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| author | Eric Snowberg <eric.snowberg@oracle.com> | 2021-01-22 13:10:51 -0500 |
|---|---|---|
| committer | David Howells <dhowells@redhat.com> | 2021-03-11 16:31:28 +0000 |
| commit | 56c5812623f95313f6a46fbf0beee7fa17c68bbf (patch) | |
| tree | 563b2242fb6013a9a277102e9874354de0c27cb4 /certs/system_keyring.c | |
| parent | 8f0bfc25c907f38e7f9dc498e8f43000d77327ef (diff) | |
| download | lwn-56c5812623f95313f6a46fbf0beee7fa17c68bbf.tar.gz lwn-56c5812623f95313f6a46fbf0beee7fa17c68bbf.zip | |
certs: Add EFI_CERT_X509_GUID support for dbx entries
This fixes CVE-2020-26541.
The Secure Boot Forbidden Signature Database, dbx, contains a list of now
revoked signatures and keys previously approved to boot with UEFI Secure
Boot enabled. The dbx is capable of containing any number of
EFI_CERT_X509_SHA256_GUID, EFI_CERT_SHA256_GUID, and EFI_CERT_X509_GUID
entries.
Currently when EFI_CERT_X509_GUID are contained in the dbx, the entries are
skipped.
Add support for EFI_CERT_X509_GUID dbx entries. When a EFI_CERT_X509_GUID
is found, it is added as an asymmetrical key to the .blacklist keyring.
Anytime the .platform keyring is used, the keys in the .blacklist keyring
are referenced, if a matching key is found, the key will be rejected.
[DH: Made the following changes:
- Added to have a config option to enable the facility. This allows a
Kconfig solution to make sure that pkcs7_validate_trust() is
enabled.[1][2]
- Moved the functions out from the middle of the blacklist functions.
- Added kerneldoc comments.]
Signed-off-by: Eric Snowberg <eric.snowberg@oracle.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
cc: Randy Dunlap <rdunlap@infradead.org>
cc: Mickaël Salaün <mic@digikod.net>
cc: Arnd Bergmann <arnd@kernel.org>
cc: keyrings@vger.kernel.org
Link: https://lore.kernel.org/r/20200901165143.10295-1-eric.snowberg@oracle.com/ # rfc
Link: https://lore.kernel.org/r/20200909172736.73003-1-eric.snowberg@oracle.com/ # v2
Link: https://lore.kernel.org/r/20200911182230.62266-1-eric.snowberg@oracle.com/ # v3
Link: https://lore.kernel.org/r/20200916004927.64276-1-eric.snowberg@oracle.com/ # v4
Link: https://lore.kernel.org/r/20210122181054.32635-2-eric.snowberg@oracle.com/ # v5
Link: https://lore.kernel.org/r/161428672051.677100.11064981943343605138.stgit@warthog.procyon.org.uk/
Link: https://lore.kernel.org/r/161433310942.902181.4901864302675874242.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/161529605075.163428.14625520893961300757.stgit@warthog.procyon.org.uk/ # v3
Link: https://lore.kernel.org/r/bc2c24e3-ed68-2521-0bf4-a1f6be4a895d@infradead.org/ [1]
Link: https://lore.kernel.org/r/20210225125638.1841436-1-arnd@kernel.org/ [2]
Diffstat (limited to 'certs/system_keyring.c')
| -rw-r--r-- | certs/system_keyring.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/certs/system_keyring.c b/certs/system_keyring.c index 4b693da488f1..ed98754d5795 100644 --- a/certs/system_keyring.c +++ b/certs/system_keyring.c @@ -242,6 +242,12 @@ int verify_pkcs7_message_sig(const void *data, size_t len, pr_devel("PKCS#7 platform keyring is not available\n"); goto error; } + + ret = is_key_on_revocation_list(pkcs7); + if (ret != -ENOKEY) { + pr_devel("PKCS#7 platform key is on revocation list\n"); + goto error; + } } ret = pkcs7_validate_trust(pkcs7, trusted_keys); if (ret < 0) { |