Commit Graph

10 Commits

Author SHA1 Message Date
Mimi Zohar
644664627d ima: fix 'd-ng' comments and documentation
Initially the 'd-ng' template field did not prefix the digest with either
"md5" or "sha1" hash algorithms.  Prior to being upstreamed this changed,
but the comments and documentation were not updated.  Fix the comments
and documentation.

Fixes: 4d7aeee73f ("ima: define new template ima-ng and template fields d-ng and n-ng")
Reported-by: Eric Biggers <ebiggers@kernel.org>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
2022-05-01 16:38:10 -04:00
Roberto Sassu
22a558f567 doc: Fix warning in Documentation/security/IMA-templates.rst
This patch fixes the warning:

Documentation/security/IMA-templates.rst:81: WARNING: Inline
substitution_reference start-string without end-string.

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
2021-06-08 16:29:10 -04:00
Roberto Sassu
88016de3ab ima: Define new template evm-sig
With the recent introduction of the evmsig template field, remote verifiers
can obtain the EVM portable signature instead of the IMA signature, to
verify file metadata.

After introducing the new fields to include file metadata in the
measurement list, this patch finally defines the evm-sig template, whose
format is:

d-ng|n-ng|evmsig|xattrnames|xattrlengths|xattrvalues|iuid|igid|imode

xattrnames, xattrlengths and xattrvalues are populated only from defined
EVM protected xattrs, i.e. the ones that EVM considers to verify the
portable signature. xattrnames and xattrlengths are populated only if the
xattr is present.

xattrnames and xattrlengths are not necessary for verifying the EVM
portable signature, but they are included for completeness of information,
if a remote verifier wants to infer more from file metadata.

Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
2021-06-03 10:02:37 -04:00
Roberto Sassu
8314b6732a ima: Define new template fields xattrnames, xattrlengths and xattrvalues
This patch defines the new template fields xattrnames, xattrlengths and
xattrvalues, which contain respectively a list of xattr names (strings,
separated by |), lengths (u32, hex) and values (hex). If an xattr is not
present, the name and length are not displayed in the measurement list.

Reported-by: kernel test robot <lkp@intel.com> (Missing prototype def)
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
2021-06-02 18:56:13 -04:00
Roberto Sassu
f8216f6b95 ima: Define new template field imode
This patch defines the new template field imode, which includes the
inode mode. It can be used by a remote verifier to verify the EVM portable
signature, if it was included with the template fields sig or evmsig.

Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
2021-06-01 15:17:30 -04:00
Roberto Sassu
7dcfeacc5a ima: Define new template fields iuid and igid
This patch defines the new template fields iuid and igid, which include
respectively the inode UID and GID. For idmapped mounts, still the original
UID and GID are provided.

These fields can be used to verify the EVM portable signature, if it was
included with the template fields sig or evmsig.

Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
2021-06-01 15:17:30 -04:00
Roberto Sassu
026d7fc92a ima: Introduce template field evmsig and write to field sig as fallback
With the patch to accept EVM portable signatures when the
appraise_type=imasig requirement is specified in the policy, appraisal can
be successfully done even if the file does not have an IMA signature.

However, remote attestation would not see that a different signature type
was used, as only IMA signatures can be included in the measurement list.
This patch solves the issue by introducing the new template field 'evmsig'
to show EVM portable signatures and by including its value in the existing
field 'sig' if the IMA signature is not found.

Suggested-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
2021-06-01 12:30:51 -04:00
Thiago Jung Bauermann
3878d505aa ima: Define ima-modsig template
Define new "d-modsig" template field which holds the digest that is
expected to match the one contained in the modsig, and also new "modsig"
template field which holds the appended file signature.

Add a new "ima-modsig" defined template descriptor with the new fields as
well as the ones from the "ima-sig" descriptor.

Change ima_store_measurement() to accept a struct modsig * argument so that
it can be passed along to the templates via struct ima_event_data.

Suggested-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
2019-08-05 18:40:25 -04:00
Prakhar Srivastava
86b4da8c0e IMA: Define a new template field buf
A buffer(kexec boot command line arguments) measured into IMA
measuremnt list cannot be appraised, without already being
aware of the buffer contents. Since hashes are non-reversible,
raw buffer is needed for validation or regenerating hash for
appraisal/attestation.

Add support to store/read the buffer contents in HEX.
The kexec cmdline hash is stored in the "d-ng" field of the
template data.  It can be verified using
sudo cat /sys/kernel/security/integrity/ima/ascii_runtime_measurements |
  grep  kexec-cmdline | cut -d' ' -f 6 | xxd -r -p | sha256sum

- Add two new fields to ima_event_data to hold the buf and
buf_len
- Add a new template field 'buf' to be used to store/read
the buffer data.
- Updated process_buffer_meaurement to add the buffer to
ima_event_data. process_buffer_measurement added in
"Define a new IMA hook to measure the boot command line
 arguments"
- Add a new template policy name ima-buf to represent
'd-ng|n-ng|buf'

Signed-off-by: Prakhar Srivastava <prsriva02@gmail.com>
Reviewed-by: Roberto Sassu <roberto.sassu@huawei.com>
Reviewed-by: James Morris <jamorris@linux.microsoft.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
2019-06-30 17:53:45 -04:00
Kees Cook
7b05b11684 doc: ReSTify IMA-templates.txt
Adjust IMA-templates.txt for ReST markup and add to the index for
security/, under the Kernel API Documentation.

Cc: Mimi Zohar <zohar@linux.vnet.ibm.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2017-05-18 10:30:14 -06:00