Subject: Re: coredump following symlinks (3)
To: Charles M. Hannum <root@ihack.net>
From: Manuel Bouyer <bouyer@antioche.lip6.fr>
List: tech-kern
Date: 08/27/1999 19:42:38
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On Fri, Aug 27, 1999 at 12:50:09PM -0400, Charles M. Hannum wrote:
>
> This part of the patch:
>
> + if ((ndp->ni_vp->v_type == VLNK) &
> + ((fmode & FNOSYMLINK) != 0)) {
>
> should read:
>
> + if (ndp->ni_vp->v_type == VLNK)
>
> You should not be able to open(2) a symlink, regardless of flag
> settings.
Sure, it seems reasonable.
Current diffs appenend below (I checked it still works :)
--
Manuel Bouyer, LIP6, Universite Paris VI. Manuel.Bouyer@lip6.fr
--
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Index: sys/fcntl.h
===================================================================
RCS file: /cvsroot/syssrc/sys/sys/fcntl.h,v
retrieving revision 1.16
diff -u -r1.16 fcntl.h
--- fcntl.h 1999/08/03 20:19:21 1.16
+++ fcntl.h 1999/08/27 17:42:17
@@ -125,6 +125,13 @@
#define FMARK 0x00001000 /* mark during gc() */
#define FDEFER 0x00002000 /* defer for next gc pass */
#define FHASLOCK 0x00004000 /* descriptor holds advisory lock */
+/*
+ * Note: The below is not a flag that can be used in the struct file.
+ * It's an option that can be passed to vn_open to make sure it doesn't
+ * follow a symlink on the last lookup
+ */
+#define FNOSYMLINK 0x00010000 /* Don't follow symlink for last
+ component */
/* bits to save after open(2) */
#define FMASK (FREAD|FWRITE|FAPPEND|FASYNC|FFSYNC|FNONBLOCK|FDSYNC|\
FRSYNC|FALTIO)
Index: kern/kern_sig.c
===================================================================
RCS file: /cvsroot/syssrc/sys/kern/kern_sig.c,v
retrieving revision 1.92
diff -u -r1.92 kern_sig.c
--- kern_sig.c 1999/07/25 06:30:34 1.92
+++ kern_sig.c 1999/08/27 17:42:17
@@ -1297,8 +1297,9 @@
sprintf(name, "core");
else
sprintf(name, "%s.core", p->p_comm);
- NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, name, p);
- error = vn_open(&nd, O_CREAT | FWRITE, S_IRUSR | S_IWUSR);
+
+ NDINIT(&nd, LOOKUP, NOFOLLOW, UIO_SYSSPACE, name, p);
+ error = vn_open(&nd, O_CREAT | FWRITE | FNOSYMLINK, S_IRUSR | S_IWUSR);
if (error)
return (error);
vp = nd.ni_vp;
Index: kern/vfs_vnops.c
===================================================================
RCS file: /cvsroot/syssrc/sys/kern/vfs_vnops.c,v
retrieving revision 1.37
diff -u -r1.37 vfs_vnops.c
--- vfs_vnops.c 1999/08/03 20:19:17 1.37
+++ vfs_vnops.c 1999/08/27 17:42:17
@@ -85,7 +85,8 @@
if (fmode & O_CREAT) {
ndp->ni_cnd.cn_nameiop = CREATE;
ndp->ni_cnd.cn_flags = LOCKPARENT | LOCKLEAF;
- if ((fmode & O_EXCL) == 0)
+ if ((fmode & O_EXCL) == 0 &&
+ ((fmode & FNOSYMLINK) == 0))
ndp->ni_cnd.cn_flags |= FOLLOW;
if ((error = namei(ndp)) != 0)
return (error);
@@ -112,6 +113,10 @@
vp = ndp->ni_vp;
if (fmode & O_EXCL) {
error = EEXIST;
+ goto bad;
+ }
+ if (ndp->ni_vp->v_type == VLNK) {
+ error = EFTYPE;
goto bad;
}
fmode &= ~O_CREAT;
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