diff options
32 files changed, 871 insertions, 203 deletions
diff --git a/Documentation/ABI/testing/ima_policy b/Documentation/ABI/testing/ima_policy index fc376a323908..29ebe9afdac4 100644 --- a/Documentation/ABI/testing/ima_policy +++ b/Documentation/ABI/testing/ima_policy @@ -37,7 +37,7 @@ Description: euid:= decimal value fowner:= decimal value lsm: are LSM specific - option: appraise_type:= [imasig] + option: appraise_type:= [imasig] [imasig|modsig] template:= name of a defined IMA template type (eg, ima-ng). Only valid when action is "measure". pcr:= decimal value @@ -105,3 +105,7 @@ Description: measure func=KEXEC_KERNEL_CHECK pcr=4 measure func=KEXEC_INITRAMFS_CHECK pcr=5 + + Example of appraise rule allowing modsig appended signatures: + + appraise func=KEXEC_KERNEL_CHECK appraise_type=imasig|modsig diff --git a/Documentation/security/IMA-templates.rst b/Documentation/security/IMA-templates.rst index 3d1cca287aa4..c5a8432972ef 100644 --- a/Documentation/security/IMA-templates.rst +++ b/Documentation/security/IMA-templates.rst @@ -68,8 +68,10 @@ descriptors by adding their identifier to the format string - 'd-ng': the digest of the event, calculated with an arbitrary hash algorithm (field format: [<hash algo>:]digest, where the digest prefix is shown only if the hash algorithm is not SHA1 or MD5); + - 'd-modsig': the digest of the event without the appended modsig; - 'n-ng': the name of the event, without size limitations; - 'sig': the file signature; + - 'modsig' the appended file signature; - 'buf': the buffer data that was used to generate the hash without size limitations; @@ -79,6 +81,7 @@ Below, there is the list of defined template descriptors: - "ima-ng" (default): its format is ``d-ng|n-ng``; - "ima-sig": its format is ``d-ng|n-ng|sig``; - "ima-buf": its format is ``d-ng|n-ng|buf``; + - "ima-modsig": its format is ``d-ng|n-ng|sig|d-modsig|modsig``; Use diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig index f933a473b128..68f7c2b16ff7 100644 --- a/arch/s390/Kconfig +++ b/arch/s390/Kconfig @@ -556,7 +556,7 @@ config ARCH_HAS_KEXEC_PURGATORY config KEXEC_VERIFY_SIG bool "Verify kernel signature during kexec_file_load() syscall" - depends on KEXEC_FILE && SYSTEM_DATA_VERIFICATION + depends on KEXEC_FILE && MODULE_SIG_FORMAT help This option makes kernel signature verification mandatory for the kexec_file_load() syscall. diff --git a/arch/s390/kernel/machine_kexec_file.c b/arch/s390/kernel/machine_kexec_file.c index fbdd3ea73667..1ac9fbc6e01e 100644 --- a/arch/s390/kernel/machine_kexec_file.c +++ b/arch/s390/kernel/machine_kexec_file.c @@ -10,7 +10,7 @@ #include <linux/elf.h> #include <linux/errno.h> #include <linux/kexec.h> -#include <linux/module.h> +#include <linux/module_signature.h> #include <linux/verification.h> #include <asm/boot_data.h> #include <asm/ipl.h> @@ -23,28 +23,6 @@ const struct kexec_file_ops * const kexec_file_loaders[] = { }; #ifdef CONFIG_KEXEC_VERIFY_SIG -/* - * Module signature information block. - * - * The constituents of the signature section are, in order: - * - * - Signer's name - * - Key identifier - * - Signature data - * - Information block - */ -struct module_signature { - u8 algo; /* Public-key crypto algorithm [0] */ - u8 hash; /* Digest algorithm [0] */ - u8 id_type; /* Key identifier type [PKEY_ID_PKCS7] */ - u8 signer_len; /* Length of signer's name [0] */ - u8 key_id_len; /* Length of key identifier [0] */ - u8 __pad[3]; - __be32 sig_len; /* Length of signature data */ -}; - -#define PKEY_ID_PKCS7 2 - int s390_verify_sig(const char *kernel, unsigned long kernel_len) { const unsigned long marker_len = sizeof(MODULE_SIG_STRING) - 1; diff --git a/certs/system_keyring.c b/certs/system_keyring.c index 1eba08a1af82..798291177186 100644 --- a/certs/system_keyring.c +++ b/certs/system_keyring.c @@ -190,33 +190,27 @@ late_initcall(load_system_certificate_list); #ifdef CONFIG_SYSTEM_DATA_VERIFICATION /** - * verify_pkcs7_signature - Verify a PKCS#7-based signature on system data. + * verify_pkcs7_message_sig - Verify a PKCS#7-based signature on system data. * @data: The data to be verified (NULL if expecting internal data). * @len: Size of @data. - * @raw_pkcs7: The PKCS#7 message that is the signature. - * @pkcs7_len: The size of @raw_pkcs7. + * @pkcs7: The PKCS#7 message that is the signature. * @trusted_keys: Trusted keys to use (NULL for builtin trusted keys only, * (void *)1UL for all trusted keys). * @usage: The use to which the key is being put. * @view_content: Callback to gain access to content. * @ctx: Context for callback. */ -int verify_pkcs7_signature(const void *data, size_t len, - const void *raw_pkcs7, size_t pkcs7_len, - struct key *trusted_keys, - enum key_being_used_for usage, - int (*view_content)(void *ctx, - const void *data, size_t len, - size_t asn1hdrlen), - void *ctx) +int verify_pkcs7_message_sig(const void *data, size_t len, + struct pkcs7_message *pkcs7, + struct key *trusted_keys, + enum key_being_used_for usage, + int (*view_content)(void *ctx, + const void *data, size_t len, + size_t asn1hdrlen), + void *ctx) { - struct pkcs7_message *pkcs7; int ret; - pkcs7 = pkcs7_parse_message(raw_pkcs7, pkcs7_len); - if (IS_ERR(pkcs7)) - return PTR_ERR(pkcs7); - /* The data should be detached - so we need to supply it. */ if (data && pkcs7_supply_detached_data(pkcs7, data, len) < 0) { pr_err("PKCS#7 signature with non-detached data\n"); @@ -269,6 +263,41 @@ int verify_pkcs7_signature(const void *data, size_t len, } error: + pr_devel("<==%s() = %d\n", __func__, ret); + return ret; +} + +/** + * verify_pkcs7_signature - Verify a PKCS#7-based signature on system data. + * @data: The data to be verified (NULL if expecting internal data). + * @len: Size of @data. + * @raw_pkcs7: The PKCS#7 message that is the signature. + * @pkcs7_len: The size of @raw_pkcs7. + * @trusted_keys: Trusted keys to use (NULL for builtin trusted keys only, + * (void *)1UL for all trusted keys). + * @usage: The use to which the key is being put. + * @view_content: Callback to gain access to content. + * @ctx: Context for callback. + */ +int verify_pkcs7_signature(const void *data, size_t len, + const void *raw_pkcs7, size_t pkcs7_len, + struct key *trusted_keys, + enum key_being_used_for usage, + int (*view_content)(void *ctx, + const void *data, size_t len, + size_t asn1hdrlen), + void *ctx) +{ + struct pkcs7_message *pkcs7; + int ret; + + pkcs7 = pkcs7_parse_message(raw_pkcs7, pkcs7_len); + if (IS_ERR(pkcs7)) + return PTR_ERR(pkcs7); + + ret = verify_pkcs7_message_sig(data, len, pkcs7, trusted_keys, usage, + view_content, ctx); + pkcs7_free_message(pkcs7); pr_devel("<==%s() = %d\n", __func__, ret); return ret; diff --git a/crypto/asymmetric_keys/pkcs7_verify.c b/crypto/asymmetric_keys/pkcs7_verify.c index 11bee67fa9cc..ce49820caa97 100644 --- a/crypto/asymmetric_keys/pkcs7_verify.c +++ b/crypto/asymmetric_keys/pkcs7_verify.c @@ -12,6 +12,7 @@ #include <linux/err.h> #include <linux/asn1.h> #include <crypto/hash.h> +#include <crypto/hash_info.h> #include <crypto/public_key.h> #include "pkcs7_parser.h" @@ -29,6 +30,10 @@ static int pkcs7_digest(struct pkcs7_message *pkcs7, kenter(",%u,%s", sinfo->index, sinfo->sig->hash_algo); + /* The digest was calculated already. */ + if (sig->digest) + return 0; + if (!sinfo->sig->hash_algo) return -ENOPKG; @@ -117,6 +122,34 @@ error_no_desc: return ret; } +int pkcs7_get_digest(struct pkcs7_message *pkcs7, const u8 **buf, u32 *len, + enum hash_algo *hash_algo) +{ + struct pkcs7_signed_info *sinfo = pkcs7->signed_infos; + int i, ret; + + /* + * This function doesn't support messages with more than one signature. + */ + if (sinfo == NULL || sinfo->next != NULL) + return -EBADMSG; + + ret = pkcs7_digest(pkcs7, sinfo); + if (ret) + return ret; + + *buf = sinfo->sig->digest; + *len = sinfo->sig->digest_size; + + for (i = 0; i < HASH_ALGO__LAST; i++) + if (!strcmp(hash_algo_name[i], sinfo->sig->hash_algo)) { + *hash_algo = i; + break; + } + + return 0; +} + /* * Find the key (X.509 certificate) to use to verify a PKCS#7 message. PKCS#7 * uses the issuer's name and the issuing certificate serial number for diff --git a/include/crypto/pkcs7.h b/include/crypto/pkcs7.h index 96071bee03ac..38ec7f5f9041 100644 --- a/include/crypto/pkcs7.h +++ b/include/crypto/pkcs7.h @@ -9,6 +9,7 @@ #define _CRYPTO_PKCS7_H #include <linux/verification.h> +#include <linux/hash_info.h> #include <crypto/public_key.h> struct key; @@ -40,4 +41,7 @@ extern int pkcs7_verify(struct pkcs7_message *pkcs7, extern int pkcs7_supply_detached_data(struct pkcs7_message *pkcs7, const void *data, size_t datalen); +extern int pkcs7_get_digest(struct pkcs7_message *pkcs7, const u8 **buf, + u32 *len, enum hash_algo *hash_algo); + #endif /* _CRYPTO_PKCS7_H */ diff --git a/include/linux/module.h b/include/linux/module.h index b1a67352d2dc..6d20895e7739 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -26,9 +26,6 @@ #include <linux/percpu.h> #include <asm/module.h> -/* In stripped ARM and x86-64 modules, ~ is surprisingly rare. */ -#define MODULE_SIG_STRING "~Module signature appended~\n" - /* Not Yet Implemented */ #define MODULE_SUPPORTED_DEVICE(name) diff --git a/include/linux/module_signature.h b/include/linux/module_signature.h new file mode 100644 index 000000000000..7eb4b00381ac --- /dev/null +++ b/include/linux/module_signature.h @@ -0,0 +1,46 @@ +/* SPDX-License-Identifier: GPL-2.0+ */ +/* + * Module signature handling. + * + * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + */ + +#ifndef _LINUX_MODULE_SIGNATURE_H +#define _LINUX_MODULE_SIGNATURE_H + +#include <linux/types.h> + +/* In stripped ARM and x86-64 modules, ~ is surprisingly rare. */ +#define MODULE_SIG_STRING "~Module signature appended~\n" + +enum pkey_id_type { + PKEY_ID_PGP, /* OpenPGP generated key ID */ + PKEY_ID_X509, /* X.509 arbitrary subjectKeyIdentifier */ + PKEY_ID_PKCS7, /* Signature in PKCS#7 message */ +}; + +/* + * Module signature information block. + * + * The constituents of the signature section are, in order: + * + * - Signer's name + * - Key identifier + * - Signature data + * - Information block + */ +struct module_signature { + u8 algo; /* Public-key crypto algorithm [0] */ + u8 hash; /* Digest algorithm [0] */ + u8 id_type; /* Key identifier type [PKEY_ID_PKCS7] */ + u8 signer_len; /* Length of signer's name [0] */ + u8 key_id_len; /* Length of key identifier [0] */ + u8 __pad[3]; + __be32 sig_len; /* Length of signature data */ +}; + +int mod_check_sig(const struct module_signature *ms, size_t file_len, + const char *name); + +#endif /* _LINUX_MODULE_SIGNATURE_H */ diff --git a/include/linux/verification.h b/include/linux/verification.h index 32d990d163c4..911ab7c2b1ab 100644 --- a/include/linux/verification.h +++ b/include/linux/verification.h @@ -32,6 +32,7 @@ extern const char *const key_being_used_for[NR__KEY_BEING_USED_FOR]; #ifdef CONFIG_SYSTEM_DATA_VERIFICATION struct key; +struct pkcs7_message; extern int verify_pkcs7_signature(const void *data, size_t len, const void *raw_pkcs7, size_t pkcs7_len, @@ -41,6 +42,15 @@ extern int verify_pkcs7_signature(const void *data, size_t len, const void *data, size_t len, size_t asn1hdrlen), void *ctx); +extern int verify_pkcs7_message_sig(const void *data, size_t len, + struct pkcs7_message *pkcs7, + struct key *trusted_keys, + enum key_being_used_for usage, + int (*view_content)(void *ctx, + const void *data, + size_t len, + size_t asn1hdrlen), + void *ctx); #ifdef CONFIG_SIGNED_PE_FILE_VERIFICATION extern int verify_pefile_signature(const void *pebuf, unsigned pelen, diff --git a/init/Kconfig b/init/Kconfig index 57123594a7ca..92c867e25a29 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -1963,6 +1963,10 @@ config BASE_SMALL default 0 if BASE_FULL default 1 if !BASE_FULL +config MODULE_SIG_FORMAT + def_bool n + select SYSTEM_DATA_VERIFICATION + menuconfig MODULES bool "Enable loadable module support" option modules @@ -2047,7 +2051,7 @@ config MODULE_SRCVERSION_ALL config MODULE_SIG bool "Module signature verification" - select SYSTEM_DATA_VERIFICATION + select MODULE_SIG_FORMAT help Check modules for valid signatures upon load: the signature is simply appended to the module. For more information see diff --git a/kernel/Makefile b/kernel/Makefile index 25f9d83d1bbf..daad787fb795 100644 --- a/kernel/Makefile +++ b/kernel/Makefile @@ -58,6 +58,7 @@ endif obj-$(CONFIG_UID16) += uid16.o obj-$(CONFIG_MODULES) += module.o obj-$(CONFIG_MODULE_SIG) += module_signing.o +obj-$(CONFIG_MODULE_SIG_FORMAT) += module_signature.o obj-$(CONFIG_KALLSYMS) += kallsyms.o obj-$(CONFIG_BSD_PROCESS_ACCT) += acct.o obj-$(CONFIG_CRASH_CORE) += crash_core.o diff --git a/kernel/module.c b/kernel/module.c index 32873bcce738..edbe42755a27 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -7,6 +7,7 @@ #include <linux/export.h> #include <linux/extable.h> #include <linux/moduleloader.h> +#include <linux/module_signature.h> #include <linux/trace_events.h> #include <linux/init.h> #include <linux/kallsyms.h> diff --git a/kernel/module_signature.c b/kernel/module_signature.c new file mode 100644 index 000000000000..4224a1086b7d --- /dev/null +++ b/kernel/module_signature.c @@ -0,0 +1,46 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * Module signature checker + * + * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + */ + +#include <linux/errno.h> +#include <linux/printk.h> +#include <linux/module_signature.h> +#include <asm/byteorder.h> + +/** + * mod_check_sig - check that the given signature is sane + * + * @ms: Signature to check. + * @file_len: Size of the file to which @ms is appended. + * @name: What is being checked. Used for error messages. + */ +int mod_check_sig(const struct module_signature *ms, size_t file_len, + const char *name) +{ + if (be32_to_cpu(ms->sig_len) >= file_len - sizeof(*ms)) + return -EBADMSG; + + if (ms->id_type != PKEY_ID_PKCS7) { + pr_err("%s: Module is not signed with expected PKCS#7 message\n", + name); + return -ENOPKG; + } + + if (ms->algo != 0 || + ms->hash != 0 || + ms->signer_len != 0 || + ms->key_id_len != 0 || + ms->__pad[0] != 0 || + ms->__pad[1] != 0 || + ms->__pad[2] != 0) { + pr_err("%s: PKCS#7 signature info has unexpected non-zero params\n", + name); + return -EBADMSG; + } + + return 0; +} diff --git a/kernel/module_signing.c b/kernel/module_signing.c index b10fb1986ca9..9d9fc678c91d 100644 --- a/kernel/module_signing.c +++ b/kernel/module_signing.c @@ -7,37 +7,13 @@ #include <linux/kernel.h> #include <linux/errno.h> +#include <linux/module.h> +#include <linux/module_signature.h> #include <linux/string.h> #include <linux/verification.h> #include <crypto/public_key.h> #include "module-internal.h" -enum pkey_id_type { - PKEY_ID_PGP, /* OpenPGP generated key ID */ - PKEY_ID_X509, /* X.509 arbitrary subjectKeyIdentifier */ - PKEY_ID_PKCS7, /* Signature in PKCS#7 message */ -}; - -/* - * Module signature information block. - * - * The constituents of the signature section are, in order: - * - * - Signer's name - * - Key identifier - * - Signature data - * - Information block - */ -struct module_signature { - u8 algo; /* Public-key crypto algorithm [0] */ - u8 hash; /* Digest algorithm [0] */ - u8 id_type; /* Key identifier type [PKEY_ID_PKCS7] */ - u8 signer_len; /* Length of signer's name [0] */ - u8 key_id_len; /* Length of key identifier [0] */ - u8 __pad[3]; - __be32 sig_len; /* Length of signature data */ -}; - /* * Verify the signature on a module. */ @@ -45,6 +21,7 @@ int mod_verify_sig(const void *mod, struct load_info *info) { struct module_signature ms; size_t sig_len, modlen = info->len; + int ret; pr_devel("==>%s(,%zu)\n", __func__, modlen); @@ -52,32 +29,15 @@ int mod_verify_sig(const void *mod, struct load_info *info) return -EBADMSG; memcpy(&ms, mod + (modlen - sizeof(ms)), sizeof(ms)); - modlen -= sizeof(ms); + + ret = mod_check_sig(&ms, modlen, info->name); + if (ret) + return ret; sig_len = be32_to_cpu(ms.sig_len); - if (sig_len >= modlen) - return -EBADMSG; - modlen -= sig_len; + modlen -= sig_len + sizeof(ms); info->len = modlen; - if (ms.id_type != PKEY_ID_PKCS7) { - pr_err("%s: Module is not signed with expected PKCS#7 message\n", - info->name); - return -ENOPKG; - } - - if (ms.algo != 0 || - ms.hash != 0 || - ms.signer_len != 0 || - ms.key_id_len != 0 || - ms.__pad[0] != 0 || - ms.__pad[1] != 0 || - ms.__pad[2] != 0) { - pr_err("%s: PKCS#7 signature info has unexpected non-zero params\n", - info->name); - return -EBADMSG; - } - return verify_pkcs7_signature(mod, modlen, mod + modlen, sig_len, VERIFY_USE_SECONDARY_KEYRING, VERIFYING_MODULE_SIGNATURE, diff --git a/scripts/Makefile b/scripts/Makefile index c42891e10ba3..3e86b300f5a1 100644 --- a/scripts/Makefile +++ b/scripts/Makefile @@ -17,7 +17,7 @@ hostprogs-$(CONFIG_VT) += conmakehash hostprogs-$(BUILD_C_RECORDMCOUNT) += recordmcount hostprogs-$(CONFIG_BUILDTIME_EXTABLE_SORT) += sortextable hostprogs-$(CONFIG_ASN1) += asn1_compiler -hostprogs-$(CONFIG_MODULE_SIG) += sign-file +hostprogs-$(CONFIG_MODULE_SIG_FORMAT) += sign-file hostprogs-$(CONFIG_SYSTEM_TRUSTED_KEYRING) += extract-cert hostprogs-$(CONFIG_SYSTEM_EXTRA_CERTIFICATE) += insert-sys-cert diff --git a/security/integrity/Kconfig b/security/integrity/Kconfig index c352532b8f84..0bae6adb63a9 100644 --- a/security/integrity/Kconfig +++ b/security/integrity/Kconfig @@ -18,8 +18,8 @@ if INTEGRITY config INTEGRITY_SIGNATURE bool "Digital signature verification using multiple keyrings" - depends on KEYS default n + select KEYS select SIGNATURE help This option enables digital signature verification support diff --git a/security/integrity/digsig.c b/security/integrity/digsig.c index 868ade3e8970..ea1aae3d07b3 100644 --- a/security/integrity/digsig.c +++ b/security/integrity/digsig.c @@ -39,11 +39,10 @@ static const char * const keyring_name[INTEGRITY_KEYRING_MAX] = { #define restrict_link_to_ima restrict_link_by_builtin_trusted #endif -int integrity_digsig_verify(const unsigned int id, const char *sig, int siglen, - const char *digest, int digestlen) +static struct key *integrity_keyring_from_id(const unsigned int id) { - if (id >= INTEGRITY_KEYRING_MAX || siglen < 2) - return -EINVAL; + if (id >= INTEGRITY_KEYRING_MAX) + return ERR_PTR(-EINVAL); if (!keyring[id]) { keyring[id] = @@ -52,23 +51,49 @@ int integrity_digsig_verify(const unsigned int id, const char *sig, int siglen, int err = PTR_ERR(keyring[id]); pr_err("no %s keyring: %d\n", keyring_name[id], err); keyring[id] = NULL; - return err; + return ERR_PTR(err); } } + return keyring[id]; +} + +int integrity_digsig_verify(const unsigned int id, const char *sig, int siglen, + const char *digest, int digestlen) +{ + struct key *keyring; + + if (siglen < 2) + return -EINVAL; + + keyring = integrity_keyring_from_id(id); + if (IS_ERR(keyring)) + return PTR_ERR(keyring); + switch (sig[1]) { case 1: /* v1 API expect signature without xattr type */ - return digsig_verify(keyring[id], sig + 1, siglen - 1, - digest, digestlen); + return digsig_verify(keyring, sig + 1, siglen - 1, digest, + digestlen); case 2: - return asymmetric_verify(keyring[id], sig, siglen, - digest, digestlen); + return asymmetric_verify(keyring, sig, siglen, digest, + digestlen); } return -EOPNOTSUPP; } +int integrity_modsig_verify(const unsigned int id, const struct modsig *modsig) +{ + struct key *keyring; + + keyring = integrity_keyring_from_id(id); + if (IS_ERR(keyring)) + return PTR_ERR(keyring); + + return ima_modsig_verify(keyring, modsig); +} + static int __init __integrity_init_keyring(const unsigned int id, key_perm_t perm, struct key_restriction *restriction) diff --git a/security/integrity/ima/Kconfig b/security/integrity/ima/Kconfig index 2ced99dde694..897bafc59a33 100644 --- a/security/integrity/ima/Kconfig +++ b/security/integrity/ima/Kconfig @@ -233,6 +233,19 @@ config IMA_APPRAISE_BOOTPARAM This option enables the different "ima_appraise=" modes (eg. fix, log) from the boot command line. +config IMA_APPRAISE_MODSIG + bool "Support module-style signatures for appraisal" + depends on IMA_APPRAISE + depends on INTEGRITY_ASYMMETRIC_KEYS + select PKCS7_MESSAGE_PARSER + select MODULE_SIG_FORMAT + default n + help + Adds support for signatures appended to files. The format of the + appended signature is the same used for signed kernel modules. + The modsig keyword can be used in the IMA policy to allow a hook + to accept such signatures. + config IMA_TRUSTED_KEYRING bool "Require all keys on the .ima keyring be signed (deprecated)" depends on IMA_APPRAISE && SYSTEM_TRUSTED_KEYRING diff --git a/security/integrity/ima/Makefile b/security/integrity/ima/Makefile index d921dc4f9eb0..31d57cdf2421 100644 --- a/security/integrity/ima/Makefile +++ b/security/integrity/ima/Makefile @@ -9,5 +9,6 @@ obj-$(CONFIG_IMA) += ima.o ima-y := ima_fs.o ima_queue.o ima_init.o ima_main.o ima_crypto.o ima_api.o \ ima_policy.o ima_template.o ima_template_lib.o ima-$(CONFIG_IMA_APPRAISE) += ima_appraise.o +ima-$(CONFIG_IMA_APPRAISE_MODSIG) += ima_modsig.o ima-$(CONFIG_HAVE_IMA_KEXEC) += ima_kexec.o obj-$(CONFIG_IMA_BLACKLIST_KEYRING) += ima_mok.o diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h index 011b91c79351..19769bf5f6ab 100644 --- a/security/integrity/ima/ima.h +++ b/security/integrity/ima/ima.h @@ -60,6 +60,7 @@ struct ima_event_data { const unsigned char *filename; struct evm_ima_xattr_data *xattr_value; int xattr_len; + const struct modsig *modsig; const char *violation; const void *buf; int buf_len; @@ -149,6 +150,7 @@ int template_desc_init_fields(const char *template_fmt, int *num_fields); struct ima_template_desc *ima_template_desc_current(void); struct ima_template_desc *lookup_template_desc(const char *name); +bool ima_template_has_modsig(const struct ima_template_desc *ima_template); int ima_restore_measurement_entry(struct ima_template_entry *entry); int ima_restore_measurement_list(loff_t bufsize, void *buf); int ima_measurements_show(struct seq_file *m, void *v); @@ -196,6 +198,10 @@ enum ima_hooks { __ima_hooks(__ima_hook_enumify) }; +extern const char *const func_tokens[]; + +struct modsig; + /* LIM API function definitions */ int ima_get_action(struct inode *inode, const struct cred *cred, u32 secid, int mask, enum ima_hooks func, int *pcr, @@ -203,11 +209,11 @@ int ima_get_action(struct inode *inode, const struct cred *cred, u32 secid, int ima_must_measure(struct inode *inode, int mask, enum ima_hooks func); int ima_collect_measurement(struct integrity_iint_cache *iint, struct file *file, void *buf, loff_t size, - enum hash_algo algo); + enum hash_algo algo, struct modsig *modsig); void ima_store_measurement(struct integrity_iint_cache *iint, struct file *file, const unsigned char *filename, struct evm_ima_xattr_data *xattr_value, - int xattr_len, int pcr, + int xattr_len, const struct modsig *modsig, int pcr, struct ima_template_desc *template_desc); void ima_audit_measurement(struct integrity_iint_cache *iint, const unsigned char *filename); @@ -249,7 +255,7 @@ int ima_appraise_measurement(enum ima_hooks func, struct integrity_iint_cache *iint, struct file *file, const unsigned char *filename, struct evm_ima_xattr_data *xattr_value, - int xattr_len); + int xattr_len, const struct modsig *modsig); int ima_must_appraise(struct inode *inode, int mask, enum ima_hooks func); void ima_update_xattr(struct integrity_iint_cache *iint, struct file *file); enum integrity_status ima_get_cache_status(struct integrity_iint_cache *iint, @@ -265,7 +271,8 @@ static inline int ima_appraise_measurement(enum ima_hooks func, struct file *file, const unsigned char *filename, struct evm_ima_xattr_data *xattr_value, - int xattr_len) + int xattr_len, + const struct modsig *modsig) { return INTEGRITY_UNKNOWN; } @@ -302,6 +309,51 @@ static inline int ima_read_xattr(struct dentry *dentry, #endif /* CONFIG_IMA_APPRAISE */ +#ifdef CONFIG_IMA_APPRAISE_MODSIG +bool ima_hook_supports_modsig(enum ima_hooks func); +int ima_read_modsig(enum ima_hooks func, const void *buf, loff_t buf_len, + struct modsig **modsig); +void ima_collect_modsig(struct modsig *modsig, const void *buf, loff_t size); +int ima_get_modsig_digest(const struct modsig *modsig, enum hash_algo *algo, + const u8 **digest, u32 *digest_size); +int ima_get_raw_modsig(const struct modsig *modsig, const void **data, + u32 *data_len); +void ima_free_modsig(struct modsig *modsig); +#else +static inline bool ima_hook_supports_modsig(enum ima_hooks func) +{ + return false; +} + +static inline int ima_read_modsig(enum ima_hooks func, const void *buf, + loff_t buf_len, struct modsig **modsig) +{ + return -EOPNOTSUPP; +} + +static inline void ima_collect_modsig(struct modsig *modsig, const void *buf, + loff_t size) +{ +} + +static inline int ima_get_modsig_digest(const struct modsig *modsig, + enum hash_algo *algo, const u8 **digest, + u32 *digest_size) +{ + return -EOPNOTSUPP; +} + +static inline int ima_get_raw_modsig(const struct modsig *modsig, + const void **data, u32 *data_len) +{ + return -EOPNOTSUPP; +} + +static inline void ima_free_modsig(struct modsig *modsig) +{ +} +#endif /* CONFIG_IMA_APPRAISE_MODSIG */ + /* LSM based policy rules require audit */ #ifdef CONFIG_IMA_LSM_RULES diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c index f614e22bf39f..610759fe63b8 100644 --- a/security/integrity/ima/ima_api.c +++ b/security/integrity/ima/ima_api.c @@ -45,8 +45,8 @@ int ima_alloc_init_template(struct ima_event_data *event_data, else template_desc = ima_template_desc_current(); - *entry = kzalloc(sizeof(**entry) + template_desc->num_fields * - sizeof(struct ima_field_data), GFP_NOFS); + *entry = kzalloc(struct_size(*entry, template_data, + template_desc->num_fields), GFP_NOFS); if (!*entry) return -ENOMEM; @@ -205,7 +205,7 @@ int ima_get_action(struct inode *inode, const struct cred *cred, u32 secid, */ int ima_collect_measurement(struct integrity_iint_cache *iint, struct file *file, void *buf, loff_t size, - enum hash_algo algo) + enum hash_algo algo, struct modsig *modsig) { const char *audit_cause = "failed"; struct inode *inode = file_inode(file); @@ -219,6 +219,14 @@ int ima_collect_measurement(struct integrity_iint_cache *iint, char digest[IMA_MAX_DIGEST_SIZE]; } hash; + /* + * Always collect the modsig, because IMA might have already collected + * the file digest without collecting the modsig in a previous + * measurement rule. + */ + if (modsig) + ima_collect_modsig(modsig, buf, size); + if (iint->flags & IMA_COLLECTED) goto out; @@ -285,7 +293,7 @@ out: void ima_store_measurement(struct integrity_iint_cache *iint, struct file *file, const unsigned char *filename, struct evm_ima_xattr_data *xattr_value, - int xattr_len, int pcr, + int xattr_len, const struct modsig *modsig, int pcr, struct ima_template_desc *template_desc) { static const char op[] = "add_template_measure"; @@ -297,10 +305,17 @@ void ima_store_measurement(struct integrity_iint_cache *iint, .file = file, .filename = filename, .xattr_value = xattr_value, - .xattr_len = xattr_len }; + .xattr_len = xattr_len, + .modsig = modsig }; int violation = 0; - if (iint->measured_pcrs & (0x1 << pcr)) + /* + * We still need to store the measurement in the case of MODSIG because + * we only have its contents to put in the list at the time of + * appraisal, but a file measurement from earlier might already exist in + * the measurement list. + */ + if (iint->measured_pcrs & (0x1 << pcr) && !modsig) return; result = ima_alloc_init_template(&event_data, &entry, template_desc); diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c index 89b83194d1dc..136ae4e0ee92 100644 --- a/security/integrity/ima/ima_appraise.c +++ b/security/integrity/ima/ima_appraise.c @@ -200,6 +200,110 @@ int ima_read_xattr(struct dentry *dentry, } /* + * xattr_verify - verify xattr digest or signature + * + * Verify whether the hash or signature matches the file contents. + * + * Return 0 on success, error code otherwise. + */ +static int xattr_verify(enum ima_hooks func, struct integrity_iint_cache *iint, + struct evm_ima_xattr_data *xattr_value, int xattr_len, + enum integrity_status *status, const char **cause) +{ + int rc = -EINVAL, hash_start = 0; + + switch (xattr_value->type) { + case IMA_XATTR_DIGEST_NG: + /* first byte contains algorithm id */ + hash_start = 1; + /* fall through */ + case IMA_XATTR_DIGEST: + if (iint->flags & IMA_DIGSIG_REQUIRED) { + *cause = "IMA-signature-required"; + *status = INTEGRITY_FAIL; + break; + } + clear_bit(IMA_DIGSIG, &iint->atomic_flags); + 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->data[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: + set_bit(IMA_DIGSIG, &iint->atomic_flags); + rc = integrity_digsig_verify(INTEGRITY_KEYRING_IMA, + (const char *)xattr_value, + xattr_len, + iint->ima_hash->digest, + iint->ima_hash->length); + if (rc == -EOPNOTSUPP) { + *status = INTEGRITY_UNKNOWN; + break; + } + if (IS_ENABLED(CONFIG_INTEGRITY_PLATFORM_KEYRING) && rc && + func == KEXEC_KERNEL_CHECK) + rc = integrity_digsig_verify(INTEGRITY_KEYRING_PLATFORM, + (const char *)xattr_value, + xattr_len, + iint->ima_hash->digest, + iint->ima_hash->length); + if (rc) { + *cause = "invalid-signature"; + *status = INTEGRITY_FAIL; + } else { + *status = INTEGRITY_PASS; + } + break; + default: + *status = INTEGRITY_UNKNOWN; + *cause = "unknown-ima-data"; + break; + } + + return rc; +} + +/* + * modsig_verify - verify modsig signature + * + * Verify whether the signature matches the file contents. + * + * Return 0 on success, error code otherwise. + */ +static int modsig_verify(enum ima_hooks func, const struct modsig *modsig, + enum integrity_status *status, const char **cause) +{ + int rc; + + rc = integrity_modsig_verify(INTEGRITY_KEYRING_IMA, modsig); + if (IS_ENABLED(CONFIG_INTEGRITY_PLATFORM_KEYRING) && rc && + func == KEXEC_KERNEL_CHECK) + rc = integrity_modsig_verify(INTEGRITY_KEYRING_PLATFORM, + modsig); + if (rc) { + *cause = "invalid-signature"; + *status = INTEGRITY_FAIL; + } else { + *status = INTEGRITY_PASS; + } + + return rc; +} + +/* * ima_appraise_measurement - appraise file measurement * * Call evm_verifyxattr() to verify the integrity of 'security.ima'. @@ -211,19 +315,22 @@ int ima_appraise_measurement(enum ima_hooks func, struct integrity_iint_cache *iint, struct file *file, const unsigned char *filename, struct evm_ima_xattr_data *xattr_value, - int xattr_len) + int xattr_len, const struct modsig *modsig) { static const char op[] = "appraise_data"; const char *cause = "unknown"; struct dentry *dentry = file_dentry(file); struct inode *inode = d_backing_inode(dentry); enum integrity_status status = INTEGRITY_UNKNOWN; - int rc = xattr_len, hash_start = 0; + int rc = xattr_len; + bool try_modsig = iint->flags & IMA_MODSIG_ALLOWED && modsig; - if (!(inode->i_opflags & IOP_XATTR)) + /* If not appraising a modsig, we need an xattr. */ + if (!(inode->i_opflags & IOP_XATTR) && !try_modsig) return INTEGRITY_UNKNOWN; - if (rc <= 0) { + /* If reading the xattr failed and there's no modsig, error out. */ + if (rc <= 0 && !try_modsig) { if (rc && rc != -ENODATA) goto out; @@ -246,6 +353,10 @@ int ima_appraise_measurement(enum ima_hooks func, case INTEGRITY_UNKNOWN: break; case INTEGRITY_NOXATTRS: /* No EVM protected xattrs. */ + /* It's fine not to have xattrs when using a modsig. */ + if (try_modsig) + break; + /* fall through */ case INTEGRITY_NOLABEL: /* No security.evm xattr. */ cause = "missing-HMAC"; goto out; @@ -256,65 +367,18 @@ int ima_appraise_measurement(enum ima_hooks func, WARN_ONCE(true, "Unexpected integrity status %d\n", status); } - switch (xattr_value->type) { - case IMA_XATTR_DIGEST_NG: - /* first byte contains algorithm id */ - hash_start = 1; - /* fall through */ - case IMA_XATTR_DIGEST: - if (iint->flags & IMA_DIGSIG_REQUIRED) { - cause = "IMA-signature-required"; - status = INTEGRITY_FAIL; - break; - } - clear_bit(IMA_DIGSIG, &iint->atomic_flags); - 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->data[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: - set_bit(IMA_DIGSIG, &iint->atomic_flags); - rc = integrity_digsig_verify(INTEGRITY_KEYRING_IMA, - (const char *)xattr_value, - xattr_len, - iint->ima_hash->digest, - iint->ima_hash->length); - if (rc == -EOPNOTSUPP) { - status = INTEGRITY_UNKNOWN; - break; - } - if (IS_ENABLED(CONFIG_INTEGRITY_PLATFORM_KEYRING) && rc && - func == KEXEC_KERNEL_CHECK) - rc = integrity_digsig_verify(INTEGRITY_KEYRING_PLATFORM, - (const char *)xattr_value, - xattr_len, - iint->ima_hash->digest, - iint->ima_hash->length); - if (rc) { - cause = "invalid-signature"; - status = INTEGRITY_FAIL; - } else { - status = INTEGRITY_PASS; - } - break; - default: - status = INTEGRITY_UNKNOWN; - cause = "unknown-ima-data"; - break; - } + if (xattr_value) + rc = xattr_verify(func, iint, xattr_value, xattr_len, &status, + &cause); + + /* + * If we have a modsig and either no imasig or the imasig's key isn't + * known, then try verifying the modsig. + */ + if (try_modsig && + (!xattr_value || xattr_value->type == IMA_XATTR_DIGEST_NG || + rc == -ENOKEY)) + rc = modsig_verify(func, modsig, &status, &cause); out: /* @@ -332,7 +396,7 @@ out: op, cause, rc, 0); } else if (status != INTEGRITY_PASS) { /* Fix mode, but don't replace file signatures. */ - if ((ima_appraise & IMA_APPRAISE_FIX) && + if ((ima_appraise & IMA_APPRAISE_FIX) && !try_modsig && (!xattr_value || xattr_value->type != EVM_IMA_XATTR_DIGSIG)) { if (!ima_fix_xattr(dentry, iint)) @@ -371,7 +435,7 @@ void ima_update_xattr(struct integrity_iint_cache *iint, struct file *file) !(iint->flags & IMA_HASH)) return; - rc = ima_collect_measurement(iint, file, NULL, 0, ima_hash_algo); + rc = ima_collect_measurement(iint, file, NULL, 0, ima_hash_algo, NULL); if (rc < 0) return; diff --git a/security/integrity/ima/ima_crypto.c b/security/integrity/ima/ima_crypto.c index d4c7b8e1b083..73044fc6a952 100644 --- a/security/integrity/ima/ima_crypto.c +++ b/security/integrity/ima/ima_crypto.c @@ -268,8 +268,16 @@ static int ima_calc_file_hash_atfm(struct file *file, rbuf_len = min_t(loff_t, i_size - offset, rbuf_size[active]); rc = integrity_kernel_read(file, offset, rbuf[active], rbuf_len); - if (rc != rbuf_len) + if (rc != rbuf_len) { + if (rc >= 0) + rc = -EINVAL; + /* + * Forward current rc, do not overwrite with return value + * from ahash_wait() + */ + ahash_wait(ahash_rc, &wait); goto out3; + } if (rbuf[1] && offset) { /* Using two buffers, and it is not the first diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c index 584019728660..79c01516211b 100644 --- a/security/integrity/ima/ima_main.c +++ b/security/integrity/ima/ima_main.c @@ -202,6 +202,7 @@ static int process_measurement(struct file *file, const struct cred *cred, int rc = 0, action, must_appraise = 0; int pcr = CONFIG_IMA_MEASURE_PCR_IDX; struct evm_ima_xattr_data *xattr_value = NULL; + struct modsig *modsig = NULL; int xattr_len = 0; bool violation_check; enum hash_algo hash_algo; @@ -302,13 +303,27 @@ static int process_measurement(struct file *file, const struct cred *cred, } if ((action & IMA_APPRAISE_SUBMASK) || - strcmp(template_desc->name, IMA_TEMPLATE_IMA_NAME) != 0) + strcmp(template_desc->name, IMA_TEMPLATE_IMA_NAME) != 0) { /* read 'security.ima' */ xattr_len = ima_read_xattr(file_dentry(file), &xattr_value); + /* + * Read the appended modsig if allowed by the policy, and allow + * an additional measurement list entry, if needed, based on the + * template format and whether the file was already measured. + */ + if (iint->flags & IMA_MODSIG_ALLOWED) { + rc = ima_read_modsig(func, buf, size, &modsig); + + if (!rc && ima_template_has_modsig(template_desc) && + iint->flags & IMA_MEASURED) + action |= IMA_MEASURE; + } + } + hash_algo = ima_get_hash_algo(xattr_value, xattr_len); - rc = ima_collect_measurement(iint, file, buf, size, hash_algo); + rc = ima_collect_measurement(iint, file, buf, size, hash_algo, modsig); if (rc != 0 && rc != -EBADF && rc != -EINVAL) goto out_locked; @@ -317,12 +332,12 @@ static int process_measurement(struct file *file, const struct cred *cred, if (action & IMA_MEASURE) ima_store_measurement(iint, file, pathname, - xattr_value, xattr_len, pcr, + xattr_value, xattr_len, modsig, pcr, template_desc); if (rc == 0 && (action & IMA_APPRAISE_SUBMASK)) { inode_lock(inode); rc = ima_appraise_measurement(func, iint, file, pathname, - xattr_value, xattr_len); + xattr_value, xattr_len, modsig); inode_unlock(inode); if (!rc) rc = mmap_violation_check(func, file, &pathbuf, @@ -339,6 +354,7 @@ out_locked: rc = -EACCES; mutex_unlock(&iint->mutex); kfree(xattr_value); + ima_free_modsig(modsig); out: if (pathbuf) __putname(pathbuf); diff --git a/security/integrity/ima/ima_modsig.c b/security/integrity/ima/ima_modsig.c new file mode 100644 index 000000000000..d106885cc495 --- /dev/null +++ b/security/integrity/ima/ima_modsig.c @@ -0,0 +1,168 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * IMA support for appraising module-style appended signatures. + * + * Copyright (C) 2019 IBM Corporation + * + * Author: + * Thiago Jung Bauermann <bauerman@linux.ibm.com> + */ + +#include <linux/types.h> +#include <linux/module_signature.h> +#include <keys/asymmetric-type.h> +#include <crypto/pkcs7.h> + +#include "ima.h" + +struct modsig { + struct pkcs7_message *pkcs7_msg; + + enum hash_algo hash_algo; + + /* This digest will go in the 'd-modsig' field of the IMA template. */ + const u8 *digest; + u32 digest_size; + + /* + * This is what will go to the measurement list if the template requires + * storing the signature. + */ + int raw_pkcs7_len; + u8 raw_pkcs7[]; +}; + +/** + * ima_hook_supports_modsig - can the policy allow modsig for this hook? + * + * modsig is only supported by hooks using ima_post_read_file(), because only + * they preload the contents of the file in a buffer. FILE_CHECK does that in + * some cases, but not when reached from vfs_open(). POLICY_CHECK can support + * it, but it's not useful in practice because it's a text file so deny. + */ +bool ima_hook_supports_modsig(enum ima_hooks func) +{ + switch (func) { + case KEXEC_KERNEL_CHECK: + case KEXEC_INITRAMFS_CHECK: + case MODULE_CHECK: + return true; + default: + return false; + } +} + +/* + * ima_read_modsig - Read modsig from buf. + * + * Return: 0 on success, error code otherwise. + */ +int ima_read_modsig(enum ima_hooks func, const void *buf, loff_t buf_len, + struct modsig **modsig) +{ + const size_t marker_len = strlen(MODULE_SIG_STRING); + const struct module_signature *sig; + struct modsig *hdr; + size_t sig_len; + const void *p; + int rc; + + if (buf_len <= marker_len + sizeof(*sig)) + return -ENOENT; + + p = buf + buf_len - marker_len; + if (memcmp(p, MODULE_SIG_STRING, marker_len)) + return -ENOENT; + + buf_len -= marker_len; + sig = (const struct module_signature *)(p - sizeof(*sig)); + + rc = mod_check_sig(sig, buf_len, func_tokens[func]); + if (rc) + return rc; + + sig_len = be32_to_cpu(sig->sig_len); + buf_len -= sig_len + sizeof(*sig); + + /* Allocate sig_len additional bytes to hold the raw PKCS#7 data. */ + hdr = kzalloc(sizeof(*hdr) + sig_len, GFP_KERNEL); + if (!hdr) + return -ENOMEM; + + hdr->pkcs7_msg = pkcs7_parse_message(buf + buf_len, sig_len); + if (IS_ERR(hdr->pkcs7_msg)) { + rc = PTR_ERR(hdr->pkcs7_msg); + kfree(hdr); + return rc; + } + + memcpy(hdr->raw_pkcs7, buf + buf_len, sig_len); + hdr->raw_pkcs7_len = sig_len; + + /* We don't know the hash algorithm yet. */ + hdr->hash_algo = HASH_ALGO__LAST; + + *modsig = hdr; + + return 0; +} + +/** + * ima_collect_modsig - Calculate the file hash without the appended signature. + * + * Since the modsig is part of the file contents, the hash used in its signature + * isn't the same one ordinarily calculated by IMA. Therefore PKCS7 code + * calculates a separate one for signature verification. + */ +void ima_collect_modsig(struct modsig *modsig, const void *buf, loff_t size) +{ + int rc; + + /* + * Provide the file contents (minus the appended sig) so that the PKCS7 + * code can calculate the file hash. + */ + size -= modsig->raw_pkcs7_len + strlen(MODULE_SIG_STRING) + + sizeof(struct module_signature); + rc = pkcs7_supply_detached_data(modsig->pkcs7_msg, buf, size); + if (rc) + return; + + /* Ask the PKCS7 code to calculate the file hash. */ + rc = pkcs7_get_digest(modsig->pkcs7_msg, &modsig->digest, + &modsig->digest_size, &modsig->hash_algo); +} + +int ima_modsig_verify(struct key *keyring, const struct modsig *modsig) +{ + return verify_pkcs7_message_sig(NULL, 0, modsig->pkcs7_msg, keyring, + VERIFYING_MODULE_SIGNATURE, NULL, NULL); +} + +int ima_get_modsig_digest(const struct modsig *modsig, enum hash_algo *algo, + const u8 **digest, u32 *digest_size) +{ + *algo = modsig->hash_algo; + *digest = modsig->digest; + *digest_size = modsig->digest_size; + + return 0; +} + +int ima_get_raw_modsig(const struct modsig *modsig, const void **data, + u32 *data_len) +{ + *data = &modsig->raw_pkcs7; + *data_len = modsig->raw_pkcs7_len; + + return 0; +} + +void ima_free_modsig(struct modsig *modsig) +{ + if (!modsig) + return; + + pkcs7_free_message(modsig->pkcs7_msg); + kfree(modsig); +} diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c index 6df7f641ff66..4badc4fcda98 100644 --- a/security/integrity/ima/ima_policy.c +++ b/security/integrity/ima/ima_policy.c @@ -6,6 +6,9 @@ * ima_policy.c * - initialize default measure policy rules */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + #include <linux/init.h> #include <linux/list.h> #include <linux/fs.h> @@ -491,6 +494,9 @@ int ima_match_policy(struct inode *inode, const struct cred *cred, u32 secid, struct ima_rule_entry *entry; int action = 0, actmask = flags | (flags << 1); + if (template_desc) + *template_desc = ima_template_desc_current(); + rcu_read_lock(); list_for_each_entry_rcu(entry, ima_rules, list) { @@ -510,6 +516,7 @@ int ima_match_policy(struct inode *inode, const struct cred *cred, u32 secid, action |= IMA_FAIL_UNVERIFIABLE_SIGS; } + if (entry->action & IMA_DO_MASK) actmask &= ~(entry->action | entry->action << 1); else @@ -520,8 +527,6 @@ int ima_match_policy(struct inode *inode, const struct cred *cred, u32 secid, if (template_desc && entry->template) *template_desc = entry->template; - else if (template_desc) - *template_desc = ima_template_desc_current(); if (!actmask) break; @@ -843,6 +848,38 @@ static void ima_log_string(struct audit_buffer *ab, char *key, char *value) ima_log_string_op(ab, key, value, NULL); } +/* + * Validating the appended signature included in the measurement list requires + * the file hash calculated without the appended signature (i.e., the 'd-modsig' + * field). Therefore, notify the user if they have the 'modsig' field but not + * the 'd-modsig' field in the template. + */ +static void check_template_modsig(const struct ima_template_desc *template) +{ +#define MSG "template with 'modsig' field also needs 'd-modsig' field\n" + bool has_modsig, has_dmodsig; + static bool checked; + int i; + + /* We only need to notify the user once. */ + if (checked) + return; + + has_modsig = has_dmodsig = false; + for (i = 0; i < template->num_fields; i++) { + if (!strcmp(template->fields[i]->field_id, "modsig")) + has_modsig = true; + else if (!strcmp(template->fields[i]->field_id, "d-modsig")) + has_dmodsig = true; + } + + if (has_modsig && !has_dmodsig) + pr_notice(MSG); + + checked = true; +#undef MSG +} + static int ima_parse_rule(char *rule, struct ima_rule_entry *entry) { struct audit_buffer *ab; @@ -1128,6 +1165,10 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry) ima_log_string(ab, "appraise_type", args[0].from); if ((strcmp(args[0].from, "imasig")) == 0) entry->flags |= IMA_DIGSIG_REQUIRED; + else if (ima_hook_supports_modsig(entry->func) && + strcmp(args[0].from, "imasig|modsig") == 0) + entry->flags |= IMA_DIGSIG_REQUIRED | + IMA_MODSIG_ALLOWED; else result = -EINVAL; break; @@ -1181,6 +1222,12 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry) else if (entry->action == APPRAISE) temp_ima_appraise |= ima_appraise_flag(entry->func); + if (!result && entry->flags & IMA_MODSIG_ALLOWED) { + template_desc = entry->template ? entry->template : + ima_template_desc_current(); + check_template_modsig(template_desc); + } + audit_log_format(ab, "res=%d", !result); audit_log_end(ab); return result; @@ -1252,6 +1299,12 @@ void ima_delete_rules(void) } } +#define __ima_hook_stringify(str) (#str), + +const char *const func_tokens[] = { + __ima_hooks(__ima_hook_stringify) +}; + #ifdef CONFIG_IMA_READ_POLICY enum { mask_exec = 0, mask_write, mask_read, mask_append @@ -1264,12 +1317,6 @@ static const char *const mask_tokens[] = { "^MAY_APPEND" }; -#define __ima_hook_stringify(str) (#str), - -static const char *const func_tokens[] = { - __ima_hooks(__ima_hook_stringify) -}; - void *ima_policy_start(struct seq_file *m, loff_t *pos) { loff_t l = *pos; @@ -1447,8 +1494,12 @@ int ima_policy_show(struct seq_file *m, void *v) } if (entry->template) seq_printf(m, "template=%s ", entry->template->name); - if (entry->flags & IMA_DIGSIG_REQUIRED) - seq_puts(m, "appraise_type=imasig "); + if (entry->flags & IMA_DIGSIG_REQUIRED) { + if (entry->flags & IMA_MODSIG_ALLOWED) + seq_puts(m, "appraise_type=imasig|modsig "); + else + seq_puts(m, "appraise_type=imasig "); + } if (entry->flags & IMA_PERMIT_DIRECTIO) seq_puts(m, "permit_directio "); rcu_read_unlock(); diff --git a/security/integrity/ima/ima_template.c b/security/integrity/ima/ima_template.c index cb349d7b2601..6aa6408603e3 100644 --- a/security/integrity/ima/ima_template.c +++ b/security/integrity/ima/ima_template.c @@ -23,6 +23,7 @@ static struct ima_template_desc builtin_templates[] = { {.name = "ima-ng", .fmt = "d-ng|n-ng"}, {.name = "ima-sig", .fmt = "d-ng|n-ng|sig"}, {.name = "ima-buf", .fmt = "d-ng|n-ng|buf"}, + {.name = "ima-modsig", .fmt = "d-ng|n-ng|sig|d-modsig|modsig"}, {.name = "", .fmt = ""}, /* placeholder for a custom format */ }; @@ -42,6 +43,10 @@ static const struct ima_template_field supported_fields[] = { .field_show = ima_show_template_sig}, {.field_id = "buf", .field_init = ima_eventbuf_init, .field_show = ima_show_template_buf}, + {.field_id = "d-modsig", .field_init = ima_eventdigest_modsig_init, + .field_show = ima_show_template_digest_ng}, + {.field_id = "modsig", .field_init = ima_eventmodsig_init, + .field_show = ima_show_template_sig}, }; /* @@ -49,10 +54,29 @@ static const struct ima_template_field supported_fields[] = { * need to be accounted for since they shouldn't be defined in the same template * description as 'd-ng' and 'n-ng' respectively. */ -#define MAX_TEMPLATE_NAME_LEN sizeof("d-ng|n-ng|sig|buf") +#define MAX_TEMPLATE_NAME_LEN sizeof("d-ng|n-ng|sig|buf|d-modisg|modsig") static struct ima_template_desc *ima_template; +/** + * ima_template_has_modsig - Check whether template has modsig-related fields. + * @ima_template: IMA template to check. + * + * Tells whether the given template has fields referencing a file's appended + * signature. + */ +bool ima_template_has_modsig(const struct ima_template_desc *ima_template) +{ + int i; + + for (i = 0; i < ima_template->num_fields; i++) + if (!strcmp(ima_template->fields[i]->field_id, "modsig") || + !strcmp(ima_template->fields[i]->field_id, "d-modsig")) + return true; + + return false; +} + static int __init ima_template_setup(char *str) { struct ima_template_desc *template_desc; @@ -282,9 +306,8 @@ static int ima_restore_template_data(struct ima_template_desc *template_desc, int ret = 0; int i; - *entry = kzalloc(sizeof(**entry) + - template_desc->num_fields * sizeof(struct ima_field_data), - GFP_NOFS); + *entry = kzalloc(struct_size(*entry, template_data, + template_desc->num_fields), GFP_NOFS); if (!*entry) return -ENOMEM; diff --git a/security/integrity/ima/ima_template_lib.c b/security/integrity/ima/ima_template_lib.c index 2fb9a10bc6b7..32ae05d88257 100644 --- a/security/integrity/ima/ima_template_lib.c +++ b/security/integrity/ima/ima_template_lib.c @@ -225,7 +225,8 @@ int ima_parse_buf(void *bufstartp, void *bufendp, void **bufcurp, return 0; } -static int ima_eventdigest_init_common(u8 *digest, u32 digestsize, u8 hash_algo, +static int ima_eventdigest_init_common(const u8 *digest, u32 digestsize, + u8 hash_algo, struct ima_field_data *field_data) { /* @@ -328,6 +329,41 @@ out: hash_algo, field_data); } +/* + * This function writes the digest of the file which is expected to match the + * digest contained in the file's appended signature. + */ +int ima_eventdigest_modsig_init(struct ima_event_data *event_data, + struct ima_field_data *field_data) +{ + enum hash_algo hash_algo; + const u8 *cur_digest; + u32 cur_digestsize; + + if (!event_data->modsig) + return 0; + + if (event_data->violation) { + /* Recording a violation. */ + hash_algo = HASH_ALGO_SHA1; + cur_digest = NULL; + cur_digestsize = 0; + } else { + int rc; + + rc = ima_get_modsig_digest(event_data->modsig, &hash_algo, + &cur_digest, &cur_digestsize); + if (rc) + return rc; + else if (hash_algo == HASH_ALGO__LAST || cur_digestsize == 0) + /* There was some error collecting the digest. */ + return -EINVAL; + } + + return ima_eventdigest_init_common(cur_digest, cur_digestsize, + hash_algo, field_data); +} + static int ima_eventname_init_common(struct ima_event_data *event_data, struct ima_field_data *field_data, bool size_limit) @@ -406,3 +442,29 @@ int ima_eventbuf_init(struct ima_event_data *event_data, event_data->buf_len, DATA_FMT_HEX, field_data); } + +/* + * ima_eventmodsig_init - include the appended file signature as part of the + * template data + */ +int ima_eventmodsig_init(struct ima_event_data *event_data, + struct ima_field_data *field_data) +{ + const void *data; + u32 data_len; + int rc; + + if (!event_data->modsig) + return 0; + + /* + * modsig is a runtime structure containing pointers. Get its raw data + * instead. + */ + rc = ima_get_raw_modsig(event_data->modsig, &data, &data_len); + if (rc) + return rc; + + return ima_write_template_field_data(data, data_len, DATA_FMT_HEX, + field_data); +} diff --git a/security/integrity/ima/ima_template_lib.h b/security/integrity/ima/ima_template_lib.h index 652aa5de81ef..9a88c79a7a61 100644 --- a/security/integrity/ima/ima_template_lib.h +++ b/security/integrity/ima/ima_template_lib.h @@ -36,10 +36,14 @@ int ima_eventname_init(struct ima_event_data *event_data, struct ima_field_data *field_data); int ima_eventdigest_ng_init(struct ima_event_data *event_data, struct ima_field_data *field_data); +int ima_eventdigest_modsig_init(struct ima_event_data *event_data, + struct ima_field_data *field_data); int ima_eventname_ng_init(struct ima_event_data *event_data, struct ima_field_data *field_data); int ima_eventsig_init(struct ima_event_data *event_data, struct ima_field_data *field_data); int ima_eventbuf_init(struct ima_event_data *event_data, struct ima_field_data *field_data); +int ima_eventmodsig_init(struct ima_event_data *event_data, + struct ima_field_data *field_data); #endif /* __LINUX_IMA_TEMPLATE_LIB_H */ diff --git a/security/integrity/integrity.h b/security/integrity/integrity.h index ed12d8e13d04..d9323d31a3a8 100644 --- a/security/integrity/integrity.h +++ b/security/integrity/integrity.h @@ -31,6 +31,7 @@ #define IMA_NEW_FILE 0x04000000 #define EVM_IMMUTABLE_DIGSIG 0x08000000 #define IMA_FAIL_UNVERIFIABLE_SIGS 0x10000000 +#define IMA_MODSIG_ALLOWED 0x20000000 #define IMA_DO_MASK (IMA_MEASURE | IMA_APPRAISE | IMA_AUDIT | \ IMA_HASH | IMA_APPRAISE_SUBMASK) @@ -147,10 +148,13 @@ int integrity_kernel_read(struct file *file, loff_t offset, extern struct dentry *integrity_dir; +struct modsig; + #ifdef CONFIG_INTEGRITY_SIGNATURE int integrity_digsig_verify(const unsigned int id, const char *sig, int siglen, const char *digest, int digestlen); +int integrity_modsig_verify(unsigned int id, const struct modsig *modsig); int __init integrity_init_keyring(const unsigned int id); int __init integrity_load_x509(const unsigned int id, const char *path); @@ -165,6 +169,12 @@ static inline int integrity_digsig_verify(const unsigned int id, return -EOPNOTSUPP; } +static inline int integrity_modsig_verify(unsigned int id, + const struct modsig *modsig) +{ + return -EOPNOTSUPP; +} + static inline int integrity_init_keyring(const unsigned int id) { return 0; @@ -190,6 +200,16 @@ static inline int asymmetric_verify(struct key *keyring, const char *sig, } #endif +#ifdef CONFIG_IMA_APPRAISE_MODSIG +int ima_modsig_verify(struct key *keyring, const struct modsig *modsig); +#else +static inline int ima_modsig_verify(struct key *keyring, + const struct modsig *modsig) +{ + return -EOPNOTSUPP; +} +#endif + #ifdef CONFIG_IMA_LOAD_X509 void __init ima_load_x509(void); #else diff --git a/tools/testing/selftests/kexec/test_kexec_file_load.sh b/tools/testing/selftests/kexec/test_kexec_file_load.sh index fa7c24e8eefb..2ff600388c30 100755 --- a/tools/testing/selftests/kexec/test_kexec_file_load.sh +++ b/tools/testing/selftests/kexec/test_kexec_file_load.sh @@ -37,11 +37,20 @@ is_ima_sig_required() # sequentially. As a result, a policy rule may be defined, but # might not necessarily be used. This test assumes if a policy # rule is specified, that is the intent. + + # First check for appended signature (modsig), then xattr if [ $ima_read_policy -eq 1 ]; then check_ima_policy "appraise" "func=KEXEC_KERNEL_CHECK" \ - "appraise_type=imasig" + "appraise_type=imasig|modsig" ret=$? - [ $ret -eq 1 ] && log_info "IMA signature required"; + if [ $ret -eq 1 ]; then + log_info "IMA or appended(modsig) signature required" + else + check_ima_policy "appraise" "func=KEXEC_KERNEL_CHECK" \ + "appraise_type=imasig" + ret=$? + [ $ret -eq 1 ] && log_info "IMA signature required"; + fi fi return $ret } @@ -84,6 +93,22 @@ check_for_imasig() return $ret } +# Return 1 for appended signature (modsig) found and 0 for not found. +check_for_modsig() +{ + local module_sig_string="~Module signature appended~" + local sig="$(tail --bytes $((${#module_sig_string} + 1)) $KERNEL_IMAGE)" + local ret=0 + + if [ "$sig" == "$module_sig_string" ]; then + ret=1 + log_info "kexec kernel image modsig signed" + else + log_info "kexec kernel image not modsig signed" + fi + return $ret +} + kexec_file_load_test() { local succeed_msg="kexec_file_load succeeded" @@ -98,7 +123,8 @@ kexec_file_load_test() # In secureboot mode with an architecture specific # policy, make sure either an IMA or PE signature exists. if [ $secureboot -eq 1 ] && [ $arch_policy -eq 1 ] && \ - [ $ima_signed -eq 0 ] && [ $pe_signed -eq 0 ]; then + [ $ima_signed -eq 0 ] && [ $pe_signed -eq 0 ] \ + && [ $ima_modsig -eq 0 ]; then log_fail "$succeed_msg (missing sig)" fi @@ -107,7 +133,8 @@ kexec_file_load_test() log_fail "$succeed_msg (missing PE sig)" fi - if [ $ima_sig_required -eq 1 ] && [ $ima_signed -eq 0 ]; then + if [ $ima_sig_required -eq 1 ] && [ $ima_signed -eq 0 ] \ + && [ $ima_modsig -eq 0 ]; then log_fail "$succeed_msg (missing IMA sig)" fi @@ -204,5 +231,8 @@ pe_signed=$? check_for_imasig ima_signed=$? +check_for_modsig +ima_modsig=$? + # Test loading the kernel image via kexec_file_load syscall kexec_file_load_test |