1 files changed, 358 insertions, 0 deletions

diff --git a/drivers/tty/tty_audit.c b/drivers/tty/tty_audit.c
new file mode 100644
index 000000000000..f64582b0f623
--- /dev/null
+++ b/drivers/tty/tty_audit.c
@@ -0,0 +1,358 @@
+/*
+ * Creating audit events from TTY input.
+ *
+ * Copyright (C) 2007 Red Hat, Inc.  All rights reserved.  This copyrighted
+ * material is made available to anyone wishing to use, modify, copy, or
+ * redistribute it subject to the terms and conditions of the GNU General
+ * Public License v.2.
+ *
+ * Authors: Miloslav Trmac <mitr@redhat.com>
+ */
+
+#include <linux/audit.h>
+#include <linux/slab.h>
+#include <linux/tty.h>
+
+struct tty_audit_buf {
+	atomic_t count;
+	struct mutex mutex;	/* Protects all data below */
+	int major, minor;	/* The TTY which the data is from */
+	unsigned icanon:1;
+	size_t valid;
+	unsigned char *data;	/* Allocated size N_TTY_BUF_SIZE */
+};
+
+static struct tty_audit_buf *tty_audit_buf_alloc(int major, int minor,
+						 int icanon)
+{
+	struct tty_audit_buf *buf;
+
+	buf = kmalloc(sizeof(*buf), GFP_KERNEL);
+	if (!buf)
+		goto err;
+	buf->data = kmalloc(N_TTY_BUF_SIZE, GFP_KERNEL);
+	if (!buf->data)
+		goto err_buf;
+	atomic_set(&buf->count, 1);
+	mutex_init(&buf->mutex);
+	buf->major = major;
+	buf->minor = minor;
+	buf->icanon = icanon;
+	buf->valid = 0;
+	return buf;
+
+err_buf:
+	kfree(buf);
+err:
+	return NULL;
+}
+
+static void tty_audit_buf_free(struct tty_audit_buf *buf)
+{
+	WARN_ON(buf->valid != 0);
+	kfree(buf->data);
+	kfree(buf);
+}
+
+static void tty_audit_buf_put(struct tty_audit_buf *buf)
+{
+	if (atomic_dec_and_test(&buf->count))
+		tty_audit_buf_free(buf);
+}
+
+static void tty_audit_log(const char *description, struct task_struct *tsk,
+			  uid_t loginuid, unsigned sessionid, int major,
+			  int minor, unsigned char *data, size_t size)
+{
+	struct audit_buffer *ab;
+
+	ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_TTY);
+	if (ab) {
+		char name[sizeof(tsk->comm)];
+		uid_t uid = task_uid(tsk);
+
+		audit_log_format(ab, "%s pid=%u uid=%u auid=%u ses=%u "
+				 "major=%d minor=%d comm=", description,
+				 tsk->pid, uid, loginuid, sessionid,
+				 major, minor);
+		get_task_comm(name, tsk);
+		audit_log_untrustedstring(ab, name);
+		audit_log_format(ab, " data=");
+		audit_log_n_hex(ab, data, size);
+		audit_log_end(ab);
+	}
+}
+
+/**
+ *	tty_audit_buf_push	-	Push buffered data out
+ *
+ *	Generate an audit message from the contents of @buf, which is owned by
+ *	@tsk with @loginuid.  @buf->mutex must be locked.
+ */
+static void tty_audit_buf_push(struct task_struct *tsk, uid_t loginuid,
+			       unsigned int sessionid,
+			       struct tty_audit_buf *buf)
+{
+	if (buf->valid == 0)
+		return;
+	if (audit_enabled == 0)
+		return;
+	tty_audit_log("tty", tsk, loginuid, sessionid, buf->major, buf->minor,
+		      buf->data, buf->valid);
+	buf->valid = 0;
+}
+
+/**
+ *	tty_audit_buf_push_current	-	Push buffered data out
+ *
+ *	Generate an audit message from the contents of @buf, which is owned by
+ *	the current task.  @buf->mutex must be locked.
+ */
+static void tty_audit_buf_push_current(struct tty_audit_buf *buf)
+{
+	uid_t auid = audit_get_loginuid(current);
+	unsigned int sessionid = audit_get_sessionid(current);
+	tty_audit_buf_push(current, auid, sessionid, buf);
+}
+
+/**
+ *	tty_audit_exit	-	Handle a task exit
+ *
+ *	Make sure all buffered data is written out and deallocate the buffer.
+ *	Only needs to be called if current->signal->tty_audit_buf != %NULL.
+ */
+void tty_audit_exit(void)
+{
+	struct tty_audit_buf *buf;
+
+	spin_lock_irq(&current->sighand->siglock);
+	buf = current->signal->tty_audit_buf;
+	current->signal->tty_audit_buf = NULL;
+	spin_unlock_irq(&current->sighand->siglock);
+	if (!buf)
+		return;
+
+	mutex_lock(&buf->mutex);
+	tty_audit_buf_push_current(buf);
+	mutex_unlock(&buf->mutex);
+
+	tty_audit_buf_put(buf);
+}
+
+/**
+ *	tty_audit_fork	-	Copy TTY audit state for a new task
+ *
+ *	Set up TTY audit state in @sig from current.  @sig needs no locking.
+ */
+void tty_audit_fork(struct signal_struct *sig)
+{
+	spin_lock_irq(&current->sighand->siglock);
+	sig->audit_tty = current->signal->audit_tty;
+	spin_unlock_irq(&current->sighand->siglock);
+}
+
+/**
+ *	tty_audit_tiocsti	-	Log TIOCSTI
+ */
+void tty_audit_tiocsti(struct tty_struct *tty, char ch)
+{
+	struct tty_audit_buf *buf;
+	int major, minor, should_audit;
+
+	spin_lock_irq(&current->sighand->siglock);
+	should_audit = current->signal->audit_tty;
+	buf = current->signal->tty_audit_buf;
+	if (buf)
+		atomic_inc(&buf->count);
+	spin_unlock_irq(&current->sighand->siglock);
+
+	major = tty->driver->major;
+	minor = tty->driver->minor_start + tty->index;
+	if (buf) {
+		mutex_lock(&buf->mutex);
+		if (buf->major == major && buf->minor == minor)
+			tty_audit_buf_push_current(buf);
+		mutex_unlock(&buf->mutex);
+		tty_audit_buf_put(buf);
+	}
+
+	if (should_audit && audit_enabled) {
+		uid_t auid;
+		unsigned int sessionid;
+
+		auid = audit_get_loginuid(current);
+		sessionid = audit_get_sessionid(current);
+		tty_audit_log("ioctl=TIOCSTI", current, auid, sessionid, major,
+			      minor, &ch, 1);
+	}
+}
+
+/**
+ * tty_audit_push_task	-	Flush task's pending audit data
+ * @tsk:		task pointer
+ * @loginuid:		sender login uid
+ * @sessionid:		sender session id
+ *
+ * Called with a ref on @tsk held. Try to lock sighand and get a
+ * reference to the tty audit buffer if available.
+ * Flush the buffer or return an appropriate error code.
+ */
+int tty_audit_push_task(struct task_struct *tsk, uid_t loginuid, u32 sessionid)
+{
+	struct tty_audit_buf *buf = ERR_PTR(-EPERM);
+	unsigned long flags;
+
+	if (!lock_task_sighand(tsk, &flags))
+		return -ESRCH;
+
+	if (tsk->signal->audit_tty) {
+		buf = tsk->signal->tty_audit_buf;
+		if (buf)
+			atomic_inc(&buf->count);
+	}
+	unlock_task_sighand(tsk, &flags);
+
+	/*
+	 * Return 0 when signal->audit_tty set
+	 * but tsk->signal->tty_audit_buf == NULL.
+	 */
+	if (!buf || IS_ERR(buf))
+		return PTR_ERR(buf);
+
+	mutex_lock(&buf->mutex);
+	tty_audit_buf_push(tsk, loginuid, sessionid, buf);
+	mutex_unlock(&buf->mutex);
+
+	tty_audit_buf_put(buf);
+	return 0;
+}
+
+/**
+ *	tty_audit_buf_get	-	Get an audit buffer.
+ *
+ *	Get an audit buffer for @tty, allocate it if necessary.  Return %NULL
+ *	if TTY auditing is disabled or out of memory.  Otherwise, return a new
+ *	reference to the buffer.
+ */
+static struct tty_audit_buf *tty_audit_buf_get(struct tty_struct *tty)
+{
+	struct tty_audit_buf *buf, *buf2;
+
+	buf = NULL;
+	buf2 = NULL;
+	spin_lock_irq(&current->sighand->siglock);
+	if (likely(!current->signal->audit_tty))
+		goto out;
+	buf = current->signal->tty_audit_buf;
+	if (buf) {
+		atomic_inc(&buf->count);
+		goto out;
+	}
+	spin_unlock_irq(&current->sighand->siglock);
+
+	buf2 = tty_audit_buf_alloc(tty->driver->major,
+				   tty->driver->minor_start + tty->index,
+				   tty->icanon);
+	if (buf2 == NULL) {
+		audit_log_lost("out of memory in TTY auditing");
+		return NULL;
+	}
+
+	spin_lock_irq(&current->sighand->siglock);
+	if (!current->signal->audit_tty)
+		goto out;
+	buf = current->signal->tty_audit_buf;
+	if (!buf) {
+		current->signal->tty_audit_buf = buf2;
+		buf = buf2;
+		buf2 = NULL;
+	}
+	atomic_inc(&buf->count);
+	/* Fall through */
+ out:
+	spin_unlock_irq(&current->sighand->siglock);
+	if (buf2)
+		tty_audit_buf_free(buf2);
+	return buf;
+}
+
+/**
+ *	tty_audit_add_data	-	Add data for TTY auditing.
+ *
+ *	Audit @data of @size from @tty, if necessary.
+ */
+void tty_audit_add_data(struct tty_struct *tty, unsigned char *data,
+			size_t size)
+{
+	struct tty_audit_buf *buf;
+	int major, minor;
+
+	if (unlikely(size == 0))
+		return;
+
+	if (tty->driver->type == TTY_DRIVER_TYPE_PTY
+	    && tty->driver->subtype == PTY_TYPE_MASTER)
+		return;
+
+	buf = tty_audit_buf_get(tty);
+	if (!buf)
+		return;
+
+	mutex_lock(&buf->mutex);
+	major = tty->driver->major;
+	minor = tty->driver->minor_start + tty->index;
+	if (buf->major != major || buf->minor != minor
+	    || buf->icanon != tty->icanon) {
+		tty_audit_buf_push_current(buf);
+		buf->major = major;
+		buf->minor = minor;
+		buf->icanon = tty->icanon;
+	}
+	do {
+		size_t run;
+
+		run = N_TTY_BUF_SIZE - buf->valid;
+		if (run > size)
+			run = size;
+		memcpy(buf->data + buf->valid, data, run);
+		buf->valid += run;
+		data += run;
+		size -= run;
+		if (buf->valid == N_TTY_BUF_SIZE)
+			tty_audit_buf_push_current(buf);
+	} while (size != 0);
+	mutex_unlock(&buf->mutex);
+	tty_audit_buf_put(buf);
+}
+
+/**
+ *	tty_audit_push	-	Push buffered data out
+ *
+ *	Make sure no audit data is pending for @tty on the current process.
+ */
+void tty_audit_push(struct tty_struct *tty)
+{
+	struct tty_audit_buf *buf;
+
+	spin_lock_irq(&current->sighand->siglock);
+	if (likely(!current->signal->audit_tty)) {
+		spin_unlock_irq(&current->sighand->siglock);
+		return;
+	}
+	buf = current->signal->tty_audit_buf;
+	if (buf)
+		atomic_inc(&buf->count);
+	spin_unlock_irq(&current->sighand->siglock);
+
+	if (buf) {
+		int major, minor;
+
+		major = tty->driver->major;
+		minor = tty->driver->minor_start + tty->index;
+		mutex_lock(&buf->mutex);
+		if (buf->major == major && buf->minor == minor)
+			tty_audit_buf_push_current(buf);
+		mutex_unlock(&buf->mutex);
+		tty_audit_buf_put(buf);
+	}
+}