On Wed, 2019-01-16 at 18:16 +0800, Kairui Song wrote:
> Currently when loading new kernel via kexec_file_load syscall, it is able
> to verify the signed PE bzimage against .builtin_trusted_keys or
> .secondary_trusted_keys. But the image could be signed with third part
> keys which will be provided by platform or firmware as EFI variable (eg.
> stored in MokListRT EFI variable), and the keys won't be available in
> keyrings mentioned above.
>
> After commit 9dc92c45177a ('integrity: Define a trusted platform keyring')
> a .platform keyring is introduced to store the keys provided by platform
> or firmware, this keyring is intended to be used for verifying kernel
> images being loaded by kexec_file_load syscall. And with a few following
> up commits, keys provided by firmware is being loaded into this keyring,
> and IMA-appraisal is able to use the keyring to verify kernel images.
> IMA is the currently the only user of that keyring.
How about simply saying, Commit "...." introduced a platform keyring
for storing preboot keys, used for verifying the kexec kernel image's
signature.
> This patch exposes the .platform, and makes it useable for other
> components. For example, kexec_file_load could use this .platform
> keyring to verify the kernel image's image.
The above statement is too generic. Please replace "and makes it
useable for other components" with " keyring, making it accessible for
verifying a PE signed kernel image".
>
> Suggested-by: Mimi Zohar <zohar@xxxxxxxxxxxxx>
> Signed-off-by: Kairui Song <kasong@xxxxxxxxxx>
Reviewed/Tested-by: Mimi Zohar <zohar@xxxxxxxxxxxxx>
> ---
> certs/system_keyring.c | 9 +++++++++
> include/keys/system_keyring.h | 5 +++++
> security/integrity/digsig.c | 6 ++++++
> 3 files changed, 20 insertions(+)
>
> diff --git a/certs/system_keyring.c b/certs/system_keyring.c
> index 81728717523d..4690ef9cda8a 100644
> --- a/certs/system_keyring.c
> +++ b/certs/system_keyring.c
> @@ -24,6 +24,9 @@ static struct key *builtin_trusted_keys;
> #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING
> static struct key *secondary_trusted_keys;
> #endif
> +#ifdef CONFIG_INTEGRITY_PLATFORM_KEYRING
> +static struct key *platform_trusted_keys;
> +#endif
>
> extern __initconst const u8 system_certificate_list[];
> extern __initconst const unsigned long system_certificate_list_size;
> @@ -265,4 +268,10 @@ int verify_pkcs7_signature(const void *data, size_t len,
> }
> EXPORT_SYMBOL_GPL(verify_pkcs7_signature);
>
> +#ifdef CONFIG_INTEGRITY_PLATFORM_KEYRING
> +void __init set_platform_trusted_keys(struct key *keyring) {
> + platform_trusted_keys = keyring;
> +}
> +#endif
> +
> #endif /* CONFIG_SYSTEM_DATA_VERIFICATION */
> diff --git a/include/keys/system_keyring.h b/include/keys/system_keyring.h
> index 359c2f936004..9e1b7849b6aa 100644
> --- a/include/keys/system_keyring.h
> +++ b/include/keys/system_keyring.h
> @@ -61,5 +61,10 @@ static inline struct key *get_ima_blacklist_keyring(void)
> }
> #endif /* CONFIG_IMA_BLACKLIST_KEYRING */
>
> +#ifdef CONFIG_INTEGRITY_PLATFORM_KEYRING
> +
> +extern void __init set_platform_trusted_keys(struct key* keyring);
> +
> +#endif /* CONFIG_INTEGRITY_PLATFORM_KEYRING */
>
> #endif /* _KEYS_SYSTEM_KEYRING_H */
> diff --git a/security/integrity/digsig.c b/security/integrity/digsig.c
> index f45d6edecf99..bfabc2a8111d 100644
> --- a/security/integrity/digsig.c
> +++ b/security/integrity/digsig.c
> @@ -89,6 +89,12 @@ static int __integrity_init_keyring(const unsigned int id, key_perm_t perm,
> keyring[id] = NULL;
> }
>
> +#ifdef CONFIG_INTEGRITY_PLATFORM_KEYRING
> + if (id == INTEGRITY_KEYRING_PLATFORM) {
> + set_platform_trusted_keys(keyring[id]);
> + }
> +#endif
> +
> return err;
> }
>
