[V40,08/29] kexec_file: split KEXEC_VERIFY_SIG into KEXEC_SIG and KEXEC_SIG_FORCE

Message ID	20190820001805.241928-9-matthewgarrett@google.com (mailing list archive)
State	New, archived
Headers	show Return-Path: <SRS0=y35J=WQ=vger.kernel.org=linux-security-module-owner@kernel.org> Date: Mon, 19 Aug 2019 17:17:44 -0700 In-Reply-To: <20190820001805.241928-1-matthewgarrett@google.com> Message-Id: <20190820001805.241928-9-matthewgarrett@google.com> Mime-Version: 1.0 References: <20190820001805.241928-1-matthewgarrett@google.com> Subject: [PATCH V40 08/29] kexec_file: split KEXEC_VERIFY_SIG into KEXEC_SIG and KEXEC_SIG_FORCE From: Matthew Garrett <matthewgarrett@google.com> To: jmorris@namei.org Cc: linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, Jiri Bohac <jbohac@suse.cz>, David Howells <dhowells@redhat.com>, Matthew Garrett <mjg59@google.com>, kexec@lists.infradead.org Content-Type: text/plain; charset="UTF-8" Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk
Series	Add kernel lockdown functionality \| expand [V40,00/29] Add kernel lockdown functionality [V40,01/29] security: Support early LSMs [V40,02/29] security: Add a "locked down" LSM hook [V40,03/29] security: Add a static lockdown policy LSM [V40,04/29] lockdown: Enforce module signatures if the kernel is locked down [V40,05/29] lockdown: Restrict /dev/{mem,kmem,port} when the kernel is locked down [V40,06/29] kexec_load: Disable at runtime if the kernel is locked down [V40,07/29] lockdown: Copy secure_boot flag in boot params across kexec reboot [V40,08/29] kexec_file: split KEXEC_VERIFY_SIG into KEXEC_SIG and KEXEC_SIG_FORCE [V40,09/29] kexec_file: Restrict at runtime if the kernel is locked down [V40,10/29] hibernate: Disable when the kernel is locked down [V40,11/29] PCI: Lock down BAR access when the kernel is locked down [V40,12/29] x86: Lock down IO port access when the kernel is locked down [V40,13/29] x86/msr: Restrict MSR access when the kernel is locked down [V40,14/29] ACPI: Limit access to custom_method when the kernel is locked down [V40,15/29] acpi: Ignore acpi_rsdp kernel param when the kernel has been locked down [V40,16/29] acpi: Disable ACPI table override if the kernel is locked down [V40,17/29] lockdown: Prohibit PCMCIA CIS storage when the kernel is locked down [V40,18/29] lockdown: Lock down TIOCSSERIAL [V40,19/29] lockdown: Lock down module params that specify hardware parameters (eg. ioport) [V40,20/29] x86/mmiotrace: Lock down the testmmiotrace module [V40,21/29] lockdown: Lock down /proc/kcore [V40,22/29] lockdown: Lock down tracing and perf kprobes when in confidentiality mode [V40,23/29] bpf: Restrict bpf when kernel lockdown is in confidentiality mode [V40,24/29] lockdown: Lock down perf when in confidentiality mode [V40,25/29] kexec: Allow kexec_file() with appropriate IMA policy when locked down [V40,26/29] debugfs: Restrict debugfs when the kernel is locked down [V40,27/29] tracefs: Restrict tracefs when the kernel is locked down [V40,28/29] efi: Restrict efivar_ssdt_load when the kernel is locked down [V40,29/29] lockdown: Print current->comm in restriction messages

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 697ea0510729..f940500a941b 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -961,7 +961,7 @@ config KEXEC_FILE for kernel and initramfs as opposed to list of segments as accepted by previous system call. -config KEXEC_VERIFY_SIG +config KEXEC_SIG bool "Verify kernel signature during kexec_file_load() syscall" depends on KEXEC_FILE help @@ -976,13 +976,13 @@ config KEXEC_VERIFY_SIG config KEXEC_IMAGE_VERIFY_SIG bool "Enable Image signature verification support" default y - depends on KEXEC_VERIFY_SIG + depends on KEXEC_SIG depends on EFI && SIGNED_PE_FILE_VERIFICATION help Enable Image signature verification support. comment "Support for PE file signature verification disabled" - depends on KEXEC_VERIFY_SIG + depends on KEXEC_SIG depends on !EFI || !SIGNED_PE_FILE_VERIFICATION config CRASH_DUMP diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig index 109243fdb6ec..c4a423f30d49 100644 --- a/arch/s390/Kconfig +++ b/arch/s390/Kconfig @@ -555,7 +555,7 @@ config ARCH_HAS_KEXEC_PURGATORY def_bool y depends on KEXEC_FILE -config KEXEC_VERIFY_SIG +config KEXEC_SIG bool "Verify kernel signature during kexec_file_load() syscall" depends on KEXEC_FILE && SYSTEM_DATA_VERIFICATION help diff --git a/arch/s390/configs/debug_defconfig b/arch/s390/configs/debug_defconfig index b0920b35f87b..525e0a6addb9 100644 --- a/arch/s390/configs/debug_defconfig +++ b/arch/s390/configs/debug_defconfig @@ -64,7 +64,7 @@ CONFIG_NUMA=y CONFIG_PREEMPT=y CONFIG_HZ_100=y CONFIG_KEXEC_FILE=y -CONFIG_KEXEC_VERIFY_SIG=y +CONFIG_KEXEC_SIG=y CONFIG_EXPOLINE=y CONFIG_EXPOLINE_AUTO=y CONFIG_MEMORY_HOTPLUG=y diff --git a/arch/s390/configs/defconfig b/arch/s390/configs/defconfig index c59b922cb6c5..4c37279acdb4 100644 --- a/arch/s390/configs/defconfig +++ b/arch/s390/configs/defconfig @@ -39,7 +39,7 @@ CONFIG_NR_CPUS=256 CONFIG_NUMA=y CONFIG_HZ_100=y CONFIG_KEXEC_FILE=y -CONFIG_KEXEC_VERIFY_SIG=y +CONFIG_KEXEC_SIG=y CONFIG_CRASH_DUMP=y CONFIG_HIBERNATION=y CONFIG_PM_DEBUG=y diff --git a/arch/s390/configs/performance_defconfig b/arch/s390/configs/performance_defconfig index 09aa5cb14873..158ad0f0d433 100644 --- a/arch/s390/configs/performance_defconfig +++ b/arch/s390/configs/performance_defconfig @@ -65,7 +65,7 @@ CONFIG_NR_CPUS=512 CONFIG_NUMA=y CONFIG_HZ_100=y CONFIG_KEXEC_FILE=y -CONFIG_KEXEC_VERIFY_SIG=y +CONFIG_KEXEC_SIG=y CONFIG_EXPOLINE=y CONFIG_EXPOLINE_AUTO=y CONFIG_MEMORY_HOTPLUG=y diff --git a/arch/s390/kernel/kexec_elf.c b/arch/s390/kernel/kexec_elf.c index 6d0635ceddd0..9b4f37a4edf1 100644 --- a/arch/s390/kernel/kexec_elf.c +++ b/arch/s390/kernel/kexec_elf.c @@ -130,7 +130,7 @@ static int s390_elf_probe(const char *buf, unsigned long len) const struct kexec_file_ops s390_kexec_elf_ops = { .probe = s390_elf_probe, .load = s390_elf_load, -#ifdef CONFIG_KEXEC_VERIFY_SIG +#ifdef CONFIG_KEXEC__SIG .verify_sig = s390_verify_sig, -#endif /* CONFIG_KEXEC_VERIFY_SIG */ +#endif /* CONFIG_KEXEC_SIG */ }; diff --git a/arch/s390/kernel/kexec_image.c b/arch/s390/kernel/kexec_image.c index 58318bf89fd9..af23eff5774d 100644 --- a/arch/s390/kernel/kexec_image.c +++ b/arch/s390/kernel/kexec_image.c @@ -59,7 +59,7 @@ static int s390_image_probe(const char *buf, unsigned long len) const struct kexec_file_ops s390_kexec_image_ops = { .probe = s390_image_probe, .load = s390_image_load, -#ifdef CONFIG_KEXEC_VERIFY_SIG +#ifdef CONFIG_KEXEC_SIG .verify_sig = s390_verify_sig, -#endif /* CONFIG_KEXEC_VERIFY_SIG */ +#endif /* CONFIG_KEXEC_SIG */ }; diff --git a/arch/s390/kernel/machine_kexec_file.c b/arch/s390/kernel/machine_kexec_file.c index fbdd3ea73667..c0f33ba49a9a 100644 --- a/arch/s390/kernel/machine_kexec_file.c +++ b/arch/s390/kernel/machine_kexec_file.c @@ -22,7 +22,7 @@ const struct kexec_file_ops * const kexec_file_loaders[] = { NULL, }; -#ifdef CONFIG_KEXEC_VERIFY_SIG +#ifdef CONFIG_KEXEC_SIG /* * Module signature information block. * @@ -90,7 +90,7 @@ int s390_verify_sig(const char *kernel, unsigned long kernel_len) VERIFYING_MODULE_SIGNATURE, NULL, NULL); } -#endif /* CONFIG_KEXEC_VERIFY_SIG */ +#endif /* CONFIG_KEXEC_SIG */ static int kexec_file_update_purgatory(struct kimage *image, struct s390_load_data *data) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 2bbbd4d1ba31..cd41998aa6e6 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -2006,20 +2006,30 @@ config KEXEC_FILE config ARCH_HAS_KEXEC_PURGATORY def_bool KEXEC_FILE -config KEXEC_VERIFY_SIG +config KEXEC_SIG bool "Verify kernel signature during kexec_file_load() syscall" depends on KEXEC_FILE ---help--- - This option makes kernel signature verification mandatory for - the kexec_file_load() syscall. - In addition to that option, you need to enable signature + This option makes the kexec_file_load() syscall check for a valid + signature of the kernel image. The image can still be loaded without + a valid signature unless you also enable KEXEC_SIG_FORCE, though if + there's a signature that we can check, then it must be valid. + + In addition to this option, you need to enable signature verification for the corresponding kernel image type being loaded in order for this to work. +config KEXEC_SIG_FORCE + bool "Require a valid signature in kexec_file_load() syscall" + depends on KEXEC_SIG + ---help--- + This option makes kernel signature verification mandatory for + the kexec_file_load() syscall. + config KEXEC_BZIMAGE_VERIFY_SIG bool "Enable bzImage signature verification support" - depends on KEXEC_VERIFY_SIG + depends on KEXEC_SIG depends on SIGNED_PE_FILE_VERIFICATION select SYSTEM_TRUSTED_KEYRING ---help--- diff --git a/arch/x86/kernel/ima_arch.c b/arch/x86/kernel/ima_arch.c index 64b973f0e985..b98890894731 100644 --- a/arch/x86/kernel/ima_arch.c +++ b/arch/x86/kernel/ima_arch.c @@ -66,9 +66,9 @@ bool arch_ima_get_secureboot(void) /* secureboot arch rules */ static const char * const sb_arch_rules[] = { -#if !IS_ENABLED(CONFIG_KEXEC_VERIFY_SIG) +#if !IS_ENABLED(CONFIG_KEXEC_SIG) "appraise func=KEXEC_KERNEL_CHECK appraise_type=imasig", -#endif /* CONFIG_KEXEC_VERIFY_SIG */ +#endif /* CONFIG_KEXEC_SIG */ "measure func=KEXEC_KERNEL_CHECK", #if !IS_ENABLED(CONFIG_MODULE_SIG) "appraise func=MODULE_CHECK appraise_type=imasig", diff --git a/crypto/asymmetric_keys/verify_pefile.c b/crypto/asymmetric_keys/verify_pefile.c index 3b303fe2f061..cc9dbcecaaca 100644 --- a/crypto/asymmetric_keys/verify_pefile.c +++ b/crypto/asymmetric_keys/verify_pefile.c @@ -96,7 +96,7 @@ static int pefile_parse_binary(const void *pebuf, unsigned int pelen, if (!ddir->certs.virtual_address || !ddir->certs.size) { pr_debug("Unsigned PE binary\n"); - return -EKEYREJECTED; + return -ENODATA; } chkaddr(ctx->header_size, ddir->certs.virtual_address, @@ -403,6 +403,8 @@ static int pefile_digest_pe(const void *pebuf, unsigned int pelen, * (*) 0 if at least one signature chain intersects with the keys in the trust * keyring, or: * + * (*) -ENODATA if there is no signature present. + * * (*) -ENOPKG if a suitable crypto module couldn't be found for a check on a * chain. * diff --git a/include/linux/kexec.h b/include/linux/kexec.h index b9b1bc5f9669..58b27c7bdc2b 100644 --- a/include/linux/kexec.h +++ b/include/linux/kexec.h @@ -125,7 +125,7 @@ typedef void *(kexec_load_t)(struct kimage *image, char *kernel_buf, unsigned long cmdline_len); typedef int (kexec_cleanup_t)(void *loader_data); -#ifdef CONFIG_KEXEC_VERIFY_SIG +#ifdef CONFIG_KEXEC_SIG typedef int (kexec_verify_sig_t)(const char *kernel_buf, unsigned long kernel_len); #endif @@ -134,7 +134,7 @@ struct kexec_file_ops { kexec_probe_t *probe; kexec_load_t *load; kexec_cleanup_t *cleanup; -#ifdef CONFIG_KEXEC_VERIFY_SIG +#ifdef CONFIG_KEXEC_SIG kexec_verify_sig_t *verify_sig; #endif }; diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c index ef7b951a8087..972931201995 100644 --- a/kernel/kexec_file.c +++ b/kernel/kexec_file.c @@ -88,7 +88,7 @@ int __weak arch_kimage_file_post_load_cleanup(struct kimage *image) return kexec_image_post_load_cleanup_default(image); } -#ifdef CONFIG_KEXEC_VERIFY_SIG +#ifdef CONFIG_KEXEC_SIG static int kexec_image_verify_sig_default(struct kimage *image, void *buf, unsigned long buf_len) { @@ -177,6 +177,51 @@ void kimage_file_post_load_cleanup(struct kimage *image) image->image_loader_data = NULL; } +#ifdef CONFIG_KEXEC_SIG +static int +kimage_validate_signature(struct kimage *image) +{ + const char *reason; + int ret; + + ret = arch_kexec_kernel_verify_sig(image, image->kernel_buf, + image->kernel_buf_len); + switch (ret) { + case 0: + break; + + /* Certain verification errors are non-fatal if we're not + * checking errors, provided we aren't mandating that there + * must be a valid signature. + */ + case -ENODATA: + reason = "kexec of unsigned image"; + goto decide; + case -ENOPKG: + reason = "kexec of image with unsupported crypto"; + goto decide; + case -ENOKEY: + reason = "kexec of image with unavailable key"; + decide: + if (IS_ENABLED(CONFIG_KEXEC_SIG_FORCE)) { + pr_notice("%s rejected\n", reason); + return ret; + } + + return 0; + + /* All other errors are fatal, including nomem, unparseable + * signatures and signature check failures - even if signatures + * aren't required. + */ + default: + pr_notice("kernel signature verification failed (%d).\n", ret); + } + + return ret; +} +#endif + /* * In file mode list of segments is prepared by kernel. Copy relevant * data from user space, do error checking, prepare segment list @@ -186,7 +231,7 @@ kimage_file_prepare_segments(struct kimage *image, int kernel_fd, int initrd_fd, const char __user *cmdline_ptr, unsigned long cmdline_len, unsigned flags) { - int ret = 0; + int ret; void *ldata; loff_t size; @@ -205,14 +250,11 @@ kimage_file_prepare_segments(struct kimage *image, int kernel_fd, int initrd_fd, if (ret) goto out; -#ifdef CONFIG_KEXEC_VERIFY_SIG - ret = arch_kexec_kernel_verify_sig(image, image->kernel_buf, - image->kernel_buf_len); - if (ret) { - pr_debug("kernel signature verification failed.\n"); +#ifdef CONFIG_KEXEC_SIG + ret = kimage_validate_signature(image); + + if (ret) goto out; - } - pr_debug("kernel signature verification successful.\n"); #endif /* It is possible that there no initramfs is being loaded */ if (!(flags & KEXEC_FILE_NO_INITRAMFS)) { diff --git a/security/integrity/ima/Kconfig b/security/integrity/ima/Kconfig index 2692c7358c2c..32cd25fa44a5 100644 --- a/security/integrity/ima/Kconfig +++ b/security/integrity/ima/Kconfig @@ -160,7 +160,7 @@ config IMA_APPRAISE config IMA_ARCH_POLICY bool "Enable loading an IMA architecture specific policy" - depends on KEXEC_VERIFY_SIG || IMA_APPRAISE && INTEGRITY_ASYMMETRIC_KEYS + depends on KEXEC_SIG || IMA_APPRAISE && INTEGRITY_ASYMMETRIC_KEYS default n help This option enables loading an IMA architecture specific policy diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c index f556e6c18f9b..1cffda4412b7 100644 --- a/security/integrity/ima/ima_main.c +++ b/security/integrity/ima/ima_main.c @@ -541,7 +541,7 @@ int ima_load_data(enum kernel_load_data_id id) switch (id) { case LOADING_KEXEC_IMAGE: - if (IS_ENABLED(CONFIG_KEXEC_VERIFY_SIG) + if (IS_ENABLED(CONFIG_KEXEC_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;

[V40,08/29] kexec_file: split KEXEC_VERIFY_SIG into KEXEC_SIG and KEXEC_SIG_FORCE

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