From 3179216135ec09825d7c7875580951a6e69dc5df Mon Sep 17 00:00:00 2001
From: Vivek Goyal <vgoyal@redhat.com>
Date: Fri, 9 Oct 2020 14:15:09 -0400
Subject: fuse: setattr should set FATTR_KILL_SUIDGID
If fc->handle_killpriv_v2 is enabled, we expect file server to clear
suid/sgid/security.capbility upon chown/truncate/write as appropriate.
Upon truncate (ATTR_SIZE), suid/sgid are cleared only if caller does not
have CAP_FSETID. File server does not know whether caller has CAP_FSETID
or not. Hence set FATTR_KILL_SUIDGID upon truncate to let file server know
that caller does not have CAP_FSETID and it should kill suid/sgid as
appropriate.
On chown (ATTR_UID/ATTR_GID) suid/sgid need to be cleared irrespective of
capabilities of calling process, so set FATTR_KILL_SUIDGID unconditionally
in that case.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
---
fs/fuse/dir.c | 10 ++++++++++
1 file changed, 10 insertions(+)
(limited to 'fs')
diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index c3e22a3dd323..28b07ae5e55f 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -1648,10 +1648,20 @@ int fuse_do_setattr(struct dentry *dentry, struct iattr *attr,
inarg.valid |= FATTR_FH;
inarg.fh = ff->fh;
}
+
+ /* Kill suid/sgid for non-directory chown unconditionally */
+ if (fc->handle_killpriv_v2 && !S_ISDIR(inode->i_mode) &&
+ attr->ia_valid & (ATTR_UID | ATTR_GID))
+ inarg.valid |= FATTR_KILL_SUIDGID;
+
if (attr->ia_valid & ATTR_SIZE) {
/* For mandatory locking in truncate */
inarg.valid |= FATTR_LOCKOWNER;
inarg.lock_owner = fuse_lock_owner_id(fc, current->files);
+
+ /* Kill suid/sgid for truncate only if no CAP_FSETID */
+ if (fc->handle_killpriv_v2 && !capable(CAP_FSETID))
+ inarg.valid |= FATTR_KILL_SUIDGID;
}
fuse_setattr_fill(fc, &args, inode, &inarg, &outarg);
err = fuse_simple_request(fm, &args);
--
cgit v1.2.3