new helper: audit_file()

... for situations when we don't have any candidate in pathnames - basically,
in descriptor-based syscalls.

[Folded the build fix for !CONFIG_AUDITSYSCALL configs from Chen Gang]
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/open.c

@@ -516,7 +516,7 @@ SYSCALL_DEFINE2(fchmod, unsigned int, fd, umode_t, mode)
 	int err = -EBADF;
 
 	if (f.file) {
-		audit_inode(NULL, f.file->f_path.dentry, 0);
+		audit_file(f.file);
 		err = chmod_common(&f.file->f_path, mode);
 		fdput(f);
 	}
@@ -642,7 +642,7 @@ SYSCALL_DEFINE3(fchown, unsigned int, fd, uid_t, user, gid_t, group)
 	error = mnt_want_write_file(f.file);
 	if (error)
 		goto out_fput;
-	audit_inode(NULL, f.file->f_path.dentry, 0);
+	audit_file(f.file);
 	error = chown_common(&f.file->f_path, user, group);
 	mnt_drop_write_file(f.file);
 out_fput:

fs/xattr.c

@@ -405,16 +405,14 @@ SYSCALL_DEFINE5(fsetxattr, int, fd, const char __user *, name,
 		const void __user *,value, size_t, size, int, flags)
 {
 	struct fd f = fdget(fd);
-	struct dentry *dentry;
 	int error = -EBADF;
 
 	if (!f.file)
 		return error;
-	dentry = f.file->f_path.dentry;
-	audit_inode(NULL, dentry, 0);
+	audit_file(f.file);
 	error = mnt_want_write_file(f.file);
 	if (!error) {
-		error = setxattr(dentry, name, value, size, flags);
+		error = setxattr(f.file->f_path.dentry, name, value, size, flags);
 		mnt_drop_write_file(f.file);
 	}
 	fdput(f);
@@ -509,7 +507,7 @@ SYSCALL_DEFINE4(fgetxattr, int, fd, const char __user *, name,
 
 	if (!f.file)
 		return error;
-	audit_inode(NULL, f.file->f_path.dentry, 0);
+	audit_file(f.file);
 	error = getxattr(f.file->f_path.dentry, name, value, size);
 	fdput(f);
 	return error;
@@ -590,7 +588,7 @@ SYSCALL_DEFINE3(flistxattr, int, fd, char __user *, list, size_t, size)
 
 	if (!f.file)
 		return error;
-	audit_inode(NULL, f.file->f_path.dentry, 0);
+	audit_file(f.file);
 	error = listxattr(f.file->f_path.dentry, list, size);
 	fdput(f);
 	return error;
@@ -651,16 +649,14 @@ SYSCALL_DEFINE2(lremovexattr, const char __user *, pathname,
 SYSCALL_DEFINE2(fremovexattr, int, fd, const char __user *, name)
 {
 	struct fd f = fdget(fd);
-	struct dentry *dentry;
 	int error = -EBADF;
 
 	if (!f.file)
 		return error;
-	dentry = f.file->f_path.dentry;
-	audit_inode(NULL, dentry, 0);
+	audit_file(f.file);
 	error = mnt_want_write_file(f.file);
 	if (!error) {
-		error = removexattr(dentry, name);
+		error = removexattr(f.file->f_path.dentry, name);
 		mnt_drop_write_file(f.file);
 	}
 	fdput(f);

include/linux/audit.h

@@ -130,6 +130,7 @@ extern void audit_putname(struct filename *name);
 #define AUDIT_INODE_HIDDEN	2	/* audit record should be hidden */
 extern void __audit_inode(struct filename *name, const struct dentry *dentry,
 				unsigned int flags);
+extern void __audit_file(const struct file *);
 extern void __audit_inode_child(const struct inode *parent,
 				const struct dentry *dentry,
 				const unsigned char type);
@@ -183,6 +184,11 @@ static inline void audit_inode(struct filename *name,
 		__audit_inode(name, dentry, flags);
 	}
 }
+static inline void audit_file(struct file *file)
+{
+	if (unlikely(!audit_dummy_context()))
+		__audit_file(file);
+}
 static inline void audit_inode_parent_hidden(struct filename *name,
 						const struct dentry *dentry)
 {
@@ -357,6 +363,9 @@ static inline void audit_inode(struct filename *name,
 				const struct dentry *dentry,
 				unsigned int parent)
 { }
+static inline void audit_file(struct file *file)
+{
+}
 static inline void audit_inode_parent_hidden(struct filename *name,
 				const struct dentry *dentry)
 { }

ipc/mqueue.c

@@ -990,7 +990,7 @@ SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr,
 		goto out_fput;
 	}
 	info = MQUEUE_I(inode);
-	audit_inode(NULL, f.file->f_path.dentry, 0);
+	audit_file(f.file);
 
 	if (unlikely(!(f.file->f_mode & FMODE_WRITE))) {
 		ret = -EBADF;
@@ -1106,7 +1106,7 @@ SYSCALL_DEFINE5(mq_timedreceive, mqd_t, mqdes, char __user *, u_msg_ptr,
 		goto out_fput;
 	}
 	info = MQUEUE_I(inode);
-	audit_inode(NULL, f.file->f_path.dentry, 0);
+	audit_file(f.file);
 
 	if (unlikely(!(f.file->f_mode & FMODE_READ))) {
 		ret = -EBADF;

kernel/auditsc.c

@@ -1897,6 +1897,11 @@ void __audit_inode(struct filename *name, const struct dentry *dentry,
 	audit_copy_inode(n, dentry, inode);
 }
 
+void __audit_file(const struct file *file)
+{
+	__audit_inode(NULL, file->f_path.dentry, 0);
+}
+
 /**
  * __audit_inode_child - collect inode info for created/removed objects
  * @parent: inode of dentry parent