[block] Allow use of a non-default EFI SAN boot filename

Some older operating systems (e.g. RHEL6) use a non-default filename
on the root disk and rely on setting an EFI variable to point to the
bootloader.  This does not work when performing a SAN boot on a
machine where the EFI variable is not present.

Fix by allowing a non-default filename to be specified via the
"sanboot --filename" option or the "san-filename" setting.  For
example:

  sanboot --filename \efi\redhat\grub.efi \
          iscsi:192.168.0.1::::iqn.2010-04.org.ipxe.demo:rhel6

or

  option ipxe.san-filename code 188 = string;
  option ipxe.san-filename "\\efi\\redhat\\grub.efi";
  option root-path "iscsi:192.168.0.1::::iqn.2010-04.org.ipxe.demo:rhel6";

Originally-implemented-by: Vishvananda Ishaya Abrams <vish.ishaya@oracle.com>
Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/arch/x86/interface/pcbios/int13.c

  * Attempt to boot from an INT 13 drive
  *
  * @v drive		Drive number
+ * @v filename		Filename (or NULL to use default)
  * @ret rc		Return status code
  *
  * This boots from the specified INT 13 drive by loading the Master
  *
  * Note that this function can never return success, by definition.
  */
-static int int13_boot ( unsigned int drive ) {
+static int int13_boot ( unsigned int drive, const char *filename __unused ) {
 	struct memory_map memmap;
 	struct segoff address;
 	int rc;

src/core/dummy_sanboot.c

  * Boot from dummy SAN device
  *
  * @v drive		Drive number
+ * @v filename		Filename (or NULL to use default)
+ * @ret rc		Return status code
  */
-static int dummy_san_boot ( unsigned int drive __unused ) {
+static int dummy_san_boot ( unsigned int drive __unused,
+			    const char *filename __unused ) {
 
 	return -EOPNOTSUPP;
 }

src/core/null_sanboot.c

 	/* Do nothing */
 }
 
-static int null_san_boot ( unsigned int drive __unused ) {
+static int null_san_boot ( unsigned int drive __unused,
+			   const char *filename __unused ) {
 	return -EOPNOTSUPP;
 }
 

src/core/settings.c

 	.type = &setting_type_string,
 };
 
+/** SAN filename setting */
+const struct setting san_filename_setting __setting ( SETTING_SANBOOT,
+						      san-filename ) = {
+	.name = "san-filename",
+	.description = "SAN filename",
+	.tag = DHCP_EB_SAN_FILENAME,
+	.type = &setting_type_string,
+};
+
 /** Username setting */
 const struct setting username_setting __setting ( SETTING_AUTH, username ) = {
 	.name = "username",

src/hci/commands/sanboot_cmd.c

 	int no_describe;
 	/** Keep SAN device */
 	int keep;
+	/** Filename */
+	char *filename;
 };
 
 /** "sanboot" option list */
 static union {
-	/* "sanboot" takes all three options */
-	struct option_descriptor sanboot[3];
+	/* "sanboot" takes all four options */
+	struct option_descriptor sanboot[4];
 	/* "sanhook" takes only --drive and --no-describe */
 	struct option_descriptor sanhook[2];
 	/* "sanunhook" takes only --drive */
 			      struct sanboot_options, no_describe, parse_flag ),
 		OPTION_DESC ( "keep", 'k', no_argument,
 			      struct sanboot_options, keep, parse_flag ),
+		OPTION_DESC ( "filename", 'f', required_argument,
+			      struct sanboot_options, filename, parse_string ),
 	},
 };
 
 		flags |= no_root_path_flags;
 
 	/* Boot from root path */
-	if ( ( rc = uriboot ( NULL, uris, count, opts.drive, flags ) ) != 0 )
+	if ( ( rc = uriboot ( NULL, uris, count, opts.drive, opts.filename,
+			      flags ) ) != 0 )
 		goto err_uriboot;
 
  err_uriboot:

src/include/ipxe/dhcp.h

  */
 #define DHCP_EB_SAN_RETRY DHCP_ENCAP_OPT ( DHCP_EB_ENCAP, 0xbb )
 
+/** SAN filename
+ *
+ * This is the path of the bootloader within the SAN device.
+ */
+#define DHCP_EB_SAN_FILENAME DHCP_ENCAP_OPT ( DHCP_EB_ENCAP, 0xbc )
+
 /** SAN drive number
  *
  * This is the drive number for a SAN-hooked drive.  For BIOS, 0x80 is

src/include/ipxe/sanboot.h

  * Attempt to boot from a SAN device
  *
  * @v drive		Drive number
+ * @v filename		Filename (or NULL to use default)
  * @ret rc		Return status code
  */
-int san_boot ( unsigned int drive );
+int san_boot ( unsigned int drive, const char *filename );
 
 /**
  * Describe SAN devices for SAN-booted operating system

src/include/ipxe/settings.h

 extern const struct setting
 root_path_setting __setting ( SETTING_SANBOOT, root-path );
 extern const struct setting
+san_filename_setting __setting ( SETTING_SANBOOT, san-filename );
+extern const struct setting
 username_setting __setting ( SETTING_AUTH, username );
 extern const struct setting
 password_setting __setting ( SETTING_AUTH, password );

src/include/usr/autoboot.h

 
 extern int uriboot ( struct uri *filename, struct uri **root_paths,
 		     unsigned int root_path_count, int drive,
-		     unsigned int flags );
+		     const char *san_filename, unsigned int flags );
 extern struct uri *
 fetch_next_server_and_filename ( struct settings *settings );
 extern int netboot ( struct net_device *netdev );

src/interface/efi/efi_block.c

  *
  * @v sandev		SAN device
  * @v handle		EFI handle
+ * @v filename		Filename (or NULL to use default)
+ * @v image		Image handle to fill in
  * @ret rc		Return status code
  */
 static int efi_block_boot_image ( struct san_device *sandev, EFI_HANDLE handle,
-				  EFI_HANDLE *image ) {
+				  const char *filename, EFI_HANDLE *image ) {
 	EFI_BOOT_SERVICES *bs = efi_systab->BootServices;
 	struct efi_block_data *block = sandev->priv;
 	union {
 	end = efi_devpath_end ( path.path );
 	prefix_len = ( ( ( void * ) end ) - ( ( void * ) path.path ) );
 	filepath_len = ( SIZE_OF_FILEPATH_DEVICE_PATH +
-			 sizeof ( efi_block_boot_filename ) );
+			 ( filename ?
+			   ( ( strlen ( filename ) + 1 /* NUL */ ) *
+			     sizeof ( filepath->PathName[0] ) ) :
+			   sizeof ( efi_block_boot_filename ) ) );
 	boot_path_len = ( prefix_len + filepath_len + sizeof ( *end ) );
 	boot_path = zalloc ( boot_path_len );
 	if ( ! boot_path ) {
 	filepath->Header.SubType = MEDIA_FILEPATH_DP;
 	filepath->Header.Length[0] = ( filepath_len & 0xff );
 	filepath->Header.Length[1] = ( filepath_len >> 8 );
-	memcpy ( filepath->PathName, efi_block_boot_filename,
-		 sizeof ( efi_block_boot_filename ) );
+	if ( filename ) {
+		efi_sprintf ( filepath->PathName, "%s", filename );
+	} else {
+		memcpy ( filepath->PathName, efi_block_boot_filename,
+			 sizeof ( efi_block_boot_filename ) );
+	}
 	end = ( ( ( void * ) filepath ) + filepath_len );
 	end->Type = END_DEVICE_PATH_TYPE;
 	end->SubType = END_ENTIRE_DEVICE_PATH_SUBTYPE;
  * Boot from EFI block device
  *
  * @v drive		Drive number
+ * @v filename		Filename (or NULL to use default)
  * @ret rc		Return status code
  */
-static int efi_block_boot ( unsigned int drive ) {
+static int efi_block_boot ( unsigned int drive, const char *filename ) {
 	EFI_BOOT_SERVICES *bs = efi_systab->BootServices;
 	struct san_device *sandev;
 	EFI_HANDLE *handles;
 	 */
 	rc = -ENOENT;
 	for ( i = 0 ; i < count ; i++ ) {
-		if ( ( rc = efi_block_boot_image ( sandev, handles[i],
+		if ( ( rc = efi_block_boot_image ( sandev, handles[i], filename,
 						   &image ) ) != 0 )
 			continue;
 		DBGC ( sandev, "EFIBLK %#02x found boot image\n",

src/usr/autoboot.c

  * @v root_paths	Root path(s)
  * @v root_path_count	Number of root paths
  * @v drive		SAN drive (if applicable)
+ * @v san_filename	SAN filename (or NULL to use default)
  * @v flags		Boot action flags
  * @ret rc		Return status code
  *
  * "skip-san-boot" options.
  */
 int uriboot ( struct uri *filename, struct uri **root_paths,
-	      unsigned int root_path_count, int drive, unsigned int flags ) {
+	      unsigned int root_path_count, int drive,
+	      const char *san_filename, unsigned int flags ) {
 	struct image *image;
 	int rc;
 
 	/* Attempt SAN boot if applicable */
 	if ( ! ( flags & URIBOOT_NO_SAN_BOOT ) ) {
 		if ( fetch_intz_setting ( NULL, &skip_san_boot_setting) == 0 ) {
-			printf ( "Booting from SAN device %#02x\n", drive );
-			rc = san_boot ( drive );
+			printf ( "Booting%s%s from SAN device %#02x\n",
+				 ( san_filename ? " " : "" ),
+				 ( san_filename ? san_filename : "" ), drive );
+			rc = san_boot ( drive, san_filename );
 			printf ( "Boot from SAN device %#02x failed: %s\n",
 				 drive, strerror ( rc ) );
 		} else {
 	root_path = expand_settings ( raw_root_path );
 	if ( ! root_path )
 		goto err_expand;
-
-	/* Parse root path */
 	if ( root_path[0] )
 		printf ( "Root path: %s\n", root_path );
+
+	/* Parse root path */
 	uri = parse_uri ( root_path );
 	if ( ! uri )
 		goto err_parse;
 	return uri;
 }
 
+/**
+ * Fetch san-filename setting
+ *
+ * @v settings		Settings block
+ * @ret san_filename	SAN filename, or NULL on failure
+ */
+static char * fetch_san_filename ( struct settings *settings ) {
+	char *raw_san_filename;
+	char *san_filename = NULL;
+
+	/* Fetch san-filename setting */
+	fetch_string_setting_copy ( settings, &san_filename_setting,
+				    &raw_san_filename );
+	if ( ! raw_san_filename )
+		goto err_fetch;
+
+	/* Expand san-filename setting */
+	san_filename = expand_settings ( raw_san_filename );
+	if ( ! san_filename )
+		goto err_expand;
+	if ( san_filename[0] )
+		printf ( "SAN filename: %s\n", san_filename );
+
+ err_expand:
+	free ( raw_san_filename );
+ err_fetch:
+	return san_filename;
+}
+
 /**
  * Check whether or not we have a usable PXE menu
  *
 int netboot ( struct net_device *netdev ) {
 	struct uri *filename;
 	struct uri *root_path;
+	char *san_filename;
 	int rc;
 
 	/* Close all other network devices */
 	/* Fetch root path (if any) */
 	root_path = fetch_root_path ( NULL );
 
+	/* Fetch SAN filename (if any) */
+	san_filename = fetch_san_filename ( NULL );
+
 	/* If we have both a filename and a root path, ignore an
 	 * unsupported or missing URI scheme in the root path, since
 	 * it may represent an NFS root.
 
 	/* Boot using next server, filename and root path */
 	if ( ( rc = uriboot ( filename, &root_path, ( root_path ? 1 : 0 ),
-			      san_default_drive(),
+			      san_default_drive(), san_filename,
 			      ( root_path ? 0 : URIBOOT_NO_SAN ) ) ) != 0 )
 		goto err_uriboot;
 
  err_uriboot:
  err_no_boot:
+	free ( san_filename );
 	uri_put ( root_path );
 	uri_put ( filename );
  err_pxe_menu_boot:

src/usr/pxemenu.c

 		return -ENOMEM;
 
 	/* Attempt boot */
-	rc = uriboot ( uri, NULL, 0, 0, URIBOOT_NO_SAN );
+	rc = uriboot ( uri, NULL, 0, 0, NULL, URIBOOT_NO_SAN );
 	uri_put ( uri );
 	return rc;
 }