Revision befb1b3c2703897c5b8ffb0044dc5d0e5f27c5d7 authored by Reinette Chatre on 19 September 2018, 17:29:06 UTC, committed by Thomas Gleixner on 28 September 2018, 20:44:53 UTC
It is possible that a failure can occur during the scheduling of a pinned event. The initial portion of perf_event_read_local() contains the various error checks an event should pass before it can be considered valid. Ensure that the potential scheduling failure of a pinned event is checked for and have a credible error. Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Reinette Chatre <reinette.chatre@intel.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: fenghua.yu@intel.com Cc: tony.luck@intel.com Cc: acme@kernel.org Cc: gavin.hindman@intel.com Cc: jithu.joseph@intel.com Cc: dave.hansen@intel.com Cc: hpa@zytor.com Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/6486385d1f30336e9973b24c8c65f5079543d3d3.1537377064.git.reinette.chatre@intel.com
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digsig.txt
==================================
Digital Signature Verification API
==================================
:Author: Dmitry Kasatkin
:Date: 06.10.2011
.. CONTENTS
1. Introduction
2. API
3. User-space utilities
Introduction
============
Digital signature verification API provides a method to verify digital signature.
Currently digital signatures are used by the IMA/EVM integrity protection subsystem.
Digital signature verification is implemented using cut-down kernel port of
GnuPG multi-precision integers (MPI) library. The kernel port provides
memory allocation errors handling, has been refactored according to kernel
coding style, and checkpatch.pl reported errors and warnings have been fixed.
Public key and signature consist of header and MPIs::
struct pubkey_hdr {
uint8_t version; /* key format version */
time_t timestamp; /* key made, always 0 for now */
uint8_t algo;
uint8_t nmpi;
char mpi[0];
} __packed;
struct signature_hdr {
uint8_t version; /* signature format version */
time_t timestamp; /* signature made */
uint8_t algo;
uint8_t hash;
uint8_t keyid[8];
uint8_t nmpi;
char mpi[0];
} __packed;
keyid equals to SHA1[12-19] over the total key content.
Signature header is used as an input to generate a signature.
Such approach insures that key or signature header could not be changed.
It protects timestamp from been changed and can be used for rollback
protection.
API
===
API currently includes only 1 function::
digsig_verify() - digital signature verification with public key
/**
* digsig_verify() - digital signature verification with public key
* @keyring: keyring to search key in
* @sig: digital signature
* @sigen: length of the signature
* @data: data
* @datalen: length of the data
* @return: 0 on success, -EINVAL otherwise
*
* Verifies data integrity against digital signature.
* Currently only RSA is supported.
* Normally hash of the content is used as a data for this function.
*
*/
int digsig_verify(struct key *keyring, const char *sig, int siglen,
const char *data, int datalen);
User-space utilities
====================
The signing and key management utilities evm-utils provide functionality
to generate signatures, to load keys into the kernel keyring.
Keys can be in PEM or converted to the kernel format.
When the key is added to the kernel keyring, the keyid defines the name
of the key: 5D2B05FC633EE3E8 in the example bellow.
Here is example output of the keyctl utility::
$ keyctl show
Session Keyring
-3 --alswrv 0 0 keyring: _ses
603976250 --alswrv 0 -1 \_ keyring: _uid.0
817777377 --alswrv 0 0 \_ user: kmk
891974900 --alswrv 0 0 \_ encrypted: evm-key
170323636 --alswrv 0 0 \_ keyring: _module
548221616 --alswrv 0 0 \_ keyring: _ima
128198054 --alswrv 0 0 \_ keyring: _evm
$ keyctl list 128198054
1 key in keyring:
620789745: --alswrv 0 0 user: 5D2B05FC633EE3E8
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