Re: [PATCH v6 12/14] x86: Secure Launch late initcall platform module

[Ross Philipson <ross.philipson@oracle.com>]

On 5/5/23 15:42, Simon Horman wrote:
> On Thu, May 04, 2023 at 02:50:21PM +0000, Ross Philipson wrote:
>> From: "Daniel P. Smith" <dpsmith@apertussolutions.com>
>>
>> The Secure Launch platform module is a late init module. During the
>> init call, the TPM event log is read and measurements taken in the
>> early boot stub code are located. These measurements are extended
>> into the TPM PCRs using the mainline TPM kernel driver.
>>
>> The platform module also registers the securityfs nodes to allow
>> access to TXT register fields on Intel along with the fetching of
>> and writing events to the late launch TPM log.
>>
>> Signed-off-by: Daniel P. Smith <dpsmith@apertussolutions.com>
>> Signed-off-by: garnetgrimm <grimmg@ainfosec.com>
>> Signed-off-by: Ross Philipson <ross.philipson@oracle.com>
> 
> Hi Ross,
> 
> a few more items from my side.
> 
> ...
> 
>> diff --git a/arch/x86/kernel/slmodule.c b/arch/x86/kernel/slmodule.c
> 
> ...
> 
>> +/*
>> + * Securityfs exposure
>> + */
>> +struct memfile {
>> +	char *name;
>> +	void *addr;
>> +	size_t size;
>> +};
>> +
>> +static struct memfile sl_evtlog = {"eventlog", 0, 0};
> 
> I don't think the 0 fields are necessary above, memset will zero
> any fields not explicitly set. But if you want to go that way, then
> I think the first one should be NULL, as the addr field is a pointer.
> 
>> +static void *txt_heap;
>> +static struct txt_heap_event_log_pointer2_1_element __iomem *evtlog20;
>> +static DEFINE_MUTEX(sl_evt_log_mutex);
> 
>> +static ssize_t sl_evtlog_read(struct file *file, char __user *buf,
>> +			      size_t count, loff_t *pos)
>> +{
>> +	ssize_t size;
>> +
>> +	if (!sl_evtlog.addr)
>> +		return 0;
>> +
>> +	mutex_lock(&sl_evt_log_mutex);
>> +	size = simple_read_from_buffer(buf, count, pos, sl_evtlog.addr,
>> +				       sl_evtlog.size);
>> +	mutex_unlock(&sl_evt_log_mutex);
>> +
>> +	return size;
>> +}
>> +
>> +static ssize_t sl_evtlog_write(struct file *file, const char __user *buf,
>> +				size_t datalen, loff_t *ppos)
> 
> nit: the line above doesn't align to the '(' on the line before that.
> 
>> +{
>> +	ssize_t result;
>> +	char *data;
>> +
>> +	if (!sl_evtlog.addr)
>> +		return 0;
>> +
>> +	/* No partial writes. */
>> +	result = -EINVAL;
>> +	if (*ppos != 0)
>> +		goto out;
>> +
>> +	data = memdup_user(buf, datalen);
>> +	if (IS_ERR(data)) {
>> +		result = PTR_ERR(data);
>> +		goto out;
>> +	}
>> +
>> +	mutex_lock(&sl_evt_log_mutex);
>> +	if (evtlog20)
>> +		result = tpm20_log_event(evtlog20, sl_evtlog.addr,
>> +					 sl_evtlog.size, datalen, data);
> 
> Sparse says that the type of the first argument of tmp20_log_event is:
> 
> 	struct txt_heap_event_log_pointer2_1_element *
> 
> However, the type of evtlog20 is:
> 
> 	struct txt_heap_event_log_pointer2_1_element __iomem *

I have to look into what is going on here. The TXT heap is just a memory 
range not IO space. I will track this down.

As to all the rest of your comments here, I will fix them.

Thanks
Ross

> 
>> +	else
>> +		result = tpm12_log_event(sl_evtlog.addr, sl_evtlog.size,
>> +					 datalen, data);
>> +	mutex_unlock(&sl_evt_log_mutex);
>> +
>> +	kfree(data);
>> +out:
>> +	return result;
>> +}
> 
> ...
> 
>> +static long slaunch_expose_securityfs(void)
>> +{
>> +	long ret = 0;
>> +	int i;
>> +
>> +	slaunch_dir = securityfs_create_dir("slaunch", NULL);
>> +	if (IS_ERR(slaunch_dir))
>> +		return PTR_ERR(slaunch_dir);
>> +
>> +	if (slaunch_get_flags() & SL_FLAG_ARCH_TXT) {
>> +		txt_dir = securityfs_create_dir("txt", slaunch_dir);
>> +		if (IS_ERR(txt_dir)) {
>> +			ret = PTR_ERR(txt_dir);
>> +			goto remove_slaunch;
>> +		}
>> +
>> +		for (i = 0; i < ARRAY_SIZE(sl_txt_files); i++) {
>> +			txt_entries[i] = securityfs_create_file(
>> +						sl_txt_files[i].name, 0440,
>> +						txt_dir, NULL,
>> +						sl_txt_files[i].fops);
>> +			if (IS_ERR(txt_entries[i])) {
>> +				ret = PTR_ERR(txt_entries[i]);
>> +				goto remove_files;
>> +			}
>> +		}
>> +
> 
> nit: no blank line here.
> 
>> +	}
>> +
>> +	if (sl_evtlog.addr > 0) {
> 
> addr is a pointer. So perhaps:
> 
> 	if (sl_evtlog.addr) {
> 
>> +		event_file = securityfs_create_file(
>> +					sl_evtlog.name, 0440,
>> +					slaunch_dir, NULL,
>> +					&sl_evtlog_ops);
>> +		if (IS_ERR(event_file)) {
>> +			ret = PTR_ERR(event_file);
>> +			goto remove_files;
>> +		}
>> +	}
>> +
>> +	return 0;
>> +
>> +remove_files:
>> +	if (slaunch_get_flags() & SL_FLAG_ARCH_TXT) {
>> +		while (--i >= 0)
>> +			securityfs_remove(txt_entries[i]);
>> +		securityfs_remove(txt_dir);
>> +	}
>> +remove_slaunch:
>> +	securityfs_remove(slaunch_dir);
>> +
>> +	return ret;
>> +}
> 
> ...
> 
>> +static void slaunch_intel_evtlog(void __iomem *txt)
>> +{
>> +	struct slr_entry_log_info *log_info;
>> +	struct txt_os_mle_data *params;
>> +	struct slr_table *slrt;
>> +	void *os_sinit_data;
>> +	u64 base, size;
>> +
>> +	memcpy_fromio(&base, txt + TXT_CR_HEAP_BASE, sizeof(base));
>> +	memcpy_fromio(&size, txt + TXT_CR_HEAP_SIZE, sizeof(size));
>> +
>> +	/* now map TXT heap */
>> +	txt_heap = memremap(base, size, MEMREMAP_WB);
>> +	if (!txt_heap)
>> +		slaunch_txt_reset(txt,
>> +			"Error failed to memremap TXT heap\n",
>> +			SL_ERROR_HEAP_MAP);
> 
> nit: These lines are not aligned to the opening '('
> 
>> +
>> +	params = (struct txt_os_mle_data *)txt_os_mle_data_start(txt_heap);
>> +
>> +	/* Get the SLRT and remap it */
>> +	slrt = memremap(params->slrt, sizeof(*slrt), MEMREMAP_WB);
>> +	if (!slrt)
>> +		slaunch_txt_reset(txt,
>> +			"Error failed to memremap SLR Table\n",
>> +			SL_ERROR_SLRT_MAP);
>> +	size = slrt->size;
>> +	memunmap(slrt);
>> +
>> +	slrt = memremap(params->slrt, size, MEMREMAP_WB);
>> +	if (!slrt)
>> +		slaunch_txt_reset(txt,
>> +			"Error failed to memremap SLR Table\n",
>> +			SL_ERROR_SLRT_MAP);
>> +
>> +	log_info = (struct slr_entry_log_info *)
>> +			slr_next_entry_by_tag(slrt, NULL, SLR_ENTRY_LOG_INFO);
>> +	if (!log_info)
>> +		slaunch_txt_reset(txt,
>> +			"Error failed to memremap SLR Table\n",
>> +			SL_ERROR_SLRT_MISSING_ENTRY);
>> +
>> +	sl_evtlog.size = log_info->size;
>> +	sl_evtlog.addr = memremap(log_info->addr, log_info->size,
>> +				  MEMREMAP_WB);
>> +	if (!sl_evtlog.addr)
>> +		slaunch_txt_reset(txt,
>> +			"Error failed to memremap TPM event log\n",
>> +			SL_ERROR_EVENTLOG_MAP);
>> +
>> +	memunmap(slrt);
>> +
>> +	/* Determine if this is TPM 1.2 or 2.0 event log */
>> +	if (memcmp(sl_evtlog.addr + sizeof(struct tcg_pcr_event),
>> +		    TCG_SPECID_SIG, sizeof(TCG_SPECID_SIG)))
>> +		return; /* looks like it is not 2.0 */
>> +
>> +	/* For TPM 2.0 logs, the extended heap element must be located */
>> +	os_sinit_data = txt_os_sinit_data_start(txt_heap);
>> +
> 
> The return type of tmp20_find_lot2_1_element() is:
> 
> 	struct txt_heap_event_log_pointer2_1_element *
> 
> However, the type of evtlog20 is:
> 
> 	struct txt_heap_event_log_pointer2_1_element __iomem *
> 
>> +	evtlog20 = tpm20_find_log2_1_element(os_sinit_data);
>> +
>> +	/*
>> +	 * If this fails, things are in really bad shape. Any attempt to write
>> +	 * events to the log will fail.
>> +	 */
>> +	if (!evtlog20)
>> +		slaunch_txt_reset(txt,
>> +			"Error failed to find TPM20 event log element\n",
>> +			SL_ERROR_TPM_INVALID_LOG20);
>> +}
>> +
>> +static void slaunch_tpm20_extend_event(struct tpm_chip *tpm, void __iomem *txt,
>> +				       struct tcg_pcr_event2_head *event)
>> +{
>> +	u16 *alg_id_field = (u16 *)((u8 *)event +
>> +				    sizeof(struct tcg_pcr_event2_head));
>> +	struct tpm_digest *digests;
>> +	u8 *dptr;
>> +	int ret;
>> +	u32 i, j;
>> +
>> +	digests = kcalloc(tpm->nr_allocated_banks, sizeof(*digests),
>> +			  GFP_KERNEL);
>> +	if (!digests)
>> +		slaunch_txt_reset(txt,
>> +			"Failed to allocate array of digests\n",
>> +			SL_ERROR_GENERIC);
>> +
>> +	for (i = 0; i < tpm->nr_allocated_banks; i++)
>> +		digests[i].alg_id = tpm->allocated_banks[i].alg_id;
>> +
>> +
> 
> nit: one blank line is enough.
> 
>> +	/* Early SL code ensured there was a max count of 2 digests */
>> +	for (i = 0; i < event->count; i++) {
>> +		dptr = (u8 *)alg_id_field + sizeof(u16);
>> +
>> +		for (j = 0; j < tpm->nr_allocated_banks; j++) {
>> +			if (digests[j].alg_id != *alg_id_field)
>> +				continue;
>> +
>> +			switch (digests[j].alg_id) {
>> +			case TPM_ALG_SHA256:
>> +				memcpy(&digests[j].digest[0], dptr,
>> +				       SHA256_DIGEST_SIZE);
>> +				alg_id_field = (u16 *)((u8 *)alg_id_field +
>> +					SHA256_DIGEST_SIZE + sizeof(u16));
>> +				break;
>> +			case TPM_ALG_SHA1:
>> +				memcpy(&digests[j].digest[0], dptr,
>> +				       SHA1_DIGEST_SIZE);
>> +				alg_id_field = (u16 *)((u8 *)alg_id_field +
>> +					SHA1_DIGEST_SIZE + sizeof(u16));
>> +			default:
>> +				break;
>> +			}
>> +		}
>> +	}
>> +
>> +	ret = tpm_pcr_extend(tpm, event->pcr_idx, digests);
>> +	if (ret) {
>> +		pr_err("Error extending TPM20 PCR, result: %d\n", ret);
>> +		slaunch_txt_reset(txt,
>> +			"Failed to extend TPM20 PCR\n",
>> +			SL_ERROR_TPM_EXTEND);
>> +	}
>> +
>> +	kfree(digests);
>> +}
>> +
>> +static void slaunch_tpm20_extend(struct tpm_chip *tpm, void __iomem *txt)
>> +{
>> +	struct tcg_pcr_event *event_header;
>> +	struct tcg_pcr_event2_head *event;
>> +	int start = 0, end = 0, size;
>> +
>> +	event_header = (struct tcg_pcr_event *)(sl_evtlog.addr +
>> +						evtlog20->first_record_offset);
> 
> Sparse says that evtlog20 shouldn't be dereferenced because it
> has a __iomem attribute.
> 
>> +
>> +	/* Skip first TPM 1.2 event to get to first TPM 2.0 event */
>> +	event = (struct tcg_pcr_event2_head *)((u8 *)event_header +
>> +						sizeof(struct tcg_pcr_event) +
>> +						event_header->event_size);
>> +
>> +	while ((void  *)event < sl_evtlog.addr + evtlog20->next_record_offset) {
> 
> Ditto.
> 
>> +		size = __calc_tpm2_event_size(event, event_header, false);
>> +		if (!size)
>> +			slaunch_txt_reset(txt,
>> +				"TPM20 invalid event in event log\n",
>> +				SL_ERROR_TPM_INVALID_EVENT);
>> +
>> +		/*
>> +		 * Marker events indicate where the Secure Launch early stub
>> +		 * started and ended adding post launch events.
>> +		 */
>> +		if (event->event_type == TXT_EVTYPE_SLAUNCH_END) {
>> +			end = 1;
>> +			break;
>> +		} else if (event->event_type == TXT_EVTYPE_SLAUNCH_START) {
>> +			start = 1;
>> +			goto next;
>> +		}
>> +
>> +		if (start)
>> +			slaunch_tpm20_extend_event(tpm, txt, event);
>> +
>> +next:
>> +		event = (struct tcg_pcr_event2_head *)((u8 *)event + size);
>> +	}
>> +
>> +	if (!start || !end)
>> +		slaunch_txt_reset(txt,
>> +			"Missing start or end events for extending TPM20 PCRs\n",
>> +			SL_ERROR_TPM_EXTEND);
>> +}
> 
> ...
> 
>> +static void slaunch_pcr_extend(void __iomem *txt)
>> +{
>> +	struct tpm_chip *tpm;
>> +
>> +	tpm = tpm_default_chip();
>> +	if (!tpm)
>> +		slaunch_txt_reset(txt,
>> +			"Could not get default TPM chip\n",
>> +			SL_ERROR_TPM_INIT);
>> +	if (evtlog20)
>> +		slaunch_tpm20_extend(tpm, txt);
>> +	else
>> +		slaunch_tpm12_extend(tpm, txt);
>> +}
>> +
>> +static int __init slaunch_module_init(void)
>> +{
>> +	void __iomem *txt;
>> +
>> +	/* Check to see if Secure Launch happened */
>> +	if ((slaunch_get_flags() & (SL_FLAG_ACTIVE|SL_FLAG_ARCH_TXT)) !=
>> +	    (SL_FLAG_ACTIVE|SL_FLAG_ARCH_TXT))
> 
> nit: spaces around '|'
>       Likewise elsewhere in this patch.
> 
> 
>> +		return 0;
>> +
>> +	txt = ioremap(TXT_PRIV_CONFIG_REGS_BASE, TXT_NR_CONFIG_PAGES *
>> +		      PAGE_SIZE);
>> +	if (!txt)
>> +		panic("Error ioremap of TXT priv registers\n");
>> +
>> +	/* Only Intel TXT is supported at this point */
>> +	slaunch_intel_evtlog(txt);
>> +
>> +	slaunch_pcr_extend(txt);
>> +
>> +	iounmap(txt);
>> +
>> +	return slaunch_expose_securityfs();
>> +}
> 
> ...