Re: [PATCH v7 1/1] use crc32 instead of md5 for hibernation e820 integrity check

[Eric Biggers]

On Tue, Apr 13, 2021 at 12:13:30PM -0400, Chris von Recklinghausen wrote:
> Suspend fails on a system in fips mode because md5 is used for the e820

Suspend to disk (hibernation), or any suspend?

>  struct restore_data_record {
>   unsigned long jump_address;
>   unsigned long jump_address_phys;
>   unsigned long cr3;
>   unsigned long magic;
> - u8 e820_digest[MD5_DIGEST_SIZE];
> + unsigned long e820_digest;
>  };

This field should probably be renamed to 'e820_crc' or 'e820_checksum', since
"digest" normally means a cryptographic digest.

- Eric

Re: [PATCH v7 1/1] use crc32 instead of md5 for hibernation e820 integrity check

[Eric Biggers]

On Tue, Apr 13, 2021 at 12:13:30PM -0400, Chris von Recklinghausen wrote:
> +static inline void get_e820_crc32(struct e820_table *table, void *buf)
>  {

This should just return the CRC-32 value as a u32.  There's no need for the
'void *buf' argument.

Also like I said, compute_e820_crc32() would be a more logical name.

> @@ -179,7 +133,8 @@ int arch_hibernation_header_save(void *addr, unsigned int 
> max_size)
>*/
>   rdr->cr3 = restore_cr3 & ~CR3_PCID_MASK;
>  
> - return hibernation_e820_save(rdr->e820_digest);
> + hibernation_e820_save(>e820_digest);
> + return 0;

Like I said, hibernation_e820_save() should just be inlined into here:

rdr->e820_digest = compute_e820_crc32(e820_table_firmware)

Having the helper function doesn't add anything.

>  /**
> @@ -200,7 +155,7 @@ int arch_hibernation_header_restore(void *addr)
>   jump_address_phys = rdr->jump_address_phys;
>   restore_cr3 = rdr->cr3;
>  
> - if (hibernation_e820_mismatch(rdr->e820_digest)) {
> + if (hibernation_e820_mismatch(>e820_digest)) {

Likewise, this should be just

if (rdr->e820_digest != compute_e820_crc32(e820_table_firmware)) {

- Eric