Re: [PATCH 1/6] efi: Retrieve Apple device properties

[Andrei Borzenkov]

27.07.2016 14:20, Lukas Wunner пишет:
> Retrieve device properties from EFI using Apple's proprietary protocol
> with GUID 91BD12FE-F6C3-44FB-A5B7-5122AB303AE0, which looks like this:
> 
> typedef struct {
>       unsigned long signature; /* 0x10000 */
>       efi_status_t (*get) (
>               IN struct apple_properties_protocol *this,
>               IN struct efi_generic_dev_path *device,
>               IN efi_char16_t *property_name,
>               OUT void *buffer,
>               IN OUT u32 *buffer_size);
>               /* EFI_SUCCESS, EFI_NOT_FOUND, EFI_BUFFER_TOO_SMALL */
>       efi_status_t (*set) (
>               IN struct apple_properties_protocol *this,
>               IN struct efi_generic_dev_path *device,
>               IN efi_char16_t *property_name,
>               IN void *property_value,
>               IN u32 property_value_len);
>               /* allocates copies of property name and value */
>               /* EFI_SUCCESS, EFI_OUT_OF_RESOURCES */
>       efi_status_t (*del) (
>               IN struct apple_properties_protocol *this,
>               IN struct efi_generic_dev_path *device,
>               IN efi_char16_t *property_name);
>               /* EFI_SUCCESS, EFI_NOT_FOUND */
>       efi_status_t (*get_all) (
>               IN struct apple_properties_protocol *this,
>               OUT void *buffer,
>               IN OUT u32 *buffer_size);
>               /* EFI_SUCCESS, EFI_BUFFER_TOO_SMALL */
> } apple_properties_protocol;
> 
> Apple's EFI driver implementing this protocol, "AAPL,PathProperties",
> is a per-device key/value store which is populated by other EFI drivers.
> On macOS, these device properties are retrieved by the bootloader
> /usr/standalone/i386/boot.efi. The extension AppleACPIPlatform.kext
> subsequently merges them into the I/O Kit registry (see ioreg(8)) where
> they can be queried by other kernel extensions and user space.
> 
> These device properties contain vital information which cannot be
> obtained any other way (e.g. Thunderbolt Device ROM). EFI drivers also
> use them to communicate the current device state so that OS drivers can
> pick up where EFI drivers left (e.g. GPU mode setting).
> 
> The get_all() function conveniently fills a buffer with all properties
> in marshalled form which can be passed to the kernel as a setup_data
> payload. Note that the device properties will only be available if the
> kernel is booted with the efistub. Distros should adjust their
> installers to always use the efistub on Macs. grub with the "linux"
> directive will not work unless the functionality of this commit is
> duplicated in grub. (The "linuxefi" directive should work but is not
> included upstream as of this writing.)
> 

Intention was to partially merge linuxefi functionality into "linux" by
autodetecting and preferring EFI stub support. Peter, any progress on this?

> Thanks to osxreverser for this blog posting which was helpful in reverse
> engineering Apple's EFI drivers and bootloader:
> https://reverse.put.as/2016/06/25/apple-efi-firmware-passwords-and-the-scbo-myth/
> 
> If someone at Apple is reading this, please note there's a memory leak
> in your implementation of the del() function as the property struct is
> freed but the name and value allocations are not.
> 
> Cc: address@hidden
> Cc: address@hidden
> Cc: Matt Fleming <address@hidden>
> Cc: Andreas Noever <address@hidden>
> Tested-by: Lukas Wunner <address@hidden> [MacBookPro9,1]
> Tested-by: Pierre Moreau <address@hidden> [MacBookPro11,3]
> Signed-off-by: Lukas Wunner <address@hidden>
> ---
>  arch/x86/boot/compressed/eboot.c      | 55 
> +++++++++++++++++++++++++++++++++++
>  arch/x86/include/uapi/asm/bootparam.h |  1 +
>  include/linux/efi.h                   | 17 +++++++++++
>  3 files changed, 73 insertions(+)
> 
> diff --git a/arch/x86/boot/compressed/eboot.c 
> b/arch/x86/boot/compressed/eboot.c
> index ff574da..7262ee4 100644
> --- a/arch/x86/boot/compressed/eboot.c
> +++ b/arch/x86/boot/compressed/eboot.c
> @@ -571,6 +571,55 @@ free_handle:
>       efi_call_early(free_pool, pci_handle);
>  }
>  
> +static void retrieve_apple_device_properties(struct boot_params *params)
> +{
> +     efi_guid_t guid = APPLE_PROPERTIES_PROTOCOL_GUID;
> +     struct setup_data *data, *new;
> +     efi_status_t status;
> +     void *properties;
> +     u32 size = 0;
> +
> +     status = efi_early->call(
> +                     (unsigned long)sys_table->boottime->locate_protocol,
> +                     &guid, NULL, &properties);
> +     if (status != EFI_SUCCESS)
> +             return;
> +
> +     do {
> +             status = efi_call_early(allocate_pool, EFI_LOADER_DATA,
> +                     size + sizeof(struct setup_data), &new);
> +             if (status != EFI_SUCCESS) {
> +                     efi_printk(sys_table,
> +                                "Failed to alloc mem for properties\n");
> +                     return;
> +             }
> +             status = efi_early->call(efi_early->is64 ?
> +                     ((apple_properties_protocol_64 *)properties)->get_all :
> +                     ((apple_properties_protocol_32 *)properties)->get_all,
> +                     properties, new->data, &size);
> +             if (status == EFI_BUFFER_TOO_SMALL)
> +                     efi_call_early(free_pool, new);
> +     } while (status == EFI_BUFFER_TOO_SMALL);
> +
> +     if (!size) {
> +             efi_call_early(free_pool, new);
> +             return;
> +     }
> +
> +     new->type = SETUP_APPLE_PROPERTIES;
> +     new->len  = size;
> +     new->next = 0;
> +
> +     data = (struct setup_data *)(unsigned long)params->hdr.setup_data;
> +     if (!data)
> +             params->hdr.setup_data = (unsigned long)new;
> +     else {
> +             while (data->next)
> +                     data = (struct setup_data *)(unsigned long)data->next;
> +             data->next = (unsigned long)new;
> +     }
> +}
> +
>  static efi_status_t
>  setup_uga32(void **uga_handle, unsigned long size, u32 *width, u32 *height)
>  {
> @@ -1098,6 +1147,7 @@ free_mem_map:
>  struct boot_params *efi_main(struct efi_config *c,
>                            struct boot_params *boot_params)
>  {
> +     efi_char16_t const apple[] = { 'A', 'p', 'p', 'l', 'e', 0 };
>       struct desc_ptr *gdt = NULL;
>       efi_loaded_image_t *image;
>       struct setup_header *hdr = &boot_params->hdr;
> @@ -1128,6 +1178,11 @@ struct boot_params *efi_main(struct efi_config *c,
>  
>       setup_efi_pci(boot_params);
>  
> +     if (!memcmp((void *)sys_table->fw_vendor, apple, sizeof(apple))) {
> +             if (IS_ENABLED(CONFIG_APPLE_PROPERTIES))
> +                     retrieve_apple_device_properties(boot_params);
> +     }
> +
>       status = efi_call_early(allocate_pool, EFI_LOADER_DATA,
>                               sizeof(*gdt), (void **)&gdt);
>       if (status != EFI_SUCCESS) {
> diff --git a/arch/x86/include/uapi/asm/bootparam.h 
> b/arch/x86/include/uapi/asm/bootparam.h
> index c18ce67..b10bf31 100644
> --- a/arch/x86/include/uapi/asm/bootparam.h
> +++ b/arch/x86/include/uapi/asm/bootparam.h
> @@ -7,6 +7,7 @@
>  #define SETUP_DTB                    2
>  #define SETUP_PCI                    3
>  #define SETUP_EFI                    4
> +#define SETUP_APPLE_PROPERTIES               5
>  
>  /* ram_size flags */
>  #define RAMDISK_IMAGE_START_MASK     0x07FF
> diff --git a/include/linux/efi.h b/include/linux/efi.h
> index 7f80a75..e53b4b2 100644
> --- a/include/linux/efi.h
> +++ b/include/linux/efi.h
> @@ -432,6 +432,22 @@ typedef struct {
>  #define EFI_PCI_IO_ATTRIBUTE_VGA_PALETTE_IO_16 0x20000
>  #define EFI_PCI_IO_ATTRIBUTE_VGA_IO_16 0x40000
>  
> +typedef struct {
> +     u32 signature;
> +     u32 get;
> +     u32 set;
> +     u32 del;
> +     u32 get_all;
> +} apple_properties_protocol_32;
> +
> +typedef struct {
> +     u64 signature;
> +     u64 get;
> +     u64 set;
> +     u64 del;
> +     u64 get_all;
> +} apple_properties_protocol_64;
> +
>  /*
>   * Types and defines for EFI ResetSystem
>   */
> @@ -580,6 +596,7 @@ void efi_native_runtime_setup(void);
>  #define EFI_RNG_PROTOCOL_GUID                        EFI_GUID(0x3152bca5, 
> 0xeade, 0x433d,  0x86, 0x2e, 0xc0, 0x1c, 0xdc, 0x29, 0x1f, 0x44)
>  #define EFI_MEMORY_ATTRIBUTES_TABLE_GUID     EFI_GUID(0xdcfa911d, 0x26eb, 
> 0x469f,  0xa2, 0x20, 0x38, 0xb7, 0xdc, 0x46, 0x12, 0x20)
>  #define EFI_CONSOLE_OUT_DEVICE_GUID          EFI_GUID(0xd3b36f2c, 0xd551, 
> 0x11d4,  0x9a, 0x46, 0x00, 0x90, 0x27, 0x3f, 0xc1, 0x4d)
> +#define APPLE_PROPERTIES_PROTOCOL_GUID               EFI_GUID(0x91bd12fe, 
> 0xf6c3, 0x44fb,  0xa5, 0xb7, 0x51, 0x22, 0xab, 0x30, 0x3a, 0xe0)
>  
>  /*
>   * This GUID is used to pass to the kernel proper the struct screen_info
>