ext4 crypto: handle unexpected lack of encryption keys
Theodore Ts'o [Thu, 4 Jun 2015 20:41:15 +0000 (16:41 -0400)]
Fix up attempts by users to try to write to a file when they don't
have access to the encryption key.

Change-Id: Iabdd438b26b409eaccf9c847fcf9c3ab52f1959e
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

fs/ext4/crypto.c
fs/ext4/crypto_policy.c
fs/ext4/file.c

index acda315..e907b6f 100644 (file)
@@ -104,7 +104,8 @@ struct ext4_crypto_ctx *ext4_get_crypto_ctx(struct inode *inode)
        unsigned long flags;
        struct ext4_crypt_info *ci = EXT4_I(inode)->i_crypt_info;
 
-       BUG_ON(ci == NULL);
+       if (ci == NULL)
+               return ERR_PTR(-ENOKEY);
 
        /*
         * We first try getting the ctx from a free list because in
index a1d434d..02c4e5d 100644 (file)
@@ -183,7 +183,8 @@ int ext4_inherit_context(struct inode *parent, struct inode *child)
        if (res < 0)
                return res;
        ci = EXT4_I(parent)->i_crypt_info;
-       BUG_ON(ci == NULL);
+       if (ci == NULL)
+               return -ENOKEY;
 
        ctx.format = EXT4_ENCRYPTION_CONTEXT_FORMAT_V1;
        if (DUMMY_ENCRYPTION_ENABLED(EXT4_SB(parent->i_sb))) {
index ed2fd99..da43705 100644 (file)
@@ -344,6 +344,8 @@ static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma)
                int err = ext4_get_encryption_info(inode);
                if (err)
                        return 0;
+               if (ext4_encryption_info(inode) == NULL)
+                       return -ENOKEY;
        }
        file_accessed(file);
        vma->vm_ops = &ext4_file_vm_ops;
@@ -391,6 +393,13 @@ static int ext4_file_open(struct inode * inode, struct file * filp)
                        ext4_journal_stop(handle);
                }
        }
+       if (ext4_encrypted_inode(inode)) {
+               ret = ext4_get_encryption_info(inode);
+               if (ret)
+                       return -EACCES;
+               if (ext4_encryption_info(inode) == NULL)
+                       return -ENOKEY;
+       }
        /*
         * Set up the jbd2_inode if we are opening the inode for
         * writing and the journal is present
@@ -400,13 +409,7 @@ static int ext4_file_open(struct inode * inode, struct file * filp)
                if (ret < 0)
                        return ret;
        }
-       ret = dquot_file_open(inode, filp);
-       if (!ret && ext4_encrypted_inode(inode)) {
-               ret = ext4_get_encryption_info(inode);
-               if (ret)
-                       ret = -EACCES;
-       }
-       return ret;
+       return dquot_file_open(inode, filp);
 }
 
 /*