Re: [PATCH v8 04/15] x86: Secure Launch Resource Table header file

From: Kim Phillips <kim.phillips@amd.com>
To: Ross Philipson <ross.philipson@oracle.com>,
	linux-kernel@vger.kernel.org, x86@kernel.org,
	linux-integrity@vger.kernel.org, linux-doc@vger.kernel.org,
	linux-crypto@vger.kernel.org, kexec@lists.infradead.org,
	linux-efi@vger.kernel.org
Cc: dpsmith@apertussolutions.com, tglx@linutronix.de,
	mingo@redhat.com, bp@alien8.de, hpa@zytor.com,
	dave.hansen@linux.intel.com, ardb@kernel.org,
	mjg59@srcf.ucam.org, James.Bottomley@hansenpartnership.com,
	peterhuewe@gmx.de, jarkko@kernel.org, jgg@ziepe.ca,
	luto@amacapital.net, nivedita@alum.mit.edu,
	herbert@gondor.apana.org.au, davem@davemloft.net,
	kanth.ghatraju@oracle.com, trenchboot-devel@googlegroups.com
Subject: Re: [PATCH v8 04/15] x86: Secure Launch Resource Table header file
Date: Fri, 29 Mar 2024 17:38:52 -0500	[thread overview]
Message-ID: <8d543a15-af62-4403-b2e0-3b395edfe9e4@amd.com> (raw)
In-Reply-To: <20240214221847.2066632-5-ross.philipson@oracle.com>

Hi Ross,

On 2/14/24 4:18 PM, Ross Philipson wrote:
> Introduce the Secure Launch Resource Table which forms the formal
> interface between the pre and post launch code.
> 
> Signed-off-by: Ross Philipson <ross.philipson@oracle.com>
> ---
>   include/linux/slr_table.h | 270 ++++++++++++++++++++++++++++++++++++++
>   1 file changed, 270 insertions(+)
>   create mode 100644 include/linux/slr_table.h

> diff --git a/include/linux/slr_table.h b/include/linux/slr_table.h
> new file mode 100644
> index 000000000000..42020988233a
> --- /dev/null
> +++ b/include/linux/slr_table.h
> @@ -0,0 +1,270 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Secure Launch Resource Table
> + *
> + * Copyright (c) 2023, Oracle and/or its affiliates.
> + */
> +
> +#ifndef _LINUX_SLR_TABLE_H
> +#define _LINUX_SLR_TABLE_H
> +
> +/* Put this in efi.h if it becomes a standard */
> +#define SLR_TABLE_GUID				EFI_GUID(0x877a9b2a, 0x0385, 0x45d1, 0xa0, 0x34, 0x9d, 0xac, 0x9c, 0x9e, 0x56, 0x5f)
> +
> +/* SLR table header values */
> +#define SLR_TABLE_MAGIC		0x4452544d
> +#define SLR_TABLE_REVISION	1
> +
> +/* Current revisions for the policy and UEFI config */
> +#define SLR_POLICY_REVISION		1
> +#define SLR_UEFI_CONFIG_REVISION	1
> +
> +/* SLR defined architectures */
> +#define SLR_INTEL_TXT		1
> +#define SLR_AMD_SKINIT		2
> +
> +/* SLR defined bootloaders */
> +#define SLR_BOOTLOADER_INVALID	0
> +#define SLR_BOOTLOADER_GRUB	1
> +
> +/* Log formats */
> +#define SLR_DRTM_TPM12_LOG	1
> +#define SLR_DRTM_TPM20_LOG	2
> +
> +/* DRTM Policy Entry Flags */
> +#define SLR_POLICY_FLAG_MEASURED	0x1
> +#define SLR_POLICY_IMPLICIT_SIZE	0x2
> +
> +/* Array Lengths */
> +#define TPM_EVENT_INFO_LENGTH		32
> +#define TXT_VARIABLE_MTRRS_LENGTH	32
> +
> +/* Tags */
> +#define SLR_ENTRY_INVALID	0x0000
> +#define SLR_ENTRY_DL_INFO	0x0001
> +#define SLR_ENTRY_LOG_INFO	0x0002
> +#define SLR_ENTRY_ENTRY_POLICY	0x0003
> +#define SLR_ENTRY_INTEL_INFO	0x0004
> +#define SLR_ENTRY_AMD_INFO	0x0005
> +#define SLR_ENTRY_ARM_INFO	0x0006
> +#define SLR_ENTRY_UEFI_INFO	0x0007
> +#define SLR_ENTRY_UEFI_CONFIG	0x0008
> +#define SLR_ENTRY_END		0xffff
> +
> +/* Entity Types */
> +#define SLR_ET_UNSPECIFIED	0x0000
> +#define SLR_ET_SLRT		0x0001
> +#define SLR_ET_BOOT_PARAMS	0x0002
> +#define SLR_ET_SETUP_DATA	0x0003
> +#define SLR_ET_CMDLINE		0x0004
> +#define SLR_ET_UEFI_MEMMAP	0x0005
> +#define SLR_ET_RAMDISK		0x0006
> +#define SLR_ET_TXT_OS2MLE	0x0010
> +#define SLR_ET_UNUSED		0xffff
> +
> +#ifndef __ASSEMBLY__
> +
> +/*
> + * Primary SLR Table Header
> + */
> +struct slr_table {
> +	u32 magic;
> +	u16 revision;
> +	u16 architecture;
> +	u32 size;
> +	u32 max_size;

Do these need to have their endianness specified with, e.g., __le32?

> +	/* entries[] */

Instead of the above line, a legit 'entries' can be enabled using:

DECLARE_FLEX_ARRAY(struct slr_entry_hdr, entries);

> +} __packed;

You'd have to move this above struct slr_table which would need it:

> +/*
> + * Common SLRT Table Header
> + */
> +struct slr_entry_hdr {
> +	u16 tag;
> +	u16 size;
> +} __packed;
> +
> +/*
> + * Boot loader context
> + */
> +struct slr_bl_context {
> +	u16 bootloader;
> +	u16 reserved;
> +	u64 context;
> +} __packed;
> +
> +/*
> + * DRTM Dynamic Launch Configuration
> + */
> +struct slr_entry_dl_info {
> +	struct slr_entry_hdr hdr;
> +	struct slr_bl_context bl_context;
> +	u64 dl_handler;
> +	u64 dce_base;
> +	u32 dce_size;
> +	u64 dlme_entry;
> +} __packed;
> +
> +/*
> + * TPM Log Information
> + */
> +struct slr_entry_log_info {
> +	struct slr_entry_hdr hdr;
> +	u16 format;
> +	u16 reserved;
> +	u64 addr;
> +	u32 size;
> +} __packed;
> +
> +/*
> + * DRTM Measurement Policy
> + */
> +struct slr_entry_policy {
> +	struct slr_entry_hdr hdr;
> +	u16 revision;
> +	u16 nr_entries;
> +	/* policy_entries[] */
> +} __packed;
> +
> +/*
> + * DRTM Measurement Entry
> + */
> +struct slr_policy_entry {
> +	u16 pcr;
> +	u16 entity_type;
> +	u16 flags;
> +	u16 reserved;
> +	u64 entity;
> +	u64 size;
> +	char evt_info[TPM_EVENT_INFO_LENGTH];
> +} __packed;
> +
> +/*
> + * Secure Launch defined MTRR saving structures
> + */
> +struct slr_txt_mtrr_pair {
> +	u64 mtrr_physbase;
> +	u64 mtrr_physmask;
> +} __packed;
> +
> +struct slr_txt_mtrr_state {
> +	u64 default_mem_type;
> +	u64 mtrr_vcnt;
> +	struct slr_txt_mtrr_pair mtrr_pair[TXT_VARIABLE_MTRRS_LENGTH];
> +} __packed;
> +
> +/*
> + * Intel TXT Info table
> + */
> +struct slr_entry_intel_info {
> +	struct slr_entry_hdr hdr;
> +	u64 saved_misc_enable_msr;
> +	struct slr_txt_mtrr_state saved_bsp_mtrrs;
> +} __packed;
> +
> +/*
> + * AMD SKINIT Info table
> + */
> +struct slr_entry_amd_info {
> +	struct slr_entry_hdr hdr;
> +} __packed;
> +
> +/*
> + * ARM DRTM Info table
> + */
> +struct slr_entry_arm_info {
> +	struct slr_entry_hdr hdr;
> +} __packed;

Shouldn't these three structs be added as part of their
separate per-vendor enablement patches?

> +struct slr_entry_uefi_config {
> +	struct slr_entry_hdr hdr;
> +	u16 revision;
> +	u16 nr_entries;
> +	/* uefi_cfg_entries[] */
> +} __packed;
> +
> +struct slr_uefi_cfg_entry {
> +	u16 pcr;
> +	u16 reserved;
> +	u64 cfg; /* address or value */
> +	u32 size;
> +	char evt_info[TPM_EVENT_INFO_LENGTH];
> +} __packed;
> +
> +static inline void *slr_end_of_entrys(struct slr_table *table)
> +{
> +	return (((void *)table) + table->size);
> +}
> +
> +static inline struct slr_entry_hdr *
> +slr_next_entry(struct slr_table *table,
> +	       struct slr_entry_hdr *curr)
> +{
> +	struct slr_entry_hdr *next = (struct slr_entry_hdr *)
> +				((u8 *)curr + curr->size);
> +
> +	if ((void *)next >= slr_end_of_entrys(table))
> +		return NULL;
> +	if (next->tag == SLR_ENTRY_END)
> +		return NULL;
> +
> +	return next;
> +}
> +
> +static inline struct slr_entry_hdr *
> +slr_next_entry_by_tag(struct slr_table *table,
> +		      struct slr_entry_hdr *entry,
> +		      u16 tag)
> +{
> +	if (!entry) /* Start from the beginning */
> +		entry = (struct slr_entry_hdr *)(((u8 *)table) + sizeof(*table));

Back to the 'entries', the above line can now be made more readable:

entry = table->entries;

That's just one example, this flex array simplification can be made
in other structs in this series, too.

Cheers,

Kim

> +
> +	for ( ; ; ) {
> +		if (entry->tag == tag)
> +			return entry;
> +
> +		entry = slr_next_entry(table, entry);
> +		if (!entry)
> +			return NULL;
> +	}
> +
> +	return NULL;
> +}
> +
> +static inline int
> +slr_add_entry(struct slr_table *table,
> +	      struct slr_entry_hdr *entry)
> +{
> +	struct slr_entry_hdr *end;
> +
> +	if ((table->size + entry->size) > table->max_size)
> +		return -1;
> +
> +	memcpy((u8 *)table + table->size - sizeof(*end), entry, entry->size);
> +	table->size += entry->size;
> +
> +	end  = (struct slr_entry_hdr *)((u8 *)table + table->size - sizeof(*end));
> +	end->tag = SLR_ENTRY_END;
> +	end->size = sizeof(*end);
> +
> +	return 0;
> +}
> +
> +static inline void
> +slr_init_table(struct slr_table *slrt, u16 architecture, u32 max_size)
> +{
> +	struct slr_entry_hdr *end;
> +
> +	slrt->magic = SLR_TABLE_MAGIC;
> +	slrt->revision = SLR_TABLE_REVISION;
> +	slrt->architecture = architecture;
> +	slrt->size = sizeof(*slrt) + sizeof(*end);
> +	slrt->max_size = max_size;
> +	end = (struct slr_entry_hdr *)((u8 *)slrt + sizeof(*slrt));
> +	end->tag = SLR_ENTRY_END;
> +	end->size = sizeof(*end);
> +}
> +
> +#endif /* !__ASSEMBLY */
> +
> +#endif /* _LINUX_SLR_TABLE_H */