Introduce funlinkat syscall that always us to check if we are removing

the file associated with the given file descriptor.

Reviewed by:	kib, asomers
Reviewed by:	cem, jilles, brooks (they reviewed previous version)
Discussed with:	pjd, and many others
Differential Revision:	https://reviews.freebsd.org/D14567

2 files changed, 12 insertions, 2 deletions

diff --git a/sys/sys/fcntl.h b/sys/sys/fcntl.h
index 04eab5e27ed1..b2e7f94199d0 100644
--- a/sys/sys/fcntl.h
+++ b/sys/sys/fcntl.h
@@ -316,6 +316,16 @@ struct __oflock {
 #define	POSIX_FADV_NOREUSE	5	/* access data only once */
 #endif
 
+
+#ifdef __BSD_VISIBLE
+/*
+ * Magic value that specify that corresponding file descriptor to filename
+ * is unknown and sanitary check should be omitted in the funlinkat() and
+ * similar syscalls.
+ */
+#define	FD_NONE			-200
+#endif
+
 #ifndef _KERNEL
 __BEGIN_DECLS
 int	open(const char *, int, ...);
diff --git a/sys/sys/syscallsubr.h b/sys/sys/syscallsubr.h
index 3545745f5a7f..f82500087f08 100644
--- a/sys/sys/syscallsubr.h
+++ b/sys/sys/syscallsubr.h
@@ -218,7 +218,7 @@ int	kern_recvit(struct thread *td, int s, struct msghdr *mp,
 	    enum uio_seg fromseg, struct mbuf **controlp);
 int	kern_renameat(struct thread *td, int oldfd, const char *old, int newfd,
 	    const char *new, enum uio_seg pathseg);
-int	kern_rmdirat(struct thread *td, int fd, const char *path,
+int	kern_frmdirat(struct thread *td, int dfd, const char *path, int fd,
 	    enum uio_seg pathseg, int flag);
 int	kern_sched_getparam(struct thread *td, struct thread *targettd,
 	    struct sched_param *param);
@@ -285,7 +285,7 @@ int	kern_thr_new(struct thread *td, struct thr_param *param);
 int	kern_thr_suspend(struct thread *td, struct timespec *tsp);
 int	kern_truncate(struct thread *td, const char *path,
 	    enum uio_seg pathseg, off_t length);
-int	kern_unlinkat(struct thread *td, int fd, const char *path,
+int	kern_funlinkat(struct thread *td, int dfd, const char *path, int fd,
 	    enum uio_seg pathseg, int flag, ino_t oldinum);
 int	kern_utimesat(struct thread *td, int fd, const char *path,
 	    enum uio_seg pathseg, struct timeval *tptr, enum uio_seg tptrseg);