[src/trunk]: src/sys/compat remove special handling for symbolic links for CO...

[jdolecek <jdolecek%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/af38ccc76c15
branches:  trunk
changeset: 973215:af38ccc76c15
user:      jdolecek <jdolecek%NetBSD.org@localhost>
date:      Wed Jun 24 10:28:16 2020 +0000

description:
remove special handling for symbolic links for COMPAT_43 lstat, it's
not necessary; this removes the only places in kernel which did namei
LOOKUP with LOCKPARENT

fixes diagnostic KASSERT() in namei() code

Reported-by: syzbot+628382ecf1438e53d08d%syzkaller.appspotmail.com@localhost

diffstat:

 sys/compat/common/vfs_syscalls_43.c |  64 +++-------------------------------
 sys/compat/sunos32/sunos32_misc.c   |  67 +++---------------------------------
 2 files changed, 14 insertions(+), 117 deletions(-)

diffs (189 lines):

diff -r ad1ed116da5e -r af38ccc76c15 sys/compat/common/vfs_syscalls_43.c
--- a/sys/compat/common/vfs_syscalls_43.c       Wed Jun 24 10:07:13 2020 +0000
+++ b/sys/compat/common/vfs_syscalls_43.c       Wed Jun 24 10:28:16 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: vfs_syscalls_43.c,v 1.65 2020/02/27 18:19:16 pgoyette Exp $    */
+/*     $NetBSD: vfs_syscalls_43.c,v 1.66 2020/06/24 10:28:16 jdolecek Exp $    */
 
 /*
  * Copyright (c) 1989, 1993
@@ -37,7 +37,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: vfs_syscalls_43.c,v 1.65 2020/02/27 18:19:16 pgoyette Exp $");
+__KERNEL_RCSID(0, "$NetBSD: vfs_syscalls_43.c,v 1.66 2020/06/24 10:28:16 jdolecek Exp $");
 
 #if defined(_KERNEL_OPT)
 #include "opt_compat_netbsd.h"
@@ -179,69 +179,19 @@
                syscallarg(char *) path;
                syscallarg(struct ostat *) ub;
        } */
-       struct vnode *vp, *dvp;
-       struct stat sb, sb1;
+       struct stat sb;
        struct stat43 osb;
        int error;
-       struct pathbuf *pb;
-       struct nameidata nd;
-       int ndflags;
 
-       error = pathbuf_copyin(SCARG(uap, path), &pb);
-       if (error) {
+       error = do_sys_stat(SCARG(uap, path), NOFOLLOW, &sb);
+       if (error)
                return error;
-       }
 
-       ndflags = NOFOLLOW | LOCKLEAF | LOCKPARENT | TRYEMULROOT;
-again:
-       NDINIT(&nd, LOOKUP, ndflags, pb);
-       if ((error = namei(&nd))) {
-               if (error == EISDIR && (ndflags & LOCKPARENT) != 0) {
-                       /*
-                        * Should only happen on '/'. Retry without LOCKPARENT;
-                        * this is safe since the vnode won't be a VLNK.
-                        */
-                       ndflags &= ~LOCKPARENT;
-                       goto again;
-               }
-               pathbuf_destroy(pb);
-               return (error);
-       }
        /*
-        * For symbolic links, always return the attributes of its
+        * For symbolic links, BSD4.3 returned the attributes of its
         * containing directory, except for mode, size, and links.
+        * This is no longer emulated, the parent directory is not consulted.
         */
-       vp = nd.ni_vp;
-       dvp = nd.ni_dvp;
-       pathbuf_destroy(pb);
-       if (vp->v_type != VLNK) {
-               if ((ndflags & LOCKPARENT) != 0) {
-                       if (dvp == vp)
-                               vrele(dvp);
-                       else
-                               vput(dvp);
-               }
-               error = vn_stat(vp, &sb);
-               vput(vp);
-               if (error)
-                       return (error);
-       } else {
-               error = vn_stat(dvp, &sb);
-               vput(dvp);
-               if (error) {
-                       vput(vp);
-                       return (error);
-               }
-               error = vn_stat(vp, &sb1);
-               vput(vp);
-               if (error)
-                       return (error);
-               sb.st_mode &= ~S_IFDIR;
-               sb.st_mode |= S_IFLNK;
-               sb.st_nlink = sb1.st_nlink;
-               sb.st_size = sb1.st_size;
-               sb.st_blocks = sb1.st_blocks;
-       }
        cvtstat(&sb, &osb);
        error = copyout((void *)&osb, (void *)SCARG(uap, ub), sizeof (osb));
        return (error);
diff -r ad1ed116da5e -r af38ccc76c15 sys/compat/sunos32/sunos32_misc.c
--- a/sys/compat/sunos32/sunos32_misc.c Wed Jun 24 10:07:13 2020 +0000
+++ b/sys/compat/sunos32/sunos32_misc.c Wed Jun 24 10:28:16 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: sunos32_misc.c,v 1.83 2019/10/26 11:34:48 christos Exp $       */
+/*     $NetBSD: sunos32_misc.c,v 1.84 2020/06/24 10:28:17 jdolecek Exp $       */
 /* from :NetBSD: sunos_misc.c,v 1.107 2000/12/01 19:25:10 jdolecek Exp */
 
 /*
@@ -77,7 +77,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: sunos32_misc.c,v 1.83 2019/10/26 11:34:48 christos Exp $");
+__KERNEL_RCSID(0, "$NetBSD: sunos32_misc.c,v 1.84 2020/06/24 10:28:17 jdolecek Exp $");
 
 #define COMPAT_SUNOS 1
 
@@ -294,72 +294,19 @@
                syscallarg(const netbsd32_charp) path;
                syscallarg(netbsd32_stat43p_t) ub;
        } */
-       struct vnode *vp, *dvp;
-       struct stat sb, sb1;
+       struct stat sb;
        struct netbsd32_stat43 sb32;
        int error;
-       struct pathbuf *pb;
-       struct nameidata nd;
-       int ndflags;
-       const char *path;
 
-       path = SCARG_P32(uap, path);
-
-       ndflags = NOFOLLOW | LOCKLEAF | LOCKPARENT | TRYEMULROOT;
-again:
-       error = pathbuf_copyin(path, &pb);
-       if (error) {
+       error = do_sys_stat(SCARG_P32(uap, path), NOFOLLOW, &sb);
+       if (error)
                return error;
-       }
 
-       NDINIT(&nd, LOOKUP, ndflags, pb);
-       if ((error = namei(&nd))) {
-               pathbuf_destroy(pb);
-               if (error == EISDIR && (ndflags & LOCKPARENT) != 0) {
-                       /*
-                        * Should only happen on '/'. Retry without LOCKPARENT;
-                        * this is safe since the vnode won't be a VLNK.
-                        */
-                       ndflags &= ~LOCKPARENT;
-                       goto again;
-               }
-               return (error);
-       }
        /*
-        * For symbolic links, always return the attributes of its
+        * For symbolic links, SunOS returned the attributes of its
         * containing directory, except for mode, size, and links.
+        * This is no longer emulated, the parent directory is not consulted.
         */
-       vp = nd.ni_vp;
-       dvp = nd.ni_dvp;
-       pathbuf_destroy(pb);
-       if (vp->v_type != VLNK) {
-               if ((ndflags & LOCKPARENT) != 0) {
-                       if (dvp == vp)
-                               vrele(dvp);
-                       else
-                               vput(dvp);
-               }
-               error = vn_stat(vp, &sb);
-               vput(vp);
-               if (error)
-                       return (error);
-       } else {
-               error = vn_stat(dvp, &sb);
-               vput(dvp);
-               if (error) {
-                       vput(vp);
-                       return (error);
-               }
-               error = vn_stat(vp, &sb1);
-               vput(vp);
-               if (error)
-                       return (error);
-               sb.st_mode &= ~S_IFDIR;
-               sb.st_mode |= S_IFLNK;
-               sb.st_nlink = sb1.st_nlink;
-               sb.st_size = sb1.st_size;
-               sb.st_blocks = sb1.st_blocks;
-       }
        sunos32_from___stat13(&sb, &sb32);
        error = copyout((void *)&sb32, SCARG_P32(uap, ub), sizeof (sb32));
        return (error);