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| author | Theodore Ts'o <tytso@mit.edu> | 2015-04-12 07:55:08 +0300 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2015-04-12 07:55:08 +0300 |
| commit | d9cdc903318171571f1cd1e5737fd0cab94186be (patch) | |
| tree | 5baa3a2fbd4a544fcf7ac7e5546b4b6a2ea25587 /fs/ext4 | |
| parent | 88bd6ccdcdd638faa11e9746affc21d5f2fe2acf (diff) | |
| download | linux-d9cdc903318171571f1cd1e5737fd0cab94186be.tar.xz | |
ext4 crypto: enforce context consistency
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>
Diffstat (limited to 'fs/ext4')
| -rw-r--r-- | fs/ext4/namei.c | 24 |
1 files changed, 23 insertions, 1 deletions
diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c index 0dbd2d2937f7..acd79198b800 100644 --- a/fs/ext4/namei.c +++ b/fs/ext4/namei.c @@ -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)) { |