original development tree for Linux kernel GTP module; now long in mainline.
You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
 
 
 
 

363 lines
8.6 KiB

/*
* 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,
kuid_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)];
kuid_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,
from_kuid(&init_user_ns, uid),
from_kuid(&init_user_ns, 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, kuid_t loginuid,
unsigned int sessionid,
struct tty_audit_buf *buf)
{
if (buf->valid == 0)
return;
if (audit_enabled == 0) {
buf->valid = 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)
{
kuid_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) {
kuid_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, kuid_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);
}
}