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From acff81ec2c79492b180fade3c2894425cd35a545 Mon Sep 17 00:00:00 2001
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From: Miklos Szeredi <miklos@szeredi.hu>
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Date: Fri, 4 Dec 2015 19:18:48 +0100
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Subject: [PATCH] ovl: fix permission checking for setattr
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[Al Viro] The bug is in being too enthusiastic about optimizing ->setattr()
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away - instead of "copy verbatim with metadata" + "chmod/chown/utimes"
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(with the former being always safe and the latter failing in case of
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insufficient permissions) it tries to combine these two. Note that copyup
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itself will have to do ->setattr() anyway; _that_ is where the elevated
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capabilities are right. Having these two ->setattr() (one to set verbatim
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copy of metadata, another to do what overlayfs ->setattr() had been asked
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to do in the first place) combined is where it breaks.
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Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
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Cc: <stable@vger.kernel.org>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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---
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fs/overlayfs/inode.c | 8 ++++----
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1 file changed, 4 insertions(+), 4 deletions(-)
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diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
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index ec0c2a050043..961284936917 100644
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--- a/fs/overlayfs/inode.c
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+++ b/fs/overlayfs/inode.c
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@@ -49,13 +49,13 @@ int ovl_setattr(struct dentry *dentry, struct iattr *attr)
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if (err)
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goto out;
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- upperdentry = ovl_dentry_upper(dentry);
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- if (upperdentry) {
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+ err = ovl_copy_up(dentry);
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+ if (!err) {
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+ upperdentry = ovl_dentry_upper(dentry);
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+
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mutex_lock(&upperdentry->d_inode->i_mutex);
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err = notify_change(upperdentry, attr, NULL);
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mutex_unlock(&upperdentry->d_inode->i_mutex);
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- } else {
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- err = ovl_copy_up_last(dentry, attr, false);
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}
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ovl_drop_write(dentry);
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out:
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--
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2.5.0
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