[PATCH 4.6 53/96] Revert "ecryptfs: forbid opening files without mmap handler"
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: 2016-08-08 19:18:52
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4.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jeff Mahoney <redacted> commit 78c4e172412de5d0456dc00d2b34050aa0b683b5 upstream. This reverts commit 2f36db71009304b3f0b95afacd8eba1f9f046b87. It fixed a local root exploit but also introduced a dependency on the lower file system implementing an mmap operation just to open a file, which is a bit of a heavy hammer. The right fix is to have mmap depend on the existence of the mmap handler instead. Signed-off-by: Jeff Mahoney <redacted> Signed-off-by: Tyler Hicks <redacted> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- fs/ecryptfs/kthread.c | 13 ++----------- 1 file changed, 2 insertions(+), 11 deletions(-)
--- a/fs/ecryptfs/kthread.c
+++ b/fs/ecryptfs/kthread.c@@ -25,7 +25,6 @@ #include <linux/slab.h> #include <linux/wait.h> #include <linux/mount.h> -#include <linux/file.h> #include "ecryptfs_kernel.h" struct ecryptfs_open_req {
@@ -148,7 +147,7 @@ int ecryptfs_privileged_open(struct file flags |= IS_RDONLY(d_inode(lower_dentry)) ? O_RDONLY : O_RDWR; (*lower_file) = dentry_open(&req.path, flags, cred); if (!IS_ERR(*lower_file)) - goto have_file; + goto out; if ((flags & O_ACCMODE) == O_RDONLY) { rc = PTR_ERR((*lower_file)); goto out;
@@ -166,16 +165,8 @@ int ecryptfs_privileged_open(struct file mutex_unlock(&ecryptfs_kthread_ctl.mux); wake_up(&ecryptfs_kthread_ctl.wait); wait_for_completion(&req.done); - if (IS_ERR(*lower_file)) { + if (IS_ERR(*lower_file)) rc = PTR_ERR(*lower_file); - goto out; - } -have_file: - if ((*lower_file)->f_op->mmap == NULL) { - fput(*lower_file); - *lower_file = NULL; - rc = -EMEDIUMTYPE; - } out: return rc; }