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authorLinus Torvalds <torvalds@linux-foundation.org>2020-03-11 13:35:34 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-03-11 13:35:34 -0700
commite6e6ec48dd0fa12e8a2d1ff6b55cd907401bd7fe (patch)
tree891f03343ce73f6945c9d65a226e79bc59ccb0d0 /fs
parentaddcb1d0ee31aa1472a7afd31a63162423af9c93 (diff)
parent2b4eae95c7361e0a147b838715c8baa1380a428f (diff)
downloadlinux-e6e6ec48dd0fa12e8a2d1ff6b55cd907401bd7fe.tar.bz2
Merge tag 'fscrypt-for-linus' of git://git.kernel.org/pub/scm/fs/fscrypt/fscrypt
Pull fscrypt fix from Eric Biggers: "Fix a bug where if userspace is writing to encrypted files while the FS_IOC_REMOVE_ENCRYPTION_KEY ioctl (introduced in v5.4) is running, dirty inodes could be evicted, causing writes could be lost or the filesystem to hang due to a use-after-free. This was encountered during real-world use, not just theoretical. Tested with the existing fscrypt xfstests, and with a new xfstest I wrote to reproduce this bug. This fix does expose an existing bug with '-o lazytime' that Ted is working on fixing, but this fix is more critical and needed anyway regardless of the lazytime fix" * tag 'fscrypt-for-linus' of git://git.kernel.org/pub/scm/fs/fscrypt/fscrypt: fscrypt: don't evict dirty inodes after removing key
Diffstat (limited to 'fs')
-rw-r--r--fs/crypto/keysetup.c9
1 files changed, 9 insertions, 0 deletions
diff --git a/fs/crypto/keysetup.c b/fs/crypto/keysetup.c
index 65cb09fa6ead..08c9f216a54d 100644
--- a/fs/crypto/keysetup.c
+++ b/fs/crypto/keysetup.c
@@ -539,6 +539,15 @@ int fscrypt_drop_inode(struct inode *inode)
mk = ci->ci_master_key->payload.data[0];
/*
+ * With proper, non-racy use of FS_IOC_REMOVE_ENCRYPTION_KEY, all inodes
+ * protected by the key were cleaned by sync_filesystem(). But if
+ * userspace is still using the files, inodes can be dirtied between
+ * then and now. We mustn't lose any writes, so skip dirty inodes here.
+ */
+ if (inode->i_state & I_DIRTY_ALL)
+ return 0;
+
+ /*
* Note: since we aren't holding ->mk_secret_sem, the result here can
* immediately become outdated. But there's no correctness problem with
* unnecessarily evicting. Nor is there a correctness problem with not