Overhaul the audit filename handling

In preparation for expanded use in the kernel, make getname_kernel() more useful by allowing it to handle any legal filename length.

Thanks to Guenter Roeck for his suggestion to substitute memcpy() for strlcpy().

CC [email protected]

CC [email protected]

CC [email protected]

Signed-off-by Paul Moore <[email protected]>

---
 fs/namei.c |   34 ++++++++++++++++++++--------------
 1 file changed, 20 insertions(+), 14 deletions(-)

fs/namei.c +18 -12

index 9eb787e..63eaaf6 100644
@@ -211,32 +211,38 @@ getname(const char __user * filename)
 	return getname_flags(filename, 0, NULL);
 }
 
-/*
- * The "getname_kernel()" interface doesn't do pathnames longer
- * than EMBEDDED_NAME_MAX. Deal with it - you're a kernel user.
- */
 struct filename *
 getname_kernel(const char * filename)
 {
 	struct filename *result;
-	char *kname;
-	int len;
-
-	len = strlen(filename);
-	if (len >= EMBEDDED_NAME_MAX)
-		return ERR_PTR(-ENAMETOOLONG);
+	int len = strlen(filename) + 1;
 
 	result = __getname();
 	if (unlikely(!result))
 		return ERR_PTR(-ENOMEM);
 
-	kname = (char *)result + sizeof(*result);
-	result->name = kname;
+	if (len <= EMBEDDED_NAME_MAX) {
+		result->name = (char *)(result) + sizeof(*result);
+		result->separate = false;
+	} else if (len <= PATH_MAX) {
+		struct filename *tmp;
+
+		tmp = kmalloc(sizeof(*tmp), GFP_KERNEL);
+		if (unlikely(!tmp)) {
+			__putname(result);
+			return ERR_PTR(-ENOMEM);
+		}
+		tmp->name = (char *)result;
+		tmp->separate = true;
+		result = tmp;
+	} else {
+		__putname(result);
+		return ERR_PTR(-ENAMETOOLONG);

Quoted 6 lines · Paul Moore

In preparation for expanded use in the kernel, make getname_kernel() more useful by allowing it to handle any legal filename length.

Thanks to Guenter Roeck for his suggestion to substitute memcpy() for strlcpy().

Quoted 4 lines

CC [email protected]

CC [email protected]

CC [email protected]

Signed-off-by Paul Moore <[email protected]>

Noted memcpy() difference (I assume to avoid races).

There are several areas in the kernel that create temporary filename objects using the following pattern:

	int func(const char *name)
	{
		struct filename *file = { .name = name };
		...
		return 0;
	}

... which for the most part works okay, but it causes havoc within the audit subsystem as the filename object does not persist beyond the lifetime of the function. This patch converts all of these temporary filename objects into proper filename objects using getname_kernel() and putname() which ensure that the filename object persists until the audit subsystem is finished with it.

Also, a special thanks to Al Viro, Guenter Roeck, and Sabrina Dubroca for helping resolve a difficult kernel panic on boot related to a use-after-free problem in kern_path_create(); the thread can be seen at the link below:

* https://lkml.org/lkml/2015/1/20/710

This patch includes code that was either based on, or directly written by Al in the above thread.

CC [email protected]

CC [email protected]

CC [email protected]

CC [email protected]

Signed-off-by Paul Moore <[email protected]>

---
 fs/exec.c  |   11 +++++++-
 fs/namei.c |   80 +++++++++++++++++++++++++++++++++++++++++++++++-------------
 fs/open.c  |   11 +++++++-
 3 files changed, 81 insertions(+), 21 deletions(-)

fs/exec.c +9 -2

index a3d33fe..d067771 100644
@@ -789,8 +789,15 @@ exit:
 
 struct file *open_exec(const char *name)
 {
-	struct filename tmp = { .name = name };
-	return do_open_exec(&tmp);
+	struct file *file;
+	struct filename *tmp;
+
+	tmp = getname_kernel(name);
+	if (unlikely(IS_ERR(tmp)))
+		return (void *)tmp;
+	file = do_open_exec(tmp);
+	putname(tmp);
+	return file;
 }
 EXPORT_SYMBOL(open_exec);
 

fs/namei.c +63 -17

index 63eaaf6..f793fe4 100644
@@ -2001,31 +2001,50 @@ static int filename_lookup(int dfd, struct filename *name,
 static int do_path_lookup(int dfd, const char *name,
 				unsigned int flags, struct nameidata *nd)
 {
-	struct filename filename = { .name = name };
+	int retval;
+	struct filename *filename;
 
-	return filename_lookup(dfd, &filename, flags, nd);
+	filename = getname_kernel(name);
+	if (unlikely(IS_ERR(filename)))
+		return PTR_ERR(filename);
+	retval = filename_lookup(dfd, filename, flags, nd);
+	putname(filename);
+	return retval;
 }
 
 /* does lookup, returns the object with parent locked */
 struct dentry *kern_path_locked(const char *name, struct path *path)
 {
+	struct filename *filename;
 	struct nameidata nd;
 	struct dentry *d;
-	int err = do_path_lookup(AT_FDCWD, name, LOOKUP_PARENT, &nd);
-	if (err)
-		return ERR_PTR(err);
+	int err;
+
+	filename = getname_kernel(name);
+	if (IS_ERR(filename))
+		return ERR_CAST(filename);
+
+	err = filename_lookup(AT_FDCWD, filename, LOOKUP_PARENT, &nd);
+	if (err) {
+		d = ERR_PTR(err);
+		goto out;
+	}
 	if (nd.last_type != LAST_NORM) {
 		path_put(&nd.path);
-		return ERR_PTR(-EINVAL);
+		d = ERR_PTR(-EINVAL);
+		goto out;
 	}
 	mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
 	d = __lookup_hash(&nd.last, nd.path.dentry, 0);
 	if (IS_ERR(d)) {
 		mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
 		path_put(&nd.path);
-		return d;
+		goto out;
 	}
 	*path = nd.path;
+
+out:
+	putname(filename);
 	return d;
 }
 

@@ -2368,8 +2387,15 @@ int
 kern_path_mountpoint(int dfd, const char *name, struct path *path,
 			unsigned int flags)
 {
-	struct filename s = {.name = name};
-	return filename_mountpoint(dfd, &s, path, flags);
+	int retval;
+	struct filename *s;
+
+	s = getname_kernel(name);
+	if (unlikely(IS_ERR(s)))
+		return PTR_ERR(s);
+	retval = filename_mountpoint(dfd, s, path, flags);
+	putname(s);
+	return retval;
 }
 EXPORT_SYMBOL(kern_path_mountpoint);
 

@@ -3259,7 +3285,7 @@ struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt,
 {
 	struct nameidata nd;
 	struct file *file;
-	struct filename filename = { .name = name };
+	struct filename *filename;
 	int flags = op->lookup_flags | LOOKUP_ROOT;
 
 	nd.root.mnt = mnt;

@@ -3268,16 +3294,22 @@ struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt,
 	if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN)
 		return ERR_PTR(-ELOOP);
 
-	file = path_openat(-1, &filename, &nd, op, flags | LOOKUP_RCU);
+	filename = getname_kernel(name);
+	if (unlikely(IS_ERR(filename)))
+		return ERR_CAST(filename);
+
+	file = path_openat(-1, filename, &nd, op, flags | LOOKUP_RCU);
 	if (unlikely(file == ERR_PTR(-ECHILD)))
-		file = path_openat(-1, &filename, &nd, op, flags);
+		file = path_openat(-1, filename, &nd, op, flags);
 	if (unlikely(file == ERR_PTR(-ESTALE)))
-		file = path_openat(-1, &filename, &nd, op, flags | LOOKUP_REVAL);
+		file = path_openat(-1, filename, &nd, op, flags | LOOKUP_REVAL);
+	putname(filename);
 	return file;
 }
 
-struct dentry *kern_path_create(int dfd, const char *pathname,
-				struct path *path, unsigned int lookup_flags)
+static struct dentry *filename_create(int dfd, struct filename *name,
+				      struct path *path,
+				      unsigned int lookup_flags)
 {
 	struct dentry *dentry = ERR_PTR(-EEXIST);
 	struct nameidata nd;

@@ -3291,7 +3323,7 @@ struct dentry *kern_path_create(int dfd, const char *pathname,
 	 */
 	lookup_flags &= LOOKUP_REVAL;
 
-	error = do_path_lookup(dfd, pathname, LOOKUP_PARENT|lookup_flags, &nd);
+	error = filename_lookup(dfd, name, LOOKUP_PARENT|lookup_flags, &nd);
 	if (error)
 		return ERR_PTR(error);
 

@@ -3345,6 +3377,20 @@ out:
 	path_put(&nd.path);
 	return dentry;
 }
+
+struct dentry *kern_path_create(int dfd, const char *pathname,
+				struct path *path, unsigned int lookup_flags)
+{
+	struct filename *filename;
+	struct dentry *res;
+
+	filename = getname_kernel(pathname);
+	if (IS_ERR(filename))
+		return ERR_CAST(filename);
+	res = filename_create(dfd, filename, path, lookup_flags);
+	putname(filename);
+	return res;
+}
 EXPORT_SYMBOL(kern_path_create);
 
 void done_path_create(struct path *path, struct dentry *dentry)

@@ -3363,7 +3409,7 @@ struct dentry *user_path_create(int dfd, const char __user *pathname,
 	struct dentry *res;
 	if (IS_ERR(tmp))
 		return ERR_CAST(tmp);
-	res = kern_path_create(dfd, tmp->name, path, lookup_flags);
+	res = filename_create(dfd, tmp, path, lookup_flags);
 	putname(tmp);
 	return res;
 }

fs/open.c +2 -2

index d6fd3ac..33839e1 100644
@@ -940,8 +940,15 @@ struct file *file_open_name(struct filename *name, int flags, umode_t mode)
  */
 struct file *filp_open(const char *filename, int flags, umode_t mode)
 {
-	struct filename name = {.name = filename};
-	return file_open_name(&name, flags, mode);
+	struct file *file;
+	struct filename *name;

In all likelihood there were some subtle, and perhaps not so subtle, bugs with filename matching in audit_inode() and audit_inode_child() for some time, however, recent changes to the audit filename code have definitely broken the filename matching code. The breakage could result in duplicate filenames in the audit log and other odd audit record entries. This patch fixes the filename matching code and restores some sanity to the filename audit records.

CC [email protected]

CC [email protected]

Signed-off-by Paul Moore <[email protected]>

---
 kernel/auditsc.c |   34 +++++++++++++++++++++++++---------
 1 file changed, 25 insertions(+), 9 deletions(-)

kernel/auditsc.c +24 -9

index c967ffc..c54b5f0 100644
@@ -1846,6 +1846,7 @@ void __audit_inode(struct filename *name, const struct dentry *dentry,
 	/* 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 +1864,17 @@ 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 */

@@ -1931,11 +1942,16 @@ 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;
 		}

@@ -1944,11 +1960,8 @@ 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) ||

@@ -1956,6 +1969,8 @@ 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;
 		}

In order to ensure that filenames are not released before the audit subsystem is done with the strings there are a number of hacks built into the fs and audit subsystems around getname() and putname(). To say these hacks are "ugly" would be kind.

This patch removes the filename hackery in favor of a more conventional reference count based approach. The diffstat below tells most of the story; lots of audit/fs specific code is replaced with a traditional reference count based approach that is easily understood, even by those not familiar with the audit and/or fs subsystems.

CC [email protected]

CC [email protected]

Signed-off-by Paul Moore <[email protected]>

---
 fs/namei.c            |   29 +++++++-------
 include/linux/audit.h |    3 -
 include/linux/fs.h    |    9 +---
 kernel/audit.h        |   17 +-------
 kernel/auditsc.c      |  105 +++++--------------------------------------------
 5 files changed, 29 insertions(+), 134 deletions(-)

fs/namei.c +14 -15

index e18a2b5..f73e757 100644
@@ -117,15 +117,6 @@
  * POSIX.1 2.4: an empty pathname is invalid (ENOENT).
  * PATH_MAX includes the nul terminator --RR.
  */
-void final_putname(struct filename *name)
-{
-	if (name->separate) {
-		__putname(name->name);
-		kfree(name);
-	} else {
-		__putname(name);
-	}
-}
 
 #define EMBEDDED_NAME_MAX	(PATH_MAX - sizeof(struct filename))
 

@@ -144,6 +135,7 @@ getname_flags(const char __user *filename, int flags, int *empty)
 	result = __getname();
 	if (unlikely(!result))
 		return ERR_PTR(-ENOMEM);
+	result->refcnt = 1;
 
 	/*
 	 * First, try to embed the struct filename inside the names_cache

@@ -178,6 +170,7 @@ recopy:
 		}
 		result->name = kname;
 		result->separate = true;
+		result->refcnt = 1;
 		max = PATH_MAX;
 		goto recopy;
 	}

@@ -201,7 +194,7 @@ recopy:
 	return result;
 
 error:
-	final_putname(result);
+	putname(result);
 	return err;
 }
 

@@ -242,19 +235,25 @@ getname_kernel(const char * filename)
 	memcpy((char *)result->name, filename, len);
 	result->uptr = NULL;
 	result->aname = NULL;
+	result->refcnt = 1;
 	audit_getname(result);
 
 	return result;
 }
 
-#ifdef CONFIG_AUDITSYSCALL
 void putname(struct filename *name)
 {
-	if (unlikely(!audit_dummy_context()))
-		return audit_putname(name);
-	final_putname(name);
+	BUG_ON(name->refcnt <= 0);
+
+	if (--name->refcnt > 0)
+		return;
+
+	if (name->separate) {
+		__putname(name->name);
+		kfree(name);
+	} else
+		__putname(name);
 }
-#endif
 
 static int check_acl(struct inode *inode, int mask)
 {

include/linux/audit.h +0 -3

index b481779..5f2ad5f 100644
@@ -127,7 +127,6 @@ extern void __audit_syscall_entry(int major, unsigned long a0, unsigned long a1,
 extern void __audit_syscall_exit(int ret_success, long ret_value);
 extern struct filename *__audit_reusename(const __user char *uptr);
 extern void __audit_getname(struct filename *name);
-extern void audit_putname(struct filename *name);
 
 #define AUDIT_INODE_PARENT	1	/* dentry represents the parent */
 #define AUDIT_INODE_HIDDEN	2	/* audit record should be hidden */

@@ -346,8 +345,6 @@ static inline struct filename *audit_reusename(const __user char *name)
 }
 static inline void audit_getname(struct filename *name)
 { }
-static inline void audit_putname(struct filename *name)
-{ }
 static inline void __audit_inode(struct filename *name,
 					const struct dentry *dentry,
 					unsigned int flags)

include/linux/fs.h +2 -7

index e11d60c..df7a047 100644
@@ -2017,6 +2017,7 @@ struct filename {
 	const char		*name;	/* pointer to actual string */
 	const __user char	*uptr;	/* original userland pointer */
 	struct audit_names	*aname;
+	int			refcnt;
 	bool			separate; /* should "name" be freed? */
 };
 

@@ -2036,6 +2037,7 @@ extern int filp_close(struct file *, fl_owner_t id);
 
 extern struct filename *getname(const char __user *);
 extern struct filename *getname_kernel(const char *);
+extern void putname(struct filename *name);
 
 enum {
 	FILE_CREATED = 1,

@@ -2056,15 +2058,8 @@ extern void __init vfs_caches_init(unsigned long);
 
 extern struct kmem_cache *names_cachep;
 
-extern void final_putname(struct filename *name);
-
 #define __getname()		kmem_cache_alloc(names_cachep, GFP_KERNEL)
 #define __putname(name)		kmem_cache_free(names_cachep, (void *)(name))
-#ifndef CONFIG_AUDITSYSCALL
-#define putname(name)		final_putname(name)
-#else
-extern void putname(struct filename *name);
-#endif
 
 #ifdef CONFIG_BLOCK
 extern int register_blkdev(unsigned int, const char *);

kernel/audit.h +2 -15

index 3cdffad..1caa0d3 100644
@@ -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;

kernel/auditsc.c +10 -92

index c54b5f0..0a93b71 100644
@@ -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

@@ -1842,11 +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.

@@ -1893,9 +1810,10 @@ out_alloc:
 	n = audit_alloc_name(context, AUDIT_TYPE_UNKNOWN);
 	if (!n)
 		return;
-	if (name)
-		/* no need to set ->name_put as the original will cleanup */
+	if (name) {
 		n->name = name;
+		name->refcnt++;
+	}
 
 out:
 	if (parent) {

Quoted 11 lines · Paul Moore

In order to ensure that filenames are not released before the audit subsystem is done with the strings there are a number of hacks built into the fs and audit subsystems around getname() and putname(). To say these hacks are "ugly" would be kind.

This patch removes the filename hackery in favor of a more conventional reference count based approach. The diffstat below tells most of the story; lots of audit/fs specific code is replaced with a traditional reference count based approach that is easily understood, even by those not familiar with the audit and/or fs subsystems.

Quoted 3 lines

CC [email protected]

CC [email protected]

Signed-off-by Paul Moore <[email protected]>

Noted change of bumping refcnt before passing back pointer to struct filename.

Reviewed-by Richard Guy Briggs <[email protected]>

This patchset has some important changes from the previous revision, namely a fix from Al Viro (included in 2/5) that resolves a boot panic on some systems as well as some smaller, less noteworthy fixes found in the linux-next announcement thread from January 20th (refcount bump in __audit_reusename() and a inode type in __audit_inode()).

This patchset still needs some additional testing to verify that the audit code still functions properly (the minor fixes mentioned above) and there is an additional patch from Al that should be included as well, but I wanted to post this and push the series to the audit next branch quickly since a number of folks were affected by the boot panic.

---

Paul Moore (5):
fs: rework getname_kernel to handle up to PATH_MAX sized filenames
fs: create proper filename objects using getname_kernel()
audit: enable filename recording via getname_kernel()
audit: fix filename matching in __audit_inode() and __audit_inode_child()
audit: replace getname()/putname() hacks with reference counters

Quoted 12 lines · Paul Moore

This patchset has some important changes from the previous revision, namely a fix from Al Viro (included in 2/5) that resolves a boot panic on some systems as well as some smaller, less noteworthy fixes found in the linux-next announcement thread from January 20th (refcount bump in __audit_reusename() and a inode type in __audit_inode()).

This patchset still needs some additional testing to verify that the audit code still functions properly (the minor fixes mentioned above) and there is an additional patch from Al that should be included as well, but I wanted to post this and push the series to the audit next branch quickly since a number of folks were affected by the boot panic.

Quoted 9 lines

---

Paul Moore (5):
fs: rework getname_kernel to handle up to PATH_MAX sized filenames
fs: create proper filename objects using getname_kernel()
audit: enable filename recording via getname_kernel()
audit: fix filename matching in __audit_inode() and __audit_inode_child()
audit: replace getname()/putname() hacks with reference counters

Hi Paul,

What is the baseline for this patch set ? Obviously -next won't work, and it does not apply to mainline either.

Quoted 23 lines · Guenter Roeck

Quoted 21 lines · Paul Moore

This patchset has some important changes from the previous revision, namely a fix from Al Viro (included in 2/5) that resolves a boot panic on some systems as well as some smaller, less noteworthy fixes found in the linux-next announcement thread from January 20th (refcount bump in __audit_reusename() and a inode type in __audit_inode()).

This patchset still needs some additional testing to verify that the audit code still functions properly (the minor fixes mentioned above) and there is an additional patch from Al that should be included as well, but I wanted to post this and push the series to the audit next branch quickly since a number of folks were affected by the boot panic.

---

Paul Moore (5):
fs: rework getname_kernel to handle up to PATH_MAX sized filenames
fs: create proper filename objects using getname_kernel()
audit: enable filename recording via getname_kernel()
audit: fix filename matching in __audit_inode() and __audit_inode_child()
audit: replace getname()/putname() hacks with reference counters

Quoted 4 lines

Hi Paul,

What is the baseline for this patch set ? Obviously -next won't work, and it does not apply to mainline either.

FWIW, I've ported that on top of vfs.git#for-next; result is in vfs.git#experimental. Paul, are you OK with that one?

Quoted 27 lines · Al Viro

Quoted 26 lines · Guenter Roeck

Quoted 14 lines · Paul Moore

This patchset has some important changes from the previous revision, namely a fix from Al Viro (included in 2/5) that resolves a boot panic on some systems as well as some smaller, less noteworthy fixes found in the linux-next announcement thread from January 20th (refcount bump in __audit_reusename() and a inode type in __audit_inode()).

This patchset still needs some additional testing to verify that the audit code still functions properly (the minor fixes mentioned above) and there is an additional patch from Al that should be included as well, but I wanted to post this and push the series to the audit next branch quickly since a number of folks were affected by the boot panic.

---

Quoted 8 lines

Paul Moore (5):
fs: rework getname_kernel to handle up to PATH_MAX sized filenames
fs: create proper filename objects using getname_kernel()
audit: enable filename recording via getname_kernel()
audit: fix filename matching in __audit_inode() and __audit_inode_child()
audit: replace getname()/putname() hacks with reference counters

Hi Paul,

Quoted 5 lines

Quoted 2 lines

What is the baseline for this patch set ? Obviously -next won't work, and it does not apply to mainline either.

FWIW, I've ported that on top of vfs.git#for-next; result is in vfs.git#experimental. Paul, are you OK with that one?

Okay, hang on let me test that ...

Your experimental branch looks good to me, thanks.

Quoted 1 line · Paul Moore

Your experimental branch looks good to me, thanks.

Pushed into for-next; I'm probably going to move that stuff into a never-rebased branch, merged into for-next and safe to pull into your tree if you want to do something on top of that set.

Quoted 6 lines · Al Viro

Quoted 1 line · Paul Moore

Your experimental branch looks good to me, thanks.

Pushed into for-next; I'm probably going to move that stuff into a never-rebased branch, merged into for-next and safe to pull into your tree if you want to do something on top of that set.

OK, vfs.git#getname is it; it's in never-to-be-rebased mode and it's merged into vfs.git#for-next (as of right now; HEAD is 9ee4c4). If you need to do something on top of that stuff, pulling vfs.git#getname is safe.

Quoted 4 lines · Al Viro

Quoted 1 line · Paul Moore

Your experimental branch looks good to me, thanks.

Quoted 3 lines

Pushed into for-next; I'm probably going to move that stuff into a never-rebased branch, merged into for-next and safe to pull into your tree if you want to do something on top of that set.

OK, vfs.git#getname is it; it's in never-to-be-rebased mode and it's merged into vfs.git#for-next (as of right now; HEAD is 9ee4c4). If you need to do something on top of that stuff, pulling vfs.git#getname is safe.

Quoted 8 lines · Al Viro

Quoted 6 lines · Al Viro

Quoted 1 line · Paul Moore

Your experimental branch looks good to me, thanks.

Pushed into for-next; I'm probably going to move that stuff into a never-rebased branch, merged into for-next and safe to pull into your tree if you want to do something on top of that set.

Quoted 5 lines

OK, vfs.git#getname is it; it's in never-to-be-rebased mode and it's merged
into vfs.git#for-next (as of right now; HEAD is 9ee4c4). If you need to do
something on top of that stuff, pulling vfs.git#getname is safe.

Unfortunately, that thing was -rc2-based, leading to conflict with mainline in kernel/auditsc.c. My fault, I hadn't realized that "audit: create private file name copies when auditing inodes" in audit tree was, in fact, present in mainline. vfs.git#getname2 is -rc3-based, same resulting kernel/auditsc.c as in #getname. Please, use that. vfs.git#for-next merges from that one now, so tomorrow -next should have no problems from vfs.git...

Quoted 5 lines · Al Viro

Quoted 4 lines · Al Viro

Quoted 1 line · Paul Moore

Your experimental branch looks good to me, thanks.

Quoted 7 lines

Quoted 3 lines

Pushed into for-next; I'm probably going to move that stuff into a never-rebased branch, merged into for-next and safe to pull into your tree if you want to do something on top of that set.

OK, vfs.git#getname is it; it's in never-to-be-rebased mode and it's merged into vfs.git#for-next (as of right now; HEAD is 9ee4c4). If you need to do something on top of that stuff, pulling vfs.git#getname is safe.

Unfortunately, that thing was -rc2-based, leading to conflict with mainline in kernel/auditsc.c. My fault, I hadn't realized that "audit: create private file name copies when auditing inodes" in audit tree was, in fact, present in mainline. vfs.git#getname2 is -rc3-based, same resulting kernel/auditsc.c as in #getname. Please, use that. vfs.git#for-next merges from that one now, so tomorrow -next should have no problems from vfs.git...

AFAICS, a new linux-next will be available on Monday (2015-01-26). I try to retest with this.

I have tested vfs.git#getname2 on top of Linux v3.19-rc5-184-gc4e00f1 (plus block-loopmq patchset) and it boots fine on Ubuntu/precise amd64.

Just curious, where will this audit-filename-handling overhaul go through? Through Paul's audit-next or Al's vfs-next tree?

Quoted 22 lines · Guenter Roeck

Quoted 21 lines · Paul Moore

This patchset has some important changes from the previous revision, namely a fix from Al Viro (included in 2/5) that resolves a boot panic on some systems as well as some smaller, less noteworthy fixes found in the linux-next announcement thread from January 20th (refcount bump in __audit_reusename() and a inode type in __audit_inode()).

This patchset still needs some additional testing to verify that the audit code still functions properly (the minor fixes mentioned above) and there is an additional patch from Al that should be included as well, but I wanted to post this and push the series to the audit next branch quickly since a number of folks were affected by the boot panic.

---

Paul Moore (5):
fs: rework getname_kernel to handle up to PATH_MAX sized filenames
fs: create proper filename objects using getname_kernel()
audit: enable filename recording via getname_kernel()
audit: fix filename matching in __audit_inode() and __audit_inode_child()
audit: replace getname()/putname() hacks with reference counters

Quoted 4 lines

Hi Paul,

What is the baseline for this patch set ? Obviously -next won't work, and it does not apply to mainline either.

FWIW, I've ported that on top of vfs.git#for-next; result is in vfs.git#experimental. Paul, are you OK with that one?

Quoted 14 lines · Paul Moore

This patchset has some important changes from the previous revision, namely a fix from Al Viro (included in 2/5) that resolves a boot panic on some systems as well as some smaller, less noteworthy fixes found in the linux-next announcement thread from January 20th (refcount bump in __audit_reusename() and a inode type in __audit_inode()).

This patchset still needs some additional testing to verify that the audit code still functions properly (the minor fixes mentioned above) and there is an additional patch from Al that should be included as well, but I wanted to post this and push the series to the audit next branch quickly since a number of folks were affected by the boot panic.

---

Quoted 7 lines

Paul Moore (5):
fs: rework getname_kernel to handle up to PATH_MAX sized filenames
fs: create proper filename objects using getname_kernel()
audit: enable filename recording via getname_kernel()
audit: fix filename matching in __audit_inode() and __audit_inode_child()
audit: replace getname()/putname() hacks with reference counters

Hi Paul,

What is the baseline for this patch set ? Obviously -next won't work, and it does not apply to mainline either.

Quoted 23 lines · Guenter Roeck

Quoted 14 lines · Paul Moore

This patchset has some important changes from the previous revision, namely a fix from Al Viro (included in 2/5) that resolves a boot panic on some systems as well as some smaller, less noteworthy fixes found in the linux-next announcement thread from January 20th (refcount bump in __audit_reusename() and a inode type in __audit_inode()).

This patchset still needs some additional testing to verify that the audit code still functions properly (the minor fixes mentioned above) and there is an additional patch from Al that should be included as well, but I wanted to post this and push the series to the audit next branch quickly since a number of folks were affected by the boot panic.

---

Quoted 7 lines

Paul Moore (5):
fs: rework getname_kernel to handle up to PATH_MAX sized filenames
fs: create proper filename objects using getname_kernel()
audit: enable filename recording via getname_kernel()
audit: fix filename matching in __audit_inode() and __audit_inode_child()
audit: replace getname()/putname() hacks with reference counters

Quoted 4 lines

Hi Paul,

What is the baseline for this patch set ? Obviously -next won't work, and it does not apply to mainline either.

This patchset currently lives, along with one other unrelated patch, in the audit next branch:

* git://git.infradead.org/users/pcmoore/audit

I'm currently testing these in combination with the patch Al posted last night. Assuming all goes well I'll drop them from the audit next branch and toss all six patches (these plus Al's) into another branch in case Al wants to pull them for the VFS tree.