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 5A8352505BD; Fri, 21 Feb 2025 21:10:06 +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=1740172207; cv=none; b=P/rPUe3swjX40r6M1AuZ8A/eNotZAh55k2JQ2eJV5at5FwtaNnlSAGkzwYCZR8A6CpAi538y48Uvygb1FY8XpAlTYTbnOgAi7AiyyglMZ8R7cS2bO3oZv25AmzC3xQPxl2aVCZw0Sz8y8IUL6Mx5wBKiv9ngKsLiKQPykAbQE/8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740172207; c=relaxed/simple; bh=WTpcEnrAfQeUkKdrqVzvIfHmXroYmr4UzluSMK6NQ2w=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=ImsTbJ/NWvE/V574LXkHKNMlOThFfvtsAeyre9BJR3Whjd5j6okODONeLmDjXVEMIIaWSoVjNT7V1ZIUEeIZGZLDY/5dE3FykPQtZu87A0mB1r9SIA1HLLCHKyV4tvNiT/LfPU+NzsjJ8Juq1Z5GzCgUr60PuqAhT2ebqMHmzLM= 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=VIxqpjej; 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="VIxqpjej" Received: from [10.17.64.59] (unknown [131.107.8.59]) by linux.microsoft.com (Postfix) with ESMTPSA id A64022053679; Fri, 21 Feb 2025 13:10:05 -0800 (PST) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com A64022053679 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1740172206; bh=0lziOMlEQrQGXDNHLwwuurA3vZdazKZBrZ/C9W/SZGI=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=VIxqpjej/OSCHR0ZVlCRJfVuJEX+zyZGmdXuTGtc1kP3oPNhC1FEG99PJyxGUstA5 oN8r/pRyJtT2u2tnzk7FsP3EuVI3zupdoA1Fy2QZ1/YX5lmPBmcQTOftCRMvSqO8VW NYJ5nOEogIpGUB8LdfY8OMe6IcTCP+p3b+HnvW1s= Message-ID: <7903ffe0-75f9-49f8-b638-9a4964897676@linux.microsoft.com> Date: Fri, 21 Feb 2025 13:10:04 -0800 Precedence: bulk X-Mailing-List: linux-security-module@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v8 7/7] 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: <20250218225502.747963-1-chenste@linux.microsoft.com> <20250218225502.747963-8-chenste@linux.microsoft.com> <436c898a39a9bdaa2ab24fc111b50d3c885aa028.camel@linux.ibm.com> Content-Language: en-US From: steven chen In-Reply-To: <436c898a39a9bdaa2ab24fc111b50d3c885aa028.camel@linux.ibm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 2/20/2025 4:46 PM, Mimi Zohar wrote: > On Tue, 2025-02-18 at 14:55 -0800, 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. >> >> The 'kexec_load' event IMA log can be found using the following command: >> sudo cat /sys/kernel/security/integrity/ima/ascii_runtime_measurements | >>    grep kexec_load >> >> The 'kexec_load' event IMA log can be found using the following command: > -> kexec_execute > >> sudo cat /sys/kernel/security/integrity/ima/ascii_runtime_measurements | >>    grep kexec_execute > 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: > > sudo cat /sys/kernel/security/integrity/ima/ascii_runtime_measurements | grep kexec_load > | cut -d' ' -f 6 | xxd -r -p | sha256sum > >> Signed-off-by: Tushar Sugandhi >> Signed-off-by: steven chen >> --- >>  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 4428fcf42167..1452c98242a4 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 6c8c203ad81e..8d0782e51ffa 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 struct seq_file ima_kexec_file; >>  static void *ima_kexec_buffer; >>  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; >> + >> + buf_size = ima_get_binary_runtime_size(); >> + len = atomic_long_read(&ima_htable.len); >> + >> + 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, >> +   strlen(ima_kexec_event), false, NULL, 0); > As previously mentioned, scnprintf() returns the length. No need to use strlen() here. > > Mimi > >> +} >> + >>  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 3dfd178d4292..6afb46989cf6 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 >> + >>   ima_measurements_suspend(); >> >>   return NOTIFY_DONE; Thanks, I will update in next version