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

From: ross.philipson@oracle.com
To: Ard Biesheuvel <ardb@kernel.org>
Cc: 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, dpsmith@apertussolutions.com,
	tglx@linutronix.de, mingo@redhat.com, bp@alien8.de,
	hpa@zytor.com, dave.hansen@linux.intel.com, 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: Thu, 22 Feb 2024 09:49:48 -0800	[thread overview]
Message-ID: <a94faec1-693e-4fe4-84e2-aa7db576c4b8@oracle.com> (raw)
In-Reply-To: <CAMj1kXGaMfUAR85jpeS2JxcmWBbpkzroCVZOtwa3WDQwStDjMw@mail.gmail.com>

On 2/15/24 12:08 AM, Ard Biesheuvel wrote:
> On Wed, 14 Feb 2024 at 23:31, Ross Philipson <ross.philipson@oracle.com> 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;
>> +       /* entries[] */
>> +} __packed;
> 
> Packing this struct has no effect on the layout so better drop the
> __packed here. If this table is part of a structure that can appear
> misaligned in memory, better to pack the outer struct or deal with it
> there in another way.
> 
>> +
>> +/*
>> + * Common SLRT Table Header
>> + */
>> +struct slr_entry_hdr {
>> +       u16 tag;
>> +       u16 size;
>> +} __packed;
> 
> Same here
> 
>> +
>> +/*
>> + * 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;
> 
> I noticed in the EFI patch that this is actually
> 
> void (*dl_handler)(struct slr_bl_context *bl_context);
> 
> so better declare it as such.
> 
>> +       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[] */
> 
> Please use a flex array here:
> 
>    struct slr_policy_entry policy_entries[];

Yes we will use flex arrays everywhere it is relevant in here going forward.

Thanks
Ross

> 
>> +} __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;
>> +
> 
> These two look preliminary, so better to drop them now and introduce
> only once you know what they will look like.
> 
>> +struct slr_entry_uefi_config {
>> +       struct slr_entry_hdr hdr;
>> +       u16 revision;
>> +       u16 nr_entries;
>> +       /* uefi_cfg_entries[] */
> 
> Use a flex array
> 
>> +} __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)
> 
> typo 'entrys' ?
> 
>> +{
>> +       return (((void *)table) + table->size);
> 
> You can drop two sets of parens here
> 
>> +}
>> +
>> +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));
>> +
>> +       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 */
>> --
>> 2.39.3
>>