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authorLinus Torvalds <torvalds@linux-foundation.org>2017-05-03 08:50:52 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2017-05-03 08:50:52 -0700
commit0302e28dee643932ee7b3c112ebccdbb9f8ec32c (patch)
tree405d4cb3f772ef069ed7f291adc4b74a4e73346e /Documentation/crypto
parent89c9fea3c8034cdb2fd745f551cde0b507fd6893 (diff)
parent8979b02aaf1d6de8d52cc143aa4da961ed32e5a2 (diff)
Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security
Pull security subsystem updates from James Morris: "Highlights: IMA: - provide ">" and "<" operators for fowner/uid/euid rules KEYS: - add a system blacklist keyring - add KEYCTL_RESTRICT_KEYRING, exposes keyring link restriction functionality to userland via keyctl() LSM: - harden LSM API with __ro_after_init - add prlmit security hook, implement for SELinux - revive security_task_alloc hook TPM: - implement contextual TPM command 'spaces'" * 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security: (98 commits) tpm: Fix reference count to main device tpm_tis: convert to using locality callbacks tpm: fix handling of the TPM 2.0 event logs tpm_crb: remove a cruft constant keys: select CONFIG_CRYPTO when selecting DH / KDF apparmor: Make path_max parameter readonly apparmor: fix parameters so that the permission test is bypassed at boot apparmor: fix invalid reference to index variable of iterator line 836 apparmor: use SHASH_DESC_ON_STACK security/apparmor/lsm.c: set debug messages apparmor: fix boolreturn.cocci warnings Smack: Use GFP_KERNEL for smk_netlbl_mls(). smack: fix double free in smack_parse_opts_str() KEYS: add SP800-56A KDF support for DH KEYS: Keyring asymmetric key restrict method with chaining KEYS: Restrict asymmetric key linkage using a specific keychain KEYS: Add a lookup_restriction function for the asymmetric key type KEYS: Add KEYCTL_RESTRICT_KEYRING KEYS: Consistent ordering for __key_link_begin and restrict check KEYS: Add an optional lookup_restriction hook to key_type ...
Diffstat (limited to 'Documentation/crypto')
-rw-r--r--Documentation/crypto/asymmetric-keys.txt51
1 files changed, 51 insertions, 0 deletions
diff --git a/Documentation/crypto/asymmetric-keys.txt b/Documentation/crypto/asymmetric-keys.txt
index 2b7816dea370..5ad6480e3fb9 100644
--- a/Documentation/crypto/asymmetric-keys.txt
+++ b/Documentation/crypto/asymmetric-keys.txt
@@ -311,3 +311,54 @@ Functions are provided to register and unregister parsers:
Parsers may not have the same name. The names are otherwise only used for
displaying in debugging messages.
+
+
+=========================
+KEYRING LINK RESTRICTIONS
+=========================
+
+Keyrings created from userspace using add_key can be configured to check the
+signature of the key being linked.
+
+Several restriction methods are available:
+
+ (1) Restrict using the kernel builtin trusted keyring
+
+ - Option string used with KEYCTL_RESTRICT_KEYRING:
+ - "builtin_trusted"
+
+ The kernel builtin trusted keyring will be searched for the signing
+ key. The ca_keys kernel parameter also affects which keys are used for
+ signature verification.
+
+ (2) Restrict using the kernel builtin and secondary trusted keyrings
+
+ - Option string used with KEYCTL_RESTRICT_KEYRING:
+ - "builtin_and_secondary_trusted"
+
+ The kernel builtin and secondary trusted keyrings will be searched for the
+ signing key. The ca_keys kernel parameter also affects which keys are used
+ for signature verification.
+
+ (3) Restrict using a separate key or keyring
+
+ - Option string used with KEYCTL_RESTRICT_KEYRING:
+ - "key_or_keyring:<key or keyring serial number>[:chain]"
+
+ Whenever a key link is requested, the link will only succeed if the key
+ being linked is signed by one of the designated keys. This key may be
+ specified directly by providing a serial number for one asymmetric key, or
+ a group of keys may be searched for the signing key by providing the
+ serial number for a keyring.
+
+ When the "chain" option is provided at the end of the string, the keys
+ within the destination keyring will also be searched for signing keys.
+ This allows for verification of certificate chains by adding each
+ cert in order (starting closest to the root) to one keyring.
+
+In all of these cases, if the signing key is found the signature of the key to
+be linked will be verified using the signing key. The requested key is added
+to the keyring only if the signature is successfully verified. -ENOKEY is
+returned if the parent certificate could not be found, or -EKEYREJECTED is
+returned if the signature check fails or the key is blacklisted. Other errors
+may be returned if the signature check could not be performed.