Index: lib/libc/sys/posix_fallocate.2
===================================================================
--- lib/libc/sys/posix_fallocate.2
+++ lib/libc/sys/posix_fallocate.2
@@ -28,7 +28,7 @@
 .\"     @(#)open.2	8.2 (Berkeley) 11/16/93
 .\" $FreeBSD$
 .\"
-.Dd January 23, 2014
+.Dd October 11, 2017
 .Dt POSIX_FALLOCATE 2
 .Os
 .Sh NAME
@@ -118,6 +118,10 @@
 .It Bq Er ENOSPC
 There is insufficient free space remaining on the file system storage
 media.
+.It Bq Er ENOTCAPABLE
+The file descriptor
+.Fa fd
+has insufficient rights.
 .It Bq Er ESPIPE
 The
 .Fa fd
Index: sys/kern/capabilities.conf
===================================================================
--- sys/kern/capabilities.conf
+++ sys/kern/capabilities.conf
@@ -488,6 +488,7 @@
 ##
 ## Allow I/O-related file descriptors, subject to capability rights.
 ##
+posix_fallocate
 pread
 preadv
 
Index: sys/kern/init_sysent.c
===================================================================
--- sys/kern/init_sysent.c
+++ sys/kern/init_sysent.c
@@ -581,7 +581,7 @@
 	{ AS(rctl_get_limits_args), (sy_call_t *)sys_rctl_get_limits, AUE_NULL, NULL, 0, 0, 0, SY_THR_STATIC },	/* 527 = rctl_get_limits */
 	{ AS(rctl_add_rule_args), (sy_call_t *)sys_rctl_add_rule, AUE_NULL, NULL, 0, 0, 0, SY_THR_STATIC },	/* 528 = rctl_add_rule */
 	{ AS(rctl_remove_rule_args), (sy_call_t *)sys_rctl_remove_rule, AUE_NULL, NULL, 0, 0, 0, SY_THR_STATIC },	/* 529 = rctl_remove_rule */
-	{ AS(posix_fallocate_args), (sy_call_t *)sys_posix_fallocate, AUE_POSIX_FALLOCATE, NULL, 0, 0, 0, SY_THR_STATIC },	/* 530 = posix_fallocate */
+	{ AS(posix_fallocate_args), (sy_call_t *)sys_posix_fallocate, AUE_POSIX_FALLOCATE, NULL, 0, 0, SYF_CAPENABLED, SY_THR_STATIC },	/* 530 = posix_fallocate */
 	{ AS(posix_fadvise_args), (sy_call_t *)sys_posix_fadvise, AUE_POSIX_FADVISE, NULL, 0, 0, 0, SY_THR_STATIC },	/* 531 = posix_fadvise */
 	{ AS(wait6_args), (sy_call_t *)sys_wait6, AUE_WAIT6, NULL, 0, 0, 0, SY_THR_STATIC },	/* 532 = wait6 */
 	{ AS(cap_rights_limit_args), (sy_call_t *)sys_cap_rights_limit, AUE_CAP_RIGHTS_LIMIT, NULL, 0, 0, SYF_CAPENABLED, SY_THR_STATIC },	/* 533 = cap_rights_limit */
Index: sys/kern/vfs_syscalls.c
===================================================================
--- sys/kern/vfs_syscalls.c
+++ sys/kern/vfs_syscalls.c
@@ -4400,7 +4400,7 @@
 	if (offset > OFF_MAX - len)
 		return (EFBIG);
 	AUDIT_ARG_FD(fd);
-	error = fget(td, fd, cap_rights_init(&rights, CAP_WRITE), &fp);
+	error = fget(td, fd, cap_rights_init(&rights, CAP_PWRITE), &fp);
 	if (error != 0)
 		return (error);
 	AUDIT_ARG_FILE(td->td_proc, fp);