partially fix up the lookup_one_noperm mess

Try to fix the mess created by sysfs braindamage. - refactor code internal to fs/namei.c a little to avoid too much duplication: o __lookup_hash_kern is renamed back to __lookup_hash o the old __lookup_hash goes away, permission checks moves to the two callers o useless inline qualifiers on above functions go away - lookup_one_len_kern loses it's last argument and is renamed to lookup_one_noperm to make it's useage a little more clear - added kerneldoc comments to describe lookup_one_len aswell as lookup_one_noperm and make it very clear that no one should use the latter ever. Signed-off-by: Christoph Hellwig <hch@lst.de> Cc: Josef 'Jeff' Sipek <jsipek@cs.sunysb.edu> Cc: Miklos Szeredi <miklos@szeredi.hu> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

partially fix up the lookup_one_noperm mess
Try to fix the mess created by sysfs braindamage. - refactor code internal to fs/namei.c a little to avoid too much duplication: o __lookup_hash_kern is renamed back to __lookup_hash o the old __lookup_hash goes away, permission checks moves to the two callers o useless inline qualifiers on above functions go away - lookup_one_len_kern loses it's last argument and is renamed to lookup_one_noperm to make it's useage a little more clear - added kerneldoc comments to describe lookup_one_len aswell as lookup_one_noperm and make it very clear that no one should use the latter ever. Signed-off-by: Christoph Hellwig <hch@lst.de> Cc: Josef 'Jeff' Sipek <jsipek@cs.sunysb.edu> Cc: Miklos Szeredi <miklos@szeredi.hu> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Christoph Hellwig · Linus Torvalds
1 parent ebb3e820b8
Showing 3 changed files with 39 additions and 26 deletions Side-by-side Diff
fs/namei.c
fs/sysfs/dir.c
include/linux/namei.h
@@ -1273,7 +1273,8 @@
 	return err;
 }
  
-static inline struct dentry *__lookup_hash_kern(struct qstr *name, struct dentry *base, struct nameidata *nd)
+static struct dentry *__lookup_hash(struct qstr *name,
+		struct dentry *base, struct nameidata *nd)
 {
 	struct dentry *dentry;
 	struct inode *inode;
  
  
  
  
@@ -1313,31 +1314,18 @@
  * needs parent already locked. Doesn't follow mounts.
  * SMP-safe.
  */
-static inline struct dentry * __lookup_hash(struct qstr *name, struct dentry *base, struct nameidata *nd)
+static struct dentry *lookup_hash(struct nameidata *nd)
 {
-	struct dentry *dentry;
-	struct inode *inode;
 	int err;
  
-	inode = base->d_inode;
-
-	err = permission(inode, MAY_EXEC, nd);
-	dentry = ERR_PTR(err);
+	err = permission(nd->dentry->d_inode, MAY_EXEC, nd);
 	if (err)
-		goto out;
-
-	dentry = __lookup_hash_kern(name, base, nd);
-out:
-	return dentry;
-}
-
-static struct dentry *lookup_hash(struct nameidata *nd)
-{
+		return ERR_PTR(err);
 	return __lookup_hash(&nd->last, nd->dentry, nd);
 }
  
-/* SMP-safe */
-static inline int __lookup_one_len(const char *name, struct qstr *this, struct dentry *base, int len)
+static int __lookup_one_len(const char *name, struct qstr *this,
+		struct dentry *base, int len)
 {
 	unsigned long hash;
 	unsigned int c;
@@ -1358,6 +1346,17 @@
 	return 0;
 }
  
+/**
+ * lookup_one_len:  filesystem helper to lookup single pathname component
+ * @name:	pathname component to lookup
+ * @base:	base directory to lookup from
+ * @len:	maximum length @len should be interpreted to
+ *
+ * Note that this routine is purely a helper for filesystem useage and should
+ * not be called by generic code.  Also note that by using this function to
+ * nameidata argument is passed to the filesystem methods and a filesystem
+ * using this helper needs to be prepared for that.
+ */
 struct dentry *lookup_one_len(const char *name, struct dentry *base, int len)
 {
 	int err;
  
  
  
@@ -1366,18 +1365,33 @@
 	err = __lookup_one_len(name, &this, base, len);
 	if (err)
 		return ERR_PTR(err);
+
+	err = permission(base->d_inode, MAY_EXEC, NULL);
+	if (err)
+		return ERR_PTR(err);
 	return __lookup_hash(&this, base, NULL);
 }
  
-struct dentry *lookup_one_len_kern(const char *name, struct dentry *base, int len)
+/**
+ * lookup_one_noperm - bad hack for sysfs
+ * @name:	pathname component to lookup
+ * @base:	base directory to lookup from
+ *
+ * This is a variant of lookup_one_len that doesn't perform any permission
+ * checks.   It's a horrible hack to work around the braindead sysfs
+ * architecture and should not be used anywhere else.
+ *
+ * DON'T USE THIS FUNCTION EVER, thanks.
+ */
+struct dentry *lookup_one_noperm(const char *name, struct dentry *base)
 {
 	int err;
 	struct qstr this;
  
-	err = __lookup_one_len(name, &this, base, len);
+	err = __lookup_one_len(name, &this, base, strlen(name));
 	if (err)
 		return ERR_PTR(err);
-	return __lookup_hash_kern(&this, base, NULL);
+	return __lookup_hash(&this, base, NULL);
 }
  
 int fastcall __user_walk_fd(int dfd, const char __user *name, unsigned flags,
@@ -112,8 +112,7 @@
 		/* look it up */
 		parent = dentry;
 		mutex_lock(&parent->d_inode->i_mutex);
-		dentry = lookup_one_len_kern(cur->s_name, parent,
-					     strlen(cur->s_name));
+		dentry = lookup_one_noperm(cur->s_name, parent);
 		mutex_unlock(&parent->d_inode->i_mutex);
 		dput(parent);
  
@@ -81,8 +81,8 @@
 extern struct file *nameidata_to_filp(struct nameidata *nd, int flags);
 extern void release_open_intent(struct nameidata *);
  
-extern struct dentry * lookup_one_len(const char *, struct dentry *, int);
-extern struct dentry *lookup_one_len_kern(const char *, struct dentry *, int);
+extern struct dentry *lookup_one_len(const char *, struct dentry *, int);
+extern struct dentry *lookup_one_noperm(const char *, struct dentry *);
  
 extern int follow_down(struct vfsmount **, struct dentry **);
 extern int follow_up(struct vfsmount **, struct dentry **);
...	...	@@ -1273,7 +1273,8 @@
1273	1273	return err;
1274	1274	}
1275	1275
1276		-static inline struct dentry __lookup_hash_kern(struct qstr name, struct dentry base, struct nameidata nd)
	1276	+static struct dentry __lookup_hash(struct qstr name,
	1277	+ struct dentry base, struct nameidata nd)
1277	1278	{
1278	1279	struct dentry *dentry;
1279	1280	struct inode *inode;
1280	1281
1281	1282
1282	1283
1283	1284
...	...	@@ -1313,31 +1314,18 @@
1313	1314	* needs parent already locked. Doesn't follow mounts.
1314	1315	* SMP-safe.
1315	1316	*/
1316		-static inline struct dentry * __lookup_hash(struct qstr name, struct dentry base, struct nameidata *nd)
	1317	+static struct dentry lookup_hash(struct nameidata nd)
1317	1318	{
1318		- struct dentry *dentry;
1319		- struct inode *inode;
1320	1319	int err;
1321	1320
1322		- inode = base->d_inode;
1323		-
1324		- err = permission(inode, MAY_EXEC, nd);
1325		- dentry = ERR_PTR(err);
	1321	+ err = permission(nd->dentry->d_inode, MAY_EXEC, nd);
1326	1322	if (err)
1327		- goto out;
1328		-
1329		- dentry = __lookup_hash_kern(name, base, nd);
1330		-out:
1331		- return dentry;
1332		-}
1333		-
1334		-static struct dentry lookup_hash(struct nameidata nd)
1335		-{
	1323	+ return ERR_PTR(err);
1336	1324	return __lookup_hash(&nd->last, nd->dentry, nd);
1337	1325	}
1338	1326
1339		-/* SMP-safe */
1340		-static inline int __lookup_one_len(const char name, struct qstr this, struct dentry *base, int len)
	1327	+static int __lookup_one_len(const char name, struct qstr this,
	1328	+ struct dentry *base, int len)
1341	1329	{
1342	1330	unsigned long hash;
1343	1331	unsigned int c;
...	...	@@ -1358,6 +1346,17 @@
1358	1346	return 0;
1359	1347	}
1360	1348
	1349	+/**
	1350	+ * lookup_one_len: filesystem helper to lookup single pathname component
	1351	+ * @name: pathname component to lookup
	1352	+ * @base: base directory to lookup from
	1353	+ * @len: maximum length @len should be interpreted to
	1354	+ *
	1355	+ * Note that this routine is purely a helper for filesystem useage and should
	1356	+ * not be called by generic code. Also note that by using this function to
	1357	+ * nameidata argument is passed to the filesystem methods and a filesystem
	1358	+ * using this helper needs to be prepared for that.
	1359	+ */
1361	1360	struct dentry lookup_one_len(const char name, struct dentry *base, int len)
1362	1361	{
1363	1362	int err;
1364	1363
1365	1364
1366	1365
...	...	@@ -1366,18 +1365,33 @@
1366	1365	err = __lookup_one_len(name, &this, base, len);
1367	1366	if (err)
1368	1367	return ERR_PTR(err);
	1368	+
	1369	+ err = permission(base->d_inode, MAY_EXEC, NULL);
	1370	+ if (err)
	1371	+ return ERR_PTR(err);
1369	1372	return __lookup_hash(&this, base, NULL);
1370	1373	}
1371	1374
1372		-struct dentry lookup_one_len_kern(const char name, struct dentry *base, int len)
	1375	+/**
	1376	+ * lookup_one_noperm - bad hack for sysfs
	1377	+ * @name: pathname component to lookup
	1378	+ * @base: base directory to lookup from
	1379	+ *
	1380	+ * This is a variant of lookup_one_len that doesn't perform any permission
	1381	+ * checks. It's a horrible hack to work around the braindead sysfs
	1382	+ * architecture and should not be used anywhere else.
	1383	+ *
	1384	+ * DON'T USE THIS FUNCTION EVER, thanks.
	1385	+ */
	1386	+struct dentry lookup_one_noperm(const char name, struct dentry *base)
1373	1387	{
1374	1388	int err;
1375	1389	struct qstr this;
1376	1390
1377		- err = __lookup_one_len(name, &this, base, len);
	1391	+ err = __lookup_one_len(name, &this, base, strlen(name));
1378	1392	if (err)
1379	1393	return ERR_PTR(err);
1380		- return __lookup_hash_kern(&this, base, NULL);
	1394	+ return __lookup_hash(&this, base, NULL);
1381	1395	}
1382	1396
1383	1397	int fastcall __user_walk_fd(int dfd, const char __user *name, unsigned flags,
...	...	@@ -112,8 +112,7 @@
112	112	/* look it up */
113	113	parent = dentry;
114	114	mutex_lock(&parent->d_inode->i_mutex);
115		- dentry = lookup_one_len_kern(cur->s_name, parent,
116		- strlen(cur->s_name));
	115	+ dentry = lookup_one_noperm(cur->s_name, parent);
117	116	mutex_unlock(&parent->d_inode->i_mutex);
118	117	dput(parent);
119	118
...	...	@@ -81,8 +81,8 @@
81	81	extern struct file nameidata_to_filp(struct nameidata nd, int flags);
82	82	extern void release_open_intent(struct nameidata *);
83	83
84		-extern struct dentry * lookup_one_len(const char , struct dentry , int);
85		-extern struct dentry lookup_one_len_kern(const char , struct dentry *, int);
	84	+extern struct dentry lookup_one_len(const char , struct dentry *, int);
	85	+extern struct dentry lookup_one_noperm(const char , struct dentry *);
86	86
87	87	extern int follow_down(struct vfsmount , struct dentry );
88	88	extern int follow_up(struct vfsmount , struct dentry );