lwn.git/security/integrity/digsig_asymmetric.c, branch docs-4.16

integrity: Small code improvements

2017-06-21T18:37:12+00:00

These changes are too small to warrant their own patches: The keyid and sig_size members of struct signature_v2_hdr are in BE format, so use a type that makes this assumption explicit. Also, use beXX_to_cpu instead of __beXX_to_cpu to read them. Change integrity_kernel_read to take a void * buffer instead of char * buffer, so that callers don't have to use a cast if they provide a buffer that isn't a char *. Add missing #endif comment in ima.h pointing out which macro it refers to. Add missing fall through comment in ima_appraise.c. Constify mask_tokens and func_tokens arrays. Signed-off-by: Thiago Jung Bauermann Signed-off-by: Mimi Zohar

X.509: Make algo identifiers text instead of enum

2016-03-03T21:49:27+00:00

Make the identifier public key and digest algorithm fields text instead of enum. Signed-off-by: David Howells Acked-by: Herbert Xu

akcipher: Move the RSA DER encoding check to the crypto layer

2016-03-03T21:49:27+00:00

Move the RSA EMSA-PKCS1-v1_5 encoding from the asymmetric-key public_key subtype to the rsa crypto module's pkcs1pad template. This means that the public_key subtype no longer has any dependencies on public key type. To make this work, the following changes have been made: (1) The rsa pkcs1pad template is now used for RSA keys. This strips off the padding and returns just the message hash. (2) In a previous patch, the pkcs1pad template gained an optional second parameter that, if given, specifies the hash used. We now give this, and pkcs1pad checks the encoded message E(M) for the EMSA-PKCS1-v1_5 encoding and verifies that the correct digest OID is present. (3) The crypto driver in crypto/asymmetric_keys/rsa.c is now reduced to something that doesn't care about what the encryption actually does and and has been merged into public_key.c. (4) CONFIG_PUBLIC_KEY_ALGO_RSA is gone. Module signing must set CONFIG_CRYPTO_RSA=y instead. Thoughts: (*) Should the encoding style (eg. raw, EMSA-PKCS1-v1_5) also be passed to the padding template? Should there be multiple padding templates registered that share most of the code? Signed-off-by: David Howells Signed-off-by: Tadeusz Struk Acked-by: Herbert Xu

integrity: convert digsig to akcipher api

2016-02-18T14:52:32+00:00

Convert asymmetric_verify to akcipher api. Signed-off-by: Tadeusz Struk Acked-by: Herbert Xu Signed-off-by: David Howells

IMA: create machine owner and blacklist keyrings

2015-12-15T15:01:43+00:00

This option creates IMA MOK and blacklist keyrings. IMA MOK is an intermediate keyring that sits between .system and .ima keyrings, effectively forming a simple CA hierarchy. To successfully import a key into .ima_mok it must be signed by a key which CA is in .system keyring. On turn any key that needs to go in .ima keyring must be signed by CA in either .system or .ima_mok keyrings. IMA MOK is empty at kernel boot. IMA blacklist keyring contains all revoked IMA keys. It is consulted before any other keyring. If the search is successful the requested operation is rejected and error is returned to the caller. Signed-off-by: Petko Manolov Signed-off-by: Mimi Zohar

integrity: do zero padding of the key id

2014-10-06T16:33:27+00:00

Latest KEYS code return error if hexadecimal string length id odd. Fix it. Signed-off-by: Dmitry Kasatkin Signed-off-by: David Howells

integrity: prevent flooding with 'Request for unknown key'

2014-09-09T14:28:44+00:00

If file has IMA signature, IMA in enforce mode, but key is missing then file access is blocked and single error message is printed. If IMA appraisal is enabled in fix mode, then system runs as usual but might produce tons of 'Request for unknown key' messages. This patch switches 'pr_warn' to 'pr_err_ratelimited'. Signed-off-by: Dmitry Kasatkin Signed-off-by: Mimi Zohar

ima: read and use signature hash algorithm

2013-10-25T21:16:59+00:00

All files on the filesystem, currently, are hashed using the same hash algorithm. In preparation for files from different packages being signed using different hash algorithms, this patch adds support for reading the signature hash algorithm from the 'security.ima' extended attribute and calculates the appropriate file data hash based on it. Changelog: - fix scripts Lindent and checkpatch msgs - Mimi - fix md5 support for older version, which occupied 20 bytes in the xattr, not the expected 16 bytes. Fix the comparison to compare only the first 16 bytes. Signed-off-by: Dmitry Kasatkin Signed-off-by: Mimi Zohar

ima: digital signature verification using asymmetric keys

2013-02-07T02:22:18+00:00

Asymmetric keys were introduced in linux-3.7 to verify the signature on signed kernel modules. The asymmetric keys infrastructure abstracts the signature verification from the crypto details. This patch adds IMA/EVM signature verification using asymmetric keys. Support for additional signature verification methods can now be delegated to the asymmetric key infrastructure. Although the module signature header and the IMA/EVM signature header could use the same format, to minimize the signature length and save space in the extended attribute, this patch defines a new IMA/EVM header format. The main difference is that the key identifier is a sha1[12 - 19] hash of the key modulus and exponent, similar to the current implementation. The only purpose of the key identifier is to identify the corresponding key in the kernel keyring. ima-evm-utils was updated to support the new signature format. While asymmetric signature verification functionality supports many different hash algorithms, the hash used in this patch is calculated during the IMA collection phase, based on the configured algorithm. The default algorithm is sha1, but for backwards compatibility md5 is supported. Due to this current limitation, signatures should be generated using a sha1 hash algorithm. Changes in this patch: - Functionality has been moved to separate source file in order to get rid of in source #ifdefs. - keyid is derived according to the RFC 3280. It does not require to assign IMA/EVM specific "description" when loading X509 certificate. Kernel asymmetric key subsystem automatically generate the description. Also loading a certificate does not require using of ima-evm-utils and can be done using keyctl only. - keyid size is reduced to 32 bits to save xattr space. Key search is done using partial match functionality of asymmetric_key_match(). - Kconfig option title was changed Signed-off-by: Dmitry Kasatkin Acked-by: David Howells Signed-off-by: Mimi Zohar