[PATCH 0/5] net: lwip: root certificates

[Jerome Forissier]

Hi Da,

On 7/15/25 06:45, Da Xue wrote:
> Hi Jerome,
> 
>> Then new Kconfig symbols are added to support providing the certificates
>> at build time, as a DER or PEM encoded X509 collection:
>> WGET_BUILTIN_CACERT=y and WGET_BUILTIN_CACERT_PATH=<some path>.
>> Note that PEM support requires MBEDTLS_LIB_X509_PEM=y (for the cacert
>> command as well as for the builtin way).
>>
>> Here is a complete example (showing only the relevant output from the
>> various commands):
>>
>>  make qemu_arm64_lwip_defconfig
>>  wget https://curl.se/ca/cacert.pem
>>  echo CONFIG_WGET_BUILTIN_CACERT=y >>.config
>>  echo CONFIG_WGET_BUILTIN_CACERT_PATH=cacert.pem >>.config
>>  make olddefconfig
>>  make -j$(nproc) CROSS_COMPILE="ccache aarch64-linux-gnu-"
>>  qemu-system-aarch64 -M virt -nographic -cpu max \
>>         -object rng-random,id=rng0,filename=/dev/urandom \
>>         -device virtio-rng-pci,rng=rng0 -bios u-boot.bin
>>  => dhcp
>>  # HTTPS transfer using the builtin CA certificates
>>  => wget https://www.google.com/
>>  18724 bytes transferred in 15 ms (1.2 MiB/s)
>>  # Disable certificate validation
>>  => wget cacert 0 0
>>  # Unsafe HTTPS transfer
>>  => wget https://www.google.com/
>>  WARNING: no CA certificates, HTTPS connections not authenticated
>>  16570 bytes transferred in 15 ms (1.1 MiB/s)
>>  # Dowload and apply CA certificates from the net
>>  => wget https://curl.se/ca/cacert.pem
>>  WARNING: no CA certificates, HTTPS connections not authenticated
>>  ##
>>  233263 bytes transferred in 61 ms (3.6 MiB/s)
>>  => wget cacert $fileaddr $filesize
>>  # Now HTTPS is authenticated against the new CA
>>  => wget https://www.google.com/
>>  18743 bytes transferred in 14 ms (1.3 MiB/s)
>>  # Drop the certificates again...
>>  => wget cacert 0 0
>>  # Check that transfer is not secure
>>  => wget https://www.google.com/
>>  WARNING: no CA certificates, HTTPS connections not authenticated
>>  # Restore the builtin CA
>>  => wget cacert builtin
>>  # No more WARNING
>>  => wget https://www.google.com/
>>  18738 bytes transferred in 15 ms (1.2 MiB/s)
> 
> Is there a simple way to convert multi-certificate root trust pem to
> der? I tried packing it as a PKCS#7 and got "Could not parse
> certificates (-8576)"

AFAICT MBed TLS should be able to parse multiple root certificates as
long as they are in DER form. U-Boot doesn't enable the PEM format at the
moment, it is less space-efficient. Please try:

openssl x509 -in cert.pem -outform DER -out cert.der

Thanks,
-- 
Jerome


> 
> Best Regards,
> Da