From patchwork Wed Apr 16 02:10:22 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: steven chen X-Patchwork-Id: 14053061 Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 6357A22A1C0; Wed, 16 Apr 2025 02:10:56 +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=1744769457; cv=none; b=FWxllNT89iz+u1MtK8ohWj33tqyAy70CbJZIoARVomM1El53dlAgEPwB3W5ZPPW2hvMjwenFER7AsEcRErSOKwD1ALhR1n1NafSFvVZM11Hs8z2pqMRokXCo3FGF5IKz4iwq/Ck9q4CQc7BxnHSG7duNVTzwuUNjEzW2PhqnCXk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744769457; c=relaxed/simple; bh=13Z/bUVD3aCXNxsjL3OfaaKL3EKFLJIssiFnJggTQ+U=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ABt/rc45FdieZmEPIorhF+tsNjnUOYz3l1eu9GTs+qYCWm8Ud+f2nDKS9bQUblTM2bRqZANPjWxNqkXeKXKe8YhW7lHDIsRmmE7RLIWciL9/yGwF/AZ7qeyYRb/vdx8aeSmjkc91U+BN4qLwE/BWo/OrKrFDwKq8Nn6K8m5ipto= 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=C4l5eqAq; 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="C4l5eqAq" Received: from DESKTOP-VOT081N.hsd1.ga.comcast.net (unknown [172.200.70.13]) by linux.microsoft.com (Postfix) with ESMTPSA id E618A210C459; Tue, 15 Apr 2025 19:10:53 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com E618A210C459 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1744769456; bh=HvthFO8LCO7AsYxeb/FYT8qI95ecDogbw/W4n/TsLTI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=C4l5eqAqZuEFpaSRRYyNRZW386Y4kiMFPL/lsWiNS3UMBzRShfTfiNXBIGfp3TPM9 Qd0qC1YW96T8cmA+9dGRjrQMM5/qMvjsvmM8EwUVzEmh2Sob+hkmjUr/K4nbzWFZO0 pg9DvwePzb/F2nkTUmt7beepu8PIFgFroVTDd8Lc= From: steven chen To: 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 Cc: madvenka@linux.microsoft.com, nramas@linux.microsoft.com, James.Bottomley@HansenPartnership.com, bhe@redhat.com, vgoyal@redhat.com, dyoung@redhat.com Subject: [PATCH v12 4/9] ima: kexec: skip IMA segment validation after kexec soft reboot Date: Tue, 15 Apr 2025 19:10:22 -0700 Message-ID: <20250416021028.1403-5-chenste@linux.microsoft.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20250416021028.1403-1-chenste@linux.microsoft.com> References: <20250416021028.1403-1-chenste@linux.microsoft.com> Precedence: bulk X-Mailing-List: linux-security-module@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: Steven Chen Currently, the function kexec_calculate_store_digests() calculates and stores the digest of the segment during the kexec_file_load syscall, where the IMA segment is also allocated. Later, the IMA segment will be updated with the measurement log at the kexec execute stage when a kexec reboot is initiated. Therefore, the digests should be updated for the IMA segment in the normal case. The problem is that 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 and the location of the memory segments cannot be changed at kexec 'execute' stage. To address this, skip the calculation and storage of the digest for the IMA segment in kexec_calculate_store_digests() so that it is not added to the purgatory_sha_regions. With this change, the IMA segment is not included in the digest calculation, storage, and verification. Cc: Eric Biederman Cc: Baoquan He Cc: Vivek Goyal Cc: Dave Young Signed-off-by: Tushar Sugandhi Signed-off-by: Steven Chen Signed-off-by: Tushar Sugandhi Signed-off-by: Steven Chen Acked-by: Baoquan He --- include/linux/kexec.h | 3 +++ kernel/kexec_file.c | 22 ++++++++++++++++++++++ security/integrity/ima/ima_kexec.c | 3 +++ 3 files changed, 28 insertions(+) diff --git a/include/linux/kexec.h b/include/linux/kexec.h index 7d6b12f8b8d0..107e726f2ef3 100644 --- a/include/linux/kexec.h +++ b/include/linux/kexec.h @@ -362,6 +362,9 @@ struct kimage { phys_addr_t ima_buffer_addr; size_t ima_buffer_size; + + unsigned long ima_segment_index; + bool is_ima_segment_index_set; #endif /* Core ELF header buffer */ diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c index 3eedb8c226ad..606132253c79 100644 --- a/kernel/kexec_file.c +++ b/kernel/kexec_file.c @@ -38,6 +38,21 @@ void set_kexec_sig_enforced(void) } #endif +#ifdef CONFIG_IMA_KEXEC +static bool check_ima_segment_index(struct kimage *image, int i) +{ + if (image->is_ima_segment_index_set && i == image->ima_segment_index) + return true; + else + return false; +} +#else +static bool check_ima_segment_index(struct kimage *image, int i) +{ + return false; +} +#endif + static int kexec_calculate_store_digests(struct kimage *image); /* Maximum size in bytes for kernel/initrd files. */ @@ -764,6 +779,13 @@ static int kexec_calculate_store_digests(struct kimage *image) if (ksegment->kbuf == pi->purgatory_buf) continue; + /* + * Skip the segment if ima_segment_index is set and matches + * the current index + */ + if (check_ima_segment_index(image, i)) + continue; + ret = crypto_shash_update(desc, ksegment->kbuf, ksegment->bufsz); if (ret) diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c index b12ac3619b8f..7e0a19c3483f 100644 --- a/security/integrity/ima/ima_kexec.c +++ b/security/integrity/ima/ima_kexec.c @@ -145,6 +145,7 @@ void ima_add_kexec_buffer(struct kimage *image) kbuf.buffer = kexec_buffer; kbuf.bufsz = kexec_buffer_size; kbuf.memsz = kexec_segment_size; + image->is_ima_segment_index_set = false; ret = kexec_add_buffer(&kbuf); if (ret) { pr_err("Error passing over kexec measurement buffer.\n"); @@ -155,6 +156,8 @@ void ima_add_kexec_buffer(struct kimage *image) image->ima_buffer_addr = kbuf.mem; image->ima_buffer_size = kexec_segment_size; image->ima_buffer = kexec_buffer; + image->ima_segment_index = image->nr_segments - 1; + image->is_ima_segment_index_set = true; kexec_dprintk("kexec measurement buffer for the loaded kernel at 0x%lx.\n", kbuf.mem);