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 931A01E7C0B; Fri, 21 Mar 2025 16:49:01 +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=1742575743; cv=none; b=CM3FsRaNfrKxCtN+X/89PNCBUzDAyUxOAli7MkYmiC07ugWJTwQc2E1I8nirpLvEfNqaclEBLYCzUT1D3gfiN1tol0b3NhiORqim0cSSQglK1C1CpHSOQ3YIudiAKma+MxS5G7C7f0Y1IlG7wf56ss1ezx7fRw8Rd37x6ywPQlE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742575743; c=relaxed/simple; bh=Jbefc2fy+6DSTbygMu6+1efbepZO0Okur+3ITUsewdU=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=Nje6VTXI9aS11U99Bc3my0NuXvCDV3jhuoExZA1shH8MyIPngkmlO4mPWBR80wTeQ73m5XOK5HXfD8xAUHCcGk3m5BhbPFbExq8WuwPjCBUvFFR3XlwJiHeKf0EfCR84rcHk8v5zRGYG6JdqlBamtw8i5zRYV9jxCXsJtU36m7Y= 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=IvJA4DLM; 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="IvJA4DLM" Received: from [10.17.64.97] (unknown [131.107.174.225]) by linux.microsoft.com (Postfix) with ESMTPSA id 08ABD202538B; Fri, 21 Mar 2025 09:49:01 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 08ABD202538B DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1742575741; bh=EDq6dkjdVz/tPxpcBKVvaAVpNAoxeUkWXPEwHqJnTOc=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=IvJA4DLMQDjLEBNN5Nhuv+QYitK6B8t83wGQvVjWhT1X6P/Fvlq+E2Xk2q5aoW9Dm TmbtrjGdXmLx6HnR5qwD4vrrWd1J/eHWsSFZcW+NLcHbK97JhYZMrLGH/hDO8Ti3wc tjmCqBSfFKm/+fce2lTr7QQ8v5yOsmJcpZdqo8fE= Message-ID: <11de6e57-f307-4382-877e-566b5a4e855e@linux.microsoft.com> Date: Fri, 21 Mar 2025 09:49:01 -0700 Precedence: bulk X-Mailing-List: linux-integrity@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v10 8/8] ima: measure kexec load and exec events as critical data To: Mimi Zohar , 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 References: <20250318010448.954-1-chenste@linux.microsoft.com> <20250318010448.954-9-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 3/19/2025 7:59 PM, Mimi Zohar wrote: > On Mon, 2025-03-17 at 18:04 -0700, steven chen wrote: >> The amount of memory allocated at kexec load, even with the extra memory >> allocated, might not be large enough for the entire measurement list. The >> indeterminate interval between kexec 'load' and 'execute' could exacerbate >> this problem. >> >> Define two new IMA events, 'kexec_load' and 'kexec_execute', to be >> measured as critical data at kexec 'load' and 'execute' respectively. >> Report the allocated kexec segment size, IMA binary log size and the >> runtime measurements count as part of those events. >> >> These events, and the values reported through them, serve as markers in >> the IMA log to verify the IMA events are captured during kexec soft >> reboot. The presence of a 'kexec_load' event in between the last two >> 'boot_aggregate' events in the IMA log implies this is a kexec soft >> reboot, and not a cold-boot. And the absence of 'kexec_execute' event >> after kexec soft reboot implies missing events in that window which >> results in inconsistency with TPM PCR quotes, necessitating a cold boot >> for a successful remote attestation. >> >> These critical data events are displayed as hex encoded ascii in the >> ascii_runtime_measurement_list. Verifying the critical data hash requires >> calculating the hash of the decoded ascii string. >> >> For example, to verify the 'kexec_load' data hash: >> >> sudo cat /sys/kernel/security/integrity/ima/ascii_runtime_measurements >>> grep kexec_load | cut -d' ' -f 6 | xxd -r -p | sha256sum >> >> To verify the 'kexec_execute' data hash: >> >> sudo cat /sys/kernel/security/integrity/ima/ascii_runtime_measurements >>> grep kexec_execute | cut -d' ' -f 6 | xxd -r -p | sha256sum >> Signed-off-by: Tushar Sugandhi >> Signed-off-by: steven chen >> Reviewed-by: Stefan Berger >> --- >> security/integrity/ima/ima.h | 6 ++++++ >> security/integrity/ima/ima_kexec.c | 21 +++++++++++++++++++++ >> security/integrity/ima/ima_queue.c | 5 +++++ >> 3 files changed, 32 insertions(+) >> >> diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h >> index 24d09ea91b87..34815baf5e21 100644 >> --- a/security/integrity/ima/ima.h >> +++ b/security/integrity/ima/ima.h >> @@ -240,6 +240,12 @@ void ima_post_key_create_or_update(struct key *keyring, struct key *key, >> unsigned long flags, bool create); >> #endif >> >> +#ifdef CONFIG_IMA_KEXEC >> +void ima_measure_kexec_event(const char *event_name); >> +#else >> +static inline void ima_measure_kexec_event(const char *event_name) {} >> +#endif >> + >> /* >> * The default binary_runtime_measurements list format is defined as the >> * platform native format. The canonical format is defined as little-endian. >> diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c >> index 0f214e41dd33..43223eb99046 100644 >> --- a/security/integrity/ima/ima_kexec.c >> +++ b/security/integrity/ima/ima_kexec.c >> @@ -17,6 +17,8 @@ >> #include "ima.h" >> >> #ifdef CONFIG_IMA_KEXEC >> +#define IMA_KEXEC_EVENT_LEN 256 >> + >> static bool ima_kexec_update_registered; >> static struct seq_file ima_kexec_file; >> static size_t kexec_segment_size; >> @@ -36,6 +38,24 @@ static void ima_free_kexec_file_buf(struct seq_file *sf) >> ima_reset_kexec_file(sf); >> } >> >> +void ima_measure_kexec_event(const char *event_name) >> +{ >> + char ima_kexec_event[IMA_KEXEC_EVENT_LEN]; >> + size_t buf_size = 0; >> + long len; >> + int n; >> + >> + buf_size = ima_get_binary_runtime_size(); >> + len = atomic_long_read(&ima_htable.len); >> + >> + n = scnprintf(ima_kexec_event, IMA_KEXEC_EVENT_LEN, >> + "kexec_segment_size=%lu;ima_binary_runtime_size=%lu;" >> + "ima_runtime_measurements_count=%ld;", >> + kexec_segment_size, buf_size, len); >> + >> + ima_measure_critical_data("ima_kexec", event_name, ima_kexec_event, n, false, NULL, 0); >> +} >> + >> static int ima_alloc_kexec_file_buf(size_t segment_size) >> { >> /* >> @@ -58,6 +78,7 @@ static int ima_alloc_kexec_file_buf(size_t segment_size) >> out: >> ima_kexec_file.read_pos = 0; >> ima_kexec_file.count = sizeof(struct ima_kexec_hdr); /* reserved space */ >> + ima_measure_kexec_event("kexec_load"); >> >> return 0; >> } >> diff --git a/security/integrity/ima/ima_queue.c b/security/integrity/ima/ima_queue.c >> index 83d53824aa98..590637e81ad1 100644 >> --- a/security/integrity/ima/ima_queue.c >> +++ b/security/integrity/ima/ima_queue.c >> @@ -241,6 +241,11 @@ static int ima_reboot_notifier(struct notifier_block *nb, >> unsigned long action, >> void *data) >> { >> +#ifdef CONFIG_IMA_KEXEC >> + if (action == SYS_RESTART && data && !strcmp(data, "kexec reboot")) >> + ima_measure_kexec_event("kexec_execute"); >> +#endif > After a kexec execute, the measurement list does not verify properly and the > "kexec_execute" critical data does not appear in the measurement list. This > makes me think the critical data IS being extended into the TPM, but the > measurement list is being copied before the "kexec_execute" critical data is > called. > > This actually makes sense since the reboot notifier ima_update_kexec_buffer() > priority is higher than ima_reboot_notifier(). > > INT_MIN: runs the callback late > INT_MAX: runs the callback early > > Either reverse the callback priorities or revert moving the "kexec_execute" > critical data to ima_reboot_notifier(). > > thanks, > > Mimi Hi Mimi, I will reverse the callback priority. Thanks, Steven >> + >> ima_measurements_suspend(); >> >> return NOTIFY_DONE;