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From:   Martin Haass <vvvrrooomm@gmail.com>
Date:   Wed, 19 Feb 2020 10:02:17 +0100
Message-ID: <CAH3oDPzeu_bzYa3fOUpcjQk4HJ5K2Rx+Qf+qbqxSrmTdrWHm5g@mail.gmail.com>
Subject: [PATCH] module support: during lockdown, log name of unsigned module
To:     Jessica Yu <jeyu@kernel.org>
Cc:     linux-kernel@vger.kernel.org,
        linux-security-module@vger.kernel.org,
        linux-modules@vger.kernel.org
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Sender: linux-kernel-owner@vger.kernel.org
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during lockdown loading of unsigned modules is restricted to signed
modules only. The old error message does not show which module misses
the signature, making it very difficult for a user to determine which
module is at fault.
This patch adds a line to the logs which additionally contains the
module name that caused the error message. The old message cannot
be replaced as it is generated by lockdown_is_locked_down
---
 kernel/module.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/kernel/module.c b/kernel/module.c
index 33569a01d6e..6dcb28139a0 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -2807,7 +2807,8 @@ static int module_sig_check(struct load_info *info,
int flags)
  const unsigned long markerlen = sizeof(MODULE_SIG_STRING) - 1;
  const char *reason;
  const void *mod = info->hdr;
-
+ int is_locked = -EPERM;
+
  /*
  * Require flags == 0, as a module with version information
  * removed is no longer the module that was signed
@@ -2843,7 +2844,12 @@ static int module_sig_check(struct load_info *info,
int flags)
  return -EKEYREJECTED;
  }

- return security_locked_down(LOCKDOWN_MODULE_SIGNATURE);
+ is_locked = security_locked_down(LOCKDOWN_MODULE_SIGNATURE);
+ if (is_locked == -EPERM) {
+ pr_notice("Lockdown: %s: rejected module '%s' cause: %s",
+ current->comm, info->name, reason);
+ }
+ return is_locked;

  /* All other errors are fatal, including nomem, unparseable
  * signatures and signature check failures - even if signatures
-- 
2.25.0