Commit 17911ff3 authored by Steven Rostedt (VMware)'s avatar Steven Rostedt (VMware)
Browse files

tracing: Add locked_down checks to the open calls of files created for tracefs 

Added various checks on open tracefs calls to see if tracefs is in lockdown
mode, and if so, to return -EPERM.

Note, the event format files (which are basically standard on all machines)
as well as the enabled_functions file (which shows what is currently being
traced) are not lockde down. Perhaps they should be, but it seems counter
intuitive to lockdown information to help you know if the system has been
modified.

Link: http://lkml.kernel.org/r/CAHk-=wj7fGPKUspr579Cii-w_y60PtRaiDgKuxVtBAMK0VNNkA@mail.gmail.com



Suggested-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
parent 8530dec6

kernel/trace/ftrace.c

+22 −1
Original line number Diff line number Diff line
@@ -18,6 +18,7 @@ 
#include <linux/clocksource.h>

#include <linux/sched/task.h>

#include <linux/kallsyms.h>

#include <linux/security.h>

#include <linux/seq_file.h>

#include <linux/tracefs.h>

#include <linux/hardirq.h>
@@ -3486,6 +3487,11 @@ static int 
ftrace_avail_open(struct inode *inode, struct file *file)

{

	struct ftrace_iterator *iter;

	int ret;



	ret = security_locked_down(LOCKDOWN_TRACEFS);

	if (ret)

		return ret;



	if (unlikely(ftrace_disabled))

		return -ENODEV;
@@ -3505,6 +3511,15 @@ ftrace_enabled_open(struct inode *inode, struct file *file) 
{

	struct ftrace_iterator *iter;



	/*

	 * This shows us what functions are currently being

	 * traced and by what. Not sure if we want lockdown

	 * to hide such critical information for an admin.

	 * Although, perhaps it can show information we don't

	 * want people to see, but if something is tracing

	 * something, we probably want to know about it.

	 */



	iter = __seq_open_private(file, &show_ftrace_seq_ops, sizeof(*iter));

	if (!iter)

		return -ENOMEM;
@@ -3625,6 +3640,7 @@ ftrace_filter_open(struct inode *inode, struct file *file) 
{

	struct ftrace_ops *ops = inode->i_private;



	/* Checks for tracefs lockdown */

	return ftrace_regex_open(ops,

			FTRACE_ITER_FILTER | FTRACE_ITER_DO_PROBES,

			inode, file);
@@ -3635,6 +3651,7 @@ ftrace_notrace_open(struct inode *inode, struct file *file) 
{

	struct ftrace_ops *ops = inode->i_private;



	/* Checks for tracefs lockdown */

	return ftrace_regex_open(ops, FTRACE_ITER_NOTRACE,

				 inode, file);

}
@@ -5203,9 +5220,13 @@ static int 
__ftrace_graph_open(struct inode *inode, struct file *file,

		    struct ftrace_graph_data *fgd)

{

	int ret = 0;

	int ret;

	struct ftrace_hash *new_hash = NULL;



	ret = security_locked_down(LOCKDOWN_TRACEFS);

	if (ret)

		return ret;



	if (file->f_mode & FMODE_WRITE) {

		const int size_bits = FTRACE_HASH_DEFAULT_BITS;

kernel/trace/trace.c

+8 −0
Original line number Diff line number Diff line
@@ -17,6 +17,7 @@ 
#include <linux/stacktrace.h>

#include <linux/writeback.h>

#include <linux/kallsyms.h>

#include <linux/security.h>

#include <linux/seq_file.h>

#include <linux/notifier.h>

#include <linux/irqflags.h>
@@ -306,6 +307,12 @@ void trace_array_put(struct trace_array *this_tr) 


int tracing_check_open_get_tr(struct trace_array *tr)

{

	int ret;



	ret = security_locked_down(LOCKDOWN_TRACEFS);

	if (ret)

		return ret;



	if (tracing_disabled)

		return -ENODEV;
@@ -6813,6 +6820,7 @@ static int snapshot_raw_open(struct inode *inode, struct file *filp) 
	struct ftrace_buffer_info *info;

	int ret;



	/* The following checks for tracefs lockdown */

	ret = tracing_buffers_open(inode, filp);

	if (ret < 0)

		return ret;

kernel/trace/trace_events.c

+8 −0
Original line number Diff line number Diff line
@@ -12,6 +12,7 @@ 
#define pr_fmt(fmt) fmt



#include <linux/workqueue.h>

#include <linux/security.h>

#include <linux/spinlock.h>

#include <linux/kthread.h>

#include <linux/tracefs.h>
@@ -1294,6 +1295,8 @@ static int trace_format_open(struct inode *inode, struct file *file) 
	struct seq_file *m;

	int ret;



	/* Do we want to hide event format files on tracefs lockdown? */



	ret = seq_open(file, &trace_format_seq_ops);

	if (ret < 0)

		return ret;
@@ -1760,6 +1763,10 @@ ftrace_event_open(struct inode *inode, struct file *file, 
	struct seq_file *m;

	int ret;



	ret = security_locked_down(LOCKDOWN_TRACEFS);

	if (ret)

		return ret;



	ret = seq_open(file, seq_ops);

	if (ret < 0)

		return ret;
@@ -1784,6 +1791,7 @@ ftrace_event_avail_open(struct inode *inode, struct file *file) 
{

	const struct seq_operations *seq_ops = &show_event_seq_ops;



	/* Checks for tracefs lockdown */

	return ftrace_event_open(inode, file, seq_ops);

}

kernel/trace/trace_events_hist.c

+11 −0
Original line number Diff line number Diff line
@@ -7,6 +7,7 @@ 


#include <linux/module.h>

#include <linux/kallsyms.h>

#include <linux/security.h>

#include <linux/mutex.h>

#include <linux/slab.h>

#include <linux/stacktrace.h>
@@ -1448,6 +1449,10 @@ static int synth_events_open(struct inode *inode, struct file *file) 
{

	int ret;



	ret = security_locked_down(LOCKDOWN_TRACEFS);

	if (ret)

		return ret;



	if ((file->f_mode & FMODE_WRITE) && (file->f_flags & O_TRUNC)) {

		ret = dyn_events_release_all(&synth_event_ops);

		if (ret < 0)
@@ -5515,6 +5520,12 @@ static int hist_show(struct seq_file *m, void *v) 


static int event_hist_open(struct inode *inode, struct file *file)

{

	int ret;



	ret = security_locked_down(LOCKDOWN_TRACEFS);

	if (ret)

		return ret;



	return single_open(file, hist_show, file);

}

kernel/trace/trace_events_trigger.c

+7 −1
Original line number Diff line number Diff line
@@ -5,6 +5,7 @@ 
 * Copyright (C) 2013 Tom Zanussi <tom.zanussi@linux.intel.com>

 */



#include <linux/security.h>

#include <linux/module.h>

#include <linux/ctype.h>

#include <linux/mutex.h>
@@ -173,7 +174,11 @@ static const struct seq_operations event_triggers_seq_ops = { 


static int event_trigger_regex_open(struct inode *inode, struct file *file)

{

	int ret = 0;

	int ret;



	ret = security_locked_down(LOCKDOWN_TRACEFS);

	if (ret)

		return ret;



	mutex_lock(&event_mutex);
@@ -292,6 +297,7 @@ event_trigger_write(struct file *filp, const char __user *ubuf, 
static int

event_trigger_open(struct inode *inode, struct file *filp)

{

	/* Checks for tracefs lockdown */

	return event_trigger_regex_open(inode, filp);

}

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