diff options
author | Michael Ellerman <mpe@ellerman.id.au> | 2019-11-13 16:52:25 +1100 |
---|---|---|
committer | Michael Ellerman <mpe@ellerman.id.au> | 2019-11-13 16:55:50 +1100 |
commit | d34a5709be85e88a8bb7537cd38b8eca8085047a (patch) | |
tree | 0371b60368b91eb954138f77d8be8704f09df44f /security | |
parent | ea458effa88e4f4739551d76fe3f702daf607995 (diff) | |
parent | 8220e22d11a05049aab9693839ab82e5e177ccde (diff) |
Merge branch 'topic/secureboot' into next
Merge the secureboot support, as well as the IMA changes needed to
support it.
From Nayna's cover letter:
In order to verify the OS kernel on PowerNV systems, secure boot
requires X.509 certificates trusted by the platform. These are
stored in secure variables controlled by OPAL, called OPAL secure
variables. In order to enable users to manage the keys, the secure
variables need to be exposed to userspace.
OPAL provides the runtime services for the kernel to be able to
access the secure variables. This patchset defines the kernel
interface for the OPAL APIs. These APIs are used by the hooks, which
load these variables to the keyring and expose them to the userspace
for reading/writing.
Overall, this patchset adds the following support:
* expose secure variables to the kernel via OPAL Runtime API interface
* expose secure variables to the userspace via kernel sysfs interface
* load kernel verification and revocation keys to .platform and
.blacklist keyring respectively.
The secure variables can be read/written using simple linux
utilities cat/hexdump.
For example:
Path to the secure variables is: /sys/firmware/secvar/vars
Each secure variable is listed as directory.
$ ls -l
total 0
drwxr-xr-x. 2 root root 0 Aug 20 21:20 db
drwxr-xr-x. 2 root root 0 Aug 20 21:20 KEK
drwxr-xr-x. 2 root root 0 Aug 20 21:20 PK
The attributes of each of the secure variables are (for example: PK):
$ ls -l
total 0
-r--r--r--. 1 root root 4096 Oct 1 15:10 data
-r--r--r--. 1 root root 65536 Oct 1 15:10 size
--w-------. 1 root root 4096 Oct 1 15:12 update
The "data" is used to read the existing variable value using
hexdump. The data is stored in ESL format. The "update" is used to
write a new value using cat. The update is to be submitted as AUTH
file.
Diffstat (limited to 'security')
-rw-r--r-- | security/integrity/Kconfig | 9 | ||||
-rw-r--r-- | security/integrity/Makefile | 7 | ||||
-rw-r--r-- | security/integrity/ima/ima.h | 11 | ||||
-rw-r--r-- | security/integrity/ima/ima_appraise.c | 33 | ||||
-rw-r--r-- | security/integrity/ima/ima_main.c | 70 | ||||
-rw-r--r-- | security/integrity/ima/ima_policy.c | 12 | ||||
-rw-r--r-- | security/integrity/integrity.h | 1 | ||||
-rw-r--r-- | security/integrity/platform_certs/keyring_handler.c | 80 | ||||
-rw-r--r-- | security/integrity/platform_certs/keyring_handler.h | 32 | ||||
-rw-r--r-- | security/integrity/platform_certs/load_powerpc.c | 96 | ||||
-rw-r--r-- | security/integrity/platform_certs/load_uefi.c | 67 |
11 files changed, 326 insertions, 92 deletions
diff --git a/security/integrity/Kconfig b/security/integrity/Kconfig index 0bae6adb63a9..71f0177e8716 100644 --- a/security/integrity/Kconfig +++ b/security/integrity/Kconfig @@ -72,6 +72,15 @@ config LOAD_IPL_KEYS depends on S390 def_bool y +config LOAD_PPC_KEYS + bool "Enable loading of platform and blacklisted keys for POWER" + depends on INTEGRITY_PLATFORM_KEYRING + depends on PPC_SECURE_BOOT + default y + help + Enable loading of keys to the .platform keyring and blacklisted + hashes to the .blacklist keyring for powerpc based platforms. + config INTEGRITY_AUDIT bool "Enables integrity auditing support " depends on AUDIT diff --git a/security/integrity/Makefile b/security/integrity/Makefile index 35e6ca773734..7ee39d66cf16 100644 --- a/security/integrity/Makefile +++ b/security/integrity/Makefile @@ -11,8 +11,11 @@ integrity-$(CONFIG_INTEGRITY_SIGNATURE) += digsig.o integrity-$(CONFIG_INTEGRITY_ASYMMETRIC_KEYS) += digsig_asymmetric.o integrity-$(CONFIG_INTEGRITY_PLATFORM_KEYRING) += platform_certs/platform_keyring.o integrity-$(CONFIG_LOAD_UEFI_KEYS) += platform_certs/efi_parser.o \ - platform_certs/load_uefi.o + platform_certs/load_uefi.o \ + platform_certs/keyring_handler.o integrity-$(CONFIG_LOAD_IPL_KEYS) += platform_certs/load_ipl_s390.o - +integrity-$(CONFIG_LOAD_PPC_KEYS) += platform_certs/efi_parser.o \ + platform_certs/load_powerpc.o \ + platform_certs/keyring_handler.o obj-$(CONFIG_IMA) += ima/ obj-$(CONFIG_EVM) += evm/ diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h index 3689081aaf38..df4ca482fb53 100644 --- a/security/integrity/ima/ima.h +++ b/security/integrity/ima/ima.h @@ -217,6 +217,9 @@ void ima_store_measurement(struct integrity_iint_cache *iint, struct file *file, struct evm_ima_xattr_data *xattr_value, int xattr_len, const struct modsig *modsig, int pcr, struct ima_template_desc *template_desc); +void process_buffer_measurement(const void *buf, int size, + const char *eventname, enum ima_hooks func, + int pcr); void ima_audit_measurement(struct integrity_iint_cache *iint, const unsigned char *filename); int ima_alloc_init_template(struct ima_event_data *event_data, @@ -253,6 +256,8 @@ int ima_policy_show(struct seq_file *m, void *v); #define IMA_APPRAISE_KEXEC 0x40 #ifdef CONFIG_IMA_APPRAISE +int ima_check_blacklist(struct integrity_iint_cache *iint, + const struct modsig *modsig, int pcr); int ima_appraise_measurement(enum ima_hooks func, struct integrity_iint_cache *iint, struct file *file, const unsigned char *filename, @@ -268,6 +273,12 @@ int ima_read_xattr(struct dentry *dentry, struct evm_ima_xattr_data **xattr_value); #else +static inline int ima_check_blacklist(struct integrity_iint_cache *iint, + const struct modsig *modsig, int pcr) +{ + return 0; +} + static inline int ima_appraise_measurement(enum ima_hooks func, struct integrity_iint_cache *iint, struct file *file, diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c index 136ae4e0ee92..300c8d2943c5 100644 --- a/security/integrity/ima/ima_appraise.c +++ b/security/integrity/ima/ima_appraise.c @@ -12,6 +12,7 @@ #include <linux/magic.h> #include <linux/ima.h> #include <linux/evm.h> +#include <keys/system_keyring.h> #include "ima.h" @@ -304,6 +305,38 @@ static int modsig_verify(enum ima_hooks func, const struct modsig *modsig, } /* + * ima_check_blacklist - determine if the binary is blacklisted. + * + * Add the hash of the blacklisted binary to the measurement list, based + * on policy. + * + * Returns -EPERM if the hash is blacklisted. + */ +int ima_check_blacklist(struct integrity_iint_cache *iint, + const struct modsig *modsig, int pcr) +{ + enum hash_algo hash_algo; + const u8 *digest = NULL; + u32 digestsize = 0; + int rc = 0; + + if (!(iint->flags & IMA_CHECK_BLACKLIST)) + return 0; + + if (iint->flags & IMA_MODSIG_ALLOWED && modsig) { + ima_get_modsig_digest(modsig, &hash_algo, &digest, &digestsize); + + rc = is_binary_blacklisted(digest, digestsize); + if ((rc == -EPERM) && (iint->flags & IMA_MEASURE)) + process_buffer_measurement(digest, digestsize, + "blacklisted-hash", NONE, + pcr); + } + + return rc; +} + +/* * ima_appraise_measurement - appraise file measurement * * Call evm_verifyxattr() to verify the integrity of 'security.ima'. diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c index 60027c643ecd..d7e987baf127 100644 --- a/security/integrity/ima/ima_main.c +++ b/security/integrity/ima/ima_main.c @@ -335,10 +335,14 @@ static int process_measurement(struct file *file, const struct cred *cred, 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, modsig); - inode_unlock(inode); + rc = ima_check_blacklist(iint, modsig, pcr); + if (rc != -EPERM) { + inode_lock(inode); + rc = ima_appraise_measurement(func, iint, file, + pathname, xattr_value, + xattr_len, modsig); + inode_unlock(inode); + } if (!rc) rc = mmap_violation_check(func, file, &pathbuf, &pathname, filename); @@ -626,14 +630,14 @@ int ima_load_data(enum kernel_load_data_id id) * @buf: pointer to the buffer that needs to be added to the log. * @size: size of buffer(in bytes). * @eventname: event name to be used for the buffer entry. - * @cred: a pointer to a credentials structure for user validation. - * @secid: the secid of the task to be validated. + * @func: IMA hook + * @pcr: pcr to extend the measurement * * Based on policy, the buffer is measured into the ima log. */ -static void process_buffer_measurement(const void *buf, int size, - const char *eventname, - const struct cred *cred, u32 secid) +void process_buffer_measurement(const void *buf, int size, + const char *eventname, enum ima_hooks func, + int pcr) { int ret = 0; struct ima_template_entry *entry = NULL; @@ -642,19 +646,45 @@ static void process_buffer_measurement(const void *buf, int size, .filename = eventname, .buf = buf, .buf_len = size}; - struct ima_template_desc *template_desc = NULL; + struct ima_template_desc *template = NULL; struct { struct ima_digest_data hdr; char digest[IMA_MAX_DIGEST_SIZE]; } hash = {}; int violation = 0; - int pcr = CONFIG_IMA_MEASURE_PCR_IDX; int action = 0; + u32 secid; - action = ima_get_action(NULL, cred, secid, 0, KEXEC_CMDLINE, &pcr, - &template_desc); - if (!(action & IMA_MEASURE)) - return; + /* + * Both LSM hooks and auxilary based buffer measurements are + * based on policy. To avoid code duplication, differentiate + * between the LSM hooks and auxilary buffer measurements, + * retrieving the policy rule information only for the LSM hook + * buffer measurements. + */ + if (func) { + security_task_getsecid(current, &secid); + action = ima_get_action(NULL, current_cred(), secid, 0, func, + &pcr, &template); + if (!(action & IMA_MEASURE)) + return; + } + + if (!pcr) + pcr = CONFIG_IMA_MEASURE_PCR_IDX; + + if (!template) { + template = lookup_template_desc("ima-buf"); + ret = template_desc_init_fields(template->fmt, + &(template->fields), + &(template->num_fields)); + if (ret < 0) { + pr_err("template %s init failed, result: %d\n", + (strlen(template->name) ? + template->name : template->fmt), ret); + return; + } + } iint.ima_hash = &hash.hdr; iint.ima_hash->algo = ima_hash_algo; @@ -664,7 +694,7 @@ static void process_buffer_measurement(const void *buf, int size, if (ret < 0) goto out; - ret = ima_alloc_init_template(&event_data, &entry, template_desc); + ret = ima_alloc_init_template(&event_data, &entry, template); if (ret < 0) goto out; @@ -686,13 +716,9 @@ out: */ void ima_kexec_cmdline(const void *buf, int size) { - u32 secid; - - if (buf && size != 0) { - security_task_getsecid(current, &secid); + if (buf && size != 0) process_buffer_measurement(buf, size, "kexec-cmdline", - current_cred(), secid); - } + KEXEC_CMDLINE, 0); } static int __init init_ima(void) diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c index 5380aca2b351..f19a895ad7cd 100644 --- a/security/integrity/ima/ima_policy.c +++ b/security/integrity/ima/ima_policy.c @@ -765,8 +765,8 @@ enum { Opt_fsuuid, Opt_uid_eq, Opt_euid_eq, Opt_fowner_eq, Opt_uid_gt, Opt_euid_gt, Opt_fowner_gt, Opt_uid_lt, Opt_euid_lt, Opt_fowner_lt, - Opt_appraise_type, Opt_permit_directio, - Opt_pcr, Opt_template, Opt_err + Opt_appraise_type, Opt_appraise_flag, + Opt_permit_directio, Opt_pcr, Opt_template, Opt_err }; static const match_table_t policy_tokens = { @@ -798,6 +798,7 @@ static const match_table_t policy_tokens = { {Opt_euid_lt, "euid<%s"}, {Opt_fowner_lt, "fowner<%s"}, {Opt_appraise_type, "appraise_type=%s"}, + {Opt_appraise_flag, "appraise_flag=%s"}, {Opt_permit_directio, "permit_directio"}, {Opt_pcr, "pcr=%s"}, {Opt_template, "template=%s"}, @@ -1172,6 +1173,11 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry) else result = -EINVAL; break; + case Opt_appraise_flag: + ima_log_string(ab, "appraise_flag", args[0].from); + if (strstr(args[0].from, "blacklist")) + entry->flags |= IMA_CHECK_BLACKLIST; + break; case Opt_permit_directio: entry->flags |= IMA_PERMIT_DIRECTIO; break; @@ -1500,6 +1506,8 @@ int ima_policy_show(struct seq_file *m, void *v) else seq_puts(m, "appraise_type=imasig "); } + if (entry->flags & IMA_CHECK_BLACKLIST) + seq_puts(m, "appraise_flag=check_blacklist "); if (entry->flags & IMA_PERMIT_DIRECTIO) seq_puts(m, "permit_directio "); rcu_read_unlock(); diff --git a/security/integrity/integrity.h b/security/integrity/integrity.h index d9323d31a3a8..73fc286834d7 100644 --- a/security/integrity/integrity.h +++ b/security/integrity/integrity.h @@ -32,6 +32,7 @@ #define EVM_IMMUTABLE_DIGSIG 0x08000000 #define IMA_FAIL_UNVERIFIABLE_SIGS 0x10000000 #define IMA_MODSIG_ALLOWED 0x20000000 +#define IMA_CHECK_BLACKLIST 0x40000000 #define IMA_DO_MASK (IMA_MEASURE | IMA_APPRAISE | IMA_AUDIT | \ IMA_HASH | IMA_APPRAISE_SUBMASK) diff --git a/security/integrity/platform_certs/keyring_handler.c b/security/integrity/platform_certs/keyring_handler.c new file mode 100644 index 000000000000..c5ba695c10e3 --- /dev/null +++ b/security/integrity/platform_certs/keyring_handler.c @@ -0,0 +1,80 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include <linux/kernel.h> +#include <linux/sched.h> +#include <linux/cred.h> +#include <linux/err.h> +#include <linux/efi.h> +#include <linux/slab.h> +#include <keys/asymmetric-type.h> +#include <keys/system_keyring.h> +#include "../integrity.h" + +static efi_guid_t efi_cert_x509_guid __initdata = EFI_CERT_X509_GUID; +static efi_guid_t efi_cert_x509_sha256_guid __initdata = + EFI_CERT_X509_SHA256_GUID; +static efi_guid_t efi_cert_sha256_guid __initdata = EFI_CERT_SHA256_GUID; + +/* + * Blacklist a hash. + */ +static __init void uefi_blacklist_hash(const char *source, const void *data, + size_t len, const char *type, + size_t type_len) +{ + char *hash, *p; + + hash = kmalloc(type_len + len * 2 + 1, GFP_KERNEL); + if (!hash) + return; + p = memcpy(hash, type, type_len); + p += type_len; + bin2hex(p, data, len); + p += len * 2; + *p = 0; + + mark_hash_blacklisted(hash); + kfree(hash); +} + +/* + * Blacklist an X509 TBS hash. + */ +static __init void uefi_blacklist_x509_tbs(const char *source, + const void *data, size_t len) +{ + uefi_blacklist_hash(source, data, len, "tbs:", 4); +} + +/* + * Blacklist the hash of an executable. + */ +static __init void uefi_blacklist_binary(const char *source, + const void *data, size_t len) +{ + uefi_blacklist_hash(source, data, len, "bin:", 4); +} + +/* + * Return the appropriate handler for particular signature list types found in + * the UEFI db and MokListRT tables. + */ +__init efi_element_handler_t get_handler_for_db(const efi_guid_t *sig_type) +{ + if (efi_guidcmp(*sig_type, efi_cert_x509_guid) == 0) + return add_to_platform_keyring; + return 0; +} + +/* + * Return the appropriate handler for particular signature list types found in + * the UEFI dbx and MokListXRT tables. + */ +__init efi_element_handler_t get_handler_for_dbx(const efi_guid_t *sig_type) +{ + if (efi_guidcmp(*sig_type, efi_cert_x509_sha256_guid) == 0) + return uefi_blacklist_x509_tbs; + if (efi_guidcmp(*sig_type, efi_cert_sha256_guid) == 0) + return uefi_blacklist_binary; + return 0; +} diff --git a/security/integrity/platform_certs/keyring_handler.h b/security/integrity/platform_certs/keyring_handler.h new file mode 100644 index 000000000000..2462bfa08fe3 --- /dev/null +++ b/security/integrity/platform_certs/keyring_handler.h @@ -0,0 +1,32 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +#ifndef PLATFORM_CERTS_INTERNAL_H +#define PLATFORM_CERTS_INTERNAL_H + +#include <linux/efi.h> + +void blacklist_hash(const char *source, const void *data, + size_t len, const char *type, + size_t type_len); + +/* + * Blacklist an X509 TBS hash. + */ +void blacklist_x509_tbs(const char *source, const void *data, size_t len); + +/* + * Blacklist the hash of an executable. + */ +void blacklist_binary(const char *source, const void *data, size_t len); + +/* + * Return the handler for particular signature list types found in the db. + */ +efi_element_handler_t get_handler_for_db(const efi_guid_t *sig_type); + +/* + * Return the handler for particular signature list types found in the dbx. + */ +efi_element_handler_t get_handler_for_dbx(const efi_guid_t *sig_type); + +#endif diff --git a/security/integrity/platform_certs/load_powerpc.c b/security/integrity/platform_certs/load_powerpc.c new file mode 100644 index 000000000000..a2900cb85357 --- /dev/null +++ b/security/integrity/platform_certs/load_powerpc.c @@ -0,0 +1,96 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2019 IBM Corporation + * Author: Nayna Jain + * + * - loads keys and hashes stored and controlled by the firmware. + */ +#include <linux/kernel.h> +#include <linux/sched.h> +#include <linux/cred.h> +#include <linux/err.h> +#include <linux/slab.h> +#include <linux/of.h> +#include <asm/secure_boot.h> +#include <asm/secvar.h> +#include "keyring_handler.h" + +/* + * Get a certificate list blob from the named secure variable. + */ +static __init void *get_cert_list(u8 *key, unsigned long keylen, uint64_t *size) +{ + int rc; + void *db; + + rc = secvar_ops->get(key, keylen, NULL, size); + if (rc) { + pr_err("Couldn't get size: %d\n", rc); + return NULL; + } + + db = kmalloc(*size, GFP_KERNEL); + if (!db) + return NULL; + + rc = secvar_ops->get(key, keylen, db, size); + if (rc) { + kfree(db); + pr_err("Error reading %s var: %d\n", key, rc); + return NULL; + } + + return db; +} + +/* + * Load the certs contained in the keys databases into the platform trusted + * keyring and the blacklisted X.509 cert SHA256 hashes into the blacklist + * keyring. + */ +static int __init load_powerpc_certs(void) +{ + void *db = NULL, *dbx = NULL; + uint64_t dbsize = 0, dbxsize = 0; + int rc = 0; + struct device_node *node; + + if (!secvar_ops) + return -ENODEV; + + /* The following only applies for the edk2-compat backend. */ + node = of_find_compatible_node(NULL, NULL, "ibm,edk2-compat-v1"); + if (!node) + return -ENODEV; + + /* + * Get db, and dbx. They might not exist, so it isn't an error if we + * can't get them. + */ + db = get_cert_list("db", 3, &dbsize); + if (!db) { + pr_err("Couldn't get db list from firmware\n"); + } else { + rc = parse_efi_signature_list("powerpc:db", db, dbsize, + get_handler_for_db); + if (rc) + pr_err("Couldn't parse db signatures: %d\n", rc); + kfree(db); + } + + dbx = get_cert_list("dbx", 4, &dbxsize); + if (!dbx) { + pr_info("Couldn't get dbx list from firmware\n"); + } else { + rc = parse_efi_signature_list("powerpc:dbx", dbx, dbxsize, + get_handler_for_dbx); + if (rc) + pr_err("Couldn't parse dbx signatures: %d\n", rc); + kfree(dbx); + } + + of_node_put(node); + + return rc; +} +late_initcall(load_powerpc_certs); diff --git a/security/integrity/platform_certs/load_uefi.c b/security/integrity/platform_certs/load_uefi.c index 81b19c52832b..4369204a19cd 100644 --- a/security/integrity/platform_certs/load_uefi.c +++ b/security/integrity/platform_certs/load_uefi.c @@ -9,6 +9,7 @@ #include <keys/asymmetric-type.h> #include <keys/system_keyring.h> #include "../integrity.h" +#include "keyring_handler.h" static efi_guid_t efi_cert_x509_guid __initdata = EFI_CERT_X509_GUID; static efi_guid_t efi_cert_x509_sha256_guid __initdata = @@ -68,72 +69,6 @@ static __init void *get_cert_list(efi_char16_t *name, efi_guid_t *guid, } /* - * Blacklist a hash. - */ -static __init void uefi_blacklist_hash(const char *source, const void *data, - size_t len, const char *type, - size_t type_len) -{ - char *hash, *p; - - hash = kmalloc(type_len + len * 2 + 1, GFP_KERNEL); - if (!hash) - return; - p = memcpy(hash, type, type_len); - p += type_len; - bin2hex(p, data, len); - p += len * 2; - *p = 0; - - mark_hash_blacklisted(hash); - kfree(hash); -} - -/* - * Blacklist an X509 TBS hash. - */ -static __init void uefi_blacklist_x509_tbs(const char *source, - const void *data, size_t len) -{ - uefi_blacklist_hash(source, data, len, "tbs:", 4); -} - -/* - * Blacklist the hash of an executable. - */ -static __init void uefi_blacklist_binary(const char *source, - const void *data, size_t len) -{ - uefi_blacklist_hash(source, data, len, "bin:", 4); -} - -/* - * Return the appropriate handler for particular signature list types found in - * the UEFI db and MokListRT tables. - */ -static __init efi_element_handler_t get_handler_for_db(const efi_guid_t * - sig_type) -{ - if (efi_guidcmp(*sig_type, efi_cert_x509_guid) == 0) - return add_to_platform_keyring; - return 0; -} - -/* - * Return the appropriate handler for particular signature list types found in - * the UEFI dbx and MokListXRT tables. - */ -static __init efi_element_handler_t get_handler_for_dbx(const efi_guid_t * - sig_type) -{ - if (efi_guidcmp(*sig_type, efi_cert_x509_sha256_guid) == 0) - return uefi_blacklist_x509_tbs; - if (efi_guidcmp(*sig_type, efi_cert_sha256_guid) == 0) - return uefi_blacklist_binary; - return 0; -} - -/* * Load the certs contained in the UEFI databases into the platform trusted * keyring and the UEFI blacklisted X.509 cert SHA256 hashes into the blacklist * keyring. |