From: Matt Brown <matt@nmatt.com>
To: gregkh@linuxfoundation.org, serge@hallyn.com, keescook@chromium.org
Cc: kernel-hardening@lists.openwall.com,
linux-security-module@vger.kernel.org,
linux-kernel@vger.kernel.org, Matt Brown <matt@nmatt.com>
Subject: [PATCH v7 1/2] security: tty: Add owner user namespace to tty_struct
Date: Mon, 29 May 2017 17:37:59 -0400 [thread overview]
Message-ID: <20170529213800.29438-2-matt@nmatt.com> (raw)
In-Reply-To: <20170529213800.29438-1-matt@nmatt.com>
This patch adds struct user_namespace *owner_user_ns to the tty_struct.
Then it is set to current_user_ns() in the alloc_tty_struct function.
This is done to facilitate capability checks against the original user
namespace that allocated the tty.
E.g. ns_capable(tty->owner_user_ns,CAP_SYS_ADMIN)
This combined with the use of user namespace's will allow hardening
protections to be built to mitigate container escapes that utilize TTY
ioctls such as TIOCSTI.
See: https://bugzilla.redhat.com/show_bug.cgi?id=1411256
Acked-by: Serge Hallyn <serge@hallyn.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Matt Brown <matt@nmatt.com>
---
drivers/tty/tty_io.c | 2 ++
include/linux/tty.h | 2 ++
2 files changed, 4 insertions(+)
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index e6d1a65..c276814 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -171,6 +171,7 @@ static void free_tty_struct(struct tty_struct *tty)
put_device(tty->dev);
kfree(tty->write_buf);
tty->magic = 0xDEADDEAD;
+ put_user_ns(tty->owner_user_ns);
kfree(tty);
}
@@ -3191,6 +3192,7 @@ struct tty_struct *alloc_tty_struct(struct tty_driver *driver, int idx)
tty->index = idx;
tty_line_name(driver, idx, tty->name);
tty->dev = tty_get_device(tty);
+ tty->owner_user_ns = get_user_ns(current_user_ns());
return tty;
}
diff --git a/include/linux/tty.h b/include/linux/tty.h
index 1017e904..d902d42 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -12,6 +12,7 @@
#include <uapi/linux/tty.h>
#include <linux/rwsem.h>
#include <linux/llist.h>
+#include <linux/user_namespace.h>
/*
@@ -333,6 +334,7 @@ struct tty_struct {
/* If the tty has a pending do_SAK, queue it here - akpm */
struct work_struct SAK_work;
struct tty_port *port;
+ struct user_namespace *owner_user_ns;
};
/* Each of a tty's open files has private_data pointing to tty_file_private */
--
2.10.2
next prev parent reply other threads:[~2017-05-29 21:39 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-29 21:37 [PATCH v7 0/2] security: tty: make TIOCSTI ioctl require CAP_SYS_ADMIN Matt Brown
2017-05-29 21:37 ` Matt Brown [this message]
2017-05-29 21:38 ` [PATCH v7 2/2] " Matt Brown
2017-05-29 22:26 ` Alan Cox
2017-05-29 23:51 ` [kernel-hardening] " Boris Lukashev
2017-05-30 0:27 ` Casey Schaufler
2017-05-30 2:00 ` Matt Brown
2017-05-30 2:46 ` Casey Schaufler
2017-05-30 3:18 ` Matt Brown
2017-05-30 12:24 ` Alan Cox
2017-05-30 16:28 ` Matt Brown
2017-05-30 16:44 ` Daniel Micay
2017-05-30 18:32 ` Stephen Smalley
2017-05-30 18:44 ` Nick Kralevich
2017-05-30 18:57 ` Matt Brown
2017-05-30 20:22 ` Daniel Micay
2017-05-30 23:00 ` Matt Brown
2017-05-30 23:40 ` Daniel Micay
2017-05-30 23:59 ` Matt Brown
2017-05-30 22:51 ` Alan Cox
2017-05-30 23:19 ` Matt Brown
2017-05-30 23:56 ` Alan Cox
2017-06-01 2:35 ` Kees Cook
2017-06-01 13:08 ` Alan Cox
2017-06-01 17:18 ` Serge E. Hallyn
2017-06-01 21:26 ` Alan Cox
2017-06-01 18:58 ` Kees Cook
2017-06-01 21:24 ` Alan Cox
2017-06-02 14:46 ` Matt Brown
2017-06-02 15:36 ` Serge E. Hallyn
2017-06-02 16:02 ` Matt Brown
2017-06-02 16:57 ` Serge E. Hallyn
2017-06-02 17:32 ` Matt Brown
2017-06-02 18:18 ` Serge E. Hallyn
2017-06-02 19:22 ` Matt Brown
2017-06-02 19:25 ` Kees Cook
2017-06-02 19:26 ` Matt Brown
2017-06-02 20:05 ` Alan Cox
2017-06-02 20:11 ` Nick Kralevich
2017-06-02 20:46 ` Matt Brown
2017-06-03 22:00 ` Alan Cox
2017-06-03 22:22 ` Matt Brown
2017-06-04 3:37 ` Peter Dolding
2017-05-30 15:20 ` Casey Schaufler
2017-05-30 16:09 ` Matt Brown
2017-06-04 6:29 ` Boris Lukashev
2017-05-31 2:48 ` James Morris
2017-05-31 4:10 ` Matt Brown
2017-05-30 0:15 ` Matt Brown
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