Calling inbuilt_key functions from inside uart callback fails

[sunkyl]

I have a setup similar to this

void program_uart_cb(struct uart_event *evt, void *data)
{
    printk("before");
    nrf_sec_tag_t sec_tag = (nrf_sec_tag_t) sec_tag_list[0];
    nrf_inbuilt_key_write(sec_tag,
            NRF_KEY_MGMT_CRED_TYPE_CA_CHAIN,
            "Hello",
            strlen("Hello"));
    printk("after");
}


void main(void)
{
    struct device *uart = device_get_binding("UART_1");
    uart_callback_set(uart, program_uart_cb, uart);
    uart_rx_enable(uart, rx_buf, sizeof(rx_buf), 50);
    while (true) {
        k_sleep(100);
    }
}

When the callback is executed, the execution will enter the inbuilt_key function and then the output will stop and the execution will halt. This seems to be the case for all nrf_inbuilt_key functions. Any help would be appreciated, thanks.

[Martin Lesund]

Hi Sunkyl,

I would need more information from your code to be able to reproduce it on my side. 
We could make this case private if there is sensitive information.

Questions that come up are, do you have bsdlib enabled etc.


I would also like to point out something from the NCS v1.2.o release notes:

• "Modem key management - provides functions to provision security credentials to the nRF9160 modem. The library replaces the nrf_inbuilt_key APIs from the BSD library."

[sunkyl]

Hi, thanks for the response.

I believe the bsdlib is enabled, and I have tested with running bsd_init() first to the same result, and the same thing with the updated modem key management function. See updated code:

#include <zephyr.h>
...
#include <nrf_key_mgmt.h>
#include <nrf_inbuilt_key.h>
#include <modem/modem_key_mgmt.h>


static u8_t rx_buf[2048];
static sec_tag_t sec_tag_list[] = { CONFIG_SEC_TAG };
/* UART Callback */
void program_uart_cb(struct uart_event *evt, void *data)
{
    nrf_sec_tag_t sec_tag = (nrf_sec_tag_t) sec_tag_list[0];
    modem_key_mgmt_write(sec_tag,
            NRF_KEY_MGMT_CRED_TYPE_CA_CHAIN,
            "Hello",
            strlen("Hello"));
}


void main(void)
{
    struct device *uart = device_get_binding("UART_1");
    int counter = 0;
    bsd_init();
    printf("alive! %d\n", counter);
    uart_callback_set(uart, program_uart_cb, uart);
    uart_rx_enable(uart, rx_buf, sizeof(rx_buf), 50);

    while (true) {
        counter++;
        k_sleep(1000);
        printf("alive! %d\n", counter);
    }
}

Removing the modem_key_mgmt_write line does provide the intended behavior. It seems to be that key management functions from an IRQ context will cause the program to halt and error. Currently I am attempting to write to a buffer and then do the key write outside the IRQ but I'm running into some other, unrelated errors when I do 3 certs at once (perhaps memory errors).

Thanks again.

[Martin Lesund]

Hi Sunkyl,
I would highly recommend that you look into the https_client sample and use the cert_provision() as a reference.

[sunkyl]

I've opted to store the cert in a buffer during the IRQ and do the cert write function after the IRQ. All seems to work fine that way. Thanks for your time.