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authorMiklos Szeredi <mszeredi@redhat.com>2016-12-06 16:18:45 +0100
committerMiklos Szeredi <mszeredi@redhat.com>2016-12-06 16:18:45 +0100
commitc01638f5d919728f565bf8b5e0a6a159642df0d9 (patch)
tree3dc341c250252908c912ad167f49d00b2fc2c734
parent3e5de27e940d00d8d504dfb96625fb654f641509 (diff)
fuse: fix clearing suid, sgid for chown()
Basically, the pjdfstests set the ownership of a file to 06555, and then chowns it (as root) to a new uid/gid. Prior to commit a09f99eddef4 ("fuse: fix killing s[ug]id in setattr"), fuse would send down a setattr with both the uid/gid change and a new mode. Now, it just sends down the uid/gid change. Technically this is NOTABUG, since POSIX doesn't _require_ that we clear these bits for a privileged process, but Linux (wisely) has done that and I think we don't want to change that behavior here. This is caused by the use of should_remove_suid(), which will always return 0 when the process has CAP_FSETID. In fact we really don't need to be calling should_remove_suid() at all, since we've already been indicated that we should remove the suid, we just don't want to use a (very) stale mode for that. This patch should fix the above as well as simplify the logic. Reported-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> Fixes: a09f99eddef4 ("fuse: fix killing s[ug]id in setattr") Cc: <stable@vger.kernel.org> Reviewed-by: Jeff Layton <jlayton@redhat.com>
-rw-r--r--fs/fuse/dir.c7
1 files changed, 2 insertions, 5 deletions
diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index b3ebe512d64c..096f79997f75 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -1739,8 +1739,6 @@ static int fuse_setattr(struct dentry *entry, struct iattr *attr)
* This should be done on write(), truncate() and chown().
*/
if (!fc->handle_killpriv) {
- int kill;
-
/*
* ia_mode calculation may have used stale i_mode.
* Refresh and recalculate.
@@ -1750,12 +1748,11 @@ static int fuse_setattr(struct dentry *entry, struct iattr *attr)
return ret;
attr->ia_mode = inode->i_mode;
- kill = should_remove_suid(entry);
- if (kill & ATTR_KILL_SUID) {
+ if (inode->i_mode & S_ISUID) {
attr->ia_valid |= ATTR_MODE;
attr->ia_mode &= ~S_ISUID;
}
- if (kill & ATTR_KILL_SGID) {
+ if ((inode->i_mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
attr->ia_valid |= ATTR_MODE;
attr->ia_mode &= ~S_ISGID;
}