Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 78ae7df9 authored by Jann Horn's avatar Jann Horn Committed by Micah Morton
Browse files

LSM: SafeSetID: refactor policy parsing 



In preparation for changing the policy parsing logic, refactor the line
parsing logic to be less verbose and move it into a separate function.

Signed-off-by: default avatarJann Horn <jannh@google.com>
Signed-off-by: default avatarMicah Morton <mortonm@chromium.org>
parent 8068866c

security/safesetid/securityfs.c

+33 −51
Original line number Diff line number Diff line
@@ -33,68 +33,50 @@ static struct safesetid_file_entry safesetid_files[] = { 


/*

 * In the case the input buffer contains one or more invalid UIDs, the kuid_t

 * variables pointed to by 'parent' and 'child' will get updated but this

 * variables pointed to by @parent and @child will get updated but this

 * function will return an error.

 * Contents of @buf may be modified.

 */

static int parse_safesetid_whitelist_policy(const char __user *buf,

					    size_t len,

					    kuid_t *parent,

					    kuid_t *child)

static int parse_policy_line(

	struct file *file, char *buf, kuid_t *parent, kuid_t *child)

{

	char *kern_buf;

	char *parent_buf;

	char *child_buf;

	const char separator[] = ":";

	char *child_str;

	int ret;

	size_t first_substring_length;

	long parsed_parent;

	long parsed_child;



	/* Duplicate string from user memory and NULL-terminate */

	kern_buf = memdup_user_nul(buf, len);

	if (IS_ERR(kern_buf))

		return PTR_ERR(kern_buf);

	u32 parsed_parent, parsed_child;



	/*

	 * Format of |buf| string should be <UID>:<UID>.

	 * Find location of ":" in kern_buf (copied from |buf|).

	 */

	first_substring_length = strcspn(kern_buf, separator);

	if (first_substring_length == 0 || first_substring_length == len) {

		ret = -EINVAL;

		goto free_kern;

	}



	parent_buf = kmemdup_nul(kern_buf, first_substring_length, GFP_KERNEL);

	if (!parent_buf) {

		ret = -ENOMEM;

		goto free_kern;

	}

	/* Format of |buf| string should be <UID>:<UID>. */

	child_str = strchr(buf, ':');

	if (child_str == NULL)

		return -EINVAL;

	*child_str = '\0';

	child_str++;



	ret = kstrtol(parent_buf, 0, &parsed_parent);

	ret = kstrtou32(buf, 0, &parsed_parent);

	if (ret)

		goto free_both;

		return ret;



	child_buf = kern_buf + first_substring_length + 1;

	ret = kstrtol(child_buf, 0, &parsed_child);

	ret = kstrtou32(child_str, 0, &parsed_child);

	if (ret)

		goto free_both;

		return ret;



	*parent = make_kuid(current_user_ns(), parsed_parent);

	if (!uid_valid(*parent)) {

		ret = -EINVAL;

		goto free_both;

	}



	*child = make_kuid(current_user_ns(), parsed_child);

	if (!uid_valid(*child)) {

		ret = -EINVAL;

		goto free_both;

	if (!uid_valid(*parent) || !uid_valid(*child))

		return -EINVAL;



	return 0;

}



free_both:

	kfree(parent_buf);

free_kern:

static int parse_safesetid_whitelist_policy(

	struct file *file, const char __user *buf, size_t len,

	kuid_t *parent, kuid_t *child)

{

	char *kern_buf = memdup_user_nul(buf, len);

	int ret;



	if (IS_ERR(kern_buf))

		return PTR_ERR(kern_buf);

	ret = parse_policy_line(file, kern_buf, parent, child);

	kfree(kern_buf);

	return ret;

}
@@ -121,8 +103,8 @@ static ssize_t safesetid_file_write(struct file *file, 
		flush_safesetid_whitelist_entries();

		break;

	case SAFESETID_WHITELIST_ADD:

		ret = parse_safesetid_whitelist_policy(buf, len, &parent,

								 &child);

		ret = parse_safesetid_whitelist_policy(file, buf, len,

						       &parent, &child);

		if (ret)

			return ret;