13663 fchmodat(AT_SYMLINK_NOFOLLOW) should work for non-symlinks

Reviewed by: Gordon Ross <Gordon.W.Ross@gmail.com>
Reviewed by: Patrick Mooney <pmooney@pfmooney.com>
Approved by: Dan McDonald <danmcd@joyent.com>

7 files changed, 103 insertions, 17 deletions

diff --git a/usr/src/man/man2/chmod.2 b/usr/src/man/man2/chmod.2
index b1e0ebf2b4..d71ba875c5 100644
--- a/usr/src/man/man2/chmod.2
+++ b/usr/src/man/man2/chmod.2
@@ -45,11 +45,10 @@
 .\" Copyright (c) 2005, Sun Microsystems, Inc.  All Rights Reserved.
 .\" Copyright (c) 2014, Joyent, Inc.
 .\"
-.TH CHMOD 2 "Dec 22, 2014"
+.TH CHMOD 2 "Jan 26, 2022"
 .SH NAME
 chmod, fchmod, fchmodat \- change access permission mode of file
 .SH SYNOPSIS
-.LP
 .nf
 #include <sys/types.h>
 #include <sys/stat.h>
@@ -68,7 +67,6 @@ chmod, fchmod, fchmodat \- change access permission mode of file
 .fi
 
 .SH DESCRIPTION
-.LP
 The \fBchmod()\fR, \fBfchmod()\fR, and \fBfchmodat()\fR functions set the access
 permission portion of the mode of the file whose name is given by \fIpath\fR or
 referenced by the open file descriptor \fIfildes\fR to the bit pattern contained
@@ -196,12 +194,10 @@ will result in an error.
 Upon successful completion, \fBchmod()\fR, \fBfchmod()\fR, \fBfchmodat()\fR mark
 for update the \fBst_ctime\fR field of the file.
 .SH RETURN VALUES
-.LP
 Upon successful completion, \fB0\fR is returned. Otherwise, \fB\(mi1\fR is
 returned, the file mode is unchanged, and \fBerrno\fR is set to indicate the
 error.
 .SH ERRORS
-.LP
 The \fBchmod()\fR, \fBfchmod()\fR, and \fBfchmodat()\fR functions will fail if:
 .sp
 .ne 2
@@ -404,7 +400,8 @@ descriptor which does not refer to a file.
 .B EOPNOTSUPP
 .ad
 .RS 16n
-The \fBAT_SYMLINK_NOFOLLOW\fR bit is set in the \fIflags\fR argument.
+The \fBAT_SYMLINK_NOFOLLOW\fR bit is set in the \fIflags\fR argument and
+\fIpath\fR refers to a symbolic link.
 .RE
 
 .sp
@@ -445,7 +442,6 @@ of this function on a pipe.
 .RE
 
 .SH EXAMPLES
-.LP
 \fBExample 1 \fRSet Read Permissions for User, Group, and Others
 .sp
 .LP
@@ -517,7 +513,6 @@ status = stat("home/cnd/mod1", &buffer;);
 .in -2
 
 .SH USAGE
-.LP
 If \fBchmod()\fR or \fBfchmod()\fR is used to change the file group owner
 permissions on a file with non-trivial ACL entries, only the ACL mask is set to
 the new permissions and the group owner permission bits in the file's mode
@@ -526,7 +521,6 @@ one whose meaning cannot be represented in the file's mode field alone. The new
 ACL mask permissions  might change the effective permissions for additional
 users and groups that have ACL entries on the file.
 .SH ATTRIBUTES
-.LP
 See \fBattributes\fR(5) for descriptions of the following attributes:
 .sp
 
@@ -543,7 +537,6 @@ MT-Level	Async-Signal-Safe
 .TE
 
 .SH SEE ALSO
-.LP
 \fBchmod\fR(1), \fBchown\fR(2), \fBcreat\fR(2), \fBfcntl\fR(2), \fBmknod\fR(2),
 \fBopen\fR(2), \fBread\fR(2), \fBrename\fR(2), \fBstat\fR(2), \fBwrite\fR(2),
 \fBfattach\fR(3C), \fBmkfifo\fR(3C), \fBstat.h\fR(3HEAD), \fBattributes\fR(5),
diff --git a/usr/src/pkg/manifests/system-test-ostest.p5m b/usr/src/pkg/manifests/system-test-ostest.p5m
index 8f8f38407c..1f89619630 100644
--- a/usr/src/pkg/manifests/system-test-ostest.p5m
+++ b/usr/src/pkg/manifests/system-test-ostest.p5m
@@ -132,6 +132,8 @@ file path=opt/os-tests/tests/stackalign/stackalign.64 mode=0555
 dir  path=opt/os-tests/tests/stress
 file path=opt/os-tests/tests/stress/dladm-kstat mode=0555
 dir  path=opt/os-tests/tests/syscall
+file path=opt/os-tests/tests/syscall/fchmodat.32 mode=0555
+file path=opt/os-tests/tests/syscall/fchmodat.64 mode=0555
 file path=opt/os-tests/tests/syscall/open.32 mode=0555
 file path=opt/os-tests/tests/syscall/open.64 mode=0555
 dir  path=opt/os-tests/tests/timer
diff --git a/usr/src/test/os-tests/runfiles/default.run b/usr/src/test/os-tests/runfiles/default.run
index 0861ede6a4..dcf65fceed 100644
--- a/usr/src/test/os-tests/runfiles/default.run
+++ b/usr/src/test/os-tests/runfiles/default.run
@@ -76,7 +76,7 @@ tests = ['conn', 'dgram', 'drop_priv', 'nosignal', 'rights.32', 'rights.64',
          'sockpair', 'recvmsg.32', 'recvmsg.64']
 
 [/opt/os-tests/tests/syscall]
-tests = ['open.32', 'open.64']
+tests = ['fchmodat.32', 'fchmodat.64', 'open.32', 'open.64']
 
 [/opt/os-tests/tests/pf_key]
 user = root
diff --git a/usr/src/test/os-tests/tests/syscall/Makefile b/usr/src/test/os-tests/tests/syscall/Makefile
index b4ba83a18b..b2842d4681 100644
--- a/usr/src/test/os-tests/tests/syscall/Makefile
+++ b/usr/src/test/os-tests/tests/syscall/Makefile
@@ -16,7 +16,7 @@
 include $(SRC)/cmd/Makefile.cmd
 include $(SRC)/test/Makefile.com
 
-PROGS = open
+PROGS = fchmodat open
 
 CSTD = $(CSTD_GNU99)
 
diff --git a/usr/src/test/os-tests/tests/syscall/fchmodat.c b/usr/src/test/os-tests/tests/syscall/fchmodat.c
new file mode 100644
index 0000000000..7a0f5caca7
--- /dev/null
+++ b/usr/src/test/os-tests/tests/syscall/fchmodat.c
@@ -0,0 +1,92 @@
+/*
+ * This file and its contents are supplied under the terms of the
+ * Common Development and Distribution License ("CDDL"), version 1.0.
+ * You may only use this file in accordance with the terms of version
+ * 1.0 of the CDDL.
+ *
+ * A full copy of the text of the CDDL should have accompanied this
+ * source.  A copy of the CDDL is also available via the Internet at
+ * http://www.illumos.org/license/CDDL.
+ */
+
+/*
+ * Copyright 2022 Marcel Telka <marcel@telka.sk>
+ */
+
+/*
+ * Test for fchmodat(AT_SYMLINK_NOFOLLOW)
+ */
+
+#include <sys/param.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+int
+main(void)
+{
+	int ret = 0;
+
+	char template[MAXPATHLEN];
+	char *path;
+	char file[MAXPATHLEN];
+	char link[MAXPATHLEN];
+
+	/* prepare template for temporary directory */
+	if (strlcpy(template, "/tmp/XXXXXX", sizeof (template))
+	    >= sizeof (template)) {
+		(void) printf("FAIL: Template copy failed\n");
+		exit(EXIT_FAILURE);
+	}
+
+	/* create temporary directory */
+	if ((path = mkdtemp(template)) == NULL) {
+		(void) printf("FAIL: Temporary directory creation failed\n");
+		exit(EXIT_FAILURE);
+	}
+
+	/* format file and link paths */
+	(void) snprintf(file, sizeof (file), "%s/file", path);
+	(void) snprintf(link, sizeof (link), "%s/link", path);
+
+	/* create the file */
+	int fd = open(file, O_WRONLY | O_CREAT, 0644);
+	if (fd < 0) {
+		(void) printf("FAIL: File %s creation failed\n", file);
+		(void) rmdir(path);
+		exit(EXIT_FAILURE);
+	}
+	(void) close(fd);
+
+	/* create symlink */
+	if (symlink("file", link) != 0) {
+		(void) printf("FAIL: Symlink %s creation failed\n", link);
+		(void) unlink(file);
+		(void) rmdir(path);
+		exit(EXIT_FAILURE);
+	}
+
+	/* test fchmodat(AT_SYMLINK_NOFOLLOW) for symlink */
+	if (fchmodat(AT_FDCWD, link, 0666, AT_SYMLINK_NOFOLLOW) == 0) {
+		(void) printf("FAIL: fchmodat(AT_SYMLINK_NOFOLLOW) "
+		    "unexpectedly succeeded for symlink\n");
+		ret = EXIT_FAILURE;
+	}
+	/* test fchmodat(AT_SYMLINK_NOFOLLOW) for regular file */
+	if (fchmodat(AT_FDCWD, file, 0666, AT_SYMLINK_NOFOLLOW) != 0) {
+		(void) printf("FAIL: fchmodat(AT_SYMLINK_NOFOLLOW) failed for "
+		    "regular file\n");
+		ret = EXIT_FAILURE;
+	}
+
+	/* cleanup */
+	(void) unlink(link);
+	(void) unlink(file);
+	(void) rmdir(path);
+
+	return (ret);
+}
diff --git a/usr/src/uts/common/os/fio.c b/usr/src/uts/common/os/fio.c
index 7b6d973b9e..c25564d85f 100644
--- a/usr/src/uts/common/os/fio.c
+++ b/usr/src/uts/common/os/fio.c
@@ -1585,7 +1585,9 @@ fsetattrat(int fd, char *path, int flags, struct vattr *vap)
 		VN_HOLD(vp);
 	}
 
-	if (vn_is_readonly(vp)) {
+	if (vp->v_type == VLNK && (vap->va_mask & AT_MODE) != 0) {
+		error = EOPNOTSUPP;
+	} else if (vn_is_readonly(vp)) {
 		error = EROFS;
 	} else {
 		error = VOP_SETATTR(vp, vap, 0, CRED(), NULL);
diff --git a/usr/src/uts/common/syscall/chmod.c b/usr/src/uts/common/syscall/chmod.c
index bed521f0b3..925219515b 100644
--- a/usr/src/uts/common/syscall/chmod.c
+++ b/usr/src/uts/common/syscall/chmod.c
@@ -24,7 +24,7 @@
  */
 
 /*	Copyright (c) 1983, 1984, 1985, 1986, 1987, 1988, 1989 AT&T	*/
-/*	  All Rights Reserved  	*/
+/*	  All Rights Reserved	*/
 
 #include <sys/param.h>
 #include <sys/isa_defs.h>
@@ -55,9 +55,6 @@ fchmodat(int fd, char *path, int mode, int flag)
 	if (flag & ~AT_SYMLINK_NOFOLLOW)
 		return (set_errno(EINVAL));
 
-	if (flag & AT_SYMLINK_NOFOLLOW)
-		return (set_errno(EOPNOTSUPP));
-
 	vattr.va_mode = mode & MODEMASK;
 	vattr.va_mask = AT_MODE;
 	error = fsetattrat(fd, path, flag, &vattr);