[PATCH V37 21/29] Lock down /proc/kcore
From: Matthew Garrett <hidden>
Date: 2019-07-31 22:18:52
Also in:
linux-api, lkml
Subsystem:
filesystems (vfs and infrastructure), kcore, lockdown security module, proc filesystem, security subsystem, the rest · Maintainers:
Alexander Viro, Christian Brauner, Omar Sandoval, Nicolas Bouchinet, Xiu Jianfeng, Paul Moore, James Morris, "Serge E. Hallyn", Linus Torvalds
From: David Howells <dhowells@redhat.com> 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 <redacted> Reviewed-by: Kees Cook <redacted> --- fs/proc/kcore.c | 5 +++++ include/linux/security.h | 1 + security/lockdown/lockdown.c | 1 + 3 files changed, 7 insertions(+)
diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c
index f5834488b67d..ee2c576cc94e 100644
--- 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 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) 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 3f7b6a4cd65a..f0cffd0977d3 100644
--- 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 37b7d7e50474..c050b82c7f9f 100644
--- 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", };
--
2.22.0.770.g0f2c4a37fd-goog