest[HASH_MAX_DIGESTSIZE];
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} __packed;
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/*
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* signature header format v2 - for using with asymmetric keys
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*
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* The signature_v2_hdr struct includes a signature format version
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* to simplify defining new signature formats.
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*
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* signature format:
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* version 2: regular file data hash based signature
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* version 3: struct ima_file_id data based signature
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*/
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struct signature_v2_hdr {
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uint8_t type; /* xattr type */
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uint8_t version; /* signature format version */
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uint8_t hash_algo; /* Digest algorithm [enum hash_algo] */
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__be32 keyid; /* IMA key identifier - not X509/PGP specific */
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__be16 sig_size; /* signature size */
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uint8_t sig[]; /* signature payload */
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} __packed;
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/*
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* IMA signature version 3 disambiguates the data that is signed, by
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* indirectly signing the hash of the ima_file_id structure data,
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* containing either the fsverity_descriptor struct digest or, in the
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* future, the regular IMA file hash.
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*
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* (The hash of the ima_file_id structure is only of the portion used.)
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*/
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struct ima_file_id {
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__u8 hash_type; /* xattr type [enum evm_ima_xattr_type] */
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__u8 hash_algorithm; /* Digest algorithm [enum hash_algo] */
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__u8 hash[HASH_MAX_DIGESTSIZE];
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} __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 mutex mutex; /* protects: version, flags, digest */
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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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unsigned long measured_pcrs;
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unsigned long atomic_flags;
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unsigned long real_ino;
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dev_t real_dev;
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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_read_status:4;
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enum integrity_status ima_creds_status:4;
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enum integrity_status evm_status:4;
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struct ima_digest_data *ima_hash;
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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_find(struct inode *inode);
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int integrity_kernel_read(struct file *file, loff_t offset,
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void *addr, unsigned long count);
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#define INTEGRITY_KEYRING_EVM 0
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#define INTEGRITY_KEYRING_IMA 1
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#define INTEGRITY_KEYRING_PLATFORM 2
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#define INTEGRITY_KEYRING_MACHINE 3
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#define INTEGRITY_KEYRING_MAX 4
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extern struct dentry *integrity_dir;
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struct modsig;
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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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int integrity_modsig_verify(unsigned int id, const struct modsig *modsig);
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int __init integrity_init_keyring(const unsigned int id);
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int __init integrity_load_x509(const unsigned int id, const char *path);
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int __init integrity_load_cert(const unsigned int id, const char *source,
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const void *data, size_t len, key_perm_t perm);
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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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static inline int integrity_modsig_verify(unsigned int id,
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const struct modsig *modsig)
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{
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return -EOPNOTSUPP;
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}
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static inline int integrity_init_keyring(const unsigned int id)
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{
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return 0;
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}
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static inline int __init integrity_load_cert(const unsigned int id,
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const char *source,
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const void *data, size_t len,
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key_perm_t perm)
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{
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return 0;
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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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#ifdef CONFIG_IMA_APPRAISE_MODSIG
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int ima_modsig_verify(struct key *keyring, const struct modsig *modsig);
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#else
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static inline int ima_modsig_verify(struct key *keyring,
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const struct modsig *modsig)
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{
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return -EOPNOTSUPP;
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}
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#endif
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#ifdef CONFIG_IMA_LOAD_X509
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void __init ima_load_x509(void);
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#else
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static inline void ima_load_x509(void)
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{
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}
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#endif
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#ifdef CONFIG_EVM_LOAD_X509
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void __init evm_load_x509(void);
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#else
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static inline void evm_load_x509(void)
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{
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}
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#endif
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#ifdef CONFIG_INTEGRITY_AUDIT
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/* declarations */
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void integrity_audit_msg(int audit_msgno, struct inode *inode,
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const unsigned char *fname, const char *op,
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const char *cause, int result, int info);
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void integrity_audit_message(int audit_msgno, struct inode *inode,
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const unsigned char *fname, const char *op,
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const char *cause, int result, int info,
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int errno);
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static inline struct audit_buffer *
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integrity_audit_log_start(struct audit_context *ctx, gfp_t gfp_mask, int type)
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{
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return audit_log_start(ctx, gfp_mask, type);
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}
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#else
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static inline void integrity_audit_msg(int audit_msgno, struct inode *inode,
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const unsigned char *fname,
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const char *op, const char *cause,
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int result, int info)
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{
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}
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static inline void integrity_audit_message(int audit_msgno,
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struct inode *inode,
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const unsigned char *fname,
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const char *op, const char *cause,
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int result, int info, int errno)
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{
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}
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static inline struct audit_buffer *
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integrity_audit_log_start(struct audit_context *ctx, gfp_t gfp_mask, int type)
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{
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return NULL;
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}
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#endif
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#ifdef CONFIG_INTEGRITY_PLATFORM_KEYRING
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void __init add_to_platform_keyring(const char *source, const void *data,
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size_t len);
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#else
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static inline void __init add_to_platform_keyring(const char *source,
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const void *data, size_t len)
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{
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}
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#endif
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#ifdef CONFIG_INTEGRITY_MACHINE_KEYRING
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void __init add_to_machine_keyring(const char *source, const void *data, size_t len);
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bool __init imputed_trust_enabled(void);
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#else
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static inline void __init add_to_machine_keyring(const char *source,
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const void *data, size_t len)
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{
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}
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static inline bool __init imputed_trust_enabled(void)
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{
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return false;
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}
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#endif
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