Merge tag 'pull-xattr' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull xattr updates from Al Viro:
 "Sanitize xattr and io_uring interactions with it, add *xattrat()
  syscalls, sanitize struct filename handling in there"

* tag 'pull-xattr' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  xattr: remove redundant check on variable err
  fs/xattr: add *at family syscalls
  new helpers: file_removexattr(), filename_removexattr()
  new helpers: file_listxattr(), filename_listxattr()
  replace do_getxattr() with saner helpers.
  replace do_setxattr() with saner helpers.
  new helper: import_xattr_name()
  fs: rename struct xattr_ctx to kernel_xattr_ctx
  xattr: switch to CLASS(fd)
  io_[gs]etxattr_prep(): just use getname()
  io_uring: IORING_OP_F[GS]ETXATTR is fine with REQ_F_FIXED_FILE
  getname_maybe_null() - the third variant of pathname copy-in
  teach filename_lookup() to treat NULL filename as ""

1 files changed, 26 insertions, 8 deletions

diff --git a/fs/namei.c b/fs/namei.c
index 72c227d12581..9d30c7aa9aa6 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -211,22 +211,38 @@ getname_flags(const char __user *filename, int flags)
 	return result;
 }
 
-struct filename *
-getname_uflags(const char __user *filename, int uflags)
+struct filename *getname_uflags(const char __user *filename, int uflags)
 {
 	int flags = (uflags & AT_EMPTY_PATH) ? LOOKUP_EMPTY : 0;
 
 	return getname_flags(filename, flags);
 }
 
-struct filename *
-getname(const char __user * filename)
+struct filename *getname(const char __user * filename)
 {
 	return getname_flags(filename, 0);
 }
 
-struct filename *
-getname_kernel(const char * filename)
+struct filename *__getname_maybe_null(const char __user *pathname)
+{
+	struct filename *name;
+	char c;
+
+	/* try to save on allocations; loss on um, though */
+	if (get_user(c, pathname))
+		return ERR_PTR(-EFAULT);
+	if (!c)
+		return NULL;
+
+	name = getname_flags(pathname, LOOKUP_EMPTY);
+	if (!IS_ERR(name) && !(name->name[0])) {
+		putname(name);
+		name = NULL;
+	}
+	return name;
+}
+
+struct filename *getname_kernel(const char * filename)
 {
 	struct filename *result;
 	int len = strlen(filename) + 1;
@@ -264,7 +280,7 @@ EXPORT_SYMBOL(getname_kernel);
 
 void putname(struct filename *name)
 {
-	if (IS_ERR(name))
+	if (IS_ERR_OR_NULL(name))
 		return;
 
 	if (WARN_ON_ONCE(!atomic_read(&name->refcnt)))
@@ -629,6 +645,7 @@ struct nameidata {
 		unsigned seq;
 	} *stack, internal[EMBEDDED_LEVELS];
 	struct filename	*name;
+	const char *pathname;
 	struct nameidata *saved;
 	unsigned	root_seq;
 	int		dfd;
@@ -647,6 +664,7 @@ static void __set_nameidata(struct nameidata *p, int dfd, struct filename *name)
 	p->depth = 0;
 	p->dfd = dfd;
 	p->name = name;
+	p->pathname = likely(name) ? name->name : "";
 	p->path.mnt = NULL;
 	p->path.dentry = NULL;
 	p->total_link_count = old ? old->total_link_count : 0;
@@ -2480,7 +2498,7 @@ OK:
 static const char *path_init(struct nameidata *nd, unsigned flags)
 {
 	int error;
-	const char *s = nd->name->name;
+	const char *s = nd->pathname;
 
 	/* LOOKUP_CACHED requires RCU, ask caller to retry */
 	if ((flags & (LOOKUP_RCU | LOOKUP_CACHED)) == LOOKUP_CACHED)