From: Eric Biggers ebiggers@google.com
commit 13a10da94615d81087e718517794f2868a8b3fab upstream.
When an encryption key can't be fully removed due to file(s) protected by it still being in-use, we shouldn't really print the path to one of these files to the kernel log, since parts of this path are likely to be encrypted on-disk, and (depending on how the system is set up) the confidentiality of this path might be lost by printing it to the log.
This is a trade-off: a single file path often doesn't matter at all, especially if it's a directory; the kernel log might still be protected in some way; and I had originally hoped that any "inode(s) still busy" bugs (which are security weaknesses in their own right) would be quickly fixed and that to do so it would be super helpful to always know the file path and not have to run 'find dir -inum $inum' after the fact.
But in practice, these bugs can be hard to fix (e.g. due to asynchronous process killing that is difficult to eliminate, for performance reasons), and also not tied to specific files, so knowing a file path doesn't necessarily help.
So to be safe, for now let's just show the inode number, not the path. If someone really wants to know a path they can use 'find -inum'.
Fixes: b1c0ec3599f4 ("fscrypt: add FS_IOC_REMOVE_ENCRYPTION_KEY ioctl") Cc: stable@vger.kernel.org # v5.4+ Link: https://lore.kernel.org/r/20200120060732.390362-1-ebiggers@kernel.org Signed-off-by: Eric Biggers ebiggers@google.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/crypto/keyring.c | 15 ++------------- 1 file changed, 2 insertions(+), 13 deletions(-)
--- a/fs/crypto/keyring.c +++ b/fs/crypto/keyring.c @@ -666,9 +666,6 @@ static int check_for_busy_inodes(struct struct list_head *pos; size_t busy_count = 0; unsigned long ino; - struct dentry *dentry; - char _path[256]; - char *path = NULL;
spin_lock(&mk->mk_decrypted_inodes_lock);
@@ -687,22 +684,14 @@ static int check_for_busy_inodes(struct struct fscrypt_info, ci_master_key_link)->ci_inode; ino = inode->i_ino; - dentry = d_find_alias(inode); } spin_unlock(&mk->mk_decrypted_inodes_lock);
- if (dentry) { - path = dentry_path(dentry, _path, sizeof(_path)); - dput(dentry); - } - if (IS_ERR_OR_NULL(path)) - path = "(unknown)"; - fscrypt_warn(NULL, - "%s: %zu inode(s) still busy after removing key with %s %*phN, including ino %lu (%s)", + "%s: %zu inode(s) still busy after removing key with %s %*phN, including ino %lu", sb->s_id, busy_count, master_key_spec_type(&mk->mk_spec), master_key_spec_len(&mk->mk_spec), (u8 *)&mk->mk_spec.u, - ino, path); + ino); return -EBUSY; }