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Commit 49a76d70 authored by Oleg Drokin's avatar Oleg Drokin Committed by Greg Kroah-Hartman
Browse files

staging/lustre/libcfs: Properly handle debugfs read- and write-only files 



It turns out that unlike procfs, debugfs does not really enforce
permissions for root (similar to regular filesystems), so we need
to ensure we are not providing ->write() method to read-only files
and ->read() method for write-only files at registration.

This fixes a couple of crashes on unexpected access.

Signed-off-by: default avatarOleg Drokin <green@linuxhacker.ru>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 5ba907a9

drivers/staging/lustre/lustre/libcfs/module.c

+25 −2
Original line number Diff line number Diff line
@@ -502,13 +502,36 @@ static ssize_t lnet_debugfs_write(struct file *filp, const char __user *buf, 
	return error;

}



static const struct file_operations lnet_debugfs_file_operations = {

static const struct file_operations lnet_debugfs_file_operations_rw = {

	.open		= simple_open,

	.read		= lnet_debugfs_read,

	.write		= lnet_debugfs_write,

	.llseek		= default_llseek,

};



static const struct file_operations lnet_debugfs_file_operations_ro = {

	.open		= simple_open,

	.read		= lnet_debugfs_read,

	.llseek		= default_llseek,

};



static const struct file_operations lnet_debugfs_file_operations_wo = {

	.open		= simple_open,

	.write		= lnet_debugfs_write,

	.llseek		= default_llseek,

};



static const struct file_operations *lnet_debugfs_fops_select(umode_t mode)

{

	if (!(mode & S_IWUGO))

		return &lnet_debugfs_file_operations_ro;



	if (!(mode & S_IRUGO))

		return &lnet_debugfs_file_operations_wo;



	return &lnet_debugfs_file_operations_rw;

}



void lustre_insert_debugfs(struct ctl_table *table,

			   const struct lnet_debugfs_symlink_def *symlinks)

{
@@ -525,7 +548,7 @@ void lustre_insert_debugfs(struct ctl_table *table, 
	for (; table->procname; table++)

		debugfs_create_file(table->procname, table->mode,

				    lnet_debugfs_root, table,

				    &lnet_debugfs_file_operations);

				    lnet_debugfs_fops_select(table->mode));



	for (; symlinks && symlinks->name; symlinks++)

		debugfs_create_symlink(symlinks->name, lnet_debugfs_root,