From: Coiby Xu <coxu@redhat.com> To: kexec@lists.infradead.org Cc: Matthew Garrett <mjg59@srcf.ucam.org>, Jiri Bohac <jbohac@suse.cz>, David Howells <dhowells@redhat.com>, linux-integrity@vger.kernel.org, Eric Biederman <ebiederm@xmission.com>, James Morris <jmorris@namei.org>, Matthew Garrett <mjg59@google.com>, linux-kernel@vger.kernel.org (open list) Subject: [PATCH] lockdown: kexec_file: prevent unsigned kernel image when KEXEC_SIG not enabled Date: Mon, 21 Nov 2022 15:29:47 +0800 [thread overview] Message-ID: <20221121072947.836672-1-coxu@redhat.com> (raw) A kernel builder may not enable KEXEC_SIG and some architectures like ppc64 simply don't have KEXEC_SIG. In these cases, unless both IMA_ARCH_POLICY and secure boot also enabled, lockdown doesn't prevent unsigned kernel image from being kexec'ed via the kexec_file_load syscall whereas it could prevent one via the kexec_load syscall. Mandate signature verification for those cases. Fixes: 155bdd30af17 ("kexec_file: Restrict at runtime if the kernel is locked down") Cc: Matthew Garrett <mjg59@srcf.ucam.org> Cc: Jiri Bohac <jbohac@suse.cz> Cc: David Howells <dhowells@redhat.com> Cc: kexec@lists.infradead.org Cc: linux-integrity@vger.kernel.org Signed-off-by: Coiby Xu <coxu@redhat.com> --- kernel/kexec_file.c | 31 +++++++++++++++++++++---------- 1 file changed, 21 insertions(+), 10 deletions(-) diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c index 45637511e0de..04d56b6e6459 100644 --- a/kernel/kexec_file.c +++ b/kernel/kexec_file.c @@ -125,6 +125,20 @@ void kimage_file_post_load_cleanup(struct kimage *image) image->image_loader_data = NULL; } +static int mandate_signatute_verification(void) +{ + /* + * If IMA is guaranteed to appraise a signature on the kexec + * image, permit it even if the kernel is otherwise locked + * down. + */ + if (!ima_appraise_signature(READING_KEXEC_IMAGE) && + security_locked_down(LOCKDOWN_KEXEC)) + return -EPERM; + + return 0; +} + #ifdef CONFIG_KEXEC_SIG #ifdef CONFIG_SIGNED_PE_FILE_VERIFICATION int kexec_kernel_verify_pe_sig(const char *kernel, unsigned long kernel_len) @@ -168,14 +182,9 @@ kimage_validate_signature(struct kimage *image) return ret; } - /* - * If IMA is guaranteed to appraise a signature on the kexec - * image, permit it even if the kernel is otherwise locked - * down. - */ - if (!ima_appraise_signature(READING_KEXEC_IMAGE) && - security_locked_down(LOCKDOWN_KEXEC)) - return -EPERM; + ret = mandate_signatute_verification(); + if (ret) + return ret; pr_debug("kernel signature verification failed (%d).\n", ret); } @@ -211,10 +220,12 @@ kimage_file_prepare_segments(struct kimage *image, int kernel_fd, int initrd_fd, #ifdef CONFIG_KEXEC_SIG ret = kimage_validate_signature(image); - +#else + ret = mandate_signatute_verification(); +#endif if (ret) goto out; -#endif + /* It is possible that there no initramfs is being loaded */ if (!(flags & KEXEC_FILE_NO_INITRAMFS)) { ret = kernel_read_file_from_fd(initrd_fd, 0, &image->initrd_buf, -- 2.38.1
WARNING: multiple messages have this Message-ID (diff)
From: Coiby Xu <coxu@redhat.com> To: kexec@lists.infradead.org Cc: Matthew Garrett <mjg59@srcf.ucam.org>, Jiri Bohac <jbohac@suse.cz>, David Howells <dhowells@redhat.com>, linux-integrity@vger.kernel.org, Eric Biederman <ebiederm@xmission.com>, James Morris <jmorris@namei.org>, Matthew Garrett <mjg59@google.com>, linux-kernel@vger.kernel.org (open list) Subject: [PATCH] lockdown: kexec_file: prevent unsigned kernel image when KEXEC_SIG not enabled Date: Mon, 21 Nov 2022 15:29:47 +0800 [thread overview] Message-ID: <20221121072947.836672-1-coxu@redhat.com> (raw) A kernel builder may not enable KEXEC_SIG and some architectures like ppc64 simply don't have KEXEC_SIG. In these cases, unless both IMA_ARCH_POLICY and secure boot also enabled, lockdown doesn't prevent unsigned kernel image from being kexec'ed via the kexec_file_load syscall whereas it could prevent one via the kexec_load syscall. Mandate signature verification for those cases. Fixes: 155bdd30af17 ("kexec_file: Restrict at runtime if the kernel is locked down") Cc: Matthew Garrett <mjg59@srcf.ucam.org> Cc: Jiri Bohac <jbohac@suse.cz> Cc: David Howells <dhowells@redhat.com> Cc: kexec@lists.infradead.org Cc: linux-integrity@vger.kernel.org Signed-off-by: Coiby Xu <coxu@redhat.com> --- kernel/kexec_file.c | 31 +++++++++++++++++++++---------- 1 file changed, 21 insertions(+), 10 deletions(-) diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c index 45637511e0de..04d56b6e6459 100644 --- a/kernel/kexec_file.c +++ b/kernel/kexec_file.c @@ -125,6 +125,20 @@ void kimage_file_post_load_cleanup(struct kimage *image) image->image_loader_data = NULL; } +static int mandate_signatute_verification(void) +{ + /* + * If IMA is guaranteed to appraise a signature on the kexec + * image, permit it even if the kernel is otherwise locked + * down. + */ + if (!ima_appraise_signature(READING_KEXEC_IMAGE) && + security_locked_down(LOCKDOWN_KEXEC)) + return -EPERM; + + return 0; +} + #ifdef CONFIG_KEXEC_SIG #ifdef CONFIG_SIGNED_PE_FILE_VERIFICATION int kexec_kernel_verify_pe_sig(const char *kernel, unsigned long kernel_len) @@ -168,14 +182,9 @@ kimage_validate_signature(struct kimage *image) return ret; } - /* - * If IMA is guaranteed to appraise a signature on the kexec - * image, permit it even if the kernel is otherwise locked - * down. - */ - if (!ima_appraise_signature(READING_KEXEC_IMAGE) && - security_locked_down(LOCKDOWN_KEXEC)) - return -EPERM; + ret = mandate_signatute_verification(); + if (ret) + return ret; pr_debug("kernel signature verification failed (%d).\n", ret); } @@ -211,10 +220,12 @@ kimage_file_prepare_segments(struct kimage *image, int kernel_fd, int initrd_fd, #ifdef CONFIG_KEXEC_SIG ret = kimage_validate_signature(image); - +#else + ret = mandate_signatute_verification(); +#endif if (ret) goto out; -#endif + /* It is possible that there no initramfs is being loaded */ if (!(flags & KEXEC_FILE_NO_INITRAMFS)) { ret = kernel_read_file_from_fd(initrd_fd, 0, &image->initrd_buf, -- 2.38.1 _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec
next reply other threads:[~2022-11-21 7:31 UTC|newest] Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-11-21 7:29 Coiby Xu [this message] 2022-11-21 7:29 ` [PATCH] lockdown: kexec_file: prevent unsigned kernel image when KEXEC_SIG not enabled Coiby Xu 2022-11-21 18:23 ` Mimi Zohar 2022-11-21 18:23 ` Mimi Zohar 2022-11-22 2:36 ` Coiby Xu 2022-11-22 2:36 ` Coiby Xu 2022-11-28 17:16 ` Mimi Zohar 2022-11-28 17:16 ` Mimi Zohar 2022-12-30 7:00 ` Coiby Xu 2022-12-30 7:00 ` Coiby Xu 2022-11-22 2:28 ` [PATCH v2] " Coiby Xu 2022-11-22 2:28 ` Coiby Xu
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