[efi] Expose downloaded images via EFI_SIMPLE_FILE_SYSTEM_PROTOCOL

Expose iPXE's images as a UEFI file system, allowing the booted image
to access all images downloaded by iPXE.

This functionality is complementary to the custom iPXE download
protocol.  The iPXE download protocol allows a booted image to utilise
iPXE to download arbitrary URIs, but requires the booted image to
specifically support the custom iPXE download protocol.  The new
functionality limits the booted image to accessing only files that
were already downloaded by iPXE (e.g. as part of a script), but can
work with any generic UEFI image (e.g. the UEFI shell).  Both
protocols are provided simultaneously, and are attached to the SNP
device handle.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

1 files changed, 594 insertions, 0 deletions

diff --git a/src/interface/efi/efi_file.c b/src/interface/efi/efi_file.c
new file mode 100644
index 00000000..ffe25fd6
--- /dev/null
+++ b/src/interface/efi/efi_file.c
@@ -0,0 +1,594 @@
+/*
+ * Copyright (C) 2013 Michael Brown <mbrown@fensystems.co.uk>.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+/**
+ * @file
+ *
+ * EFI file protocols
+ *
+ */
+
+#include <stddef.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <wchar.h>
+#include <ipxe/image.h>
+#include <ipxe/efi/efi.h>
+#include <ipxe/efi/Protocol/SimpleFileSystem.h>
+#include <ipxe/efi/Protocol/BlockIo.h>
+#include <ipxe/efi/Guid/FileInfo.h>
+#include <ipxe/efi/Guid/FileSystemInfo.h>
+#include <ipxe/efi/efi_strings.h>
+#include <ipxe/efi/efi_file.h>
+
+/** EFI simple file system protocol GUID */
+static EFI_GUID efi_simple_file_system_protocol_guid
+	= EFI_SIMPLE_FILE_SYSTEM_PROTOCOL_GUID;
+
+/** EFI file information GUID */
+static EFI_GUID efi_file_info_id = EFI_FILE_INFO_ID;
+
+/** EFI file system information GUID */
+static EFI_GUID efi_file_system_info_id = EFI_FILE_SYSTEM_INFO_ID;
+
+/** EFI block I/O protocol GUID */
+static EFI_GUID efi_block_io_protocol_guid
+	= EFI_BLOCK_IO_PROTOCOL_GUID;
+
+/** EFI media ID */
+#define EFI_MEDIA_ID_MAGIC 0x69505845
+
+/** An image exposed as an EFI file */
+struct efi_file {
+	/** EFI file protocol */
+	EFI_FILE_PROTOCOL file;
+	/** Image */
+	struct image *image;
+	/** Current file position */
+	size_t pos;
+};
+
+static struct efi_file efi_file_root;
+
+/**
+ * Get EFI file name (for debugging)
+ *
+ * @v file		EFI file
+ * @ret name		Name
+ */
+static const char * efi_file_name ( struct efi_file *file ) {
+
+	return ( file->image ? file->image->name : "<root>" );
+}
+
+/**
+ * Open file
+ *
+ * @v this		EFI file
+ * @ret new		New EFI file
+ * @v wname		Filename
+ * @v mode		File mode
+ * @v attributes	File attributes (for newly-created files)
+ * @ret efirc		EFI status code
+ */
+static EFI_STATUS EFIAPI
+efi_file_open ( EFI_FILE_PROTOCOL *this, EFI_FILE_PROTOCOL **new,
+		CHAR16 *wname, UINT64 mode __unused,
+		UINT64 attributes __unused ) {
+	struct efi_file *file = container_of ( this, struct efi_file, file );
+	char name[ wcslen ( wname ) + 1 /* NUL */ ];
+	struct efi_file *new_file;
+	struct image *image;
+
+	/* Initial '\' indicates opening from the root directory */
+	while ( *wname == L'\\' ) {
+		file = &efi_file_root;
+		wname++;
+	}
+
+	/* Allow root directory itself to be opened */
+	if ( ( wname[0] == L'\0' ) || ( wname[0] == L'.' ) ) {
+		*new = &efi_file_root.file;
+		return 0;
+	}
+
+	/* Fail unless opening from the root */
+	if ( file->image ) {
+		DBGC ( file, "EFIFILE %s is not a directory\n",
+		       efi_file_name ( file ) );
+		return EFI_NOT_FOUND;
+	}
+
+	/* Identify image */
+	snprintf ( name, sizeof ( name ), "%ls", wname );
+	image = find_image ( name );
+	if ( ! image ) {
+		DBGC ( file, "EFIFILE \"%s\" does not exist\n", name );
+		return EFI_NOT_FOUND;
+	}
+
+	/* Fail unless opening read-only */
+	if ( mode != EFI_FILE_MODE_READ ) {
+		DBGC ( file, "EFIFILE %s cannot be opened in mode %#08llx\n",
+		       image->name, mode );
+		return EFI_WRITE_PROTECTED;
+	}
+
+	/* Allocate and initialise file */
+	new_file = zalloc ( sizeof ( *new_file ) );
+	memcpy ( &new_file->file, &efi_file_root.file,
+		 sizeof ( new_file->file ) );
+	new_file->image = image_get ( image );
+	*new = &new_file->file;
+	DBGC ( new_file, "EFIFILE %s opened\n", efi_file_name ( new_file ) );
+
+	return 0;
+}
+
+/**
+ * Close file
+ *
+ * @v this		EFI file
+ * @ret efirc		EFI status code
+ */
+static EFI_STATUS EFIAPI efi_file_close ( EFI_FILE_PROTOCOL *this ) {
+	struct efi_file *file = container_of ( this, struct efi_file, file );
+
+	/* Do nothing if this is the root */
+	if ( ! file->image )
+		return 0;
+
+	/* Close file */
+	DBGC ( file, "EFIFILE %s closed\n", efi_file_name ( file ) );
+	image_put ( file->image );
+	free ( file );
+
+	return 0;
+}
+
+/**
+ * Close and delete file
+ *
+ * @v this		EFI file
+ * @ret efirc		EFI status code
+ */
+static EFI_STATUS EFIAPI efi_file_delete ( EFI_FILE_PROTOCOL *this ) {
+	struct efi_file *file = container_of ( this, struct efi_file, file );
+
+	DBGC ( file, "EFIFILE %s cannot be deleted\n", efi_file_name ( file ) );
+
+	/* Close file */
+	efi_file_close ( this );
+
+	/* Warn of failure to delete */
+	return EFI_WARN_DELETE_FAILURE;
+}
+
+/**
+ * Return variable-length data structure
+ *
+ * @v base		Base data structure (starting with UINT64)
+ * @v base_len		Length of base data structure
+ * @v name		Name to append to base data structure
+ * @v len		Length of data buffer
+ * @v data		Data buffer
+ * @ret efirc		EFI status code
+ */
+static EFI_STATUS efi_file_varlen ( UINT64 *base, size_t base_len,
+				    const char *name, UINTN *len, VOID *data ) {
+	size_t name_len;
+
+	/* Calculate structure length */
+	name_len = strlen ( name );
+	*base = ( base_len + ( name_len + 1 /* NUL */ ) * sizeof ( wchar_t ) );
+	if ( *len < *base ) {
+		*len = *base;
+		return EFI_BUFFER_TOO_SMALL;
+	}
+
+	/* Copy data to buffer */
+	*len = *base;
+	memcpy ( data, base, base_len );
+	efi_snprintf ( ( data + base_len ), ( name_len + 1 /* NUL */ ),
+		       "%s", name );
+
+	return 0;
+}
+
+/**
+ * Return file information structure
+ *
+ * @v image		Image, or NULL for the root directory
+ * @v len		Length of data buffer
+ * @v data		Data buffer
+ * @ret efirc		EFI status code
+ */
+static EFI_STATUS efi_file_info ( struct image *image, UINTN *len,
+				  VOID *data ) {
+	EFI_FILE_INFO info;
+	const char *name;
+
+	/* Populate file information */
+	memset ( &info, 0, sizeof ( info ) );
+	if ( image ) {
+		info.FileSize = image->len;
+		info.PhysicalSize = image->len;
+		info.Attribute = EFI_FILE_READ_ONLY;
+		name = image->name;
+	} else {
+		info.Attribute = ( EFI_FILE_READ_ONLY | EFI_FILE_DIRECTORY );
+		name = "";
+	}
+
+	return efi_file_varlen ( &info.Size, SIZE_OF_EFI_FILE_INFO, name,
+				 len, data );
+}
+
+/**
+ * Read directory entry
+ *
+ * @v file		EFI file
+ * @v len		Length to read
+ * @v data		Data buffer
+ * @ret efirc		EFI status code
+ */
+static EFI_STATUS efi_file_read_dir ( struct efi_file *file, UINTN *len,
+				      VOID *data ) {
+	EFI_STATUS efirc;
+	struct image *image;
+	unsigned int index;
+
+	/* Construct directory entry at current position */
+	index = file->pos;
+	for_each_image ( image ) {
+		if ( index-- == 0 ) {
+			efirc = efi_file_info ( image, len, data );
+			if ( efirc == 0 )
+				file->pos++;
+			return efirc;
+		}
+	}
+
+	/* No more entries */
+	*len = 0;
+	return 0;
+}
+
+/**
+ * Read from file
+ *
+ * @v this		EFI file
+ * @v len		Length to read
+ * @v data		Data buffer
+ * @ret efirc		EFI status code
+ */
+static EFI_STATUS EFIAPI efi_file_read ( EFI_FILE_PROTOCOL *this,
+					 UINTN *len, VOID *data ) {
+	struct efi_file *file = container_of ( this, struct efi_file, file );
+	size_t remaining;
+
+	/* If this is the root directory, then construct a directory entry */
+	if ( ! file->image )
+		return efi_file_read_dir ( file, len, data );
+
+	/* Read from the file */
+	remaining = ( file->image->len - file->pos );
+	if ( *len > remaining )
+		*len = remaining;
+	DBGC ( file, "EFIFILE %s read [%#08zx,%#08zx)\n",
+	       efi_file_name ( file ), file->pos,
+	       ( ( size_t ) ( file->pos + *len ) ) );
+	copy_from_user ( data, file->image->data, file->pos, *len );
+	file->pos += *len;
+	return 0;
+}
+
+/**
+ * Write to file
+ *
+ * @v this		EFI file
+ * @v len		Length to write
+ * @v data		Data buffer
+ * @ret efirc		EFI status code
+ */
+static EFI_STATUS EFIAPI efi_file_write ( EFI_FILE_PROTOCOL *this,
+					  UINTN *len, VOID *data __unused ) {
+	struct efi_file *file = container_of ( this, struct efi_file, file );
+
+	DBGC ( file, "EFIFILE %s cannot write [%#08zx, %#08zx)\n",
+	       efi_file_name ( file ), file->pos,
+	       ( ( size_t ) ( file->pos + *len ) ) );
+	return EFI_WRITE_PROTECTED;
+}
+
+/**
+ * Set file position
+ *
+ * @v this		EFI file
+ * @v position		New file position
+ * @ret efirc		EFI status code
+ */
+static EFI_STATUS EFIAPI efi_file_set_position ( EFI_FILE_PROTOCOL *this,
+						 UINT64 position ) {
+	struct efi_file *file = container_of ( this, struct efi_file, file );
+
+	/* If this is the root directory, reset to the start */
+	if ( ! file->image ) {
+		DBGC ( file, "EFIFILE root directory rewound\n" );
+		file->pos = 0;
+		return 0;
+	}
+
+	/* Check for the magic end-of-file value */
+	if ( position == 0xffffffffffffffffULL )
+		position = file->image->len;
+
+	/* Fail if we attempt to seek past the end of the file (since
+	 * we do not support writes).
+	 */
+	if ( position > file->image->len ) {
+		DBGC ( file, "EFIFILE %s cannot seek to %#08llx of %#08zx\n",
+		       efi_file_name ( file ), position, file->image->len );
+		return EFI_UNSUPPORTED;
+	}
+
+	/* Set position */
+	file->pos = position;
+	DBGC ( file, "EFIFILE %s position set to %#08zx\n",
+	       efi_file_name ( file ), file->pos );
+
+	return 0;
+}
+
+/**
+ * Get file position
+ *
+ * @v this		EFI file
+ * @ret position	New file position
+ * @ret efirc		EFI status code
+ */
+static EFI_STATUS EFIAPI efi_file_get_position ( EFI_FILE_PROTOCOL *this,
+						 UINT64 *position ) {
+	struct efi_file *file = container_of ( this, struct efi_file, file );
+
+	*position = file->pos;
+	return 0;
+}
+
+/**
+ * Get file information
+ *
+ * @v this		EFI file
+ * @v type		Type of information
+ * @v len		Buffer size
+ * @v data		Buffer
+ * @ret efirc		EFI status code
+ */
+static EFI_STATUS EFIAPI efi_file_get_info ( EFI_FILE_PROTOCOL *this,
+					     EFI_GUID *type,
+					     UINTN *len, VOID *data ) {
+	struct efi_file *file = container_of ( this, struct efi_file, file );
+	EFI_FILE_SYSTEM_INFO fsinfo;
+	struct image *image;
+
+	/* Determine information to return */
+	if ( memcmp ( type, &efi_file_info_id, sizeof ( *type ) ) == 0 ) {
+
+		/* Get file information */
+		DBGC ( file, "EFIFILE %s get file information\n",
+		       efi_file_name ( file ) );
+		return efi_file_info ( file->image, len, data );
+
+	} else if ( memcmp ( type, &efi_file_system_info_id,
+			     sizeof ( *type ) ) == 0 ) {
+
+		/* Get file system information */
+		DBGC ( file, "EFIFILE %s get file system information\n",
+		       efi_file_name ( file ) );
+		memset ( &fsinfo, 0, sizeof ( fsinfo ) );
+		fsinfo.ReadOnly = 1;
+		for_each_image ( image )
+			fsinfo.VolumeSize += image->len;
+		return efi_file_varlen ( &fsinfo.Size,
+					 SIZE_OF_EFI_FILE_SYSTEM_INFO, "iPXE",
+					 len, data );
+	} else {
+
+		DBGC ( file, "EFIFILE %s cannot get information of type %s\n",
+		       efi_file_name ( file ),
+		       uuid_ntoa ( ( union uuid * ) type ) );
+		return EFI_UNSUPPORTED;
+	}
+}
+
+/**
+ * Set file information
+ *
+ * @v this		EFI file
+ * @v type		Type of information
+ * @v len		Buffer size
+ * @v data		Buffer
+ * @ret efirc		EFI status code
+ */
+static EFI_STATUS EFIAPI
+efi_file_set_info ( EFI_FILE_PROTOCOL *this, EFI_GUID *type,
+		    UINTN len __unused, VOID *data __unused ) {
+	struct efi_file *file = container_of ( this, struct efi_file, file );
+
+	DBGC ( file, "EFIFILE %s cannot set information of type %s\n",
+	       efi_file_name ( file ), uuid_ntoa ( ( union uuid * ) type ) );
+	return EFI_WRITE_PROTECTED;
+}
+
+/**
+ * Flush file modified data
+ *
+ * @v this		EFI file
+ * @v type		Type of information
+ * @v len		Buffer size
+ * @v data		Buffer
+ * @ret efirc		EFI status code
+ */
+static EFI_STATUS EFIAPI efi_file_flush ( EFI_FILE_PROTOCOL *this ) {
+	struct efi_file *file = container_of ( this, struct efi_file, file );
+
+	DBGC ( file, "EFIFILE %s flushed\n", efi_file_name ( file ) );
+	return 0;
+}
+
+/** Root directory */
+static struct efi_file efi_file_root = {
+	.file = {
+		.Revision = EFI_FILE_PROTOCOL_REVISION,
+		.Open = efi_file_open,
+		.Close = efi_file_close,
+		.Delete = efi_file_delete,
+		.Read = efi_file_read,
+		.Write = efi_file_write,
+		.GetPosition = efi_file_get_position,
+		.SetPosition = efi_file_set_position,
+		.GetInfo = efi_file_get_info,
+		.SetInfo = efi_file_set_info,
+		.Flush = efi_file_flush,
+	},
+	.image = NULL,
+};
+
+/**
+ * Open root directory
+ *
+ * @v filesystem	EFI simple file system
+ * @ret file		EFI file handle
+ * @ret efirc		EFI status code
+ */
+static EFI_STATUS EFIAPI
+efi_file_open_volume ( EFI_SIMPLE_FILE_SYSTEM_PROTOCOL *filesystem __unused,
+		       EFI_FILE_PROTOCOL **file ) {
+
+	*file = &efi_file_root.file;
+	return 0;
+}
+
+/** EFI simple file system protocol */
+static EFI_SIMPLE_FILE_SYSTEM_PROTOCOL efi_simple_file_system_protocol = {
+	.Revision = EFI_SIMPLE_FILE_SYSTEM_PROTOCOL_REVISION,
+	.OpenVolume = efi_file_open_volume,
+};
+
+/** Dummy block I/O reset */
+static EFI_STATUS EFIAPI
+efi_block_io_reset ( EFI_BLOCK_IO_PROTOCOL *this __unused,
+		     BOOLEAN extended __unused ) {
+	return 0;
+}
+
+/** Dummy block I/O read */
+static EFI_STATUS EFIAPI
+efi_block_io_read_blocks ( EFI_BLOCK_IO_PROTOCOL *this __unused,
+			   UINT32 MediaId __unused, EFI_LBA lba __unused,
+			   UINTN len __unused, VOID *data __unused ) {
+	return EFI_DEVICE_ERROR;
+}
+
+/** Dummy block I/O write */
+static EFI_STATUS EFIAPI
+efi_block_io_write_blocks ( EFI_BLOCK_IO_PROTOCOL *this __unused,
+			    UINT32 MediaId __unused, EFI_LBA lba __unused,
+			    UINTN len __unused, VOID *data __unused ) {
+	return EFI_DEVICE_ERROR;
+}
+
+/** Dummy block I/O flush */
+static EFI_STATUS EFIAPI
+efi_block_io_flush_blocks ( EFI_BLOCK_IO_PROTOCOL *this __unused ) {
+	return 0;
+}
+
+/** Dummy block I/O media */
+static EFI_BLOCK_IO_MEDIA efi_block_io_media = {
+	.MediaId = EFI_MEDIA_ID_MAGIC,
+	.MediaPresent = 1,
+	.ReadOnly = 1,
+	.BlockSize = 1,
+};
+
+/** Dummy EFI block I/O protocol */
+static EFI_BLOCK_IO_PROTOCOL efi_block_io_protocol = {
+	.Revision = EFI_BLOCK_IO_PROTOCOL_REVISION,
+	.Media = &efi_block_io_media,
+	.Reset = efi_block_io_reset,
+	.ReadBlocks = efi_block_io_read_blocks,
+	.WriteBlocks = efi_block_io_write_blocks,
+	.FlushBlocks = efi_block_io_flush_blocks,
+};
+
+/**
+ * Install EFI simple file system protocol
+ *
+ * @v handle		EFI handle
+ * @ret rc		Return status code
+ */
+int efi_file_install ( EFI_HANDLE *handle ) {
+	EFI_BOOT_SERVICES *bs = efi_systab->BootServices;
+	EFI_STATUS efirc;
+
+	/* Install the simple file system protocol and the block I/O
+	 * protocol.  We don't have a block device, but large parts of
+	 * the EDK2 codebase make the assumption that file systems are
+	 * normally attached to block devices, and so we create a
+	 * dummy block device on the same handle just to keep things
+	 * looking normal.
+	 */
+	if ( ( efirc = bs->InstallMultipleProtocolInterfaces (
+			handle,
+			&efi_block_io_protocol_guid,
+			&efi_block_io_protocol,
+			&efi_simple_file_system_protocol_guid,
+			&efi_simple_file_system_protocol, NULL ) ) != 0 ) {
+		DBGC ( handle, "Could not install simple file system protocol: "
+		       "%s\n", efi_strerror ( efirc ) );
+		return EFIRC_TO_RC ( efirc );
+	}
+
+	return 0;
+}
+
+/**
+ * Uninstall EFI simple file system protocol
+ *
+ * @v handle		EFI handle
+ */
+void efi_file_uninstall ( EFI_HANDLE handle ) {
+	EFI_BOOT_SERVICES *bs = efi_systab->BootServices;
+
+	/* We must install the file system protocol first, since
+	 * otherwise the EDK2 code will attempt to helpfully uninstall
+	 * it when the block I/O protocol is uninstalled, leading to a
+	 * system lock-up.
+	 */
+	bs->UninstallMultipleProtocolInterfaces (
+			handle,
+			&efi_simple_file_system_protocol_guid,
+			&efi_simple_file_system_protocol,
+			&efi_block_io_protocol_guid,
+			&efi_block_io_protocol, NULL );
+}