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Date: Fri, 5 May 2023 21:42:08 +0200
From: Simon Horman <horms@...nel.org>
To: Ross Philipson <ross.philipson@...cle.com>
Cc: linux-kernel@...r.kernel.org, x86@...nel.org,
linux-integrity@...r.kernel.org, linux-doc@...r.kernel.org,
linux-crypto@...r.kernel.org, iommu@...ts.linux-foundation.org,
kexec@...ts.infradead.org, linux-efi@...r.kernel.org,
dpsmith@...rtussolutions.com, tglx@...utronix.de, mingo@...hat.com,
bp@...en8.de, hpa@...or.com, ardb@...nel.org, mjg59@...f.ucam.org,
James.Bottomley@...senpartnership.com, luto@...capital.net,
nivedita@...m.mit.edu, kanth.ghatraju@...cle.com,
trenchboot-devel@...glegroups.com
Subject: Re: [PATCH v6 12/14] x86: Secure Launch late initcall platform module
On Thu, May 04, 2023 at 02:50:21PM +0000, Ross Philipson wrote:
> From: "Daniel P. Smith" <dpsmith@...rtussolutions.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@...rtussolutions.com>
> Signed-off-by: garnetgrimm <grimmg@...fosec.com>
> Signed-off-by: Ross Philipson <ross.philipson@...cle.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 *
> + 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();
> +}
...
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