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authorCarlos Llamas <cmllamas@google.com>2021-07-15 03:18:03 +0000
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2021-07-21 13:46:36 +0200
commitfc470abf54b2bd6e539065e07905e767b443d719 (patch)
treeac746b9cd1efba812b39a1abbea55e0cf05e0f0e /drivers/android/binderfs.c
parentec7b5eda8ae1a7a12cf1618ad7afb3509f593812 (diff)
downloadlwn-fc470abf54b2bd6e539065e07905e767b443d719.tar.gz
lwn-fc470abf54b2bd6e539065e07905e767b443d719.zip
binderfs: add support for feature files
Provide userspace with a mechanism to discover features supported by the binder driver to refrain from using any unsupported ones in the first place. Starting with "oneway_spam_detection" only new features are to be listed under binderfs and all previous ones are assumed to be supported. Assuming an instance of binderfs has been mounted at /dev/binderfs, binder feature files can be found under /dev/binderfs/features/. Usage example: $ mkdir /dev/binderfs $ mount -t binder binder /dev/binderfs $ cat /dev/binderfs/features/oneway_spam_detection 1 Acked-by: Christian Brauner <christian.brauner@ubuntu.com> Signed-off-by: Carlos Llamas <cmllamas@google.com> Link: https://lore.kernel.org/r/20210715031805.1725878-1-cmllamas@google.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/android/binderfs.c')
-rw-r--r--drivers/android/binderfs.c39
1 files changed, 39 insertions, 0 deletions
diff --git a/drivers/android/binderfs.c b/drivers/android/binderfs.c
index e80ba93c62a9..e3605cdd4335 100644
--- a/drivers/android/binderfs.c
+++ b/drivers/android/binderfs.c
@@ -58,6 +58,10 @@ enum binderfs_stats_mode {
binderfs_stats_mode_global,
};
+struct binder_features {
+ bool oneway_spam_detection;
+};
+
static const struct constant_table binderfs_param_stats[] = {
{ "global", binderfs_stats_mode_global },
{}
@@ -69,6 +73,10 @@ static const struct fs_parameter_spec binderfs_fs_parameters[] = {
{}
};
+static struct binder_features binder_features = {
+ .oneway_spam_detection = true,
+};
+
static inline struct binderfs_info *BINDERFS_SB(const struct super_block *sb)
{
return sb->s_fs_info;
@@ -583,6 +591,33 @@ out:
return dentry;
}
+static int binder_features_show(struct seq_file *m, void *unused)
+{
+ bool *feature = m->private;
+
+ seq_printf(m, "%d\n", *feature);
+
+ return 0;
+}
+DEFINE_SHOW_ATTRIBUTE(binder_features);
+
+static int init_binder_features(struct super_block *sb)
+{
+ struct dentry *dentry, *dir;
+
+ dir = binderfs_create_dir(sb->s_root, "features");
+ if (IS_ERR(dir))
+ return PTR_ERR(dir);
+
+ dentry = binderfs_create_file(dir, "oneway_spam_detection",
+ &binder_features_fops,
+ &binder_features.oneway_spam_detection);
+ if (IS_ERR(dentry))
+ return PTR_ERR(dentry);
+
+ return 0;
+}
+
static int init_binder_logs(struct super_block *sb)
{
struct dentry *binder_logs_root_dir, *dentry, *proc_log_dir;
@@ -723,6 +758,10 @@ static int binderfs_fill_super(struct super_block *sb, struct fs_context *fc)
name++;
}
+ ret = init_binder_features(sb);
+ if (ret)
+ return ret;
+
if (info->mount_opts.stats_mode == binderfs_stats_mode_global)
return init_binder_logs(sb);