linux/drivers/tty/tty_audit.c
Greg Kroah-Hartman e5656d43dc tty: Remove redundant license text
Now that the SPDX tag is in all tty files, that identifies the license
in a specific and legally-defined manner.  So the extra GPL text wording
can be removed as it is no longer needed at all.

This is done on a quest to remove the 700+ different ways that files in
the kernel describe the GPL license text.  And there's unneeded stuff
like the address (sometimes incorrect) for the FSF which is never
needed.

No copyright headers or other non-license-description text was removed.

Cc: Jiri Slaby <jslaby@suse.com>
Cc: James Hogan <jhogan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-08 13:08:12 +01:00

249 lines
5.5 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* Creating audit events from TTY input.
*
* Copyright (C) 2007 Red Hat, Inc. All rights reserved.
*
* Authors: Miloslav Trmac <mitr@redhat.com>
*/
#include <linux/audit.h>
#include <linux/slab.h>
#include <linux/tty.h>
struct tty_audit_buf {
struct mutex mutex; /* Protects all data below */
dev_t dev; /* 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_ref(void)
{
struct tty_audit_buf *buf;
buf = current->signal->tty_audit_buf;
WARN_ON(buf == ERR_PTR(-ESRCH));
return buf;
}
static struct tty_audit_buf *tty_audit_buf_alloc(void)
{
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;
mutex_init(&buf->mutex);
buf->dev = MKDEV(0, 0);
buf->icanon = 0;
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_log(const char *description, dev_t dev,
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(dev), MINOR(dev));
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->dev, 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.
*
* The process is single-threaded at this point; no other threads share
* current->signal.
*/
void tty_audit_exit(void)
{
struct tty_audit_buf *buf;
buf = xchg(&current->signal->tty_audit_buf, ERR_PTR(-ESRCH));
if (!buf)
return;
tty_audit_buf_push(buf);
tty_audit_buf_free(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;
}
/**
* tty_audit_tiocsti - Log TIOCSTI
*/
void tty_audit_tiocsti(struct tty_struct *tty, char ch)
{
dev_t dev;
dev = MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index;
if (tty_audit_push())
return;
if (audit_enabled)
tty_audit_log("ioctl=TIOCSTI", dev, &ch, 1);
}
/**
* tty_audit_push - Flush current's pending audit data
*
* Returns 0 if success, -EPERM if tty audit is disabled
*/
int tty_audit_push(void)
{
struct tty_audit_buf *buf;
if (~current->signal->audit_tty & AUDIT_TTY_ENABLE)
return -EPERM;
buf = tty_audit_buf_ref();
if (!IS_ERR_OR_NULL(buf)) {
mutex_lock(&buf->mutex);
tty_audit_buf_push(buf);
mutex_unlock(&buf->mutex);
}
return 0;
}
/**
* tty_audit_buf_get - Get an audit buffer.
*
* Get an audit buffer, allocate it if necessary. Return %NULL
* if out of memory or ERR_PTR(-ESRCH) if tty_audit_exit() has already
* occurred. Otherwise, return a new reference to the buffer.
*/
static struct tty_audit_buf *tty_audit_buf_get(void)
{
struct tty_audit_buf *buf;
buf = tty_audit_buf_ref();
if (buf)
return buf;
buf = tty_audit_buf_alloc();
if (buf == NULL) {
audit_log_lost("out of memory in TTY auditing");
return NULL;
}
/* Race to use this buffer, free it if another wins */
if (cmpxchg(&current->signal->tty_audit_buf, NULL, buf) != NULL)
tty_audit_buf_free(buf);
return tty_audit_buf_ref();
}
/**
* 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, const void *data, size_t size)
{
struct tty_audit_buf *buf;
unsigned int icanon = !!L_ICANON(tty);
unsigned int audit_tty;
dev_t dev;
audit_tty = READ_ONCE(current->signal->audit_tty);
if (~audit_tty & AUDIT_TTY_ENABLE)
return;
if (unlikely(size == 0))
return;
if (tty->driver->type == TTY_DRIVER_TYPE_PTY
&& tty->driver->subtype == PTY_TYPE_MASTER)
return;
if ((~audit_tty & AUDIT_TTY_LOG_PASSWD) && icanon && !L_ECHO(tty))
return;
buf = tty_audit_buf_get();
if (IS_ERR_OR_NULL(buf))
return;
mutex_lock(&buf->mutex);
dev = MKDEV(tty->driver->major, tty->driver->minor_start) + tty->index;
if (buf->dev != dev || buf->icanon != icanon) {
tty_audit_buf_push(buf);
buf->dev = dev;
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);
}