Implement chflagsat(2) system call, similar to fchmodat(2), but operates on

file flags.

Reviewed by:	kib, jilles
Sponsored by:	The FreeBSD Foundation

contrib/openbsm/etc/audit_event

@@ -570,6 +570,7 @@
 43206:AUE_CAP_FCNTLS_GET:cap_fcntls_get(2):fm
 43207:AUE_BINDAT:bindat(2):nt
 43208:AUE_CONNECTAT:connectat(2):nt
+43209:AUE_CHFLAGSAT:chflagsat(2):fm
 #
 # Solaris userspace events.
 #

lib/libc/sys/Symbol.map

@@ -386,6 +386,7 @@ FBSD_1.3 {
 	cap_rights_get;
 	cap_rights_limit;
 	cap_sandboxed;
+	chflagsat;
 	clock_getcpuclockid2;
 	connectat;
 	ffclock_getcounter;

sys/bsm/audit_kevents.h

@@ -610,6 +610,7 @@
 #define	AUE_CAP_FCNTLS_GET	43206	/* TrustedBSD. */
 #define	AUE_BINDAT		43207	/* TrustedBSD. */
 #define	AUE_CONNECTAT		43208	/* TrustedBSD. */
+#define	AUE_CHFLAGSAT		43209	/* FreeBSD-specific. */
 
 /*
  * Darwin BSM uses a number of AUE_O_* definitions, which are aliased to the

sys/compat/freebsd32/syscalls.master

@@ -1020,3 +1020,5 @@
 				    int namelen); }
 539	AUE_CONNECTAT	NOPROTO	{ int connectat(int fd, int s, caddr_t name, \
 				    int namelen); }
+540	AUE_CHFLAGSAT	NOPROTO	{ int chflagsat(int fd, const char *path, \
+				    u_long flags, int atflag); }

sys/kern/capabilities.conf

@@ -445,6 +445,7 @@ olio_listio
 ##
 ## Operations relative to directory capabilities.
 ##
+chflagsat
 faccessat
 fchmodat
 fchownat

sys/kern/syscalls.master

@@ -970,5 +970,7 @@
 				    int namelen); }
 539	AUE_CONNECTAT	STD	{ int connectat(int fd, int s, caddr_t name, \
 				    int namelen); }
+540	AUE_CHFLAGSAT	STD	{ int chflagsat(int fd, const char *path, \
+				    u_long flags, int atflag); }
 ; Please copy any additions and changes to the following compatability tables:
 ; sys/compat/freebsd32/syscalls.master

sys/kern/vfs_syscalls.c

@@ -101,6 +101,10 @@ SDT_PROBE_ARGTYPE(vfs, , stat, reg, 1, "int");
 
 static int chroot_refuse_vdir_fds(struct filedesc *fdp);
 static int getutimes(const struct timeval *, enum uio_seg, struct timespec *);
+static int kern_chflags(struct thread *td, const char *path,
+    enum uio_seg pathseg, u_long flags);
+static int kern_chflagsat(struct thread *td, int fd, const char *path,
+    enum uio_seg pathseg, u_long flags, int atflag);
 static int setfflags(struct thread *td, struct vnode *, u_long);
 static int setutimes(struct thread *td, struct vnode *,
     const struct timespec *, int, int);
@@ -2669,17 +2673,38 @@ sys_chflags(td, uap)
 		u_long flags;
 	} */ *uap;
 {
-	int error;
-	struct nameidata nd;
 
-	AUDIT_ARG_FFLAGS(uap->flags);
-	NDINIT(&nd, LOOKUP, FOLLOW | AUDITVNODE1, UIO_USERSPACE, uap->path, td);
-	if ((error = namei(&nd)) != 0)
-		return (error);
-	NDFREE(&nd, NDF_ONLY_PNBUF);
-	error = setfflags(td, nd.ni_vp, uap->flags);
-	vrele(nd.ni_vp);
-	return (error);
+	return (kern_chflags(td, uap->path, UIO_USERSPACE, uap->flags));
+}
+
+#ifndef _SYS_SYSPROTO_H_
+struct chflagsat_args {
+	int	fd;
+	const char *path;
+	u_long	flags;
+	int	atflag;
+}
+#endif
+int
+sys_chflagsat(struct thread *td, struct chflagsat_args *uap)
+{
+	int fd = uap->fd;
+	char *path = uap->path;
+	u_long flags = uap->flags;
+	int atflag = uap->atflag;
+
+	if (atflag & ~AT_SYMLINK_NOFOLLOW)
+		return (EINVAL);
+
+	return (kern_chflagsat(td, fd, path, UIO_USERSPACE, flags, atflag));
+}
+
+static int
+kern_chflags(struct thread *td, const char *path, enum uio_seg pathseg,
+    u_long flags)
+{
+
+	return (kern_chflagsat(td, AT_FDCWD, path, pathseg, flags, 0));
 }
 
 /*
@@ -2693,16 +2718,26 @@ sys_lchflags(td, uap)
 		u_long flags;
 	} */ *uap;
 {
-	int error;
-	struct nameidata nd;
 
-	AUDIT_ARG_FFLAGS(uap->flags);
-	NDINIT(&nd, LOOKUP, NOFOLLOW | AUDITVNODE1, UIO_USERSPACE, uap->path,
-	    td);
+	return (kern_chflagsat(td, AT_FDCWD, uap->path, UIO_USERSPACE,
+	    uap->flags, AT_SYMLINK_NOFOLLOW));
+}
+
+static int
+kern_chflagsat(struct thread *td, int fd, const char *path,
+    enum uio_seg pathseg, u_long flags, int atflag)
+{
+	struct nameidata nd;
+	int error, follow;
+
+	AUDIT_ARG_FFLAGS(flags);
+	follow = (atflag & AT_SYMLINK_NOFOLLOW) ? NOFOLLOW : FOLLOW;
+	NDINIT_ATRIGHTS(&nd, LOOKUP, follow | AUDITVNODE1, pathseg, path, fd,
+	    CAP_FCHFLAGS, td);
 	if ((error = namei(&nd)) != 0)
 		return (error);
 	NDFREE(&nd, NDF_ONLY_PNBUF);
-	error = setfflags(td, nd.ni_vp, uap->flags);
+	error = setfflags(td, nd.ni_vp, flags);
 	vrele(nd.ni_vp);
 	return (error);
 }

sys/sys/capability.h

@@ -102,6 +102,7 @@
 /* VFS methods. */
 #define	CAP_FCHDIR		0x0000000000000200ULL
 #define	CAP_FCHFLAGS		0x0000000000000100ULL
+#define	CAP_CHFLAGSAT		CAP_FCHFLAGS
 #define	CAP_FCHMOD		0x0000000000000400ULL
 #define	CAP_FCHMODAT		CAP_FCHMOD
 #define	CAP_FCHOWN		0x0000000000000800ULL

sys/sys/stat.h

@@ -293,6 +293,7 @@ struct nstat {
 __BEGIN_DECLS
 #if __BSD_VISIBLE
 int	chflags(const char *, unsigned long);
+int	chflagsat(int, const char *, unsigned long, int);
 #endif
 int	chmod(const char *, mode_t);
 #if __BSD_VISIBLE