lockdown: Lock down /proc/kcore

Disallow access to /proc/kcore when the kernel is locked down to prevent
access to cryptographic data. This is limited to lockdown
confidentiality mode and is still permitted in integrity mode.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Matthew Garrett <mjg59@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: James Morris <jmorris@namei.org>

diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c
index f583448..ee2c576 100644 (file)
--- a/fs/proc/kcore.c
+++ b/fs/proc/kcore.c
@@ -31,6 +31,7 @@
 #include <linux/ioport.h>
 #include <linux/memory.h>
 #include <linux/sched/task.h>
+#include <linux/security.h>
 #include <asm/sections.h>
 #include "internal.h"
 
@@ -545,6 +546,10 @@ out:
 
 static int open_kcore(struct inode *inode, struct file *filp)
 {
+       int ret = security_locked_down(LOCKDOWN_KCORE);
+
+       if (ret)
+               return ret;
        if (!capable(CAP_SYS_RAWIO))
                return -EPERM;
 

diff --git a/include/linux/security.h b/include/linux/security.h
index d8db7ea..669e8de 100644 (file)
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -116,6 +116,7 @@ enum lockdown_reason {
        LOCKDOWN_MODULE_PARAMETERS,
        LOCKDOWN_MMIOTRACE,
        LOCKDOWN_INTEGRITY_MAX,
+       LOCKDOWN_KCORE,
        LOCKDOWN_CONFIDENTIALITY_MAX,
 };
 

diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
index 2eadbe0..403b303 100644 (file)
--- a/security/lockdown/lockdown.c
+++ b/security/lockdown/lockdown.c
@@ -31,6 +31,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
        [LOCKDOWN_MODULE_PARAMETERS] = "unsafe module parameters",
        [LOCKDOWN_MMIOTRACE] = "unsafe mmio",
        [LOCKDOWN_INTEGRITY_MAX] = "integrity",
+       [LOCKDOWN_KCORE] = "/proc/kcore access",
        [LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
 };