[src/trunk]: src/sys/miscfs/procfs If the calling process is running under li...

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

details:   https://anonhg.NetBSD.org/src/rev/5b7c9e91931d
branches:  trunk
changeset: 359689:5b7c9e91931d
user:      bouyer <bouyer%NetBSD.org@localhost>
date:      Mon Jan 17 11:20:00 2022 +0000

description:
If the calling process is running under linux emulation, make /proc/xxx/fd/
return only symlinks pointing to the original file in the filesystem,
instead of a hard link. This matches the linux behavior, and some
linux programs relies on it (they unconditionally call readlink() on
/proc/xxx/fd/yy and don't deal with it returning EINVAL).
Proposed on tech-kern@ in
http://mail-index.netbsd.org/tech-kern/2022/01/11/msg027877.html

diffstat:

 sys/miscfs/procfs/procfs.h        |  10 +++++++++-
 sys/miscfs/procfs/procfs_vfsops.c |   7 ++++---
 sys/miscfs/procfs/procfs_vnops.c  |  10 ++++++----
 3 files changed, 19 insertions(+), 8 deletions(-)

diffs (90 lines):

diff -r 84e7c938c571 -r 5b7c9e91931d sys/miscfs/procfs/procfs.h
--- a/sys/miscfs/procfs/procfs.h        Mon Jan 17 11:12:28 2022 +0000
+++ b/sys/miscfs/procfs/procfs.h        Mon Jan 17 11:20:00 2022 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: procfs.h,v 1.80 2020/04/29 07:18:24 riastradh Exp $    */
+/*     $NetBSD: procfs.h,v 1.81 2022/01/17 11:20:00 bouyer Exp $       */
 
 /*
  * Copyright (c) 1993
@@ -213,6 +213,14 @@
 
 struct proc *procfs_proc_find(struct mount *, pid_t);
 bool procfs_use_linux_compat(struct mount *);
+
+static inline bool
+procfs_proc_is_linux_compat(void)
+{
+       const char *emulname = curlwp->l_proc->p_emul->e_name;
+       return (strncmp(emulname, "linux", 5) == 0);
+}
+
 int procfs_proc_lock(struct mount *, int, struct proc **, int);
 void procfs_proc_unlock(struct proc *);
 int procfs_allocvp(struct mount *, struct vnode **, pid_t, pfstype, int);
diff -r 84e7c938c571 -r 5b7c9e91931d sys/miscfs/procfs/procfs_vfsops.c
--- a/sys/miscfs/procfs/procfs_vfsops.c Mon Jan 17 11:12:28 2022 +0000
+++ b/sys/miscfs/procfs/procfs_vfsops.c Mon Jan 17 11:20:00 2022 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: procfs_vfsops.c,v 1.110 2020/12/28 22:36:16 riastradh Exp $    */
+/*     $NetBSD: procfs_vfsops.c,v 1.111 2022/01/17 11:20:00 bouyer Exp $       */
 
 /*
  * Copyright (c) 1993
@@ -76,7 +76,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: procfs_vfsops.c,v 1.110 2020/12/28 22:36:16 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: procfs_vfsops.c,v 1.111 2022/01/17 11:20:00 bouyer Exp $");
 
 #if defined(_KERNEL_OPT)
 #include "opt_compat_netbsd.h"
@@ -343,7 +343,8 @@
                                 * We make symlinks for directories
                                 * to avoid cycles.
                                 */
-                               if (vxp->v_type == VDIR)
+                               if (vxp->v_type == VDIR ||
+                                   procfs_proc_is_linux_compat())
                                        goto symlink;
                                vp->v_type = vxp->v_type;
                                break;
diff -r 84e7c938c571 -r 5b7c9e91931d sys/miscfs/procfs/procfs_vnops.c
--- a/sys/miscfs/procfs/procfs_vnops.c  Mon Jan 17 11:12:28 2022 +0000
+++ b/sys/miscfs/procfs/procfs_vnops.c  Mon Jan 17 11:20:00 2022 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: procfs_vnops.c,v 1.226 2022/01/14 23:46:56 christos Exp $      */
+/*     $NetBSD: procfs_vnops.c,v 1.227 2022/01/17 11:20:00 bouyer Exp $        */
 
 /*-
  * Copyright (c) 2006, 2007, 2008, 2020 The NetBSD Foundation, Inc.
@@ -105,7 +105,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: procfs_vnops.c,v 1.226 2022/01/14 23:46:56 christos Exp $");
+__KERNEL_RCSID(0, "$NetBSD: procfs_vnops.c,v 1.227 2022/01/17 11:20:00 bouyer Exp $");
 
 #include <sys/param.h>
 #include <sys/atomic.h>
@@ -1143,7 +1143,8 @@
                fvp = fp->f_vnode;
 
                /* Don't show directories */
-               if (fp->f_type == DTYPE_VNODE && fvp->v_type != VDIR) {
+               if (fp->f_type == DTYPE_VNODE && fvp->v_type != VDIR &&
+                   !procfs_proc_is_linux_compat()) {
                        vref(fvp);
                        closef(fp);
                        procfs_proc_unlock(p);
@@ -1651,7 +1652,8 @@
                switch (fp->f_type) {
                case DTYPE_VNODE:
                        vxp = fp->f_vnode;
-                       if (vxp->v_type != VDIR) {
+                       if (vxp->v_type != VDIR &&
+                           !procfs_proc_is_linux_compat()) {
                                error = EINVAL;
                                break;
                        }