linux-kernel - [PATCH 61/73] union-mount: Make various syscalls aware (link, chmod, chown, utimes & setxattr) [ver #2]

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Date:	Tue, 21 Feb 2012 18:05:09 +0000
From:	David Howells <dhowells@...hat.com>
To:	linux-fsdevel@...r.kernel.org, viro@...IV.linux.org.uk,
	valerie.aurora@...il.com
Cc:	linux-kernel@...r.kernel.org, David Howells <dhowells@...hat.com>
Subject: [PATCH 61/73] union-mount: Make various syscalls aware (link, chmod,
 chown, utimes & setxattr) [ver #2]

Make the link, chmod, chown, utimes and setxattr syscalls and their variants
aware of unionmounts by passing LOOKUP_COPY_UP to pathwalk.

This has the downside that the copyup will occur even if permission is later
denied to perform the operation.

Signed-off-by: David Howells <dhowells@...hat.com>
---

 fs/namei.c  |    2 +-
 fs/open.c   |    5 +++--
 fs/utimes.c |    2 +-
 fs/xattr.c  |   10 ++++++----
 4 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index 6ec5725..efad85e 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -3583,7 +3583,7 @@ SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname,
 	if (flags & AT_SYMLINK_FOLLOW)
 		how |= LOOKUP_FOLLOW;
 
-	error = user_path_at(olddfd, oldname, how, &old_path);
+	error = user_path_at(olddfd, oldname, how | LOOKUP_COPY_UP, &old_path);
 	if (error)
 		return error;
 
diff --git a/fs/open.c b/fs/open.c
index d3be9e3..bce645b 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -516,7 +516,8 @@ SYSCALL_DEFINE3(fchmodat, int, dfd, const char __user *, filename, umode_t, mode
 	struct path path;
 	int error;
 
-	error = user_path_at(dfd, filename, LOOKUP_FOLLOW, &path);
+	error = user_path_at(dfd, filename, LOOKUP_FOLLOW | LOOKUP_COPY_UP,
+			     &path);
 	if (!error) {
 		error = chmod_common(&path, mode);
 		path_put(&path);
@@ -569,7 +570,7 @@ SYSCALL_DEFINE5(fchownat, int, dfd, const char __user *, filename, uid_t, user,
 	lookup_flags = (flag & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
 	if (flag & AT_EMPTY_PATH)
 		lookup_flags |= LOOKUP_EMPTY;
-	error = user_path_at(dfd, filename, lookup_flags, &path);
+	error = user_path_at(dfd, filename, lookup_flags | LOOKUP_COPY_UP, &path);
 	if (error)
 		goto out;
 	error = mnt_want_write(path.mnt);
diff --git a/fs/utimes.c b/fs/utimes.c
index ba653f3..5fe9ed5 100644
--- a/fs/utimes.c
+++ b/fs/utimes.c
@@ -154,7 +154,7 @@ long do_utimes(int dfd, const char __user *filename, struct timespec *times,
 		fput(file);
 	} else {
 		struct path path;
-		int lookup_flags = 0;
+		int lookup_flags = LOOKUP_COPY_UP;
 
 		if (!(flags & AT_SYMLINK_NOFOLLOW))
 			lookup_flags |= LOOKUP_FOLLOW;
diff --git a/fs/xattr.c b/fs/xattr.c
index 82f4337..b1d8b4c 100644
--- a/fs/xattr.c
+++ b/fs/xattr.c
@@ -351,7 +351,8 @@ SYSCALL_DEFINE5(setxattr, const char __user *, pathname,
 	struct path path;
 	int error;
 
-	error = user_path(pathname, &path);
+	error = user_path_at(AT_FDCWD, pathname, LOOKUP_FOLLOW | LOOKUP_COPY_UP,
+			     &path);
 	if (error)
 		return error;
 	error = mnt_want_write(path.mnt);
@@ -370,7 +371,7 @@ SYSCALL_DEFINE5(lsetxattr, const char __user *, pathname,
 	struct path path;
 	int error;
 
-	error = user_lpath(pathname, &path);
+	error = user_path_at(AT_FDCWD, pathname, LOOKUP_COPY_UP, &path);
 	if (error)
 		return error;
 	error = mnt_want_write(path.mnt);
@@ -580,7 +581,8 @@ SYSCALL_DEFINE2(removexattr, const char __user *, pathname,
 	struct path path;
 	int error;
 
-	error = user_path(pathname, &path);
+	error = user_path_at(AT_FDCWD, pathname, LOOKUP_FOLLOW | LOOKUP_COPY_UP,
+			     &path);
 	if (error)
 		return error;
 	error = mnt_want_write(path.mnt);
@@ -598,7 +600,7 @@ SYSCALL_DEFINE2(lremovexattr, const char __user *, pathname,
 	struct path path;
 	int error;
 
-	error = user_lpath(pathname, &path);
+	error = user_path_at(AT_FDCWD, pathname, LOOKUP_COPY_UP, &path);
 	if (error)
 		return error;
 	error = mnt_want_write(path.mnt);

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