From patchwork Tue Aug 20 00:17:44 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthew Garrett X-Patchwork-Id: 11102373 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 360881398 for ; Tue, 20 Aug 2019 00:18:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0180422CE8 for ; Tue, 20 Aug 2019 00:18:34 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="URfPq3OD" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728962AbfHTASd (ORCPT ); Mon, 19 Aug 2019 20:18:33 -0400 Received: from mail-pf1-f202.google.com ([209.85.210.202]:54023 "EHLO mail-pf1-f202.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728953AbfHTASc (ORCPT ); Mon, 19 Aug 2019 20:18:32 -0400 Received: by mail-pf1-f202.google.com with SMTP id 191so3514838pfy.20 for ; Mon, 19 Aug 2019 17:18:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=bC7ewIpOD7kKRv4zgEwcJ/YudS1s9NTZWLzeTQRmanE=; b=URfPq3ODlEY2xBjCdcYfrSPpu5TgIjKf8zYvzddN03jGNVkCBho81L6lWf1m027tUQ HkA1v54fNVgVAY5G5597pvwIpHxmuqdLgZX56kdiMWiLQjHN3h6tcmJxQkjKQfGBaDuy 2ENi4+VmUWVTHHDq/fCJNxRwsmp4hVzFCDF43Sh+PJ1o+U57tsaoSNlbtGS8O+LHjcco irvf5qbgvO+/1IWbmyFQ4cte+zOHPxJf/KT3TsLI+vwOcLgnz3RwAICV07tJHoDfP2YZ cMAzwfG+gQXXsNMVB7md0Tp0mE6ngM71Yks5gtjVGhb7PvMZ1F2Mrguz08HumraiPB9q qEaw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=bC7ewIpOD7kKRv4zgEwcJ/YudS1s9NTZWLzeTQRmanE=; b=FBva/6Y38YQYosx5RI0YhtWcjOLje+kWvTkHUikbhDAWgvJ2meBZl1skhXz3gLnu0a Enh3VnfLii+FPOjPceFvNvi3Fn/87ZX6S22ty43MQtLdn94MjVktrz968NXNHxN7BxY/ QR8jMK2aPm13C0ATwVtE9SElWbkWKciDdUs8cKslTH/HdavXcMds9AGltq7XP3GLiwoe IN38eX80G3q1Ngz2j1cZaRqnGnPHfVyhuzlrz16EzgiS3vW0W7+TRG+THkp/J/FeJ5kd 9iJFyZhCymwy/xiavqEfN98IFdtcm8IrVOBT3Pg4hvYpVh3pZkD/qWwbxAmVbn63toYi WHyw== X-Gm-Message-State: APjAAAUKowAUM0nIDMnpa3mvKOo2Foz+TS0Sj3pqzIvKHCd0IvwicGse IUb8oInza8xzFhuBdgiWQEBHm9Cl1baGAi3b4JsjwQ== X-Google-Smtp-Source: APXvYqwIhWHZGyd8iGulecMwl621eBwYwjIu2poTs2trYo9QmU74aijoZ+0dXwjmZLzmdC5xxDfld7Wqi+WYZt4J1YODpw== X-Received: by 2002:a63:2043:: with SMTP id r3mr22349910pgm.311.1566260311059; Mon, 19 Aug 2019 17:18:31 -0700 (PDT) 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> X-Mailer: git-send-email 2.23.0.rc1.153.gdeed80330f-goog Subject: [PATCH V40 08/29] kexec_file: split KEXEC_VERIFY_SIG into KEXEC_SIG and KEXEC_SIG_FORCE From: Matthew Garrett To: jmorris@namei.org Cc: linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, Jiri Bohac , David Howells , Matthew Garrett , kexec@lists.infradead.org Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: From: Jiri Bohac This is a preparatory patch for kexec_file_load() lockdown. A locked down kernel needs to prevent unsigned kernel images from being loaded with kexec_file_load(). Currently, the only way to force the signature verification is compiling with KEXEC_VERIFY_SIG. This prevents loading usigned images even when the kernel is not locked down at runtime. This patch splits KEXEC_VERIFY_SIG into KEXEC_SIG and KEXEC_SIG_FORCE. Analogous to the MODULE_SIG and MODULE_SIG_FORCE for modules, KEXEC_SIG turns on the signature verification but allows unsigned images to be loaded. KEXEC_SIG_FORCE disallows images without a valid signature. Signed-off-by: Jiri Bohac Signed-off-by: David Howells Signed-off-by: Matthew Garrett cc: kexec@lists.infradead.org --- arch/arm64/Kconfig | 6 +-- arch/s390/Kconfig | 2 +- arch/s390/configs/debug_defconfig | 2 +- arch/s390/configs/defconfig | 2 +- arch/s390/configs/performance_defconfig | 2 +- arch/s390/kernel/kexec_elf.c | 4 +- arch/s390/kernel/kexec_image.c | 4 +- arch/s390/kernel/machine_kexec_file.c | 4 +- arch/x86/Kconfig | 20 ++++++--- arch/x86/kernel/ima_arch.c | 4 +- crypto/asymmetric_keys/verify_pefile.c | 4 +- include/linux/kexec.h | 4 +- kernel/kexec_file.c | 60 +++++++++++++++++++++---- security/integrity/ima/Kconfig | 2 +- security/integrity/ima/ima_main.c | 2 +- 15 files changed, 88 insertions(+), 34 deletions(-) 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;