i_rwsem needs to be acquired while setting an encryption policy so that
concurrent calls to FS_IOC_SET_ENCRYPTION_POLICY are correctly
serialized (especially the ->get_context() + ->set_context() pair), and
so that new files cannot be created in the directory during or after the
->empty_dir() check.
Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
---
Note: to be applied without conflict, this patch needs the changes from
v4.8-rc6.
---
fs/crypto/policy.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/fs/crypto/policy.c b/fs/crypto/policy.c
index ed115ac..6865663 100644
--- a/fs/crypto/policy.c
+++ b/fs/crypto/policy.c
@@ -109,6 +109,8 @@ int fscrypt_process_policy(struct file *filp,
if (ret)
return ret;
+ inode_lock(inode);
+
if (!inode_has_encryption_context(inode)) {
if (!S_ISDIR(inode->i_mode))
ret = -EINVAL;
@@ -127,6 +129,8 @@ int fscrypt_process_policy(struct file *filp,
ret = -EINVAL;
}
+ inode_unlock(inode);
+
mnt_drop_write_file(filp);
return ret;
}
--
2.8.0.rc3.226.g39d4020
--
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