From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 397331EB36; Wed, 5 Mar 2025 00:55:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=13.77.154.182 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741136135; cv=none; b=JQ1vw2v7kxAhrMcZ68XnLNE45kGSHy5gFoFoMu0djMMvHdQa7RhjOScLp1+FFsa7F/6VsYW7ON6YIDvPiONG3TatGiXZUQQy1/KxJCpW9VoVt8MdRwZ8L5D1Qa73v1GPEEnB2n7fAks0uhOC5suvxf/RBrJs0RpLKWZMPsys/R4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741136135; c=relaxed/simple; bh=iPV4w7owvHfPr5ZNWrsGQO/OhGEdz3OAJY0g6rOy6bg=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=C51QXSYb4eKlWcKsCTpNmUbIMy2RCZxlO31KLOFIXluFoVutTPRX4rIWfFVgChlxn8mmlZYV1w+NOk+k2xL6AJceH+h9BkRN70IINkADDoXuz0J2FBYOiSnzaccly78+yhrFMDCEy8XQTpNcxx5X7tKGSLsgvxj/pcCchmnyqhE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.microsoft.com; spf=pass smtp.mailfrom=linux.microsoft.com; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b=Q5XbfO3s; arc=none smtp.client-ip=13.77.154.182 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.microsoft.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.microsoft.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b="Q5XbfO3s" Received: from [10.17.64.124] (unknown [131.107.8.124]) by linux.microsoft.com (Postfix) with ESMTPSA id 719E5210EAF8; Tue, 4 Mar 2025 16:55:33 -0800 (PST) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 719E5210EAF8 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1741136133; bh=H4AhP6jMEhJGpBHUcIilmpOFGmGyNrWrR7ArRzfcffA=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=Q5XbfO3sQRMPEjEjiuHvgPgBodNGY9XthIiuorr4yo2BWztHbo7TU63BQ8w7hPZnQ focqn8ATU2iMizxoVlxHtYUpW2DsOmqrbxT0QCRLf6NmOBplG8GXSEPGPGycsQfZZL a+8Ce6g6xdDS8kmqEjzyXwphUdimgHHXpZnKQBKc= Message-ID: <97c27a30-a5ee-4825-ab7e-82dcddedd688@linux.microsoft.com> Date: Tue, 4 Mar 2025 16:55:32 -0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v9 2/7] kexec: define functions to map and unmap segments To: Jarkko Sakkinen 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, bhe@redhat.com, vgoyal@redhat.com, dyoung@redhat.com References: <20250304190351.96975-1-chenste@linux.microsoft.com> <20250304190351.96975-3-chenste@linux.microsoft.com> Content-Language: en-US From: steven chen In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 3/4/2025 2:23 PM, Jarkko Sakkinen wrote: > On Tue, Mar 04, 2025 at 11:03:46AM -0800, steven chen wrote: >> The content of memory segments carried over to the new kernel during the >> kexec systemcall can be changed at kexec 'execute' stage, but the size of >> the memory segments cannot be changed at kexec 'execute' stage. >> >> To copy IMA measurement logs during the kexec operation, IMA needs to >> allocate 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. > How does IMA work with kexec without having this? Just interested > (and confused). Currently, all IMA-related operations during a soft reboot, such as memory allocation and IMA log list copy, are handled in the kexec 'load' stage, so the map/unmap mechanism is not required. The new design separates these two operations into different stages: memory allocation remains in the kexec 'load' stage, while the IMA log list copy is moved to the kexec 'execute' stage. Therefore, the map/unmap mechanism is introduced. Please refer to "[PATCH v9 0/7] ima: kexec: measure events between kexec load and execute" for the reason why to add this. Steven >> Implement kimage_map_segment() to enable IMA to map measurement log list to >> the kimage structure during 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(+) >> >> 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..63e4d16b6023 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 eaddr = addr + size; >> + unsigned long src_page_addr, dest_page_addr; >> + unsigned int npages; >> + struct page **src_pages; >> + int i; >> + kimage_entry_t *ptr, entry; >> + void *vaddr = NULL; >> + >> + /* >> + * 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 >> >> > BR, Jarkko