Commit d9aab0b1 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'landlock-6.10-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/mic/linux 

Pull landlock fix from Mickaël Salaün:
 "This fixes a wrong path walk triggered by syzkaller"

* tag 'landlock-6.10-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/mic/linux:
  selftests/landlock: Add layout1.refer_mount_root
  landlock: Fix d_parent walk
parents cc8ed4d0 0055f53a

security/landlock/fs.c

+11 −2
Original line number Diff line number Diff line
@@ -1110,6 +1110,7 @@ static int current_check_refer_path(struct dentry *const old_dentry, 
	bool allow_parent1, allow_parent2;

	access_mask_t access_request_parent1, access_request_parent2;

	struct path mnt_dir;

	struct dentry *old_parent;

	layer_mask_t layer_masks_parent1[LANDLOCK_NUM_ACCESS_FS] = {},

		     layer_masks_parent2[LANDLOCK_NUM_ACCESS_FS] = {};
@@ -1157,9 +1158,17 @@ static int current_check_refer_path(struct dentry *const old_dentry, 
	mnt_dir.mnt = new_dir->mnt;

	mnt_dir.dentry = new_dir->mnt->mnt_root;



	/*

	 * old_dentry may be the root of the common mount point and

	 * !IS_ROOT(old_dentry) at the same time (e.g. with open_tree() and

	 * OPEN_TREE_CLONE).  We do not need to call dget(old_parent) because

	 * we keep a reference to old_dentry.

	 */

	old_parent = (old_dentry == mnt_dir.dentry) ? old_dentry :

						      old_dentry->d_parent;



	/* new_dir->dentry is equal to new_dentry->d_parent */

	allow_parent1 = collect_domain_accesses(dom, mnt_dir.dentry,

						old_dentry->d_parent,

	allow_parent1 = collect_domain_accesses(dom, mnt_dir.dentry, old_parent,

						&layer_masks_parent1);

	allow_parent2 = collect_domain_accesses(

		dom, mnt_dir.dentry, new_dir->dentry, &layer_masks_parent2);

tools/testing/selftests/landlock/fs_test.c

+45 −0
Original line number Diff line number Diff line
@@ -35,6 +35,7 @@ 
 * See https://sourceware.org/glibc/wiki/Synchronizing_Headers.

 */

#include <linux/fs.h>

#include <linux/mount.h>



#include "common.h"
@@ -47,6 +48,13 @@ int renameat2(int olddirfd, const char *oldpath, int newdirfd, 
}

#endif



#ifndef open_tree

int open_tree(int dfd, const char *filename, unsigned int flags)

{

	return syscall(__NR_open_tree, dfd, filename, flags);

}

#endif



#ifndef RENAME_EXCHANGE

#define RENAME_EXCHANGE (1 << 1)

#endif
@@ -2400,6 +2408,43 @@ TEST_F_FORK(layout1, refer_denied_by_default4) 
				layer_dir_s1d1_refer);

}



/*

 * Tests walking through a denied root mount.

 */

TEST_F_FORK(layout1, refer_mount_root_deny)

{

	const struct landlock_ruleset_attr ruleset_attr = {

		.handled_access_fs = LANDLOCK_ACCESS_FS_MAKE_DIR,

	};

	int root_fd, ruleset_fd;



	/* Creates a mount object from a non-mount point. */

	set_cap(_metadata, CAP_SYS_ADMIN);

	root_fd =

		open_tree(AT_FDCWD, dir_s1d1,

			  AT_EMPTY_PATH | OPEN_TREE_CLONE | OPEN_TREE_CLOEXEC);

	clear_cap(_metadata, CAP_SYS_ADMIN);

	ASSERT_LE(0, root_fd);



	ruleset_fd =

		landlock_create_ruleset(&ruleset_attr, sizeof(ruleset_attr), 0);

	ASSERT_LE(0, ruleset_fd);



	ASSERT_EQ(0, prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0));

	ASSERT_EQ(0, landlock_restrict_self(ruleset_fd, 0));

	EXPECT_EQ(0, close(ruleset_fd));



	/* Link denied by Landlock: EACCES. */

	EXPECT_EQ(-1, linkat(root_fd, ".", root_fd, "does_not_exist", 0));

	EXPECT_EQ(EACCES, errno);



	/* renameat2() always returns EBUSY. */

	EXPECT_EQ(-1, renameat2(root_fd, ".", root_fd, "does_not_exist", 0));

	EXPECT_EQ(EBUSY, errno);



	EXPECT_EQ(0, close(root_fd));

}



TEST_F_FORK(layout1, reparent_link)

{

	const struct rule layer1[] = {