crypto-handle-unexpected-missing-keys

   1 ext4 crypto: handle unexpected lack of encryption keys
   2
   3 Fix up attempts by users to try to write to a file when they don't
   4 have access to the encryption key.
   5
   6 Signed-off-by: Theodore Ts'o <tytso@mit.edu>
   7 ---
   8  fs/ext4/crypto.c        |  3 ++-
   9  fs/ext4/crypto_policy.c |  3 ++-
  10  fs/ext4/file.c          | 17 ++++++++++-------
  11  3 files changed, 14 insertions(+), 9 deletions(-)
  12
  13 diff --git a/fs/ext4/crypto.c b/fs/ext4/crypto.c
  14 index ac2419c..6634478 100644
  15 --- a/fs/ext4/crypto.c
  16 +++ b/fs/ext4/crypto.c
  17 @@ -104,7 +104,8 @@ struct ext4_crypto_ctx *ext4_get_crypto_ctx(struct inode *inode)
  18         unsigned long flags;
  19         struct ext4_crypt_info *ci = EXT4_I(inode)->i_crypt_info;
  20
  21 -       BUG_ON(ci == NULL);
  22 +       if (ci == NULL)
  23 +               return ERR_PTR(-ENOKEY);
  24
  25         /*
  26          * We first try getting the ctx from a free list because in
  27 diff --git a/fs/ext4/crypto_policy.c b/fs/ext4/crypto_policy.c
  28 index a1d434d..02c4e5d 100644
  29 --- a/fs/ext4/crypto_policy.c
  30 +++ b/fs/ext4/crypto_policy.c
  31 @@ -183,7 +183,8 @@ int ext4_inherit_context(struct inode *parent, struct inode *child)
  32         if (res < 0)
  33                 return res;
  34         ci = EXT4_I(parent)->i_crypt_info;
  35 -       BUG_ON(ci == NULL);
  36 +       if (ci == NULL)
  37 +               return -ENOKEY;
  38
  39         ctx.format = EXT4_ENCRYPTION_CONTEXT_FORMAT_V1;
  40         if (DUMMY_ENCRYPTION_ENABLED(EXT4_SB(parent->i_sb))) {
  41 diff --git a/fs/ext4/file.c b/fs/ext4/file.c
  42 index 875ca6b..ac517f1 100644
  43 --- a/fs/ext4/file.c
  44 +++ b/fs/ext4/file.c
  45 @@ -226,6 +226,8 @@ static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma)
  46                 int err = ext4_get_encryption_info(inode);
  47                 if (err)
  48                         return 0;
  49 +               if (ext4_encryption_info(inode) == NULL)
  50 +                       return -ENOKEY;
  51         }
  52         file_accessed(file);
  53         if (IS_DAX(file_inode(file))) {
  54 @@ -278,6 +280,13 @@ static int ext4_file_open(struct inode * inode, struct file * filp)
  55                         ext4_journal_stop(handle);
  56                 }
  57         }
  58 +       if (ext4_encrypted_inode(inode)) {
  59 +               ret = ext4_get_encryption_info(inode);
  60 +               if (ret)
  61 +                       return -EACCES;
  62 +               if (ext4_encryption_info(inode) == NULL)
  63 +                       return -ENOKEY;
  64 +       }
  65         /*
  66          * Set up the jbd2_inode if we are opening the inode for
  67          * writing and the journal is present
  68 @@ -287,13 +296,7 @@ static int ext4_file_open(struct inode * inode, struct file * filp)
  69                 if (ret < 0)
  70                         return ret;
  71         }
  72 -       ret = dquot_file_open(inode, filp);
  73 -       if (!ret && ext4_encrypted_inode(inode)) {
  74 -               ret = ext4_get_encryption_info(inode);
  75 -               if (ret)
  76 -                       ret = -EACCES;
  77 -       }
  78 -       return ret;
  79 +       return dquot_file_open(inode, filp);
  80  }
  81
  82  /*