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Revert "ecryptfs: forbid opening files without mmap handler"

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commit 78c4e17241 upstream.

This reverts commit 2f36db7100.

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 <jeffm@suse.com>
Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jeff Mahoney
2016-07-05 17:32:29 -04:00
committed by Greg Kroah-Hartman
parent a3bdfa7b61
commit ae159a0278
1 changed files with 2 additions and 11 deletions
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13
fs/ecryptfs/kthread.c
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@@ -25,7 +25,6 @@
#include <linux/slab.h> #include <linux/slab.h>
#include <linux/wait.h> #include <linux/wait.h>
#include <linux/mount.h> #include <linux/mount.h>
#include <linux/file.h>
#include "ecryptfs_kernel.h" #include "ecryptfs_kernel.h"
struct ecryptfs_open_req { struct ecryptfs_open_req {
@@ -148,7 +147,7 @@ int ecryptfs_privileged_open(struct file **lower_file,
flags |= IS_RDONLY(d_inode(lower_dentry)) ? O_RDONLY : O_RDWR; flags |= IS_RDONLY(d_inode(lower_dentry)) ? O_RDONLY : O_RDWR;
(*lower_file) = dentry_open(&req.path, flags, cred); (*lower_file) = dentry_open(&req.path, flags, cred);
if (!IS_ERR(*lower_file)) if (!IS_ERR(*lower_file))
goto have_file; goto out;
if ((flags & O_ACCMODE) == O_RDONLY) { if ((flags & O_ACCMODE) == O_RDONLY) {
rc = PTR_ERR((*lower_file)); rc = PTR_ERR((*lower_file));
goto out; goto out;
@@ -166,16 +165,8 @@ int ecryptfs_privileged_open(struct file **lower_file,
mutex_unlock(&ecryptfs_kthread_ctl.mux); mutex_unlock(&ecryptfs_kthread_ctl.mux);
wake_up(&ecryptfs_kthread_ctl.wait); wake_up(&ecryptfs_kthread_ctl.wait);
wait_for_completion(&req.done); wait_for_completion(&req.done);
if (IS_ERR(*lower_file)) { if (IS_ERR(*lower_file))
rc = PTR_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: out:
return rc; return rc;
} }