+++ Martin Haass [19/02/20 10:02 +0100]:
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;
Hi!
Actually, I think we can just reuse the pr_notice() from the previous if
(is_module_sig_enforced()) block. It already logs the module name as well as
the reason. And we'd better leave the lockdown-specific messages to the LSM.
Something like this perhaps?
diff --git a/kernel/module.c b/kernel/module.c
index b88ec9cd2a7f..2c881e3b9d92 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -2838,12 +2838,13 @@ static int module_sig_check(struct load_info *info, int flags)
case -ENOKEY:
reason = "Loading of module with unavailable key";
decide:
- if (is_module_sig_enforced()) {
+ err = is_module_sig_enforced() ? \
+ -EKEYREJECTED : security_locked_down(LOCKDOWN_MODULE_SIGNATURE);
+
+ if (err)
pr_notice("%s: %s is rejected\n", info->name, reason);
- return -EKEYREJECTED;
- }
- return security_locked_down(LOCKDOWN_MODULE_SIGNATURE);
+ return err;
/* All other errors are fatal, including nomem, unparseable
* signatures and signature check failures - even if signatures
