[efi] Provide access to files stored on EFI filesystems

Provide access to local files via the "file://" URI scheme.  There are
three syntaxes:

  - An opaque URI with a relative path (e.g. "file:script.ipxe").
    This will be interpreted as a path relative to the iPXE binary.

  - A hierarchical URI with a non-network absolute path
    (e.g. "file:/boot/script.ipxe").  This will be interpreted as a
    path relative to the root of the filesystem from which the iPXE
    binary was loaded.

  - A hierarchical URI with a network path in which the authority is a
    volume label (e.g. "file://bootdisk/script.ipxe").  This will be
    interpreted as a path relative to the root of the filesystem with
    the specified volume label.

Note that the potentially desirable shell mappings (e.g. "fs0:" and
"blk0:") are concepts internal to the UEFI shell binary, and do not
seem to be exposed in any way to external executables.  The old
EFI_SHELL_PROTOCOL (which did provide access to these mappings) is no
longer installed by current versions of the UEFI shell.

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

1 files changed, 573 insertions, 0 deletions

diff --git a/src/interface/efi/efi_local.c b/src/interface/efi/efi_local.c
new file mode 100644
index 00000000..bd010ad2
--- /dev/null
+++ b/src/interface/efi/efi_local.c
@@ -0,0 +1,573 @@
+/*
+ * Copyright (C) 2016 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 (at your option) 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.
+ *
+ * You can also choose to distribute this program under the terms of
+ * the Unmodified Binary Distribution Licence (as given in the file
+ * COPYING.UBDL), provided that you have satisfied its requirements.
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
+
+#include <string.h>
+#include <strings.h>
+#include <stdio.h>
+#include <errno.h>
+#include <assert.h>
+#include <ipxe/refcnt.h>
+#include <ipxe/malloc.h>
+#include <ipxe/xfer.h>
+#include <ipxe/open.h>
+#include <ipxe/uri.h>
+#include <ipxe/iobuf.h>
+#include <ipxe/process.h>
+#include <ipxe/efi/efi.h>
+#include <ipxe/efi/efi_strings.h>
+#include <ipxe/efi/efi_utils.h>
+#include <ipxe/efi/Protocol/SimpleFileSystem.h>
+#include <ipxe/efi/Guid/FileInfo.h>
+#include <ipxe/efi/Guid/FileSystemInfo.h>
+
+/** @file
+ *
+ * EFI local file access
+ *
+ */
+
+/** Download blocksize */
+#define EFI_LOCAL_BLKSIZE 4096
+
+/** An EFI local file */
+struct efi_local {
+	/** Reference count */
+	struct refcnt refcnt;
+	/** Data transfer interface */
+	struct interface xfer;
+	/** Download process */
+	struct process process;
+
+	/** EFI root directory */
+	EFI_FILE_PROTOCOL *root;
+	/** EFI file */
+	EFI_FILE_PROTOCOL *file;
+	/** Length of file */
+	size_t len;
+};
+
+/**
+ * Close local file
+ *
+ * @v local		Local file
+ * @v rc		Reason for close
+ */
+static void efi_local_close ( struct efi_local *local, int rc ) {
+
+	/* Stop process */
+	process_del ( &local->process );
+
+	/* Shut down data transfer interface */
+	intf_shutdown ( &local->xfer, rc );
+
+	/* Close EFI file */
+	if ( local->file ) {
+		local->file->Close ( local->file );
+		local->file = NULL;
+	}
+
+	/* Close EFI root directory */
+	if ( local->root ) {
+		local->root->Close ( local->root );
+		local->root = NULL;
+	}
+}
+
+/**
+ * Local file process
+ *
+ * @v local		Local file
+ */
+static void efi_local_step ( struct efi_local *local ) {
+	EFI_FILE_PROTOCOL *file = local->file;
+	struct io_buffer *iobuf = NULL;
+	size_t remaining;
+	size_t frag_len;
+	UINTN size;
+	EFI_STATUS efirc;
+	int rc;
+
+	/* Wait until data transfer interface is ready */
+	if ( ! xfer_window ( &local->xfer ) )
+		return;
+
+	/* Presize receive buffer */
+	remaining = local->len;
+	xfer_seek ( &local->xfer, remaining );
+	xfer_seek ( &local->xfer, 0 );
+
+	/* Get file contents */
+	while ( remaining ) {
+
+		/* Calculate length for this fragment */
+		frag_len = remaining;
+		if ( frag_len > EFI_LOCAL_BLKSIZE )
+			frag_len = EFI_LOCAL_BLKSIZE;
+
+		/* Allocate I/O buffer */
+		iobuf = xfer_alloc_iob ( &local->xfer, frag_len );
+		if ( ! iobuf ) {
+			rc = -ENOMEM;
+			goto err;
+		}
+
+		/* Read block */
+		size = frag_len;
+		if ( ( efirc = file->Read ( file, &size, iobuf->data ) ) != 0 ){
+			rc = -EEFI ( efirc );
+			DBGC ( local, "LOCAL %p could not read from file: %s\n",
+			       local, strerror ( rc ) );
+			goto err;
+		}
+		assert ( size <= frag_len );
+		iob_put ( iobuf, size );
+
+		/* Deliver data */
+		if ( ( rc = xfer_deliver_iob ( &local->xfer,
+					       iob_disown ( iobuf ) ) ) != 0 ) {
+			DBGC ( local, "LOCAL %p could not deliver data: %s\n",
+			       local, strerror ( rc ) );
+			goto err;
+		}
+
+		/* Move to next block */
+		remaining -= frag_len;
+	}
+
+	/* Close download */
+	efi_local_close ( local, 0 );
+
+	return;
+
+ err:
+	free_iob ( iobuf );
+	efi_local_close ( local, rc );
+}
+
+/** Data transfer interface operations */
+static struct interface_operation efi_local_operations[] = {
+	INTF_OP ( xfer_window_changed, struct efi_local *, efi_local_step ),
+	INTF_OP ( intf_close, struct efi_local *, efi_local_close ),
+};
+
+/** Data transfer interface descriptor */
+static struct interface_descriptor efi_local_xfer_desc =
+	INTF_DESC ( struct efi_local, xfer, efi_local_operations );
+
+/** Process descriptor */
+static struct process_descriptor efi_local_process_desc =
+	PROC_DESC_ONCE ( struct efi_local, process, efi_local_step );
+
+/**
+ * Check for matching volume name
+ *
+ * @v local		Local file
+ * @v device		Device handle
+ * @v root		Root filesystem handle
+ * @v volume		Volume name
+ * @ret rc		Return status code
+ */
+static int efi_local_check_volume_name ( struct efi_local *local,
+					 EFI_HANDLE device,
+					 EFI_FILE_PROTOCOL *root,
+					 const char *volume ) {
+	EFI_FILE_SYSTEM_INFO *info;
+	UINTN size;
+	char *label;
+	EFI_STATUS efirc;
+	int rc;
+
+	/* Get length of file system information */
+	size = 0;
+	root->GetInfo ( root, &efi_file_system_info_id, &size, NULL );
+
+	/* Allocate file system information */
+	info = malloc ( size );
+	if ( ! info ) {
+		rc = -ENOMEM;
+		goto err_alloc_info;
+	}
+
+	/* Get file system information */
+	if ( ( efirc = root->GetInfo ( root, &efi_file_system_info_id, &size,
+				       info ) ) != 0 ) {
+		rc = -EEFI ( efirc );
+		DBGC ( local, "LOCAL %p could not get file system info on %s: "
+		       "%s\n", local, efi_handle_name ( device ),
+		       strerror ( rc ) );
+		goto err_get_info;
+	}
+	DBGC2 ( local, "LOCAL %p found %s with label \"%ls\"\n",
+		local, efi_handle_name ( device ), info->VolumeLabel );
+
+	/* Construct volume label for comparison */
+	if ( asprintf ( &label, "%ls", info->VolumeLabel ) < 0 ) {
+		rc = -ENOMEM;
+		goto err_alloc_label;
+	}
+
+	/* Compare volume label */
+	if ( strcasecmp ( volume, label ) != 0 ) {
+		rc = -ENOENT;
+		goto err_compare;
+	}
+
+	/* Success */
+	rc = 0;
+
+ err_compare:
+	free ( label );
+ err_alloc_label:
+ err_get_info:
+	free ( info );
+ err_alloc_info:
+	return rc;
+}
+
+/**
+ * Open root filesystem
+ *
+ * @v local		Local file
+ * @v device		Device handle
+ * @v root		Root filesystem handle to fill in
+ * @ret rc		Return status code
+ */
+static int efi_local_open_root ( struct efi_local *local, EFI_HANDLE device,
+				 EFI_FILE_PROTOCOL **root ) {
+	EFI_BOOT_SERVICES *bs = efi_systab->BootServices;
+	union {
+		void *interface;
+		EFI_SIMPLE_FILE_SYSTEM_PROTOCOL *fs;
+	} u;
+	EFI_STATUS efirc;
+	int rc;
+
+	/* Open file system protocol */
+	if ( ( efirc = bs->OpenProtocol ( device,
+					  &efi_simple_file_system_protocol_guid,
+					  &u.interface, efi_image_handle,
+					  device,
+					  EFI_OPEN_PROTOCOL_GET_PROTOCOL ))!=0){
+		rc = -EEFI ( efirc );
+		DBGC ( local, "LOCAL %p could not open filesystem on %s: %s\n",
+		       local, efi_handle_name ( device ), strerror ( rc ) );
+		goto err_filesystem;
+	}
+
+	/* Open root directory */
+	if ( ( efirc = u.fs->OpenVolume ( u.fs, root ) ) != 0 ) {
+		rc = -EEFI ( efirc );
+		DBGC ( local, "LOCAL %p could not open volume on %s: %s\n",
+		       local, efi_handle_name ( device ), strerror ( rc ) );
+		goto err_volume;
+	}
+
+	/* Success */
+	rc = 0;
+
+ err_volume:
+	bs->CloseProtocol ( device, &efi_simple_file_system_protocol_guid,
+			    efi_image_handle, device );
+ err_filesystem:
+	return rc;
+}
+
+/**
+ * Open root filesystem of specified volume
+ *
+ * @v local		Local file
+ * @v volume		Volume name, or NULL to use loaded image's device
+ * @ret rc		Return status code
+ */
+static int efi_local_open_volume ( struct efi_local *local,
+				   const char *volume ) {
+	EFI_BOOT_SERVICES *bs = efi_systab->BootServices;
+	EFI_GUID *protocol = &efi_simple_file_system_protocol_guid;
+	int ( * check ) ( struct efi_local *local, EFI_HANDLE device,
+			  EFI_FILE_PROTOCOL *root, const char *volume );
+	EFI_FILE_PROTOCOL *root;
+	EFI_HANDLE *handles;
+	EFI_HANDLE device;
+	UINTN num_handles;
+	UINTN i;
+	EFI_STATUS efirc;
+	int rc;
+
+	/* Identify candidate handles */
+	if ( volume ) {
+		/* Locate all filesystem handles */
+		if ( ( efirc = bs->LocateHandleBuffer ( ByProtocol, protocol,
+							NULL, &num_handles,
+							&handles ) ) != 0 ) {
+			rc = -EEFI ( efirc );
+			DBGC ( local, "LOCAL %p could not enumerate handles: "
+			       "%s\n", local, strerror ( rc ) );
+			return rc;
+		}
+		check = efi_local_check_volume_name;
+	} else {
+		/* Use our loaded image's device handle */
+		handles = &efi_loaded_image->DeviceHandle;
+		num_handles = 1;
+		check = NULL;
+	}
+
+	/* Find matching handle */
+	for ( i = 0 ; i < num_handles ; i++ ) {
+
+		/* Get this device handle */
+		device = handles[i];
+
+		/* Open root directory */
+		if ( ( rc = efi_local_open_root ( local, device, &root ) ) != 0)
+			continue;
+
+		/* Check volume name, if applicable */
+		if ( ( check == NULL ) ||
+		     ( ( rc = check ( local, device, root, volume ) ) == 0 ) ) {
+			DBGC ( local, "LOCAL %p using %s",
+			       local, efi_handle_name ( device ) );
+			if ( volume )
+				DBGC ( local, " with label \"%s\"", volume );
+			DBGC ( local, "\n" );
+			local->root = root;
+			break;
+		}
+
+		/* Close root directory */
+		root->Close ( root );
+	}
+
+	/* Free handles, if applicable */
+	if ( volume )
+		bs->FreePool ( handles );
+
+	/* Fail if we found no matching handle */
+	if ( ! local->root ) {
+		DBGC ( local, "LOCAL %p found no matching handle\n", local );
+		return -ENOENT;
+	}
+
+	return 0;
+}
+
+/**
+ * Open fully-resolved path
+ *
+ * @v local		Local file
+ * @v resolved		Resolved path
+ * @ret rc		Return status code
+ */
+static int efi_local_open_resolved ( struct efi_local *local,
+				     const char *resolved ) {
+	size_t name_len = strlen ( resolved );
+	CHAR16 name[ name_len + 1 /* wNUL */ ];
+	EFI_FILE_PROTOCOL *file;
+	EFI_STATUS efirc;
+	int rc;
+
+	/* Construct filename */
+	efi_snprintf ( name, ( name_len + 1 /* wNUL */ ), "%s", resolved );
+
+	/* Open file */
+	if ( ( efirc = local->root->Open ( local->root, &file, name,
+					   EFI_FILE_MODE_READ, 0 ) ) != 0 ) {
+		rc = -EEFI ( efirc );
+		DBGC ( local, "LOCAL %p could not open \"%s\": %s\n",
+		       local, resolved, strerror ( rc ) );
+		return rc;
+	}
+	local->file = file;
+
+	return 0;
+}
+
+/**
+ * Open specified path
+ *
+ * @v local		Local file
+ * @v path		Path to file
+ * @ret rc		Return status code
+ */
+static int efi_local_open_path ( struct efi_local *local, const char *path ) {
+	FILEPATH_DEVICE_PATH *fp = container_of ( efi_loaded_image->FilePath,
+						  FILEPATH_DEVICE_PATH, Header);
+	size_t fp_len = ( fp ? efi_devpath_len ( &fp->Header ) : 0 );
+	char base[ fp_len / 2 /* Cannot exceed this length */ ];
+	size_t remaining = sizeof ( base );
+	size_t len;
+	char *resolved;
+	char *tmp;
+	int rc;
+
+	/* Construct base path to our own image, if possible */
+	memset ( base, 0, sizeof ( base ) );
+	tmp = base;
+	while ( fp && ( fp->Header.Type != END_DEVICE_PATH_TYPE ) ) {
+		len = snprintf ( tmp, remaining, "%ls", fp->PathName );
+		assert ( len < remaining );
+		tmp += len;
+		remaining -= len;
+		fp = ( ( ( void * ) fp ) + ( ( fp->Header.Length[1] << 8 ) |
+					     fp->Header.Length[0] ) );
+	}
+	DBGC2 ( local, "LOCAL %p base path \"%s\"\n",
+		local, base );
+
+	/* Convert to sane path separators */
+	for ( tmp = base ; *tmp ; tmp++ ) {
+		if ( *tmp == '\\' )
+			*tmp = '/';
+	}
+
+	/* Resolve path */
+	resolved = resolve_path ( base, path );
+	if ( ! resolved ) {
+		rc = -ENOMEM;
+		goto err_resolve;
+	}
+
+	/* Convert to insane path separators */
+	for ( tmp = resolved ; *tmp ; tmp++ ) {
+		if ( *tmp == '/' )
+			*tmp = '\\';
+	}
+	DBGC ( local, "LOCAL %p using \"%s\"\n",
+	       local, resolved );
+
+	/* Open resolved path */
+	if ( ( rc = efi_local_open_resolved ( local, resolved ) ) != 0 )
+		goto err_open;
+
+ err_open:
+	free ( resolved );
+ err_resolve:
+	return rc;
+}
+
+/**
+ * Get file length
+ *
+ * @v local		Local file
+ * @ret rc		Return status code
+ */
+static int efi_local_len ( struct efi_local *local ) {
+	EFI_FILE_PROTOCOL *file = local->file;
+	EFI_FILE_INFO *info;
+	EFI_STATUS efirc;
+	UINTN size;
+	int rc;
+
+	/* Get size of file information */
+	size = 0;
+	file->GetInfo ( file, &efi_file_info_id, &size, NULL );
+
+	/* Allocate file information */
+	info = malloc ( size );
+	if ( ! info ) {
+		rc = -ENOMEM;
+		goto err_alloc;
+	}
+
+	/* Get file information */
+	if ( ( efirc = file->GetInfo ( file, &efi_file_info_id, &size,
+				       info ) ) != 0 ) {
+		rc = -EEFI ( efirc );
+		DBGC ( local, "LOCAL %p could not get file info: %s\n",
+		       local, strerror ( rc ) );
+		goto err_info;
+	}
+
+	/* Record file length */
+	local->len = info->FileSize;
+
+	/* Success */
+	rc = 0;
+
+ err_info:
+	free ( info );
+ err_alloc:
+	return rc;
+}
+
+/**
+ * Open local file
+ *
+ * @v xfer		Data transfer interface
+ * @v uri		Request URI
+ * @ret rc		Return status code
+ */
+static int efi_local_open ( struct interface *xfer, struct uri *uri ) {
+	struct efi_local *local;
+	const char *volume;
+	const char *path;
+	int rc;
+
+	/* Parse URI */
+	volume = ( ( uri->host && uri->host[0] ) ? uri->host : NULL );
+	path = ( uri->opaque ? uri->opaque : uri->path );
+
+	/* Allocate and initialise structure */
+	local = zalloc ( sizeof ( *local ) );
+	if ( ! local ) {
+		rc = -ENOMEM;
+		goto err_alloc;
+	}
+	ref_init ( &local->refcnt, NULL );
+	intf_init ( &local->xfer, &efi_local_xfer_desc, &local->refcnt );
+	process_init ( &local->process, &efi_local_process_desc,
+		       &local->refcnt );
+
+	/* Open specified volume */
+	if ( ( rc = efi_local_open_volume ( local, volume ) ) != 0 )
+		goto err_open_root;
+
+	/* Open specified path */
+	if ( ( rc = efi_local_open_path ( local, path ) ) != 0 )
+		goto err_open_file;
+
+	/* Get length of file */
+	if ( ( rc = efi_local_len ( local ) ) != 0 )
+		goto err_len;
+
+	/* Attach to parent interface, mortalise self, and return */
+	intf_plug_plug ( &local->xfer, xfer );
+	ref_put ( &local->refcnt );
+	return 0;
+
+ err_len:
+ err_open_file:
+ err_open_root:
+	efi_local_close ( local, 0 );
+	ref_put ( &local->refcnt );
+ err_alloc:
+	return rc;
+}
+
+/** EFI local file URI opener */
+struct uri_opener efi_local_uri_opener __uri_opener = {
+	.scheme	= "file",
+	.open	= efi_local_open,
+};