[PATCH v3 5/5] security: kernel_pinctrl: fixup pinctrl in kernel dts

[Ahmad Fatoum]

Hello,

On 3/18/26 10:22, Fabian Pflug wrote:
> Going through the kernel dts and replacing
> barebox,policy-<active_policy> with default in order to change pinctrl
> not only for barebox, but also for kernel when booting with security
> profiles.
> 
> Signed-off-by: Fabian Pflug <f.pflug at pengutronix.de>
> ---
>  security/Makefile         |  1 +
>  security/kernel_pinctrl.c | 56 +++++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 57 insertions(+)
> 
> diff --git a/security/Makefile b/security/Makefile
> index 1096cbfb9b..2e8cdfe7c2 100644
> --- a/security/Makefile
> +++ b/security/Makefile
> @@ -2,6 +2,7 @@
>  
>  obj-$(CONFIG_SECURITY_POLICY)		+= policy.o
>  obj-$(CONFIG_SECURITY_POLICY_NAMES)	+= sconfig_names.o
> +obj-$(CONFIG_SECURITY_POLICY_PINCTRL)	+= kernel_pinctrl.o
>  obj-$(CONFIG_CRYPTO_KEYSTORE)	+= keystore.o
>  obj-$(CONFIG_JWT)		+= jwt.o
>  obj-pbl-$(CONFIG_HAVE_OPTEE)	+= optee.o
> diff --git a/security/kernel_pinctrl.c b/security/kernel_pinctrl.c
> new file mode 100644
> index 0000000000..01ccac3ec3
> --- /dev/null
> +++ b/security/kernel_pinctrl.c
> @@ -0,0 +1,56 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +
> +#include <common.h>
> +#include <linux/printk.h>
> +#include <pinctrl.h>
> +#include <security/policy.h>
> +#include <security/config.h>
> +
> +/* Maximun number of names to be available in pinctrl-names. Best guess.*/
> +#define MAX_NAMES	10
> +
> +
> +/**
> + * Replace 'default' with 'old_default' and 'barebox,policy-<active_policy>'
> + * with 'default', if both are found in pinctrl.
> + */
> +static void kernel_of_fixup_pinctrl(struct device_node *root_node, char *policy_name)
> +{
> +	struct device_node *node;
> +
> +	list_for_each_entry(node, &root_node->list, list) {

I am surprised of.h didn't have a macro for that.

> +		const char *names[MAX_NAMES];
> +		int num_read, pos_default = -1, pos_policy = -1;
> +
> +		num_read = of_property_read_string_array(node, "pinctrl-names", names, MAX_NAMES);
> +
> +		for (int i = 0; i < num_read; i++) {
> +			if (strcmp(policy_name, names[i]) == 0)
> +				pos_policy = i;
> +			if (strcmp("default", names[i]) == 0)
> +				pos_default = i;
> +		}
> +
> +		if (pos_default >= 0 && pos_policy >= 0) {
> +			names[pos_default] = "old_default";
> +			names[pos_policy] = "default";
> +			of_property_write_string_array(node, "pinctrl-names", names, num_read);
> +		}

Wouldn't it be simpler to use of_property_for_each_string()?

> +	}
> +}
> +
> +static int kernel_of_fixup_pinctrl_start(struct device_node *root, void *unused)
> +{
> +	char *policy_pinctrl;
> +
> +	policy_pinctrl = basprintf("barebox,policy-%s", active_policy->name);
> +	kernel_of_fixup_pinctrl(root, policy_pinctrl);
> +	free(policy_pinctrl);
> +	return 0;
> +}

What's the point of this intermediary function?

> +
> +static int policy_console_pinctrl_init(void)
> +{
> +	return of_register_fixup(kernel_of_fixup_pinctrl_start, NULL);
> +}
> +late_initcall(policy_console_pinctrl_init);
> 


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