Merge branch 'getname2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull getname/putname updates from Al Viro:
 "Rework of getname/getname_kernel/etc., mostly from Paul Moore.  Gets
  rid of quite a pile of kludges between namei and audit..."

* 'getname2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  audit: replace getname()/putname() hacks with reference counters
  audit: fix filename matching in __audit_inode() and __audit_inode_child()
  audit: enable filename recording via getname_kernel()
  simpler calling conventions for filename_mountpoint()
  fs: create proper filename objects using getname_kernel()
  fs: rework getname_kernel to handle up to PATH_MAX sized filenames
  cut down the number of do_path_lookup() callers

2 files changed, 37 insertions, 151 deletions

diff --git a/kernel/audit.h b/kernel/audit.h
index 3cdffad5a1d9..1caa0d345d90 100644
--- a/kernel/audit.h
+++ b/kernel/audit.h
@@ -24,12 +24,6 @@
 #include <linux/skbuff.h>
 #include <uapi/linux/mqueue.h>
 
-/* 0 = no checking
-   1 = put_count checking
-   2 = verbose put_count checking
-*/
-#define AUDIT_DEBUG 0
-
 /* AUDIT_NAMES is the number of slots we reserve in the audit_context
  * for saving names from getname().  If we get more names we will allocate
  * a name dynamically and also add those to the list anchored by names_list. */
@@ -74,9 +68,8 @@ struct audit_cap_data {
 	};
 };
 
-/* When fs/namei.c:getname() is called, we store the pointer in name and
- * we don't let putname() free it (instead we free all of the saved
- * pointers at syscall exit time).
+/* When fs/namei.c:getname() is called, we store the pointer in name and bump
+ * the refcnt in the associated filename struct.
  *
  * Further, in fs/namei.c:path_lookup() we store the inode and device.
  */
@@ -86,7 +79,6 @@ struct audit_names {
 	struct filename		*name;
 	int			name_len;	/* number of chars to log */
 	bool			hidden;		/* don't log this record */
-	bool			name_put;	/* call __putname()? */
 
 	unsigned long		ino;
 	dev_t			dev;
@@ -208,11 +200,6 @@ struct audit_context {
 	};
 	int fds[2];
 	struct audit_proctitle proctitle;
-
-#if AUDIT_DEBUG
-	int		    put_count;
-	int		    ino_count;
-#endif
 };
 
 extern u32 audit_ever_enabled;
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 55f82fce2526..dc4ae70a7413 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -866,33 +866,10 @@ static inline void audit_free_names(struct audit_context *context)
 {
 	struct audit_names *n, *next;
 
-#if AUDIT_DEBUG == 2
-	if (context->put_count + context->ino_count != context->name_count) {
-		int i = 0;
-
-		pr_err("%s:%d(:%d): major=%d in_syscall=%d"
-		       " name_count=%d put_count=%d ino_count=%d"
-		       " [NOT freeing]\n", __FILE__, __LINE__,
-		       context->serial, context->major, context->in_syscall,
-		       context->name_count, context->put_count,
-		       context->ino_count);
-		list_for_each_entry(n, &context->names_list, list) {
-			pr_err("names[%d] = %p = %s\n", i++, n->name,
-			       n->name->name ?: "(null)");
-		}
-		dump_stack();
-		return;
-	}
-#endif
-#if AUDIT_DEBUG
-	context->put_count  = 0;
-	context->ino_count  = 0;
-#endif
-
 	list_for_each_entry_safe(n, next, &context->names_list, list) {
 		list_del(&n->list);
-		if (n->name && n->name_put)
-			final_putname(n->name);
+		if (n->name)
+			putname(n->name);
 		if (n->should_free)
 			kfree(n);
 	}
@@ -1711,9 +1688,6 @@ static struct audit_names *audit_alloc_name(struct audit_context *context,
 	list_add_tail(&aname->list, &context->names_list);
 
 	context->name_count++;
-#if AUDIT_DEBUG
-	context->ino_count++;
-#endif
 	return aname;
 }
 
@@ -1734,8 +1708,10 @@ __audit_reusename(const __user char *uptr)
 	list_for_each_entry(n, &context->names_list, list) {
 		if (!n->name)
 			continue;
-		if (n->name->uptr == uptr)
+		if (n->name->uptr == uptr) {
+			n->name->refcnt++;
 			return n->name;
+		}
 	}
 	return NULL;
 }
@@ -1752,19 +1728,8 @@ void __audit_getname(struct filename *name)
 	struct audit_context *context = current->audit_context;
 	struct audit_names *n;
 
-	if (!context->in_syscall) {
-#if AUDIT_DEBUG == 2
-		pr_err("%s:%d(:%d): ignoring getname(%p)\n",
-		       __FILE__, __LINE__, context->serial, name);
-		dump_stack();
-#endif
+	if (!context->in_syscall)
 		return;
-	}
-
-#if AUDIT_DEBUG
-	/* The filename _must_ have a populated ->name */
-	BUG_ON(!name->name);
-#endif
 
 	n = audit_alloc_name(context, AUDIT_TYPE_UNKNOWN);
 	if (!n)
@@ -1772,56 +1737,13 @@ void __audit_getname(struct filename *name)
 
 	n->name = name;
 	n->name_len = AUDIT_NAME_FULL;
-	n->name_put = true;
 	name->aname = n;
+	name->refcnt++;
 
 	if (!context->pwd.dentry)
 		get_fs_pwd(current->fs, &context->pwd);
 }
 
-/* audit_putname - intercept a putname request
- * @name: name to intercept and delay for putname
- *
- * If we have stored the name from getname in the audit context,
- * then we delay the putname until syscall exit.
- * Called from include/linux/fs.h:putname().
- */
-void audit_putname(struct filename *name)
-{
-	struct audit_context *context = current->audit_context;
-
-	BUG_ON(!context);
-	if (!name->aname || !context->in_syscall) {
-#if AUDIT_DEBUG == 2
-		pr_err("%s:%d(:%d): final_putname(%p)\n",
-		       __FILE__, __LINE__, context->serial, name);
-		if (context->name_count) {
-			struct audit_names *n;
-			int i = 0;
-
-			list_for_each_entry(n, &context->names_list, list)
-				pr_err("name[%d] = %p = %s\n", i++, n->name,
-				       n->name->name ?: "(null)");
-			}
-#endif
-		final_putname(name);
-	}
-#if AUDIT_DEBUG
-	else {
-		++context->put_count;
-		if (context->put_count > context->name_count) {
-			pr_err("%s:%d(:%d): major=%d in_syscall=%d putname(%p)"
-			       " name_count=%d put_count=%d\n",
-			       __FILE__, __LINE__,
-			       context->serial, context->major,
-			       context->in_syscall, name->name,
-			       context->name_count, context->put_count);
-			dump_stack();
-		}
-	}
-#endif
-}
-
 /**
  * __audit_inode - store the inode and device from a lookup
  * @name: name being audited
@@ -1842,10 +1764,6 @@ void __audit_inode(struct filename *name, const struct dentry *dentry,
 	if (!name)
 		goto out_alloc;
 
-#if AUDIT_DEBUG
-	/* The struct filename _must_ have a populated ->name */
-	BUG_ON(!name->name);
-#endif
 	/*
 	 * If we have a pointer to an audit_names entry already, then we can
 	 * just use it directly if the type is correct.
@@ -1863,7 +1781,17 @@ void __audit_inode(struct filename *name, const struct dentry *dentry,
 	}
 
 	list_for_each_entry_reverse(n, &context->names_list, list) {
-		if (!n->name || strcmp(n->name->name, name->name))
+		if (n->ino) {
+			/* valid inode number, use that for the comparison */
+			if (n->ino != inode->i_ino ||
+			    n->dev != inode->i_sb->s_dev)
+				continue;
+		} else if (n->name) {
+			/* inode number has not been set, check the name */
+			if (strcmp(n->name->name, name->name))
+				continue;
+		} else
+			/* no inode and no name (?!) ... this is odd ... */
 			continue;
 
 		/* match the correct record type */
@@ -1882,44 +1810,11 @@ out_alloc:
 	n = audit_alloc_name(context, AUDIT_TYPE_UNKNOWN);
 	if (!n)
 		return;
-	/* unfortunately, while we may have a path name to record with the
-	 * inode, we can't always rely on the string lasting until the end of
-	 * the syscall so we need to create our own copy, it may fail due to
-	 * memory allocation issues, but we do our best */
 	if (name) {
-		/* we can't use getname_kernel() due to size limits */
-		size_t len = strlen(name->name) + 1;
-		struct filename *new = __getname();
-
-		if (unlikely(!new))
-			goto out;
-
-		if (len <= (PATH_MAX - sizeof(*new))) {
-			new->name = (char *)(new) + sizeof(*new);
-			new->separate = false;
-		} else if (len <= PATH_MAX) {
-			/* this looks odd, but is due to final_putname() */
-			struct filename *new2;
-
-			new2 = kmalloc(sizeof(*new2), GFP_KERNEL);
-			if (unlikely(!new2)) {
-				__putname(new);
-				goto out;
-			}
-			new2->name = (char *)new;
-			new2->separate = true;
-			new = new2;
-		} else {
-			/* we should never get here, but let's be safe */
-			__putname(new);
-			goto out;
-		}
-		strlcpy((char *)new->name, name->name, len);
-		new->uptr = NULL;
-		new->aname = n;
-		n->name = new;
-		n->name_put = true;
+		n->name = name;
+		name->refcnt++;
 	}
+
 out:
 	if (parent) {
 		n->name_len = n->name ? parent_len(n->name->name) : AUDIT_NAME_FULL;
@@ -1970,11 +1865,16 @@ void __audit_inode_child(const struct inode *parent,
 
 	/* look for a parent entry first */
 	list_for_each_entry(n, &context->names_list, list) {
-		if (!n->name || n->type != AUDIT_TYPE_PARENT)
+		if (!n->name ||
+		    (n->type != AUDIT_TYPE_PARENT &&
+		     n->type != AUDIT_TYPE_UNKNOWN))
 			continue;
 
-		if (n->ino == parent->i_ino &&
-		    !audit_compare_dname_path(dname, n->name->name, n->name_len)) {
+		if (n->ino == parent->i_ino && n->dev == parent->i_sb->s_dev &&
+		    !audit_compare_dname_path(dname,
+					      n->name->name, n->name_len)) {
+			if (n->type == AUDIT_TYPE_UNKNOWN)
+				n->type = AUDIT_TYPE_PARENT;
 			found_parent = n;
 			break;
 		}
@@ -1983,11 +1883,8 @@ void __audit_inode_child(const struct inode *parent,
 	/* is there a matching child entry? */
 	list_for_each_entry(n, &context->names_list, list) {
 		/* can only match entries that have a name */
-		if (!n->name || n->type != type)
-			continue;
-
-		/* if we found a parent, make sure this one is a child of it */
-		if (found_parent && (n->name != found_parent->name))
+		if (!n->name ||
+		    (n->type != type && n->type != AUDIT_TYPE_UNKNOWN))
 			continue;
 
 		if (!strcmp(dname, n->name->name) ||
@@ -1995,6 +1892,8 @@ void __audit_inode_child(const struct inode *parent,
 						found_parent ?
 						found_parent->name_len :
 						AUDIT_NAME_FULL)) {
+			if (n->type == AUDIT_TYPE_UNKNOWN)
+				n->type = type;
 			found_child = n;
 			break;
 		}
@@ -2019,10 +1918,10 @@ void __audit_inode_child(const struct inode *parent,
 		if (found_parent) {
 			found_child->name = found_parent->name;
 			found_child->name_len = AUDIT_NAME_FULL;
-			/* don't call __putname() */
-			found_child->name_put = false;
+			found_child->name->refcnt++;
 		}
 	}
+
 	if (inode)
 		audit_copy_inode(found_child, dentry, inode);
 	else