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module: limit enabling module.sig_enforce
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Irrespective as to whether CONFIG_MODULE_SIG is configured, specifying
"module.sig_enforce=1" on the boot command line sets "sig_enforce".
Only allow "sig_enforce" to be set when CONFIG_MODULE_SIG is configured.

This patch makes the presence of /sys/module/module/parameters/sig_enforce
dependent on CONFIG_MODULE_SIG=y.

Fixes: fda784e ("module: export module signature enforcement status")
Reported-by: Nayna Jain <nayna@linux.ibm.com>
Tested-by: Mimi Zohar <zohar@linux.ibm.com>
Tested-by: Jessica Yu <jeyu@kernel.org>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Jessica Yu <jeyu@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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mimizohar authored and torvalds committed Jun 22, 2021
1 parent a96bfed commit 0c18f29
Showing 1 changed file with 9 additions and 5 deletions.
14 changes: 9 additions & 5 deletions kernel/module.c
Original file line number Diff line number Diff line change
Expand Up @@ -266,9 +266,18 @@ static void module_assert_mutex_or_preempt(void)
#endif
}

#ifdef CONFIG_MODULE_SIG
static bool sig_enforce = IS_ENABLED(CONFIG_MODULE_SIG_FORCE);
module_param(sig_enforce, bool_enable_only, 0644);

void set_module_sig_enforced(void)
{
sig_enforce = true;
}
#else
#define sig_enforce false
#endif

/*
* Export sig_enforce kernel cmdline parameter to allow other subsystems rely
* on that instead of directly to CONFIG_MODULE_SIG_FORCE config.
Expand All @@ -279,11 +288,6 @@ bool is_module_sig_enforced(void)
}
EXPORT_SYMBOL(is_module_sig_enforced);

void set_module_sig_enforced(void)
{
sig_enforce = true;
}

/* Block module loading/unloading? */
int modules_disabled = 0;
core_param(nomodule, modules_disabled, bint, 0);
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