From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 61200C35FFA for ; Wed, 19 Mar 2025 10:12:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=nyrQ69Ih495D1dgtb4loaIIF309AdjN+SDwQz13P988=; b=as8kcSoelD7SPsSnxnFEnLn0qk jnHue59oPezlkfffj2/ANGZJoeaEbv+r5R7OP7pmD2ODatlH+AmS6jfoAPXYc/wT/rJAZayzoXzIW QmrYhP7+bN71e7TyOrpYzPKJArRFp5O1dZGKSmCyn+EvQ2I6Ue+H2+UFXipP8QSP+//sVp8hUeHtV z2Gqo4EOZM8K6fyMX4ELAEEKhwLodtuqa6auZwX6z7/e5Z2+4z6SUMXM+Z+Tu3gqrJ5RIRRSNPJKD tSnHrEqYOh7RcoR9hXnYE4iD21LqvMma++fLmGka9n82wdG3u9ordzFKM5THnB5/wbyakRhmpH1gt 4pdBuhMg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1tuqPk-00000008cwY-33K1; Wed, 19 Mar 2025 10:12:44 +0000 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by bombadil.infradead.org with esmtps (Exim 4.98 #2 (Red Hat Linux)) id 1tuqPh-00000008cw6-0R4z for kexec@lists.infradead.org; Wed, 19 Mar 2025 10:12:43 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1742379159; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=nyrQ69Ih495D1dgtb4loaIIF309AdjN+SDwQz13P988=; b=CKCCajwboGef80muGnAD8thZ3yy0HI4Xq1Z0VGQ7aO1cVq/9vrWvHZDOjAwKDK7wIO9Odx ykIZbVfAY1Ocx2G0WqxpJn9rKCLFZ8hp44eg5FbNXXCY7ZB/QayZvYt1kcqtGWJOJ14pyt jQ7YW8BL4lG8lUKpLlZcj8LWBiIKCHI= Received: from mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-60-UQDTJZ7_ObixN70czgvFuw-1; Wed, 19 Mar 2025 06:12:35 -0400 X-MC-Unique: UQDTJZ7_ObixN70czgvFuw-1 X-Mimecast-MFC-AGG-ID: UQDTJZ7_ObixN70czgvFuw_1742379153 Received: from mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.17]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 136611809CA6; Wed, 19 Mar 2025 10:12:32 +0000 (UTC) Received: from localhost (unknown [10.72.112.30]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 1B1961955DCD; Wed, 19 Mar 2025 10:12:28 +0000 (UTC) Date: Wed, 19 Mar 2025 18:12:23 +0800 From: Baoquan He To: steven chen Cc: zohar@linux.ibm.com, stefanb@linux.ibm.com, roberto.sassu@huaweicloud.com, roberto.sassu@huawei.com, eric.snowberg@oracle.com, ebiederm@xmission.com, paul@paul-moore.com, code@tyhicks.com, bauermann@kolabnow.com, linux-integrity@vger.kernel.org, kexec@lists.infradead.org, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, madvenka@linux.microsoft.com, nramas@linux.microsoft.com, James.Bottomley@hansenpartnership.com, vgoyal@redhat.com, dyoung@redhat.com Subject: Re: [PATCH v10 3/8] kexec: define functions to map and unmap segments Message-ID: References: <20250318010448.954-1-chenste@linux.microsoft.com> <20250318010448.954-4-chenste@linux.microsoft.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250318010448.954-4-chenste@linux.microsoft.com> X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250319_031241_250427_A540E1D1 X-CRM114-Status: GOOD ( 37.86 ) X-BeenThere: kexec@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "kexec" Errors-To: kexec-bounces+kexec=archiver.kernel.org@lists.infradead.org On 03/17/25 at 06:04pm, steven chen wrote: > Currently, the kernel behavior during kexec load is to fetch the IMA > measurements log from TPM PCRs and store it in a buffer. When a kexec > reboot is triggered, this stored log buffer is carried over to the second > kernel. However, the time gap between kexec load and kexec reboot can be > very long. During this time window, new events extended into TPM PCRs miss > the chance to be carried over to the second kernel. This results in a > mismatch between TPM PCR quotes and the actual IMA measurements list after > kexec reboot, leading to remote attestation failure. > > To solve this problem, the new design defers reading TPM PCRs content into > the kexec buffer to the kexec reboot phase, while still allocating the > necessary buffer at kexec load time because it is not appropriate to > allocate memory at the kexec reboot moment. > > The content of memory segments carried over to the new kernel during the > kexec system call can be changed at the kexec 'execute' stage, but the size > of the memory segments cannot be changed at the kexec 'execute' stage. > > To copy IMA measurement logs during the kexec operation, IMA allocates > memory at the kexec 'load' stage and map the segments to the kimage > structure. The mapped address will then be used to copy IMA measurements > during the kexec 'execute' stage. > > Currently, the mechanism to map and unmap segments to the kimage structure > is not available to subsystems outside of kexec. > > Implement kimage_map_segment() to enable IMA to map the measurement log > list to the kimage structure during the kexec 'load' stage. This function > takes a kimage pointer, a memory address, and a size, then gathers the > source pages within the specified address range, creates an array of page > pointers, and maps these to a contiguous virtual address range. The > function returns the start virtual address of this range if successful, > or NULL on failure. > > Implement kimage_unmap_segment() for unmapping segments using vunmap(). > > From: Tushar Sugandhi > Signed-off-by: Tushar Sugandhi > Cc: Eric Biederman > Cc: Baoquan He > Cc: Vivek Goyal > Cc: Dave Young > Signed-off-by: steven chen > --- > include/linux/kexec.h | 6 +++++ > kernel/kexec_core.c | 54 +++++++++++++++++++++++++++++++++++++++++++ > 2 files changed, 60 insertions(+) The log is a little verbose, otherwise it looks good to me. Acked-by: Baoquan He > > diff --git a/include/linux/kexec.h b/include/linux/kexec.h > index f0e9f8eda7a3..7d6b12f8b8d0 100644 > --- a/include/linux/kexec.h > +++ b/include/linux/kexec.h > @@ -467,13 +467,19 @@ extern bool kexec_file_dbg_print; > #define kexec_dprintk(fmt, arg...) \ > do { if (kexec_file_dbg_print) pr_info(fmt, ##arg); } while (0) > > +extern void *kimage_map_segment(struct kimage *image, unsigned long addr, unsigned long size); > +extern void kimage_unmap_segment(void *buffer); > #else /* !CONFIG_KEXEC_CORE */ > struct pt_regs; > struct task_struct; > +struct kimage; > static inline void __crash_kexec(struct pt_regs *regs) { } > static inline void crash_kexec(struct pt_regs *regs) { } > static inline int kexec_should_crash(struct task_struct *p) { return 0; } > static inline int kexec_crash_loaded(void) { return 0; } > +static inline void *kimage_map_segment(struct kimage *image, unsigned long addr, unsigned long size) > +{ return NULL; } > +static inline void kimage_unmap_segment(void *buffer) { } > #define kexec_in_progress false > #endif /* CONFIG_KEXEC_CORE */ > > diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c > index c0bdc1686154..a5e378e1dc7f 100644 > --- a/kernel/kexec_core.c > +++ b/kernel/kexec_core.c > @@ -867,6 +867,60 @@ int kimage_load_segment(struct kimage *image, > return result; > } > > +void *kimage_map_segment(struct kimage *image, > + unsigned long addr, unsigned long size) > +{ > + unsigned long src_page_addr, dest_page_addr = 0; > + unsigned long eaddr = addr + size; > + kimage_entry_t *ptr, entry; > + struct page **src_pages; > + unsigned int npages; > + void *vaddr = NULL; > + int i; > + > + /* > + * Collect the source pages and map them in a contiguous VA range. > + */ > + npages = PFN_UP(eaddr) - PFN_DOWN(addr); > + src_pages = kmalloc_array(npages, sizeof(*src_pages), GFP_KERNEL); > + if (!src_pages) { > + pr_err("Could not allocate ima pages array.\n"); > + return NULL; > + } > + > + i = 0; > + for_each_kimage_entry(image, ptr, entry) { > + if (entry & IND_DESTINATION) { > + dest_page_addr = entry & PAGE_MASK; > + } else if (entry & IND_SOURCE) { > + if (dest_page_addr >= addr && dest_page_addr < eaddr) { > + src_page_addr = entry & PAGE_MASK; > + src_pages[i++] = > + virt_to_page(__va(src_page_addr)); > + if (i == npages) > + break; > + dest_page_addr += PAGE_SIZE; > + } > + } > + } > + > + /* Sanity check. */ > + WARN_ON(i < npages); > + > + vaddr = vmap(src_pages, npages, VM_MAP, PAGE_KERNEL); > + kfree(src_pages); > + > + if (!vaddr) > + pr_err("Could not map ima buffer.\n"); > + > + return vaddr; > +} > + > +void kimage_unmap_segment(void *segment_buffer) > +{ > + vunmap(segment_buffer); > +} > + > struct kexec_load_limit { > /* Mutex protects the limit count. */ > struct mutex mutex; > -- > 2.25.1 >