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| author | Niklas Cassel <cassel@kernel.org> | 2026-09-16 15:00:32 +0200 |
|---|---|---|
| committer | Niklas Cassel <cassel@kernel.org> | 2026-09-16 16:18:00 +0200 |
| commit | 8d836581f9b1f57ceaa2b47654754ef1260b410b (patch) | |
| tree | 1dbd4d0dfb99c2e238356cbe947e5b0be3e3a571 /Documentation/security/digsig.rst | |
| download | linux-stable-8d836581f9b1f57ceaa2b47654754ef1260b410b.tar.gz linux-stable-8d836581f9b1f57ceaa2b47654754ef1260b410b.zip | |
ata: libata-scsi: fix ata_dsm_trim_pages() kernel-docgrafted
make htmldocs fails with:
Documentation/driver-api/libata:604: ./drivers/ata/libata-scsi.c:2301:
ERROR: Unexpected indentation. [docutils]
The Return: section of ata_dsm_trim_pages() ends its first sentence with
a colon and continues with an indented bullet list. reStructuredText
requires a blank line before an indented block, so docutils chokes on
the list.
Simply adding the missing blank line does not work either: Return: is a
kernel-doc "special section", which is terminated by the first blank
line, so the bullet list would end up in the Description section,
detached from the sentence introducing it.
Spell the two bounds out as prose instead, so that the Return: section
stays self-contained. Documentation-only change.
Fixes: e64e6b5dc867 ("ata: libata-scsi: scale DSM TRIM payload by MAX PAGES PER DSM COMMAND")
Reported-by: Thomas Huth <thuth@redhat.com>
Closes: https://lore.kernel.org/linux-ide/b0a0b8e8-cc4f-4c7b-8bc5-fee0712d405a@redhat.com/
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Link: https://lore.kernel.org/r/20260916130031.29990-2-cassel@kernel.org
Signed-off-by: Niklas Cassel <cassel@kernel.org>
Diffstat (limited to 'Documentation/security/digsig.rst')
| -rw-r--r-- | Documentation/security/digsig.rst | 101 |
1 files changed, 101 insertions, 0 deletions
diff --git a/Documentation/security/digsig.rst b/Documentation/security/digsig.rst new file mode 100644 index 000000000..de035f282 --- /dev/null +++ b/Documentation/security/digsig.rst @@ -0,0 +1,101 @@ +================================== +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 below. + +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 |
