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commit f218a29c25ad8abdb961435d6b8139f462061364
parent 8e143b90e4d45cca3dc53760d3cfab988bc74571
Author: Linus Torvalds <torvalds@linux-foundation.org>
Date:   Wed,  2 Jan 2019 09:43:14 -0800

Merge branch 'next-integrity' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security

Pull integrity updates from James Morris:
 "In Linux 4.19, a new LSM hook named security_kernel_load_data was
  upstreamed, allowing LSMs and IMA to prevent the kexec_load syscall.
  Different signature verification methods exist for verifying the
  kexec'ed kernel image. This adds additional support in IMA to prevent
  loading unsigned kernel images via the kexec_load syscall,
  independently of the IMA policy rules, based on the runtime "secure
  boot" flag. An initial IMA kselftest is included.

  In addition, this pull request defines a new, separate keyring named
  ".platform" for storing the preboot/firmware keys needed for verifying
  the kexec'ed kernel image's signature and includes the associated IMA
  kexec usage of the ".platform" keyring.

  (David Howell's and Josh Boyer's patches for reading the
  preboot/firmware keys, which were previously posted for a different
  use case scenario, are included here)"

* 'next-integrity' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security:
  integrity: Remove references to module keyring
  ima: Use inode_is_open_for_write
  ima: Support platform keyring for kernel appraisal
  efi: Allow the "db" UEFI variable to be suppressed
  efi: Import certificates from UEFI Secure Boot
  efi: Add an EFI signature blob parser
  efi: Add EFI signature data types
  integrity: Load certs to the platform keyring
  integrity: Define a trusted platform keyring
  selftests/ima: kexec_load syscall test
  ima: don't measure/appraise files on efivarfs
  x86/ima: retry detecting secure boot mode
  docs: Extend trusted keys documentation for TPM 2.0
  x86/ima: define arch_get_ima_policy() for x86
  ima: add support for arch specific policies
  ima: refactor ima_init_policy()
  ima: prevent kexec_load syscall based on runtime secureboot flag
  x86/ima: define arch_ima_get_secureboot
  integrity: support new struct public_key_signature encoding field

Diffstat:
MDocumentation/security/keys/trusted-encrypted.rst | 31++++++++++++++++++++++++++++++-
March/x86/kernel/Makefile | 4++++
Aarch/x86/kernel/ima_arch.c | 75+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Minclude/linux/efi.h | 34++++++++++++++++++++++++++++++++++
Minclude/linux/ima.h | 15+++++++++++++++
Msecurity/integrity/Kconfig | 11+++++++++++
Msecurity/integrity/Makefile | 5+++++
Msecurity/integrity/digsig.c | 111++++++++++++++++++++++++++++++++++++++++++++++++++++---------------------------
Msecurity/integrity/ima/Kconfig | 10+++++++++-
Msecurity/integrity/ima/ima_appraise.c | 14++++++++++++--
Msecurity/integrity/ima/ima_main.c | 21++++++++++++++-------
Msecurity/integrity/ima/ima_policy.c | 171+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++--------------------
Msecurity/integrity/integrity.h | 22+++++++++++++++++++++-
Asecurity/integrity/platform_certs/efi_parser.c | 108+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Asecurity/integrity/platform_certs/load_uefi.c | 194+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Asecurity/integrity/platform_certs/platform_keyring.c | 58++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Mtools/testing/selftests/Makefile | 1+
Atools/testing/selftests/ima/Makefile | 11+++++++++++
Atools/testing/selftests/ima/config | 4++++
Atools/testing/selftests/ima/test_kexec_load.sh | 54++++++++++++++++++++++++++++++++++++++++++++++++++++++
20 files changed, 861 insertions(+), 93 deletions(-)

diff --git a/Documentation/security/keys/trusted-encrypted.rst b/Documentation/security/keys/trusted-encrypted.rst @@ -18,10 +18,33 @@ integrity verifications match. A loaded Trusted Key can be updated with new when the kernel and initramfs are updated. The same key can have many saved blobs under different PCR values, so multiple boots are easily supported. +TPM 1.2 +------- + By default, trusted keys are sealed under the SRK, which has the default authorization value (20 zeros). This can be set at takeownership time with the trouser's utility: "tpm_takeownership -u -z". +TPM 2.0 +------- + +The user must first create a storage key and make it persistent, so the key is +available after reboot. This can be done using the following commands. + +With the IBM TSS 2 stack:: + + #> tsscreateprimary -hi o -st + Handle 80000000 + #> tssevictcontrol -hi o -ho 80000000 -hp 81000001 + +Or with the Intel TSS 2 stack:: + + #> tpm2_createprimary --hierarchy o -G rsa2048 -o key.ctxt + [...] + handle: 0x800000FF + #> tpm2_evictcontrol -c key.ctxt -p 0x81000001 + persistentHandle: 0x81000001 + Usage:: keyctl add trusted name "new keylen [options]" ring @@ -30,7 +53,9 @@ Usage:: keyctl print keyid options: - keyhandle= ascii hex value of sealing key default 0x40000000 (SRK) + keyhandle= ascii hex value of sealing key + TPM 1.2: default 0x40000000 (SRK) + TPM 2.0: no default; must be passed every time keyauth= ascii hex auth for sealing key default 0x00...i (40 ascii zeros) blobauth= ascii hex auth for sealed data default 0x00... @@ -84,6 +109,10 @@ Examples of trusted and encrypted key usage: Create and save a trusted key named "kmk" of length 32 bytes:: +Note: When using a TPM 2.0 with a persistent key with handle 0x81000001, +append 'keyhandle=0x81000001' to statements between quotes, such as +"new 32 keyhandle=0x81000001". + $ keyctl add trusted kmk "new 32" @u 440502848 diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile @@ -150,3 +150,7 @@ ifeq ($(CONFIG_X86_64),y) obj-$(CONFIG_MMCONF_FAM10H) += mmconf-fam10h_64.o obj-y += vsmp_64.o endif + +ifdef CONFIG_EFI +obj-$(CONFIG_IMA) += ima_arch.o +endif diff --git a/arch/x86/kernel/ima_arch.c b/arch/x86/kernel/ima_arch.c @@ -0,0 +1,75 @@ +/* SPDX-License-Identifier: GPL-2.0+ */ +/* + * Copyright (C) 2018 IBM Corporation + */ +#include <linux/efi.h> +#include <linux/ima.h> + +extern struct boot_params boot_params; + +static enum efi_secureboot_mode get_sb_mode(void) +{ + efi_char16_t efi_SecureBoot_name[] = L"SecureBoot"; + efi_guid_t efi_variable_guid = EFI_GLOBAL_VARIABLE_GUID; + efi_status_t status; + unsigned long size; + u8 secboot; + + size = sizeof(secboot); + + /* Get variable contents into buffer */ + status = efi.get_variable(efi_SecureBoot_name, &efi_variable_guid, + NULL, &size, &secboot); + if (status == EFI_NOT_FOUND) { + pr_info("ima: secureboot mode disabled\n"); + return efi_secureboot_mode_disabled; + } + + if (status != EFI_SUCCESS) { + pr_info("ima: secureboot mode unknown\n"); + return efi_secureboot_mode_unknown; + } + + if (secboot == 0) { + pr_info("ima: secureboot mode disabled\n"); + return efi_secureboot_mode_disabled; + } + + pr_info("ima: secureboot mode enabled\n"); + return efi_secureboot_mode_enabled; +} + +bool arch_ima_get_secureboot(void) +{ + static enum efi_secureboot_mode sb_mode; + static bool initialized; + + if (!initialized && efi_enabled(EFI_BOOT)) { + sb_mode = boot_params.secure_boot; + + if (sb_mode == efi_secureboot_mode_unset) + sb_mode = get_sb_mode(); + initialized = true; + } + + if (sb_mode == efi_secureboot_mode_enabled) + return true; + else + return false; +} + +/* secureboot arch rules */ +static const char * const sb_arch_rules[] = { +#if !IS_ENABLED(CONFIG_KEXEC_VERIFY_SIG) + "appraise func=KEXEC_KERNEL_CHECK appraise_type=imasig", +#endif /* CONFIG_KEXEC_VERIFY_SIG */ + "measure func=KEXEC_KERNEL_CHECK", + NULL +}; + +const char * const *arch_get_ima_policy(void) +{ + if (IS_ENABLED(CONFIG_IMA_ARCH_POLICY) && arch_ima_get_secureboot()) + return sb_arch_rules; + return NULL; +} diff --git a/include/linux/efi.h b/include/linux/efi.h @@ -663,6 +663,10 @@ void efi_native_runtime_setup(void); #define EFI_IMAGE_SECURITY_DATABASE_GUID EFI_GUID(0xd719b2cb, 0x3d3a, 0x4596, 0xa3, 0xbc, 0xda, 0xd0, 0x0e, 0x67, 0x65, 0x6f) #define EFI_SHIM_LOCK_GUID EFI_GUID(0x605dab50, 0xe046, 0x4300, 0xab, 0xb6, 0x3d, 0xd8, 0x10, 0xdd, 0x8b, 0x23) +#define EFI_CERT_SHA256_GUID EFI_GUID(0xc1c41626, 0x504c, 0x4092, 0xac, 0xa9, 0x41, 0xf9, 0x36, 0x93, 0x43, 0x28) +#define EFI_CERT_X509_GUID EFI_GUID(0xa5c059a1, 0x94e4, 0x4aa7, 0x87, 0xb5, 0xab, 0x15, 0x5c, 0x2b, 0xf0, 0x72) +#define EFI_CERT_X509_SHA256_GUID EFI_GUID(0x3bd2a492, 0x96c0, 0x4079, 0xb4, 0x20, 0xfc, 0xf9, 0x8e, 0xf1, 0x03, 0xed) + /* * This GUID is used to pass to the kernel proper the struct screen_info * structure that was populated by the stub based on the GOP protocol instance @@ -934,6 +938,27 @@ typedef struct { efi_memory_desc_t entry[0]; } efi_memory_attributes_table_t; +typedef struct { + efi_guid_t signature_owner; + u8 signature_data[]; +} efi_signature_data_t; + +typedef struct { + efi_guid_t signature_type; + u32 signature_list_size; + u32 signature_header_size; + u32 signature_size; + u8 signature_header[]; + /* efi_signature_data_t signatures[][] */ +} efi_signature_list_t; + +typedef u8 efi_sha256_hash_t[32]; + +typedef struct { + efi_sha256_hash_t to_be_signed_hash; + efi_time_t time_of_revocation; +} efi_cert_x509_sha256_t; + /* * All runtime access to EFI goes through this structure: */ @@ -1113,6 +1138,15 @@ extern int efi_memattr_apply_permissions(struct mm_struct *mm, char * __init efi_md_typeattr_format(char *buf, size_t size, const efi_memory_desc_t *md); + +typedef void (*efi_element_handler_t)(const char *source, + const void *element_data, + size_t element_size); +extern int __init parse_efi_signature_list( + const char *source, + const void *data, size_t size, + efi_element_handler_t (*get_handler_for_guid)(const efi_guid_t *)); + /** * efi_range_is_wc - check the WC bit on an address range * @start: starting kvirt address diff --git a/include/linux/ima.h b/include/linux/ima.h @@ -30,6 +30,21 @@ extern void ima_post_path_mknod(struct dentry *dentry); extern void ima_add_kexec_buffer(struct kimage *image); #endif +#if defined(CONFIG_X86) && defined(CONFIG_EFI) +extern bool arch_ima_get_secureboot(void); +extern const char * const *arch_get_ima_policy(void); +#else +static inline bool arch_ima_get_secureboot(void) +{ + return false; +} + +static inline const char * const *arch_get_ima_policy(void) +{ + return NULL; +} +#endif + #else static inline int ima_bprm_check(struct linux_binprm *bprm) { diff --git a/security/integrity/Kconfig b/security/integrity/Kconfig @@ -51,6 +51,17 @@ config INTEGRITY_TRUSTED_KEYRING .evm keyrings be signed by a key on the system trusted keyring. +config INTEGRITY_PLATFORM_KEYRING + bool "Provide keyring for platform/firmware trusted keys" + depends on INTEGRITY_ASYMMETRIC_KEYS + depends on SYSTEM_BLACKLIST_KEYRING + depends on EFI + help + Provide a separate, distinct keyring for platform trusted keys, which + the kernel automatically populates during initialization from values + provided by the platform for verifying the kexec'ed kerned image + and, possibly, the initramfs signature. + config INTEGRITY_AUDIT bool "Enables integrity auditing support " depends on AUDIT diff --git a/security/integrity/Makefile b/security/integrity/Makefile @@ -9,6 +9,11 @@ integrity-y := iint.o integrity-$(CONFIG_INTEGRITY_AUDIT) += integrity_audit.o integrity-$(CONFIG_INTEGRITY_SIGNATURE) += digsig.o integrity-$(CONFIG_INTEGRITY_ASYMMETRIC_KEYS) += digsig_asymmetric.o +integrity-$(CONFIG_INTEGRITY_PLATFORM_KEYRING) += platform_certs/platform_keyring.o \ + platform_certs/efi_parser.o \ + platform_certs/load_uefi.o +obj-$(CONFIG_LOAD_UEFI_KEYS) += platform_certs/load_uefi.o +$(obj)/load_uefi.o: KBUILD_CFLAGS += -fshort-wchar subdir-$(CONFIG_IMA) += ima obj-$(CONFIG_IMA) += ima/ diff --git a/security/integrity/digsig.c b/security/integrity/digsig.c @@ -34,7 +34,7 @@ static const char * const keyring_name[INTEGRITY_KEYRING_MAX] = { ".evm", ".ima", #endif - "_module", + ".platform", }; #ifdef CONFIG_IMA_KEYRINGS_PERMIT_SIGNED_BY_BUILTIN_OR_SECONDARY @@ -73,12 +73,38 @@ int integrity_digsig_verify(const unsigned int id, const char *sig, int siglen, return -EOPNOTSUPP; } -int __init integrity_init_keyring(const unsigned int id) +static int __integrity_init_keyring(const unsigned int id, key_perm_t perm, + struct key_restriction *restriction) { const struct cred *cred = current_cred(); - struct key_restriction *restriction; int err = 0; + keyring[id] = keyring_alloc(keyring_name[id], KUIDT_INIT(0), + KGIDT_INIT(0), cred, perm, + KEY_ALLOC_NOT_IN_QUOTA, restriction, NULL); + if (IS_ERR(keyring[id])) { + err = PTR_ERR(keyring[id]); + pr_info("Can't allocate %s keyring (%d)\n", + keyring_name[id], err); + keyring[id] = NULL; + } + + return err; +} + +int __init integrity_init_keyring(const unsigned int id) +{ + struct key_restriction *restriction; + key_perm_t perm; + + perm = (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_VIEW + | KEY_USR_READ | KEY_USR_SEARCH; + + if (id == INTEGRITY_KEYRING_PLATFORM) { + restriction = NULL; + goto out; + } + if (!IS_ENABLED(CONFIG_INTEGRITY_TRUSTED_KEYRING)) return 0; @@ -87,32 +113,43 @@ int __init integrity_init_keyring(const unsigned int id) return -ENOMEM; restriction->check = restrict_link_to_ima; + perm |= KEY_USR_WRITE; - keyring[id] = keyring_alloc(keyring_name[id], KUIDT_INIT(0), - KGIDT_INIT(0), cred, - ((KEY_POS_ALL & ~KEY_POS_SETATTR) | - KEY_USR_VIEW | KEY_USR_READ | - KEY_USR_WRITE | KEY_USR_SEARCH), - KEY_ALLOC_NOT_IN_QUOTA, - restriction, NULL); - if (IS_ERR(keyring[id])) { - err = PTR_ERR(keyring[id]); - pr_info("Can't allocate %s keyring (%d)\n", - keyring_name[id], err); - keyring[id] = NULL; +out: + return __integrity_init_keyring(id, perm, restriction); +} + +int __init integrity_add_key(const unsigned int id, const void *data, + off_t size, key_perm_t perm) +{ + key_ref_t key; + int rc = 0; + + if (!keyring[id]) + return -EINVAL; + + key = key_create_or_update(make_key_ref(keyring[id], 1), "asymmetric", + NULL, data, size, perm, + KEY_ALLOC_NOT_IN_QUOTA); + if (IS_ERR(key)) { + rc = PTR_ERR(key); + pr_err("Problem loading X.509 certificate %d\n", rc); + } else { + pr_notice("Loaded X.509 cert '%s'\n", + key_ref_to_ptr(key)->description); + key_ref_put(key); } - return err; + + return rc; + } int __init integrity_load_x509(const unsigned int id, const char *path) { - key_ref_t key; void *data; loff_t size; int rc; - - if (!keyring[id]) - return -EINVAL; + key_perm_t perm; rc = kernel_read_file_from_path(path, &data, &size, 0, READING_X509_CERTIFICATE); @@ -121,23 +158,21 @@ int __init integrity_load_x509(const unsigned int id, const char *path) return rc; } - key = key_create_or_update(make_key_ref(keyring[id], 1), - "asymmetric", - NULL, - data, - size, - ((KEY_POS_ALL & ~KEY_POS_SETATTR) | - KEY_USR_VIEW | KEY_USR_READ), - KEY_ALLOC_NOT_IN_QUOTA); - if (IS_ERR(key)) { - rc = PTR_ERR(key); - pr_err("Problem loading X.509 certificate (%d): %s\n", - rc, path); - } else { - pr_notice("Loaded X.509 cert '%s': %s\n", - key_ref_to_ptr(key)->description, path); - key_ref_put(key); - } + perm = (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_VIEW | KEY_USR_READ; + + pr_info("Loading X.509 certificate: %s\n", path); + rc = integrity_add_key(id, (const void *)data, size, perm); + vfree(data); - return 0; + return rc; +} + +int __init integrity_load_cert(const unsigned int id, const char *source, + const void *data, size_t len, key_perm_t perm) +{ + if (!data) + return -EINVAL; + + pr_info("Loading X.509 certificate: %s\n", source); + return integrity_add_key(id, data, len, perm); } diff --git a/security/integrity/ima/Kconfig b/security/integrity/ima/Kconfig @@ -157,6 +157,14 @@ config IMA_APPRAISE <http://linux-ima.sourceforge.net> If unsure, say N. +config IMA_ARCH_POLICY + bool "Enable loading an IMA architecture specific policy" + depends on KEXEC_VERIFY_SIG || IMA_APPRAISE && INTEGRITY_ASYMMETRIC_KEYS + default n + help + This option enables loading an IMA architecture specific policy + based on run time secure boot flags. + config IMA_APPRAISE_BUILD_POLICY bool "IMA build time configured policy rules" depends on IMA_APPRAISE && INTEGRITY_ASYMMETRIC_KEYS @@ -217,7 +225,7 @@ config IMA_APPRAISE_REQUIRE_POLICY_SIGS config IMA_APPRAISE_BOOTPARAM bool "ima_appraise boot parameter" - depends on IMA_APPRAISE + depends on IMA_APPRAISE && !IMA_ARCH_POLICY default y help This option enables the different "ima_appraise=" modes diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c @@ -289,12 +289,22 @@ int ima_appraise_measurement(enum ima_hooks func, case EVM_IMA_XATTR_DIGSIG: set_bit(IMA_DIGSIG, &iint->atomic_flags); rc = integrity_digsig_verify(INTEGRITY_KEYRING_IMA, - (const char *)xattr_value, rc, + (const char *)xattr_value, + xattr_len, iint->ima_hash->digest, iint->ima_hash->length); if (rc == -EOPNOTSUPP) { status = INTEGRITY_UNKNOWN; - } else if (rc) { + 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 { diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c @@ -105,7 +105,7 @@ static void ima_rdwr_violation_check(struct file *file, } else { if (must_measure) set_bit(IMA_MUST_MEASURE, &iint->atomic_flags); - if ((atomic_read(&inode->i_writecount) > 0) && must_measure) + if (inode_is_open_for_write(inode) && must_measure) send_writers = true; } @@ -507,20 +507,26 @@ int ima_post_read_file(struct file *file, void *buf, loff_t size, */ int ima_load_data(enum kernel_load_data_id id) { - bool sig_enforce; + bool ima_enforce, sig_enforce; - if ((ima_appraise & IMA_APPRAISE_ENFORCE) != IMA_APPRAISE_ENFORCE) - return 0; + ima_enforce = + (ima_appraise & IMA_APPRAISE_ENFORCE) == IMA_APPRAISE_ENFORCE; switch (id) { case LOADING_KEXEC_IMAGE: - if (ima_appraise & IMA_APPRAISE_KEXEC) { + if (IS_ENABLED(CONFIG_KEXEC_VERIFY_SIG) + && arch_ima_get_secureboot()) { + pr_err("impossible to appraise a kernel image without a file descriptor; try using kexec_file_load syscall.\n"); + return -EACCES; + } + + if (ima_enforce && (ima_appraise & IMA_APPRAISE_KEXEC)) { pr_err("impossible to appraise a kernel image without a file descriptor; try using kexec_file_load syscall.\n"); return -EACCES; /* INTEGRITY_UNKNOWN */ } break; case LOADING_FIRMWARE: - if (ima_appraise & IMA_APPRAISE_FIRMWARE) { + if (ima_enforce && (ima_appraise & IMA_APPRAISE_FIRMWARE)) { pr_err("Prevent firmware sysfs fallback loading.\n"); return -EACCES; /* INTEGRITY_UNKNOWN */ } @@ -528,7 +534,8 @@ int ima_load_data(enum kernel_load_data_id id) case LOADING_MODULE: sig_enforce = is_module_sig_enforced(); - if (!sig_enforce && (ima_appraise & IMA_APPRAISE_MODULES)) { + if (ima_enforce && (!sig_enforce + && (ima_appraise & IMA_APPRAISE_MODULES))) { pr_err("impossible to appraise a module without a file descriptor. sig_enforce kernel parameter might help\n"); return -EACCES; /* INTEGRITY_UNKNOWN */ } diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c @@ -20,6 +20,7 @@ #include <linux/rculist.h> #include <linux/genhd.h> #include <linux/seq_file.h> +#include <linux/ima.h> #include "ima.h" @@ -58,6 +59,8 @@ enum lsm_rule_types { LSM_OBJ_USER, LSM_OBJ_ROLE, LSM_OBJ_TYPE, enum policy_types { ORIGINAL_TCB = 1, DEFAULT_TCB }; +enum policy_rule_list { IMA_DEFAULT_POLICY = 1, IMA_CUSTOM_POLICY }; + struct ima_rule_entry { struct list_head list; int action; @@ -104,7 +107,8 @@ static struct ima_rule_entry dont_measure_rules[] __ro_after_init = { .flags = IMA_FSMAGIC}, {.action = DONT_MEASURE, .fsmagic = CGROUP2_SUPER_MAGIC, .flags = IMA_FSMAGIC}, - {.action = DONT_MEASURE, .fsmagic = NSFS_MAGIC, .flags = IMA_FSMAGIC} + {.action = DONT_MEASURE, .fsmagic = NSFS_MAGIC, .flags = IMA_FSMAGIC}, + {.action = DONT_MEASURE, .fsmagic = EFIVARFS_MAGIC, .flags = IMA_FSMAGIC} }; static struct ima_rule_entry original_measurement_rules[] __ro_after_init = { @@ -147,6 +151,7 @@ static struct ima_rule_entry default_appraise_rules[] __ro_after_init = { {.action = DONT_APPRAISE, .fsmagic = SELINUX_MAGIC, .flags = IMA_FSMAGIC}, {.action = DONT_APPRAISE, .fsmagic = SMACK_MAGIC, .flags = IMA_FSMAGIC}, {.action = DONT_APPRAISE, .fsmagic = NSFS_MAGIC, .flags = IMA_FSMAGIC}, + {.action = DONT_APPRAISE, .fsmagic = EFIVARFS_MAGIC, .flags = IMA_FSMAGIC}, {.action = DONT_APPRAISE, .fsmagic = CGROUP_SUPER_MAGIC, .flags = IMA_FSMAGIC}, {.action = DONT_APPRAISE, .fsmagic = CGROUP2_SUPER_MAGIC, .flags = IMA_FSMAGIC}, #ifdef CONFIG_IMA_WRITE_POLICY @@ -193,6 +198,9 @@ static struct ima_rule_entry secure_boot_rules[] __ro_after_init = { .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED}, }; +/* An array of architecture specific rules */ +struct ima_rule_entry *arch_policy_entry __ro_after_init; + static LIST_HEAD(ima_default_rules); static LIST_HEAD(ima_policy_rules); static LIST_HEAD(ima_temp_rules); @@ -473,6 +481,75 @@ static int ima_appraise_flag(enum ima_hooks func) return 0; } +static void add_rules(struct ima_rule_entry *entries, int count, + enum policy_rule_list policy_rule) +{ + int i = 0; + + for (i = 0; i < count; i++) { + struct ima_rule_entry *entry; + + if (policy_rule & IMA_DEFAULT_POLICY) + list_add_tail(&entries[i].list, &ima_default_rules); + + if (policy_rule & IMA_CUSTOM_POLICY) { + entry = kmemdup(&entries[i], sizeof(*entry), + GFP_KERNEL); + if (!entry) + continue; + + list_add_tail(&entry->list, &ima_policy_rules); + } + if (entries[i].action == APPRAISE) + temp_ima_appraise |= ima_appraise_flag(entries[i].func); + if (entries[i].func == POLICY_CHECK) + temp_ima_appraise |= IMA_APPRAISE_POLICY; + } +} + +static int ima_parse_rule(char *rule, struct ima_rule_entry *entry); + +static int __init ima_init_arch_policy(void) +{ + const char * const *arch_rules; + const char * const *rules; + int arch_entries = 0; + int i = 0; + + arch_rules = arch_get_ima_policy(); + if (!arch_rules) + return arch_entries; + + /* Get number of rules */ + for (rules = arch_rules; *rules != NULL; rules++) + arch_entries++; + + arch_policy_entry = kcalloc(arch_entries + 1, + sizeof(*arch_policy_entry), GFP_KERNEL); + if (!arch_policy_entry) + return 0; + + /* Convert each policy string rules to struct ima_rule_entry format */ + for (rules = arch_rules, i = 0; *rules != NULL; rules++) { + char rule[255]; + int result; + + result = strlcpy(rule, *rules, sizeof(rule)); + + INIT_LIST_HEAD(&arch_policy_entry[i].list); + result = ima_parse_rule(rule, &arch_policy_entry[i]); + if (result) { + pr_warn("Skipping unknown architecture policy rule: %s\n", + rule); + memset(&arch_policy_entry[i], 0, + sizeof(*arch_policy_entry)); + continue; + } + i++; + } + return i; +} + /** * ima_init_policy - initialize the default measure rules. * @@ -481,68 +558,68 @@ static int ima_appraise_flag(enum ima_hooks func) */ void __init ima_init_policy(void) { - int i, measure_entries, appraise_entries, secure_boot_entries; + int build_appraise_entries, arch_entries; - /* if !ima_policy set entries = 0 so we load NO default rules */ - measure_entries = ima_policy ? ARRAY_SIZE(dont_measure_rules) : 0; - appraise_entries = ima_use_appraise_tcb ? - ARRAY_SIZE(default_appraise_rules) : 0; - secure_boot_entries = ima_use_secure_boot ? - ARRAY_SIZE(secure_boot_rules) : 0; - - for (i = 0; i < measure_entries; i++) - list_add_tail(&dont_measure_rules[i].list, &ima_default_rules); + /* if !ima_policy, we load NO default rules */ + if (ima_policy) + add_rules(dont_measure_rules, ARRAY_SIZE(dont_measure_rules), + IMA_DEFAULT_POLICY); switch (ima_policy) { case ORIGINAL_TCB: - for (i = 0; i < ARRAY_SIZE(original_measurement_rules); i++) - list_add_tail(&original_measurement_rules[i].list, - &ima_default_rules); + add_rules(original_measurement_rules, + ARRAY_SIZE(original_measurement_rules), + IMA_DEFAULT_POLICY); break; case DEFAULT_TCB: - for (i = 0; i < ARRAY_SIZE(default_measurement_rules); i++) - list_add_tail(&default_measurement_rules[i].list, - &ima_default_rules); + add_rules(default_measurement_rules, + ARRAY_SIZE(default_measurement_rules), + IMA_DEFAULT_POLICY); default: break; } /* + * Based on runtime secure boot flags, insert arch specific measurement + * and appraise rules requiring file signatures for both the initial + * and custom policies, prior to other appraise rules. + * (Highest priority) + */ + arch_entries = ima_init_arch_policy(); + if (!arch_entries) + pr_info("No architecture policies found\n"); + else + add_rules(arch_policy_entry, arch_entries, + IMA_DEFAULT_POLICY | IMA_CUSTOM_POLICY); + + /* * Insert the builtin "secure_boot" policy rules requiring file - * signatures, prior to any other appraise rules. + * signatures, prior to other appraise rules. */ - for (i = 0; i < secure_boot_entries; i++) { - list_add_tail(&secure_boot_rules[i].list, &ima_default_rules); - temp_ima_appraise |= - ima_appraise_flag(secure_boot_rules[i].func); - } + if (ima_use_secure_boot) + add_rules(secure_boot_rules, ARRAY_SIZE(secure_boot_rules), + IMA_DEFAULT_POLICY); /* * Insert the build time appraise rules requiring file signatures * for both the initial and custom policies, prior to other appraise - * rules. + * rules. As the secure boot rules includes all of the build time + * rules, include either one or the other set of rules, but not both. */ - for (i = 0; i < ARRAY_SIZE(build_appraise_rules); i++) { - struct ima_rule_entry *entry; - - if (!secure_boot_entries) - list_add_tail(&build_appraise_rules[i].list, - &ima_default_rules); - - entry = kmemdup(&build_appraise_rules[i], sizeof(*entry), - GFP_KERNEL); - if (entry) - list_add_tail(&entry->list, &ima_policy_rules); - build_ima_appraise |= - ima_appraise_flag(build_appraise_rules[i].func); + build_appraise_entries = ARRAY_SIZE(build_appraise_rules); + if (build_appraise_entries) { + if (ima_use_secure_boot) + add_rules(build_appraise_rules, build_appraise_entries, + IMA_CUSTOM_POLICY); + else + add_rules(build_appraise_rules, build_appraise_entries, + IMA_DEFAULT_POLICY | IMA_CUSTOM_POLICY); } - for (i = 0; i < appraise_entries; i++) { - list_add_tail(&default_appraise_rules[i].list, - &ima_default_rules); - if (default_appraise_rules[i].func == POLICY_CHECK) - temp_ima_appraise |= IMA_APPRAISE_POLICY; - } + if (ima_use_appraise_tcb) + add_rules(default_appraise_rules, + ARRAY_SIZE(default_appraise_rules), + IMA_DEFAULT_POLICY); ima_rules = &ima_default_rules; ima_update_policy_flag(); @@ -576,6 +653,14 @@ void ima_update_policy(void) if (ima_rules != policy) { ima_policy_flag = 0; ima_rules = policy; + + /* + * IMA architecture specific policy rules are specified + * as strings and converted to an array of ima_entry_rules + * on boot. After loading a custom policy, free the + * architecture specific rules stored as an array. + */ + kfree(arch_policy_entry); } ima_update_policy_flag(); } diff --git a/security/integrity/integrity.h b/security/integrity/integrity.h @@ -141,7 +141,7 @@ int integrity_kernel_read(struct file *file, loff_t offset, #define INTEGRITY_KEYRING_EVM 0 #define INTEGRITY_KEYRING_IMA 1 -#define INTEGRITY_KEYRING_MODULE 2 +#define INTEGRITY_KEYRING_PLATFORM 2 #define INTEGRITY_KEYRING_MAX 3 extern struct dentry *integrity_dir; @@ -153,6 +153,8 @@ int integrity_digsig_verify(const unsigned int id, const char *sig, int siglen, int __init integrity_init_keyring(const unsigned int id); int __init integrity_load_x509(const unsigned int id, const char *path); +int __init integrity_load_cert(const unsigned int id, const char *source, + const void *data, size_t len, key_perm_t perm); #else static inline int integrity_digsig_verify(const unsigned int id, @@ -166,6 +168,14 @@ static inline int integrity_init_keyring(const unsigned int id) { return 0; } + +static inline int __init integrity_load_cert(const unsigned int id, + const char *source, + const void *data, size_t len, + key_perm_t perm) +{ + return 0; +} #endif /* CONFIG_INTEGRITY_SIGNATURE */ #ifdef CONFIG_INTEGRITY_ASYMMETRIC_KEYS @@ -222,3 +232,13 @@ integrity_audit_log_start(struct audit_context *ctx, gfp_t gfp_mask, int type) } #endif + +#ifdef CONFIG_INTEGRITY_PLATFORM_KEYRING +void __init add_to_platform_keyring(const char *source, const void *data, + size_t len); +#else +static inline void __init add_to_platform_keyring(const char *source, + const void *data, size_t len) +{ +} +#endif diff --git a/security/integrity/platform_certs/efi_parser.c b/security/integrity/platform_certs/efi_parser.c @@ -0,0 +1,108 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* EFI signature/key/certificate list parser + * + * Copyright (C) 2012, 2016 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + */ + +#define pr_fmt(fmt) "EFI: "fmt +#include <linux/module.h> +#include <linux/printk.h> +#include <linux/err.h> +#include <linux/efi.h> + +/** + * parse_efi_signature_list - Parse an EFI signature list for certificates + * @source: The source of the key + * @data: The data blob to parse + * @size: The size of the data blob + * @get_handler_for_guid: Get the handler func for the sig type (or NULL) + * + * Parse an EFI signature list looking for elements of interest. A list is + * made up of a series of sublists, where all the elements in a sublist are of + * the same type, but sublists can be of different types. + * + * For each sublist encountered, the @get_handler_for_guid function is called + * with the type specifier GUID and returns either a pointer to a function to + * handle elements of that type or NULL if the type is not of interest. + * + * If the sublist is of interest, each element is passed to the handler + * function in turn. + * + * Error EBADMSG is returned if the list doesn't parse correctly and 0 is + * returned if the list was parsed correctly. No error can be returned from + * the @get_handler_for_guid function or the element handler function it + * returns. + */ +int __init parse_efi_signature_list( + const char *source, + const void *data, size_t size, + efi_element_handler_t (*get_handler_for_guid)(const efi_guid_t *)) +{ + efi_element_handler_t handler; + unsigned int offs = 0; + + pr_devel("-->%s(,%zu)\n", __func__, size); + + while (size > 0) { + const efi_signature_data_t *elem; + efi_signature_list_t list; + size_t lsize, esize, hsize, elsize; + + if (size < sizeof(list)) + return -EBADMSG; + + memcpy(&list, data, sizeof(list)); + pr_devel("LIST[%04x] guid=%pUl ls=%x hs=%x ss=%x\n", + offs, + list.signature_type.b, list.signature_list_size, + list.signature_header_size, list.signature_size); + + lsize = list.signature_list_size; + hsize = list.signature_header_size; + esize = list.signature_size; + elsize = lsize - sizeof(list) - hsize; + + if (lsize > size) { + pr_devel("<--%s() = -EBADMSG [overrun @%x]\n", + __func__, offs); + return -EBADMSG; + } + + if (lsize < sizeof(list) || + lsize - sizeof(list) < hsize || + esize < sizeof(*elem) || + elsize < esize || + elsize % esize != 0) { + pr_devel("- bad size combo @%x\n", offs); + return -EBADMSG; + } + + handler = get_handler_for_guid(&list.signature_type); + if (!handler) { + data += lsize; + size -= lsize; + offs += lsize; + continue; + } + + data += sizeof(list) + hsize; + size -= sizeof(list) + hsize; + offs += sizeof(list) + hsize; + + for (; elsize > 0; elsize -= esize) { + elem = data; + + pr_devel("ELEM[%04x]\n", offs); + handler(source, + &elem->signature_data, + esize - sizeof(*elem)); + + data += esize; + size -= esize; + offs += esize; + } + } + + return 0; +} diff --git a/security/integrity/platform_certs/load_uefi.c b/security/integrity/platform_certs/load_uefi.c @@ -0,0 +1,194 @@ +// 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; + +/* + * Look to see if a UEFI variable called MokIgnoreDB exists and return true if + * it does. + * + * This UEFI variable is set by the shim if a user tells the shim to not use + * the certs/hashes in the UEFI db variable for verification purposes. If it + * is set, we should ignore the db variable also and the true return indicates + * this. + */ +static __init bool uefi_check_ignore_db(void) +{ + efi_status_t status; + unsigned int db = 0; + unsigned long size = sizeof(db); + efi_guid_t guid = EFI_SHIM_LOCK_GUID; + + status = efi.get_variable(L"MokIgnoreDB", &guid, NULL, &size, &db); + return status == EFI_SUCCESS; +} + +/* + * Get a certificate list blob from the named EFI variable. + */ +static __init void *get_cert_list(efi_char16_t *name, efi_guid_t *guid, + unsigned long *size) +{ + efi_status_t status; + unsigned long lsize = 4; + unsigned long tmpdb[4]; + void *db; + + status = efi.get_variable(name, guid, NULL, &lsize, &tmpdb); + if (status != EFI_BUFFER_TOO_SMALL) { + pr_err("Couldn't get size: 0x%lx\n", status); + return NULL; + } + + db = kmalloc(lsize, GFP_KERNEL); + if (!db) + return NULL; + + status = efi.get_variable(name, guid, NULL, &lsize, db); + if (status != EFI_SUCCESS) { + kfree(db); + pr_err("Error reading db var: 0x%lx\n", status); + return NULL; + } + + *size = lsize; + return db; +} + +/* + * 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. + */ +static int __init load_uefi_certs(void) +{ + efi_guid_t secure_var = EFI_IMAGE_SECURITY_DATABASE_GUID; + efi_guid_t mok_var = EFI_SHIM_LOCK_GUID; + void *db = NULL, *dbx = NULL, *mok = NULL; + unsigned long dbsize = 0, dbxsize = 0, moksize = 0; + int rc = 0; + + if (!efi.get_variable) + return false; + + /* Get db, MokListRT, and dbx. They might not exist, so it isn't + * an error if we can't get them. + */ + if (!uefi_check_ignore_db()) { + db = get_cert_list(L"db", &secure_var, &dbsize); + if (!db) { + pr_err("MODSIGN: Couldn't get UEFI db list\n"); + } else { + rc = parse_efi_signature_list("UEFI:db", + db, dbsize, get_handler_for_db); + if (rc) + pr_err("Couldn't parse db signatures: %d\n", + rc); + kfree(db); + } + } + + mok = get_cert_list(L"MokListRT", &mok_var, &moksize); + if (!mok) { + pr_info("Couldn't get UEFI MokListRT\n"); + } else { + rc = parse_efi_signature_list("UEFI:MokListRT", + mok, moksize, get_handler_for_db); + if (rc) + pr_err("Couldn't parse MokListRT signatures: %d\n", rc); + kfree(mok); + } + + dbx = get_cert_list(L"dbx", &secure_var, &dbxsize); + if (!dbx) { + pr_info("Couldn't get UEFI dbx list\n"); + } else { + rc = parse_efi_signature_list("UEFI:dbx", + dbx, dbxsize, + get_handler_for_dbx); + if (rc) + pr_err("Couldn't parse dbx signatures: %d\n", rc); + kfree(dbx); + } + + return rc; +} +late_initcall(load_uefi_certs); diff --git a/security/integrity/platform_certs/platform_keyring.c b/security/integrity/platform_certs/platform_keyring.c @@ -0,0 +1,58 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * Platform keyring for firmware/platform keys + * + * Copyright IBM Corporation, 2018 + * Author(s): Nayna Jain <nayna@linux.ibm.com> + */ + +#include <linux/export.h> +#include <linux/kernel.h> +#include <linux/sched.h> +#include <linux/cred.h> +#include <linux/err.h> +#include <linux/slab.h> +#include "../integrity.h" + +/** + * add_to_platform_keyring - Add to platform keyring without validation. + * @source: Source of key + * @data: The blob holding the key + * @len: The length of the data blob + * + * Add a key to the platform keyring without checking its trust chain. This + * is available only during kernel initialisation. + */ +void __init add_to_platform_keyring(const char *source, const void *data, + size_t len) +{ + key_perm_t perm; + int rc; + + perm = (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_VIEW; + + rc = integrity_load_cert(INTEGRITY_KEYRING_PLATFORM, source, data, len, + perm); + if (rc) + pr_info("Error adding keys to platform keyring %s\n", source); +} + +/* + * Create the trusted keyrings. + */ +static __init int platform_keyring_init(void) +{ + int rc; + + rc = integrity_init_keyring(INTEGRITY_KEYRING_PLATFORM); + if (rc) + return rc; + + pr_notice("Platform Keyring initialized\n"); + return 0; +} + +/* + * Must be initialised before we try and load the keys into the keyring. + */ +device_initcall(platform_keyring_init); diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile @@ -14,6 +14,7 @@ TARGETS += firmware TARGETS += ftrace TARGETS += futex TARGETS += gpio +TARGETS += ima TARGETS += intel_pstate TARGETS += ipc TARGETS += ir diff --git a/tools/testing/selftests/ima/Makefile b/tools/testing/selftests/ima/Makefile @@ -0,0 +1,11 @@ +# Makefile for kexec_load + +uname_M := $(shell uname -m 2>/dev/null || echo not) +ARCH ?= $(shell echo $(uname_M) | sed -e s/i.86/x86/ -e s/x86_64/x86/) + +ifeq ($(ARCH),x86) +TEST_PROGS := test_kexec_load.sh + +include ../lib.mk + +endif diff --git a/tools/testing/selftests/ima/config b/tools/testing/selftests/ima/config @@ -0,0 +1,4 @@ +CONFIG_IMA_APPRAISE +CONFIG_IMA_ARCH_POLICY +CONFIG_SECURITYFS +CONFIG_KEXEC_VERIFY_SIG diff --git a/tools/testing/selftests/ima/test_kexec_load.sh b/tools/testing/selftests/ima/test_kexec_load.sh @@ -0,0 +1,54 @@ +#!/bin/sh +# SPDX-License-Identifier: GPL-2.0+ +# Loading a kernel image via the kexec_load syscall should fail +# when the kerne is CONFIG_KEXEC_VERIFY_SIG enabled and the system +# is booted in secureboot mode. + +TEST="$0" +EFIVARFS="/sys/firmware/efi/efivars" +rc=0 + +# Kselftest framework requirement - SKIP code is 4. +ksft_skip=4 + +# kexec requires root privileges +if [ $UID != 0 ]; then + echo "$TEST: must be run as root" >&2 + exit $ksft_skip +fi + +# Make sure that efivars is mounted in the normal location +if ! grep -q "^\S\+ $EFIVARFS efivarfs" /proc/mounts; then + echo "$TEST: efivars is not mounted on $EFIVARFS" >&2 + exit $ksft_skip +fi + +# Get secureboot mode +file="$EFIVARFS/SecureBoot-*" +if [ ! -e $file ]; then + echo "$TEST: unknown secureboot mode" >&2 + exit $ksft_skip +fi +secureboot=`hexdump $file | awk '{print substr($4,length($4),1)}'` + +# kexec_load should fail in secure boot mode +KERNEL_IMAGE="/boot/vmlinuz-`uname -r`" +kexec -l $KERNEL_IMAGE &>> /dev/null +if [ $? == 0 ]; then + kexec -u + if [ "$secureboot" == "1" ]; then + echo "$TEST: kexec_load succeeded [FAIL]" + rc=1 + else + echo "$TEST: kexec_load succeeded [PASS]" + fi +else + if [ "$secureboot" == "1" ]; then + echo "$TEST: kexec_load failed [PASS]" + else + echo "$TEST: kexec_load failed [FAIL]" + rc=1 + fi +fi + +exit $rc