ext4 crypto: enforce context consistency (d9cdc903) · Commits · 戴 / test

Enforce the following inheritance policy: 1) An unencrypted directory may contain encrypted or unencrypted files or directories. 2) All files or directories in a directory must be protected using the same key as their containing directory. As a result, assuming the following setup: mke2fs -t ext4 -Fq -O encrypt /dev/vdc mount -t ext4 /dev/vdc /vdc mkdir /vdc/a /vdc/b /vdc/c echo foo | e4crypt add_key /vdc/a echo bar | e4crypt add_key /vdc/b for i in a b c ; do cp /etc/motd /vdc/$i/motd-$i ; done Then we will see the following results: cd /vdc mv a b # will fail; /vdc/a and /vdc/b have different keys mv b/motd-b a # will fail, see above ln a/motd-a b # will fail, see above mv c a # will fail; all inodes in an encrypted directory # must be encrypted ln c/motd-c b # will fail, see above mv a/motd-a c # will succeed mv c/motd-a a # will succeed Signed-off-by:

Michael Halcrow <mhalcrow@google.com> Signed-off-by:

Theodore Ts'o <tytso@mit.edu>

fs/ext4/namei.c

+23 −1

Original line number	Diff line number	Diff line
		@@ -1416,6 +1416,18 @@ static struct dentry ext4_lookup(struct inode dir, struct dentry *dentry, unsi
		ino);
		return ERR_PTR(-EIO);
		}
		if (!IS_ERR(inode) && ext4_encrypted_inode(dir) &&
		(S_ISREG(inode->i_mode) \|\| S_ISDIR(inode->i_mode) \|\|
		S_ISLNK(inode->i_mode)) &&
		!ext4_is_child_context_consistent_with_parent(dir,
		inode)) {
		iput(inode);
		ext4_warning(inode->i_sb,
		"Inconsistent encryption contexts: %lu/%lu\n",
		(unsigned long) dir->i_ino,
		(unsigned long) inode->i_ino);
		return ERR_PTR(-EPERM);
		}
		}
		return d_splice_alias(inode, dentry);
		}
		@@ -2944,7 +2956,9 @@ static int ext4_link(struct dentry *old_dentry,

		if (inode->i_nlink >= EXT4_LINK_MAX)
		return -EMLINK;

		if (ext4_encrypted_inode(dir) &&
		!ext4_is_child_context_consistent_with_parent(dir, inode))
		return -EPERM;
		dquot_initialize(dir);

		retry:
		@@ -3245,6 +3259,14 @@ static int ext4_rename(struct inode old_dir, struct dentry old_dentry,
		if (!old.bh \|\| le32_to_cpu(old.de->inode) != old.inode->i_ino)
		goto end_rename;

		if ((old.dir != new.dir) &&
		ext4_encrypted_inode(new.dir) &&
		!ext4_is_child_context_consistent_with_parent(new.dir,
		old.inode)) {
		retval = -EPERM;
		goto end_rename;
		}

		new.bh = ext4_find_entry(new.dir, &new.dentry->d_name,
		&new.de, &new.inlined);
		if (IS_ERR(new.bh)) {

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