ext4 crypto: move context consistency check to ext4_file_open()

In the case where the per-file key for the directory is cached, but
root does not have access to the key needed to derive the per-file key
for the files in the directory, we allow the lookup to succeed, so
that lstat(2) and unlink(2) can suceed.  However, if a program tries
to open the file, it will get an ENOKEY error.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 1126436..474f1a4 100644 (file)
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -350,6 +350,7 @@ static int ext4_file_open(struct inode * inode, struct file * filp)
        struct super_block *sb = inode->i_sb;
        struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
        struct vfsmount *mnt = filp->f_path.mnt;
+       struct inode *dir = filp->f_path.dentry->d_parent->d_inode;
        struct path path;
        char buf[64], *cp;
        int ret;
@@ -393,6 +394,14 @@ static int ext4_file_open(struct inode * inode, struct file * filp)
                if (ext4_encryption_info(inode) == NULL)
                        return -ENOKEY;
        }
+       if (ext4_encrypted_inode(dir) &&
+           !ext4_is_child_context_consistent_with_parent(dir, inode)) {
+               ext4_warning(inode->i_sb,
+                            "Inconsistent encryption contexts: %lu/%lu\n",
+                            (unsigned long) dir->i_ino,
+                            (unsigned long) inode->i_ino);
+               return -EPERM;
+       }
        /*
         * Set up the jbd2_inode if we are opening the inode for
         * writing and the journal is present

diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index 5de8483..48e4b89 100644 (file)
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -1603,11 +1603,15 @@ static struct dentry *ext4_lookup(struct inode *dir, struct dentry *dentry, unsi
                        return ERR_PTR(-EFSCORRUPTED);
                }
                if (!IS_ERR(inode) && ext4_encrypted_inode(dir) &&
-                   (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
-                    S_ISLNK(inode->i_mode)) &&
+                   (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode)) &&
                    !ext4_is_child_context_consistent_with_parent(dir,
                                                                  inode)) {
+                       int nokey = ext4_encrypted_inode(inode) &&
+                               !ext4_encryption_info(inode);
+
                        iput(inode);
+                       if (nokey)
+                               return ERR_PTR(-ENOKEY);
                        ext4_warning(inode->i_sb,
                                     "Inconsistent encryption contexts: %lu/%lu\n",
                                     (unsigned long) dir->i_ino,