LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Mimi Zohar <zohar@linux.vnet.ibm.com>
To: linux-integrity@vger.kernel.org
Cc: Eric Biederman <ebiederm@xmission.com>,
	David Howells <dhowells@redhat.com>,
	Mimi Zohar <zohar@linux.vnet.ibm.com>,
	linux-security-module@vger.kernel.org, kexec@lists.infradead.org,
	linux-kernel@vger.kernel.org, Kees Cook <keescook@chromium.org>,
	Matthew Garrett <mjg59@google.com>,
	Casey Schaufler <casey@schaufler-ca.com>
Subject: [PATCH 2/3] kexec: call LSM hook for kexec_load syscall
Date: Thu, 10 May 2018 21:36:47 -0400	[thread overview]
Message-ID: <1526002608-27474-3-git-send-email-zohar@linux.vnet.ibm.com> (raw)
In-Reply-To: <1526002608-27474-1-git-send-email-zohar@linux.vnet.ibm.com>

In order for LSMs and IMA-appraisal to differentiate between the
kexec_load and kexec_file_load_syscalls, an LSM call needs to be added
to the original kexec_load syscall.  From a technical perspective there
is no need for defining a new LSM hook, as the existing
security_kernel_kexec_load() works just fine.  However, the name is
confusing.  For this reason, instead of defining a new LSM hook, this
patch defines security_kexec_load() as a wrapper for the existing LSM
security_kernel_file_read() hook.

Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Matthew Garrett <mjg59@google.com>
Cc: Casey Schaufler <casey@schaufler-ca.com>

Changelog v1:
- Define and call security_kexec_load(), a wrapper for
security_kernel_read_file().
---
 include/linux/security.h |  6 ++++++
 kernel/kexec.c           | 11 +++++++++++
 security/security.c      |  6 ++++++
 3 files changed, 23 insertions(+)

diff --git a/include/linux/security.h b/include/linux/security.h
index 63030c85ee19..26f6d85903ed 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -323,6 +323,7 @@ int security_kernel_module_request(char *kmod_name);
 int security_kernel_read_file(struct file *file, enum kernel_read_file_id id);
 int security_kernel_post_read_file(struct file *file, char *buf, loff_t size,
 				   enum kernel_read_file_id id);
+int security_kexec_load(void);
 int security_task_fix_setuid(struct cred *new, const struct cred *old,
 			     int flags);
 int security_task_setpgid(struct task_struct *p, pid_t pgid);
@@ -922,6 +923,11 @@ static inline int security_kernel_post_read_file(struct file *file,
 	return 0;
 }
 
+static inline int security_kexec_load(void)
+{
+	return 0;
+}
+
 static inline int security_task_fix_setuid(struct cred *new,
 					   const struct cred *old,
 					   int flags)
diff --git a/kernel/kexec.c b/kernel/kexec.c
index aed8fb2564b3..6b44b0e9a60b 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -11,6 +11,7 @@
 #include <linux/capability.h>
 #include <linux/mm.h>
 #include <linux/file.h>
+#include <linux/security.h>
 #include <linux/kexec.h>
 #include <linux/mutex.h>
 #include <linux/list.h>
@@ -195,11 +196,21 @@ static int do_kexec_load(unsigned long entry, unsigned long nr_segments,
 static inline int kexec_load_check(unsigned long nr_segments,
 				   unsigned long flags)
 {
+	int result;
+
 	/* We only trust the superuser with rebooting the system. */
 	if (!capable(CAP_SYS_BOOT) || kexec_load_disabled)
 		return -EPERM;
 
 	/*
+	 * Allow LSMs and IMA to differentiate between kexec_load and
+	 * kexec_file_load syscalls.
+	 */
+	result = security_kexec_load();
+	if (result < 0)
+		return result;
+
+	/*
 	 * Verify we have a legal set of flags
 	 * This leaves us room for future extensions.
 	 */
diff --git a/security/security.c b/security/security.c
index 68f46d849abe..0f3390000156 100644
--- a/security/security.c
+++ b/security/security.c
@@ -1044,6 +1044,12 @@ int security_kernel_read_file(struct file *file, enum kernel_read_file_id id)
 }
 EXPORT_SYMBOL_GPL(security_kernel_read_file);
 
+int security_kexec_load()
+{
+	return security_kernel_read_file(NULL, READING_KEXEC_IMAGE);
+}
+EXPORT_SYMBOL_GPL(security_kexec_load);
+
 int security_kernel_post_read_file(struct file *file, char *buf, loff_t size,
 				   enum kernel_read_file_id id)
 {
-- 
2.7.5

  parent reply	other threads:[~2018-05-11  1:37 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-11  1:36 [PATCH 0/3] kexec: limit " Mimi Zohar
2018-05-11  1:36 ` [PATCH 1/3] ima: based on the "secure_boot" policy limit syscalls Mimi Zohar
2018-05-11  1:36 ` Mimi Zohar [this message]
2018-05-11  1:36 ` [PATCH 3/3] ima: based on policy require signed kexec kernel images Mimi Zohar
  -- strict thread matches above, loose matches on Subject: below --
2018-04-12 22:41 [PATCH 0/3] kexec: limit kexec_load syscall Mimi Zohar
2018-04-12 22:41 ` [PATCH 2/3] kexec: call LSM hook for " Mimi Zohar
2018-05-02 14:45   ` Eric W. Biederman
2018-05-02 15:45     ` Mimi Zohar
2018-05-03 15:51       ` Eric W. Biederman
2018-05-03 16:05         ` Casey Schaufler
2018-05-03 16:42           ` Eric W. Biederman
2018-05-03 21:06             ` Mimi Zohar
2018-05-03 21:36               ` Eric W. Biederman

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=1526002608-27474-3-git-send-email-zohar@linux.vnet.ibm.com \
    --to=zohar@linux.vnet.ibm.com \
    --cc=casey@schaufler-ca.com \
    --cc=dhowells@redhat.com \
    --cc=ebiederm@xmission.com \
    --cc=keescook@chromium.org \
    --cc=kexec@lists.infradead.org \
    --cc=linux-integrity@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-security-module@vger.kernel.org \
    --cc=mjg59@google.com \
    --subject='Re: [PATCH 2/3] kexec: call LSM hook for kexec_load syscall' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).