// 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>#include "tty.h" #define TTY_AUDIT_BUF_SIZE	4096 struct tty_audit_buf {	struct mutex mutex;	/* Protects all data below */	dev_t dev;		/* The TTY which the data is from */	bool icanon;	size_t valid;	u8 *data;		/* Allocated size TTY_AUDIT_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 = kzalloc_obj(*buf);	if (!buf)		goto err; 	buf->data = kmalloc(TTY_AUDIT_BUF_SIZE, GFP_KERNEL);	if (!buf->data)		goto err_buf; 	mutex_init(&buf->mutex); 	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,			  const u8 *data, size_t size){	struct audit_buffer *ab;	pid_t pid = task_pid_nr(current);	uid_t uid = from_kuid(&init_user_ns, task_uid(current));	uid_t loginuid = from_kuid(&init_user_ns, audit_get_loginuid(current));	unsigned int sessionid = audit_get_sessionid(current);	char name[TASK_COMM_LEN]; 	ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_TTY);	if (!ab)		return; 	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, current);	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 == AUDIT_OFF) {		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(const struct tty_struct *tty, u8 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(const struct tty_struct *tty, const void *data,			size_t size){	struct tty_audit_buf *buf;	unsigned int audit_tty;	bool icanon = L_ICANON(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 = TTY_AUDIT_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 == TTY_AUDIT_BUF_SIZE)			tty_audit_buf_push(buf);	} while (size != 0);	mutex_unlock(&buf->mutex);}