Proof-of-concept implementation of chown() for union mounts.
---
fs/open.c | 24 +++++++++++++++++++++---
1 files changed, 21 insertions(+), 3 deletions(-)
diff --git a/fs/open.c b/fs/open.c
index 686fcd2..325852d 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -30,6 +30,7 @@
#include <linux/falloc.h>
#include <linux/fs_struct.h>
#include <linux/ima.h>
+#include <linux/union.h>
#include "internal.h"
@@ -717,18 +718,35 @@ static int chown_common(struct path *path, uid_t user, gid_t group)
SYSCALL_DEFINE3(chown, const char __user *, filename, uid_t, user, gid_t, group)
{
struct path path;
+ struct nameidata nd;
+ struct vfsmount *mnt;
+ char *tmp;
int error;
- error = user_path(filename, &path);
+ error = user_path_nd(AT_FDCWD, filename, LOOKUP_FOLLOW,
+ &nd, &path, &tmp);
if (error)
goto out;
- error = mnt_want_write(path.mnt);
+
+ if (IS_UNIONED_DIR(&nd.path))
+ mnt = nd.path.mnt;
+ else
+ mnt = path.mnt;
+
+ error = mnt_want_write(mnt);
if (error)
goto out_release;
+
+ error = union_copyup(&nd, &path);
+ if (error)
+ goto out_drop_write;
error = chown_common(&path, user, group);
- mnt_drop_write(path.mnt);
+out_drop_write:
+ mnt_drop_write(mnt);
out_release:
path_put(&path);
+ path_put(&nd.path);
+ putname(tmp);
out:
return error;
}
--
1.6.3.3
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