From: Roberto Sassu <roberto.sassu@huawei.com> hulk inclusion category: feature feature: IMA Digest Lists extension bugzilla: 46797 ------------------------------------------------- Commit 5feeb61183dd ("evm: Allow non-SHA1 digital signatures") introduced the possibility to use different hash algorithm for signatures, but kept the algorithm for the HMAC hard-coded (SHA1). Switching to a different algorithm for HMAC would require to change the code in different places. This patch introduces a new global variable called evm_hash_algo, and consistently uses it whenever EVM perform HMAC-related operations. It also introduces a new kernel configuration option called CONFIG_EVM_DEFAULT_HASH so that evm_hash_algo can be defined at kernel compilation time. Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com> Acked-by: Hanjun Guo <guohanjun@huawei.com> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com> Signed-off-by: Tianxing Zhang <zhangtianxing3@huawei.com> Reviewed-by: Jason Yan <yanaijie@huawei.com> Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com> Signed-off-by: zhoushuiqing <zhoushuiqing2@huawei.com> --- security/integrity/evm/Kconfig | 32 +++++++++++++++++++++++++++++ security/integrity/evm/evm.h | 1 + security/integrity/evm/evm_crypto.c | 15 +++++++++----- security/integrity/evm/evm_main.c | 15 +++++++++----- security/integrity/integrity.h | 2 +- 5 files changed, 54 insertions(+), 11 deletions(-) diff --git a/security/integrity/evm/Kconfig b/security/integrity/evm/Kconfig index a6e19d23e700..844f2686cce7 100644 --- a/security/integrity/evm/Kconfig +++ b/security/integrity/evm/Kconfig @@ -13,6 +13,38 @@ config EVM If you are unsure how to answer this question, answer N. +choice + prompt "Default EVM hash algorithm" + default EVM_DEFAULT_HASH_SHA256 + depends on EVM + help + Select the default hash algorithm used for the HMAC. + + config EVM_DEFAULT_HASH_SHA1 + bool "SHA1 (default)" + depends on CRYPTO_SHA1=y + + config EVM_DEFAULT_HASH_SHA256 + bool "SHA256" + depends on CRYPTO_SHA256=y + + config EVM_DEFAULT_HASH_SHA512 + bool "SHA512" + depends on CRYPTO_SHA512=y + + config EVM_DEFAULT_HASH_WP512 + bool "WP512" + depends on CRYPTO_WP512=y +endchoice + +config EVM_DEFAULT_HASH + string + depends on EVM + default "sha1" if EVM_DEFAULT_HASH_SHA1 + default "sha256" if EVM_DEFAULT_HASH_SHA256 + default "sha512" if EVM_DEFAULT_HASH_SHA512 + default "wp512" if EVM_DEFAULT_HASH_WP512 + config EVM_ATTR_FSUUID bool "FSUUID (version 2)" default y diff --git a/security/integrity/evm/evm.h b/security/integrity/evm/evm.h index f8b8c5004fc7..72776e20c0a8 100644 --- a/security/integrity/evm/evm.h +++ b/security/integrity/evm/evm.h @@ -33,6 +33,7 @@ struct xattr_list { }; extern int evm_initialized; +extern enum hash_algo evm_hash_algo; #define EVM_ATTR_FSUUID 0x0001 diff --git a/security/integrity/evm/evm_crypto.c b/security/integrity/evm/evm_crypto.c index 259c7c98bb35..a6215dbe50b1 100644 --- a/security/integrity/evm/evm_crypto.c +++ b/security/integrity/evm/evm_crypto.c @@ -35,7 +35,7 @@ static DEFINE_MUTEX(mutex); static unsigned long evm_set_key_flags; -static const char evm_hmac[] = "hmac(sha1)"; +enum hash_algo evm_hash_algo __ro_after_init = HASH_ALGO_SHA1; /** * evm_set_key() - set EVM HMAC key from the kernel @@ -76,8 +76,12 @@ static struct shash_desc *init_desc(char type, uint8_t hash_algo) long rc; const char *algo; struct crypto_shash **tfm, *tmp_tfm; + char evm_hmac[CRYPTO_MAX_ALG_NAME]; struct shash_desc *desc; + snprintf(evm_hmac, sizeof(evm_hmac), "hmac(%s)", + CONFIG_EVM_DEFAULT_HASH); + if (type == EVM_XATTR_HMAC) { if (!(evm_initialized & EVM_INIT_HMAC)) { pr_err_once("HMAC key is not set\n"); @@ -373,7 +377,7 @@ int evm_update_evmxattr(struct dentry *dentry, const char *xattr_name, if (rc) return -EPERM; - data.hdr.algo = HASH_ALGO_SHA1; + data.hdr.algo = evm_hash_algo; rc = evm_calc_hmac(dentry, xattr_name, xattr_value, xattr_value_len, &data); if (rc == 0) { @@ -381,7 +385,8 @@ int evm_update_evmxattr(struct dentry *dentry, const char *xattr_name, rc = __vfs_setxattr_noperm(&nop_mnt_idmap, dentry, XATTR_NAME_EVM, &data.hdr.xattr.data[1], - SHA1_DIGEST_SIZE + 1, 0); + hash_digest_size[evm_hash_algo] + 1, + 0); } else if (rc == -ENODATA && (inode->i_opflags & IOP_XATTR)) { rc = __vfs_removexattr(&nop_mnt_idmap, dentry, XATTR_NAME_EVM); } @@ -393,7 +398,7 @@ int evm_init_hmac(struct inode *inode, const struct xattr *lsm_xattr, { struct shash_desc *desc; - desc = init_desc(EVM_XATTR_HMAC, HASH_ALGO_SHA1); + desc = init_desc(EVM_XATTR_HMAC, evm_hash_algo); if (IS_ERR(desc)) { pr_info("init_desc failed\n"); return PTR_ERR(desc); @@ -406,7 +411,7 @@ int evm_init_hmac(struct inode *inode, const struct xattr *lsm_xattr, } /* - * Get the key from the TPM for the SHA1-HMAC + * Get the key from the TPM for the HMAC */ int evm_init_key(void) { diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c index 842fe18ad58e..305afa22ab9c 100644 --- a/security/integrity/evm/evm_main.c +++ b/security/integrity/evm/evm_main.c @@ -231,18 +231,18 @@ static enum integrity_status evm_verify_hmac(struct dentry *dentry, /* check value type */ switch (xattr_data->type) { case EVM_XATTR_HMAC: - if (xattr_len != sizeof(struct evm_xattr)) { + if (xattr_len != hash_digest_size[evm_hash_algo] + 1) { evm_status = INTEGRITY_FAIL; goto out; } - digest.hdr.algo = HASH_ALGO_SHA1; + digest.hdr.algo = evm_hash_algo; rc = evm_calc_hmac(dentry, xattr_name, xattr_value, xattr_value_len, &digest); if (rc) break; rc = crypto_memneq(xattr_data->data, digest.digest, - SHA1_DIGEST_SIZE); + hash_digest_size[evm_hash_algo]); if (rc) rc = -EINVAL; break; @@ -955,7 +955,7 @@ int evm_inode_init_security(struct inode *inode, goto out; evm_xattr->value = xattr_data; - evm_xattr->value_len = sizeof(*xattr_data); + evm_xattr->value_len = hash_digest_size[evm_hash_algo] + 1; evm_xattr->name = XATTR_EVM_SUFFIX; return 0; out: @@ -977,9 +977,14 @@ void __init evm_load_x509(void) static int __init init_evm(void) { - int error; + int error, i; struct list_head *pos, *q; + i = match_string(hash_algo_name, HASH_ALGO__LAST, + CONFIG_EVM_DEFAULT_HASH); + if (i >= 0) + evm_hash_algo = i; + evm_init_config(); error = integrity_init_keyring(INTEGRITY_KEYRING_EVM); diff --git a/security/integrity/integrity.h b/security/integrity/integrity.h index a93ad2bcd809..4f0167052b26 100644 --- a/security/integrity/integrity.h +++ b/security/integrity/integrity.h @@ -96,7 +96,7 @@ struct evm_ima_xattr_data { /* Only used in the EVM HMAC code. */ struct evm_xattr { struct evm_ima_xattr_data data; - u8 digest[SHA1_DIGEST_SIZE]; + u8 digest[SHA512_DIGEST_SIZE]; } __packed; #define IMA_MAX_DIGEST_SIZE HASH_MAX_DIGESTSIZE -- 2.33.0