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lockdown: Lock down /proc/kcore

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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>
This commit is contained in:
David Howells 2019-08-19 17:17:57 -07:00 committed by James Morris
parent 906357f77a
commit 02e935bf5b
3 changed files with 7 additions and 0 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

5
fs/proc/kcore.c
View file

@ -31,6 +31,7 @@
#include <linux/ioport.h> #include <linux/ioport.h>
#include <linux/memory.h> #include <linux/memory.h>
#include <linux/sched/task.h> #include <linux/sched/task.h>
#include <linux/security.h>
#include <asm/sections.h> #include <asm/sections.h>
#include "internal.h" #include "internal.h"
@ -545,6 +546,10 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos)
static int open_kcore(struct inode *inode, struct file *filp) 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)) if (!capable(CAP_SYS_RAWIO))
return -EPERM; return -EPERM;

1
include/linux/security.h
View file

@ -116,6 +116,7 @@ enum lockdown_reason {
LOCKDOWN_MODULE_PARAMETERS, LOCKDOWN_MODULE_PARAMETERS,
LOCKDOWN_MMIOTRACE, LOCKDOWN_MMIOTRACE,
LOCKDOWN_INTEGRITY_MAX, LOCKDOWN_INTEGRITY_MAX,
LOCKDOWN_KCORE,
LOCKDOWN_CONFIDENTIALITY_MAX, LOCKDOWN_CONFIDENTIALITY_MAX,
}; };

1
security/lockdown/lockdown.c
View file

@ -31,6 +31,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
[LOCKDOWN_MODULE_PARAMETERS] = "unsafe module parameters", [LOCKDOWN_MODULE_PARAMETERS] = "unsafe module parameters",
[LOCKDOWN_MMIOTRACE] = "unsafe mmio", [LOCKDOWN_MMIOTRACE] = "unsafe mmio",
[LOCKDOWN_INTEGRITY_MAX] = "integrity", [LOCKDOWN_INTEGRITY_MAX] = "integrity",
[LOCKDOWN_KCORE] = "/proc/kcore access",
[LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality", [LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
}; };