From: David Howells <dhowells@xxxxxxxxxx> The testmmiotrace module shouldn't be permitted when the kernel is locked down as it can be used to arbitrarily read and write MMIO space. This is a runtime check rather than buildtime in order to allow configurations where the same kernel may be run in both locked down or permissive modes depending on local policy. Suggested-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Signed-off-by: David Howells <dhowells@xxxxxxxxxx Signed-off-by: Matthew Garrett <mjg59@xxxxxxxxxx> Acked-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx> Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx> cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> cc: Steven Rostedt <rostedt@xxxxxxxxxxx> cc: Ingo Molnar <mingo@xxxxxxxxxx> cc: "H. Peter Anvin" <hpa@xxxxxxxxx> cc: x86@xxxxxxxxxx Signed-off-by: James Morris <jmorris@xxxxxxxxx> --- arch/x86/mm/testmmiotrace.c | 5 +++++ include/linux/security.h | 1 + security/lockdown/lockdown.c | 1 + 3 files changed, 7 insertions(+) diff --git a/arch/x86/mm/testmmiotrace.c b/arch/x86/mm/testmmiotrace.c index 0881e1ff1e58..a8bd952e136d 100644 --- a/arch/x86/mm/testmmiotrace.c +++ b/arch/x86/mm/testmmiotrace.c @@ -8,6 +8,7 @@ #include <linux/module.h> #include <linux/io.h> #include <linux/mmiotrace.h> +#include <linux/security.h> static unsigned long mmio_address; module_param_hw(mmio_address, ulong, iomem, 0); @@ -115,6 +116,10 @@ static void do_test_bulk_ioremapping(void) static int __init init(void) { unsigned long size = (read_far) ? (8 << 20) : (16 << 10); + int ret = security_locked_down(LOCKDOWN_MMIOTRACE); + + if (ret) + return ret; if (mmio_address == 0) { pr_err("you have to use the module argument mmio_address.\n"); diff --git a/include/linux/security.h b/include/linux/security.h index 1a3404f9c060..d8db7ea4c4bf 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -114,6 +114,7 @@ enum lockdown_reason { LOCKDOWN_PCMCIA_CIS, LOCKDOWN_TIOCSSERIAL, LOCKDOWN_MODULE_PARAMETERS, + LOCKDOWN_MMIOTRACE, LOCKDOWN_INTEGRITY_MAX, LOCKDOWN_CONFIDENTIALITY_MAX, }; diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c index 0fa434294667..2eadbe0667e7 100644 --- a/security/lockdown/lockdown.c +++ b/security/lockdown/lockdown.c @@ -29,6 +29,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = { [LOCKDOWN_PCMCIA_CIS] = "direct PCMCIA CIS storage", [LOCKDOWN_TIOCSSERIAL] = "reconfiguration of serial port IO", [LOCKDOWN_MODULE_PARAMETERS] = "unsafe module parameters", + [LOCKDOWN_MMIOTRACE] = "unsafe mmio", [LOCKDOWN_INTEGRITY_MAX] = "integrity", [LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality", }; -- 2.23.0.rc1.153.gdeed80330f-goog