linux-kernel - Re: [PATCH v5 1/1] ipe: add errno field to IPE policy load auditing

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Message-ID: <CAKtyLkGuRraMbArSQCGxb+m5p+M8G5WZCTHk-7dKVfQd2EJYxw@mail.gmail.com>
Date: Mon, 17 Mar 2025 13:59:08 -0700
From: Fan Wu <wufan@...nel.org>
To: Jasjiv Singh <jasjivsingh@...ux.microsoft.com>
Cc: corbet@....net, jmorris@...ei.org, serge@...lyn.com, eparis@...hat.com, 
	paul@...l-moore.com, linux-doc@...r.kernel.org, 
	linux-security-module@...r.kernel.org, audit@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 1/1] ipe: add errno field to IPE policy load auditing

On Thu, Mar 13, 2025 at 2:51 PM Jasjiv Singh
<jasjivsingh@...ux.microsoft.com> wrote:
>
> Users of IPE require a way to identify when and why an operation fails,
> allowing them to both respond to violations of policy and be notified
> of potentially malicious actions on their systems with respect to IPE.
>
> This patch introduces a new error field to the AUDIT_IPE_POLICY_LOAD event
> to log policy loading failures. Currently, IPE only logs successful policy
> loads, but not failures. Tracking failures is crucial to detect malicious
> attempts and ensure a complete audit trail for security events.
>
> The new error field will capture the following error codes:
>
> * -ENOKEY: Key used to sign the IPE policy not found in the keyring
> * -ESTALE: Attempting to update an IPE policy with an older version
> * -EKEYREJECTED: IPE signature verification failed
> * -ENOENT: Policy was deleted while updating
> * -EEXIST: Same name policy already deployed
> * -ERANGE: Policy version number overflow
> * -EINVAL: Policy version parsing error
> * -EPERM: Insufficient permission
> * -ENOMEM: Out of memory (OOM)
> * -EBADMSG: Policy is invalid
>
> Here are some examples of the updated audit record types:
>
> AUDIT_IPE_POLICY_LOAD(1422):
> audit:  AUDIT1422 policy_name="Test_Policy" policy_version=0.0.1
> policy_digest=sha256:84EFBA8FA71E62AE0A537FAB962F8A2BD1053964C4299DCA
> 92BFFF4DB82E86D3 auid=1000 ses=3 lsm=ipe res=1 errno=0
>
> The above record shows a new policy has been successfully loaded into
> the kernel with the policy name, version, and hash with the errno=0.
>
> AUDIT_IPE_POLICY_LOAD(1422) with error:
>
> audit: AUDIT1422 policy_name=? policy_version=? policy_digest=?
> auid=1000 ses=3 lsm=ipe res=0 errno=-74
>
> The above record shows a policy load failure due to an invalid policy
> (-EBADMSG).
>
> By adding this error field, we ensure that all policy load attempts,
> whether successful or failed, are logged, providing a comprehensive
> audit trail for IPE policy management.
>
> Signed-off-by: Jasjiv Singh <jasjivsingh@...ux.microsoft.com>
> ---
>  Documentation/admin-guide/LSM/ipe.rst | 69 +++++++++++++++++++--------
>  security/ipe/audit.c                  | 19 ++++++--
>  security/ipe/fs.c                     | 25 ++++++----
>  security/ipe/policy.c                 | 17 ++++---
>  security/ipe/policy_fs.c              | 28 ++++++++---
>  5 files changed, 113 insertions(+), 45 deletions(-)
>

...

> diff --git a/security/ipe/policy.c b/security/ipe/policy.c
> index b628f696e32b..1c58c29886e8 100644
> --- a/security/ipe/policy.c
> +++ b/security/ipe/policy.c
> @@ -84,8 +84,11 @@ static int set_pkcs7_data(void *ctx, const void *data, size_t len,
>   * ipe_new_policy.
>   *
>   * Context: Requires root->i_rwsem to be held.
> - * Return: %0 on success. If an error occurs, the function will return
> - * the -errno.
> + * Return:
> + * * %0        - Success
> + * * %-ENOENT  - Policy was deleted while updating
> + * * %-EINVAL  - Policy name mismatch
> + * * %-ESTALE  - Policy version too old
>   */
>  int ipe_update_policy(struct inode *root, const char *text, size_t textlen,
>                       const char *pkcs7, size_t pkcs7len)
> @@ -146,10 +149,12 @@ int ipe_update_policy(struct inode *root, const char *text, size_t textlen,
>   *
>   * Return:
>   * * a pointer to the ipe_policy structure     - Success
> - * * %-EBADMSG                                 - Policy is invalid
> - * * %-ENOMEM                                  - Out of memory (OOM)
> - * * %-ERANGE                                  - Policy version number overflow
> - * * %-EINVAL                                  - Policy version parsing error
> + * * %-EBADMSG                         - Policy is invalid
> + * * %-ENOMEM                          - Out of memory (OOM)
> + * * %-ERANGE                          - Policy version number overflow
> + * * %-EINVAL                          - Policy version parsing error
> + * * %-ENOKEY                          - Policy signing key not found
> + * * %-EKEYREJECTED                    - Policy signature verification failed
>   */

The indentation here is not aligned.

I don't see any other issue, if there is no objection from the audit
folks, I will pull this into ipe's tree.

-Fan

.