path: root/security/lockdown
diff options
authorMatthew Garrett <>2019-08-19 17:17:41 -0700
committerJames Morris <>2019-08-19 21:54:15 -0700
commit9b9d8dda1ed72e9bd560ab0ca93d322a9440510e (patch)
treeaa5a6719f76556e20ce1ca6e286d10660f1746f5 /security/lockdown
parent49fcf732bdae0550721ef73af7c45109ce26b2a9 (diff)
lockdown: Restrict /dev/{mem,kmem,port} when the kernel is locked down
Allowing users to read and write to core kernel memory makes it possible for the kernel to be subverted, avoiding module loading restrictions, and also to steal cryptographic information. Disallow /dev/mem and /dev/kmem from being opened this when the kernel has been locked down to prevent this. Also disallow /dev/port from being opened to prevent raw ioport access and thus DMA from being used to accomplish the same thing. Signed-off-by: David Howells <> Signed-off-by: Matthew Garrett <> Reviewed-by: Kees Cook <> Cc: Signed-off-by: James Morris <>
Diffstat (limited to 'security/lockdown')
1 files changed, 1 insertions, 0 deletions
diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
index d8e42125a5dd..240ecaa10a1d 100644
--- a/security/lockdown/lockdown.c
+++ b/security/lockdown/lockdown.c
@@ -19,6 +19,7 @@ static enum lockdown_reason kernel_locked_down;
static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
[LOCKDOWN_NONE] = "none",
[LOCKDOWN_MODULE_SIGNATURE] = "unsigned module loading",
+ [LOCKDOWN_DEV_MEM] = "/dev/mem,kmem,port",