[PATCH] common: setting the root= command line parameter

[Fabian Pflug <f.pflug@pengutronix.de>]

In verified boot settings, it might not be wanted to have a root=
command line parameter for the kernel, because if the initramfs is not
configured, or barebox boots the kernel directly due to
misconfiguration, the device might boot correctly, but without verified
boot, because the kernel will parse root=

Allowing to change the parameter name will help circumvent such errors,
as there now needs to be multiple misconfigurations for the verified
boot to go wrong and the initramfs can use a the different name from the
commandline to get the rootfs.

Signed-off-by: Fabian Pflug <f.pflug@pengutronix.de>
---
 common/Kconfig         | 13 +++++++++++++
 common/block.c         |  3 +--
 common/bootm.c         |  8 ++++----
 drivers/mci/mci-core.c |  2 +-
 fs/9p/vfs_super.c      |  2 +-
 fs/nfs.c               |  2 +-
 fs/squashfs/squashfs.c |  2 +-
 fs/ubifs/ubifs.c       |  2 +-
 8 files changed, 23 insertions(+), 11 deletions(-)

diff --git a/common/Kconfig b/common/Kconfig
index d923d4c4b6..62797a9e69 100644
--- a/common/Kconfig
+++ b/common/Kconfig
@@ -1252,6 +1252,19 @@ config SERIAL_NUMBER_FIXUP_SYSTEMD_HOSTNAME
 	  This option without effect if global.bootm.provide_hostname
 	  is unset.
 
+config ROOT_COMMANDLINE_PARAMETER
+	string "parameter name for root partition"
+	default "root"
+	help
+	  When setting the root partition on the commandline string to the os, use
+	  this name as an indicator of the root partition.
+
+	  Changing this could be useful in verified boot contexts to not give the
+	  kernel the chance to boot a non-secure image, but still use the power of
+	  barebox to get the right disk for the rootfs.
+
+	  If unsure, leave as default (root)
+
 config SYSTEMD_OF_WATCHDOG
 	bool "inform devicetree-enabled kernel of used watchdog"
 	depends on WATCHDOG && OFTREE && FLEXIBLE_BOOTARGS
diff --git a/common/block.c b/common/block.c
index ca2ed37dbd..bb8b01c0a0 100644
--- a/common/block.c
+++ b/common/block.c
@@ -601,11 +601,10 @@ char *cdev_get_linux_rootarg(const struct cdev *partcdev)
 	if (blk->ops->get_rootarg)
 		rootarg = blk->ops->get_rootarg(blk, partcdev);
 	if (!rootarg && partcdev->partuuid[0] != 0)
-		rootarg = basprintf("root=PARTUUID=%s", partcdev->partuuid);
+		rootarg = basprintf(CONFIG_ROOT_COMMANDLINE_PARAMETER "=PARTUUID=%s", partcdev->partuuid);
 
 	if (IS_ENABLED(CONFIG_ROOTWAIT_BOOTARG) && blk->rootwait)
 		rootarg = linux_bootargs_append_rootwait(rootarg);
 
 	return rootarg;
 }
-
diff --git a/common/bootm.c b/common/bootm.c
index 17792b2a1d..4549bfeb8b 100644
--- a/common/bootm.c
+++ b/common/bootm.c
@@ -852,10 +852,10 @@ int bootm_boot(struct bootm_data *bootm_data)
 				rootarg = ERR_PTR(-EINVAL);
 
 				if (!root_cdev)
-					pr_err("no cdev found for %s, cannot set root= option\n",
+					pr_err("no cdev found for %s, cannot set " CONFIG_ROOT_COMMANDLINE_PARAMETER "= option\n",
 						root_dev_name);
 				else if (!root_cdev->partuuid[0])
-					pr_err("%s doesn't have a PARTUUID, cannot set root= option\n",
+					pr_err("%s doesn't have a PARTUUID, cannot set " CONFIG_ROOT_COMMANDLINE_PARAMETER "= option\n",
 						root_dev_name);
 			}
 
@@ -866,7 +866,7 @@ int bootm_boot(struct bootm_data *bootm_data)
 		}
 
 		if (IS_ERR(rootarg)) {
-			pr_err("Failed to append kernel cmdline parameter 'root='\n");
+			pr_err("Failed to append kernel cmdline parameter '" CONFIG_ROOT_COMMANDLINE_PARAMETER "='\n");
 		} else {
 			pr_info("Adding \"%s\" to Kernel commandline\n", rootarg);
 			globalvar_add_simple("linux.bootargs.bootm.appendroot",
@@ -1165,7 +1165,7 @@ BAREBOX_MAGICVAR(global.bootm.dryrun, "bootm default dryrun level");
 BAREBOX_MAGICVAR(global.bootm.verify, "bootm default verify level");
 BAREBOX_MAGICVAR(global.bootm.verbose, "bootm default verbosity level (0=quiet)");
 BAREBOX_MAGICVAR(global.bootm.earlycon, "Add earlycon option to Kernel for early log output");
-BAREBOX_MAGICVAR(global.bootm.appendroot, "Add root= option to Kernel to mount rootfs from the device the Kernel comes from (default, device can be overridden via global.bootm.root_dev)");
+BAREBOX_MAGICVAR(global.bootm.appendroot, "Add " CONFIG_ROOT_COMMANDLINE_PARAMETER "= option to Kernel to mount rootfs from the device the Kernel comes from (default, device can be overridden via global.bootm.root_dev)");
 BAREBOX_MAGICVAR(global.bootm.root_dev, "bootm default root device (overrides default device in global.bootm.appendroot)");
 BAREBOX_MAGICVAR(global.bootm.provide_machine_id, "If true, append systemd.machine_id=$global.machine_id to Kernel command line");
 BAREBOX_MAGICVAR(global.bootm.provide_hostname, "If true, append systemd.hostname=$global.hostname to Kernel command line");
diff --git a/drivers/mci/mci-core.c b/drivers/mci/mci-core.c
index 57825bc849..79cebe19f3 100644
--- a/drivers/mci/mci-core.c
+++ b/drivers/mci/mci-core.c
@@ -2691,7 +2691,7 @@ static char *mci_get_linux_mmcblkdev(struct block_device *blk,
 		 * skipping it.
 		 */
 		if (cdev_partname_equal(partcdev, cdev))
-			return basprintf("root=/dev/mmcblk%dp%d", id, partnum);
+			return basprintf(CONFIG_ROOT_COMMANDLINE_PARAMETER "=/dev/mmcblk%dp%d", id, partnum);
 		if (cdev->flags & DEVFS_PARTITION_FROM_TABLE)
 			partnum++;
 	}
diff --git a/fs/9p/vfs_super.c b/fs/9p/vfs_super.c
index 6a451d9ef5..39a8529a4e 100644
--- a/fs/9p/vfs_super.c
+++ b/fs/9p/vfs_super.c
@@ -70,7 +70,7 @@ static void v9fs_set_rootarg(struct v9fs_session_info *v9ses,
 	trans = v9ses->clnt->trans_mod->name;
 	path = v9ses->aname;
 
-	str = basprintf("root=%s rootfstype=9p rootflags=trans=%s,msize=%d,"
+	str = basprintf(CONFIG_ROOT_COMMANDLINE_PARAMETER "=%s rootfstype=9p rootflags=trans=%s,msize=%d,"
 			"cache=loose,uname=%s,dfltuid=0,dfltgid=0,aname=%s",
 			tag, trans, v9ses->clnt->msize, tag, path);
 
diff --git a/fs/nfs.c b/fs/nfs.c
index 5c2476cd88..9db23c5d18 100644
--- a/fs/nfs.c
+++ b/fs/nfs.c
@@ -1558,7 +1558,7 @@ static void nfs_set_rootarg(struct nfs_priv *npriv, struct fs_device *fsdev)
 	char *str, *tmp;
 	const char *bootargs;
 
-	str = basprintf("root=/dev/nfs nfsroot=%pI4:%s%s%s", &npriv->server, npriv->path,
+	str = basprintf(CONFIG_ROOT_COMMANDLINE_PARAMETER "=/dev/nfs nfsroot=%pI4:%s%s%s", &npriv->server, npriv->path,
 			  rootnfsopts[0] ? "," : "", rootnfsopts);
 
 	/* forward specific mount options on demand */
diff --git a/fs/squashfs/squashfs.c b/fs/squashfs/squashfs.c
index e30372627a..8267e3cba0 100644
--- a/fs/squashfs/squashfs.c
+++ b/fs/squashfs/squashfs.c
@@ -60,7 +60,7 @@ static void squashfs_set_rootarg(struct fs_device *fsdev)
 	ubi_get_device_info(vi.ubi_num, &di);
 	mtd = di.mtd;
 
-	str = basprintf("root=/dev/ubiblock%d_%d ubi.mtd=%s ubi.block=%d,%d rootfstype=squashfs",
+	str = basprintf(CONFIG_ROOT_COMMANDLINE_PARAMETER "=/dev/ubiblock%d_%d ubi.mtd=%s ubi.block=%d,%d rootfstype=squashfs",
 			vi.ubi_num, vi.vol_id, mtd->cdev.partname, vi.ubi_num, vi.vol_id);
 
 	fsdev_set_linux_rootarg(fsdev, str);
diff --git a/fs/ubifs/ubifs.c b/fs/ubifs/ubifs.c
index 37986acbb2..34151a0c9f 100644
--- a/fs/ubifs/ubifs.c
+++ b/fs/ubifs/ubifs.c
@@ -442,7 +442,7 @@ static void ubifs_set_rootarg(struct ubifs_priv *priv,
 
 	mtd = di.mtd;
 
-	str = basprintf("root=ubi0:%s ubi.mtd=%s rootfstype=ubifs",
+	str = basprintf(CONFIG_ROOT_COMMANDLINE_PARAMETER "=ubi0:%s ubi.mtd=%s rootfstype=ubifs",
 			  vi.name, mtd->cdev.partname);
 
 	fsdev_set_linux_rootarg(fsdev, str);
-- 
2.47.3