--- /dev/null
+/*
+ * 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,
+ unsigned 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, int major, int minor,
+ unsigned char *data, size_t size)
+{
+ struct audit_buffer *ab;
+ struct task_struct *tsk = current;
+ pid_t pid = task_pid_nr(tsk);
+ uid_t uid = from_kuid(&init_user_ns, task_uid(tsk));
+ uid_t loginuid = from_kuid(&init_user_ns, audit_get_loginuid(tsk));
+ unsigned int sessionid = audit_get_sessionid(tsk);
+
+ ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_TTY);
+ if (ab) {
+ char name[sizeof(tsk->comm)];
+
+ audit_log_format(ab, "%s pid=%u uid=%u auid=%u ses=%u major=%d"
+ " minor=%d comm=", description, 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
+ * the current task. @buf->mutex must be locked.
+ */
+static void tty_audit_buf_push(struct tty_audit_buf *buf)
+{
+ if (buf->valid == 0)
+ return;
+ if (audit_enabled == 0) {
+ buf->valid = 0;
+ return;
+ }
+ tty_audit_log("tty", buf->major, buf->minor, buf->data, buf->valid);
+ buf->valid = 0;
+}
+
+/**
+ * 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;
+
+ buf = current->signal->tty_audit_buf;
+ current->signal->tty_audit_buf = NULL;
+ if (!buf)
+ return;
+
+ mutex_lock(&buf->mutex);
+ tty_audit_buf_push(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)
+{
+ sig->audit_tty = current->signal->audit_tty;
+ sig->audit_tty_log_passwd = current->signal->audit_tty_log_passwd;
+}
+
+/**
+ * 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;
+ unsigned long flags;
+
+ spin_lock_irqsave(¤t->sighand->siglock, flags);
+ should_audit = current->signal->audit_tty;
+ buf = current->signal->tty_audit_buf;
+ if (buf)
+ atomic_inc(&buf->count);
+ spin_unlock_irqrestore(¤t->sighand->siglock, flags);
+
+ 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(buf);
+ mutex_unlock(&buf->mutex);
+ tty_audit_buf_put(buf);
+ }
+
+ if (should_audit && audit_enabled) {
+ kuid_t auid;
+ unsigned int sessionid;
+
+ auid = audit_get_loginuid(current);
+ sessionid = audit_get_sessionid(current);
+ tty_audit_log("ioctl=TIOCSTI", major, minor, &ch, 1);
+ }
+}
+
+/**
+ * tty_audit_push_current - Flush current's pending audit data
+ *
+ * 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_current(void)
+{
+ struct tty_audit_buf *buf = ERR_PTR(-EPERM);
+ struct task_struct *tsk = current;
+ 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(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,
+ unsigned icanon)
+{
+ struct tty_audit_buf *buf, *buf2;
+ unsigned long flags;
+
+ buf = NULL;
+ buf2 = NULL;
+ spin_lock_irqsave(¤t->sighand->siglock, flags);
+ if (likely(!current->signal->audit_tty))
+ goto out;
+ buf = current->signal->tty_audit_buf;
+ if (buf) {
+ atomic_inc(&buf->count);
+ goto out;
+ }
+ spin_unlock_irqrestore(¤t->sighand->siglock, flags);
+
+ buf2 = tty_audit_buf_alloc(tty->driver->major,
+ tty->driver->minor_start + tty->index,
+ icanon);
+ if (buf2 == NULL) {
+ audit_log_lost("out of memory in TTY auditing");
+ return NULL;
+ }
+
+ spin_lock_irqsave(¤t->sighand->siglock, flags);
+ 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_irqrestore(¤t->sighand->siglock, flags);
+ 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, unsigned icanon)
+{
+ struct tty_audit_buf *buf;
+ int major, minor;
+ int audit_log_tty_passwd;
+ unsigned long flags;
+
+ if (unlikely(size == 0))
+ return;
+
+ spin_lock_irqsave(¤t->sighand->siglock, flags);
+ audit_log_tty_passwd = current->signal->audit_tty_log_passwd;
+ spin_unlock_irqrestore(¤t->sighand->siglock, flags);
+ if (!audit_log_tty_passwd && icanon && !L_ECHO(tty))
+ return;
+
+ if (tty->driver->type == TTY_DRIVER_TYPE_PTY
+ && tty->driver->subtype == PTY_TYPE_MASTER)
+ return;
+
+ buf = tty_audit_buf_get(tty, icanon);
+ 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 != icanon) {
+ tty_audit_buf_push(buf);
+ buf->major = major;
+ buf->minor = minor;
+ buf->icanon = 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(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;
+ unsigned long flags;
+
+ spin_lock_irqsave(¤t->sighand->siglock, flags);
+ if (likely(!current->signal->audit_tty)) {
+ spin_unlock_irqrestore(¤t->sighand->siglock, flags);
+ return;
+ }
+ buf = current->signal->tty_audit_buf;
+ if (buf)
+ atomic_inc(&buf->count);
+ spin_unlock_irqrestore(¤t->sighand->siglock, flags);
+
+ 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(buf);
+ mutex_unlock(&buf->mutex);
+ tty_audit_buf_put(buf);
+ }
+}
Code Review / kvmfornfv.git / blobdiff