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authorAleksa Sarai <asarai@suse.de>2017-06-04 00:15:15 +1000
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-06-09 12:27:54 +0200
commit54ebbfb1603415d9953c150535850d30609ef077 (patch)
treeedf8b41d6f34528641d97f2e5ee1fad5ea2df9c6 /arch/sparc/include/uapi/asm
parent5f0f187fd0cc755cfa7d51b50f68a16fca41c813 (diff)
tty: add TIOCGPTPEER ioctl
When opening the slave end of a PTY, it is not possible for userspace to safely ensure that /dev/pts/$num is actually a slave (in cases where the mount namespace in which devpts was mounted is controlled by an untrusted process). In addition, there are several unresolvable race conditions if userspace were to attempt to detect attacks through stat(2) and other similar methods [in addition it is not clear how userspace could detect attacks involving FUSE]. Resolve this by providing an interface for userpace to safely open the "peer" end of a PTY file descriptor by using the dentry cached by devpts. Since it is not possible to have an open master PTY without having its slave exposed in /dev/pts this interface is safe. This interface currently does not provide a way to get the master pty (since it is not clear whether such an interface is safe or even useful). Cc: Christian Brauner <christian.brauner@ubuntu.com> Cc: Valentin Rothberg <vrothberg@suse.com> Signed-off-by: Aleksa Sarai <asarai@suse.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch/sparc/include/uapi/asm')
-rw-r--r--arch/sparc/include/uapi/asm/ioctls.h3
1 files changed, 2 insertions, 1 deletions
diff --git a/arch/sparc/include/uapi/asm/ioctls.h b/arch/sparc/include/uapi/asm/ioctls.h
index 06b3f6c3bb9a..6d27398632ea 100644
--- a/arch/sparc/include/uapi/asm/ioctls.h
+++ b/arch/sparc/include/uapi/asm/ioctls.h
@@ -27,7 +27,7 @@
#define TIOCGRS485 _IOR('T', 0x41, struct serial_rs485)
#define TIOCSRS485 _IOWR('T', 0x42, struct serial_rs485)
-/* Note that all the ioctls that are not available in Linux have a
+/* Note that all the ioctls that are not available in Linux have a
* double underscore on the front to: a) avoid some programs to
* think we support some ioctls under Linux (autoconfiguration stuff)
*/
@@ -88,6 +88,7 @@
#define TIOCGPTN _IOR('t', 134, unsigned int) /* Get Pty Number */
#define TIOCSPTLCK _IOW('t', 135, int) /* Lock/unlock PTY */
#define TIOCSIG _IOW('t', 136, int) /* Generate signal on Pty slave */
+#define TIOCGPTPEER _IOR('t', 137, int) /* Safely open the slave */
/* Little f */
#define FIOCLEX _IO('f', 1)

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