tracing: Disable "other" permission bits in the tracefs files

When building the files in the tracefs file system, do not by default set
any permissions for OTH (other). This will make it easier for admins who
want to define a group for accessing tracefs and not having to first
disable all the permission bits for "other" in the file system.

As tracing can leak sensitive information, it should never by default
allowing all users access. An admin can still set the permission bits for
others to have access, which may be useful for creating a honeypot and
seeing who takes advantage of it and roots the machine.

Link: https://lkml.kernel.org/r/20210818153038.864149276@goodmis.org

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

1 files changed, 37 insertions, 36 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index dcced07a45e67..985390cb84418 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1690,7 +1690,8 @@ static void trace_create_maxlat_file(struct trace_array *tr,
 {
 	INIT_WORK(&tr->fsnotify_work, latency_fsnotify_workfn);
 	init_irq_work(&tr->fsnotify_irqwork, latency_fsnotify_workfn_irq);
-	tr->d_max_latency = trace_create_file("tracing_max_latency", 0644,
+	tr->d_max_latency = trace_create_file("tracing_max_latency",
+					      TRACE_MODE_WRITE,
 					      d_tracer, &tr->max_latency,
 					      &tracing_max_lat_fops);
 }
@@ -1727,8 +1728,8 @@ void latency_fsnotify(struct trace_array *tr)
 #else
 
 #define trace_create_maxlat_file(tr, d_tracer)				\
-	trace_create_file("tracing_max_latency", 0644, d_tracer,	\
-			  &tr->max_latency, &tracing_max_lat_fops)
+	trace_create_file("tracing_max_latency", TRACE_MODE_WRITE,	\
+			  d_tracer, &tr->max_latency, &tracing_max_lat_fops)
 
 #endif
 
@@ -6054,7 +6055,7 @@ trace_insert_eval_map_file(struct module *mod, struct trace_eval_map **start,
 
 static void trace_create_eval_file(struct dentry *d_tracer)
 {
-	trace_create_file("eval_map", 0444, d_tracer,
+	trace_create_file("eval_map", TRACE_MODE_READ, d_tracer,
 			  NULL, &tracing_eval_map_fops);
 }
 
@@ -8567,27 +8568,27 @@ tracing_init_tracefs_percpu(struct trace_array *tr, long cpu)
 	}
 
 	/* per cpu trace_pipe */
-	trace_create_cpu_file("trace_pipe", 0444, d_cpu,
+	trace_create_cpu_file("trace_pipe", TRACE_MODE_READ, d_cpu,
 				tr, cpu, &tracing_pipe_fops);
 
 	/* per cpu trace */
-	trace_create_cpu_file("trace", 0644, d_cpu,
+	trace_create_cpu_file("trace", TRACE_MODE_WRITE, d_cpu,
 				tr, cpu, &tracing_fops);
 
-	trace_create_cpu_file("trace_pipe_raw", 0444, d_cpu,
+	trace_create_cpu_file("trace_pipe_raw", TRACE_MODE_READ, d_cpu,
 				tr, cpu, &tracing_buffers_fops);
 
-	trace_create_cpu_file("stats", 0444, d_cpu,
+	trace_create_cpu_file("stats", TRACE_MODE_READ, d_cpu,
 				tr, cpu, &tracing_stats_fops);
 
-	trace_create_cpu_file("buffer_size_kb", 0444, d_cpu,
+	trace_create_cpu_file("buffer_size_kb", TRACE_MODE_READ, d_cpu,
 				tr, cpu, &tracing_entries_fops);
 
 #ifdef CONFIG_TRACER_SNAPSHOT
-	trace_create_cpu_file("snapshot", 0644, d_cpu,
+	trace_create_cpu_file("snapshot", TRACE_MODE_WRITE, d_cpu,
 				tr, cpu, &snapshot_fops);
 
-	trace_create_cpu_file("snapshot_raw", 0444, d_cpu,
+	trace_create_cpu_file("snapshot_raw", TRACE_MODE_READ, d_cpu,
 				tr, cpu, &snapshot_raw_fops);
 #endif
 }
@@ -8793,8 +8794,8 @@ create_trace_option_file(struct trace_array *tr,
 	topt->opt = opt;
 	topt->tr = tr;
 
-	topt->entry = trace_create_file(opt->name, 0644, t_options, topt,
-				    &trace_options_fops);
+	topt->entry = trace_create_file(opt->name, TRACE_MODE_WRITE,
+					t_options, topt, &trace_options_fops);
 
 }
 
@@ -8869,7 +8870,7 @@ create_trace_option_core_file(struct trace_array *tr,
 	if (!t_options)
 		return NULL;
 
-	return trace_create_file(option, 0644, t_options,
+	return trace_create_file(option, TRACE_MODE_WRITE, t_options,
 				 (void *)&tr->trace_flags_index[index],
 				 &trace_options_core_fops);
 }
@@ -9394,28 +9395,28 @@ init_tracer_tracefs(struct trace_array *tr, struct dentry *d_tracer)
 	struct trace_event_file *file;
 	int cpu;
 
-	trace_create_file("available_tracers", 0444, d_tracer,
+	trace_create_file("available_tracers", TRACE_MODE_READ, d_tracer,
 			tr, &show_traces_fops);
 
-	trace_create_file("current_tracer", 0644, d_tracer,
+	trace_create_file("current_tracer", TRACE_MODE_WRITE, d_tracer,
 			tr, &set_tracer_fops);
 
-	trace_create_file("tracing_cpumask", 0644, d_tracer,
+	trace_create_file("tracing_cpumask", TRACE_MODE_WRITE, d_tracer,
 			  tr, &tracing_cpumask_fops);
 
-	trace_create_file("trace_options", 0644, d_tracer,
+	trace_create_file("trace_options", TRACE_MODE_WRITE, d_tracer,
 			  tr, &tracing_iter_fops);
 
-	trace_create_file("trace", 0644, d_tracer,
+	trace_create_file("trace", TRACE_MODE_WRITE, d_tracer,
 			  tr, &tracing_fops);
 
-	trace_create_file("trace_pipe", 0444, d_tracer,
+	trace_create_file("trace_pipe", TRACE_MODE_READ, d_tracer,
 			  tr, &tracing_pipe_fops);
 
-	trace_create_file("buffer_size_kb", 0644, d_tracer,
+	trace_create_file("buffer_size_kb", TRACE_MODE_WRITE, d_tracer,
 			  tr, &tracing_entries_fops);
 
-	trace_create_file("buffer_total_size_kb", 0444, d_tracer,
+	trace_create_file("buffer_total_size_kb", TRACE_MODE_READ, d_tracer,
 			  tr, &tracing_total_entries_fops);
 
 	trace_create_file("free_buffer", 0200, d_tracer,
@@ -9426,25 +9427,25 @@ init_tracer_tracefs(struct trace_array *tr, struct dentry *d_tracer)
 
 	file = __find_event_file(tr, "ftrace", "print");
 	if (file && file->dir)
-		trace_create_file("trigger", 0644, file->dir, file,
-				  &event_trigger_fops);
+		trace_create_file("trigger", TRACE_MODE_WRITE, file->dir,
+				  file, &event_trigger_fops);
 	tr->trace_marker_file = file;
 
 	trace_create_file("trace_marker_raw", 0220, d_tracer,
 			  tr, &tracing_mark_raw_fops);
 
-	trace_create_file("trace_clock", 0644, d_tracer, tr,
+	trace_create_file("trace_clock", TRACE_MODE_WRITE, d_tracer, tr,
 			  &trace_clock_fops);
 
-	trace_create_file("tracing_on", 0644, d_tracer,
+	trace_create_file("tracing_on", TRACE_MODE_WRITE, d_tracer,
 			  tr, &rb_simple_fops);
 
-	trace_create_file("timestamp_mode", 0444, d_tracer, tr,
+	trace_create_file("timestamp_mode", TRACE_MODE_READ, d_tracer, tr,
 			  &trace_time_stamp_mode_fops);
 
 	tr->buffer_percent = 50;
 
-	trace_create_file("buffer_percent", 0444, d_tracer,
+	trace_create_file("buffer_percent", TRACE_MODE_READ, d_tracer,
 			tr, &buffer_percent_fops);
 
 	create_trace_options_dir(tr);
@@ -9457,11 +9458,11 @@ init_tracer_tracefs(struct trace_array *tr, struct dentry *d_tracer)
 		MEM_FAIL(1, "Could not allocate function filter files");
 
 #ifdef CONFIG_TRACER_SNAPSHOT
-	trace_create_file("snapshot", 0644, d_tracer,
+	trace_create_file("snapshot", TRACE_MODE_WRITE, d_tracer,
 			  tr, &snapshot_fops);
 #endif
 
-	trace_create_file("error_log", 0644, d_tracer,
+	trace_create_file("error_log", TRACE_MODE_WRITE, d_tracer,
 			  tr, &tracing_err_log_fops);
 
 	for_each_tracing_cpu(cpu)
@@ -9654,19 +9655,19 @@ static __init int tracer_init_tracefs(void)
 	init_tracer_tracefs(&global_trace, NULL);
 	ftrace_init_tracefs_toplevel(&global_trace, NULL);
 
-	trace_create_file("tracing_thresh", 0644, NULL,
+	trace_create_file("tracing_thresh", TRACE_MODE_WRITE, NULL,
 			&global_trace, &tracing_thresh_fops);
 
-	trace_create_file("README", 0444, NULL,
+	trace_create_file("README", TRACE_MODE_READ, NULL,
 			NULL, &tracing_readme_fops);
 
-	trace_create_file("saved_cmdlines", 0444, NULL,
+	trace_create_file("saved_cmdlines", TRACE_MODE_READ, NULL,
 			NULL, &tracing_saved_cmdlines_fops);
 
-	trace_create_file("saved_cmdlines_size", 0644, NULL,
+	trace_create_file("saved_cmdlines_size", TRACE_MODE_WRITE, NULL,
 			  NULL, &tracing_saved_cmdlines_size_fops);
 
-	trace_create_file("saved_tgids", 0444, NULL,
+	trace_create_file("saved_tgids", TRACE_MODE_READ, NULL,
 			NULL, &tracing_saved_tgids_fops);
 
 	trace_eval_init();
@@ -9678,7 +9679,7 @@ static __init int tracer_init_tracefs(void)
 #endif
 
 #ifdef CONFIG_DYNAMIC_FTRACE
-	trace_create_file("dyn_ftrace_total_info", 0444, NULL,
+	trace_create_file("dyn_ftrace_total_info", TRACE_MODE_READ, NULL,
 			NULL, &tracing_dyn_info_fops);
 #endif