Add another flags argument to vn_open_cred. Use it to specify that some

vn_open_cred invocations shall not audit namei path.

In particular, specify VN_OPEN_NOAUDIT for dotdot lookup performed by
default implementation of vop_vptocnp, and for the open done for core
file. vn_fullpath is called from the audit code, and vn_open there need
to disable audit to avoid infinite recursion. Core file is created on
return to user mode, that, in particular, happens during syscall return.
The creation of the core file is audited by direct calls, and we do not
want to overwrite audit information for syscall.

Reported, reviewed and tested by: rwatson

8 files changed, 22 insertions, 16 deletions

diff --git a/sys/cddl/compat/opensolaris/kern/opensolaris_kobj.c b/sys/cddl/compat/opensolaris/kern/opensolaris_kobj.c
index 21b2f23..328bba1 100644
--- a/sys/cddl/compat/opensolaris/kern/opensolaris_kobj.c
+++ b/sys/cddl/compat/opensolaris/kern/opensolaris_kobj.c
@@ -85,7 +85,8 @@ kobj_open_file_vnode(const char *file)
 
 	flags = FREAD;
 	NDINIT(&nd, LOOKUP, MPSAFE, UIO_SYSSPACE, file, td);
-	error = vn_open_cred(&nd, &flags, O_NOFOLLOW, curthread->td_ucred, NULL);
+	error = vn_open_cred(&nd, &flags, O_NOFOLLOW, 0, curthread->td_ucred,
+	    NULL);
 	NDFREE(&nd, NDF_ONLY_PNBUF);
 	if (error != 0)
 		return (NULL);
diff --git a/sys/cddl/compat/opensolaris/sys/vnode.h b/sys/cddl/compat/opensolaris/sys/vnode.h
index 44741d2..bf11e67 100644
--- a/sys/cddl/compat/opensolaris/sys/vnode.h
+++ b/sys/cddl/compat/opensolaris/sys/vnode.h
@@ -182,7 +182,7 @@ vn_openat(char *pnamep, enum uio_seg seg, int filemode, int createmode,
 		vref(startvp);
 	NDINIT_ATVP(&nd, operation, MPSAFE, UIO_SYSSPACE, pnamep, startvp, td);
 	filemode |= O_NOFOLLOW;
-	error = vn_open_cred(&nd, &filemode, createmode, td->td_ucred, NULL);
+	error = vn_open_cred(&nd, &filemode, createmode, 0, td->td_ucred, NULL);
 	NDFREE(&nd, NDF_ONLY_PNBUF);
 	if (error == 0) {
 		/* We just unlock so we hold a reference. */
diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c
index a7f47b2..2cf4304 100644
--- a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c
+++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c
@@ -4519,7 +4519,7 @@ vop_getextattr {
 	flags = FREAD;
 	NDINIT_ATVP(&nd, LOOKUP, NOFOLLOW | MPSAFE, UIO_SYSSPACE, attrname,
 	    xvp, td);
-	error = vn_open_cred(&nd, &flags, 0, ap->a_cred, NULL);
+	error = vn_open_cred(&nd, &flags, 0, 0, ap->a_cred, NULL);
 	vp = nd.ni_vp;
 	NDFREE(&nd, NDF_ONLY_PNBUF);
 	if (error != 0) {
@@ -4640,7 +4640,7 @@ vop_setextattr {
 	flags = FFLAGS(O_WRONLY | O_CREAT);
 	NDINIT_ATVP(&nd, LOOKUP, NOFOLLOW | MPSAFE, UIO_SYSSPACE, attrname,
 	    xvp, td);
-	error = vn_open_cred(&nd, &flags, 0600, ap->a_cred, NULL);
+	error = vn_open_cred(&nd, &flags, 0600, 0, ap->a_cred, NULL);
 	vp = nd.ni_vp;
 	NDFREE(&nd, NDF_ONLY_PNBUF);
 	if (error != 0) {
diff --git a/sys/kern/kern_alq.c b/sys/kern/kern_alq.c
index 5296928..a4ece79 100644
--- a/sys/kern/kern_alq.c
+++ b/sys/kern/kern_alq.c
@@ -351,7 +351,7 @@ alq_open(struct alq **alqp, const char *file, struct ucred *cred, int cmode,
 	NDINIT(&nd, LOOKUP, NOFOLLOW | MPSAFE, UIO_SYSSPACE, file, td);
 	flags = FWRITE | O_NOFOLLOW | O_CREAT;
 
-	error = vn_open_cred(&nd, &flags, cmode, cred, NULL);
+	error = vn_open_cred(&nd, &flags, cmode, 0, cred, NULL);
 	if (error)
 		return (error);
 
diff --git a/sys/kern/kern_sig.c b/sys/kern/kern_sig.c
index 5c1d553..57afc23 100644
--- a/sys/kern/kern_sig.c
+++ b/sys/kern/kern_sig.c
@@ -2940,7 +2940,8 @@ coredump(struct thread *td)
 restart:
 	NDINIT(&nd, LOOKUP, NOFOLLOW | MPSAFE, UIO_SYSSPACE, name, td);
 	flags = O_CREAT | FWRITE | O_NOFOLLOW;
-	error = vn_open(&nd, &flags, S_IRUSR | S_IWUSR, NULL);
+	error = vn_open_cred(&nd, &flags, S_IRUSR | S_IWUSR, VN_OPEN_NOAUDIT,
+	    NULL, NULL);
 	if (error) {
 #ifdef AUDIT
 		audit_proc_coredump(td, name, error);
diff --git a/sys/kern/vfs_default.c b/sys/kern/vfs_default.c
index 7b82a96..c98dad0 100644
--- a/sys/kern/vfs_default.c
+++ b/sys/kern/vfs_default.c
@@ -723,7 +723,7 @@ vop_stdvptocnp(struct vop_vptocnp_args *ap)
 	NDINIT_ATVP(&nd, LOOKUP, FOLLOW | LOCKLEAF, UIO_SYSSPACE,
 	    "..", vp, td);
 	flags = FREAD;
-	error = vn_open(&nd, &flags, 0, NULL);
+	error = vn_open_cred(&nd, &flags, 0, VN_OPEN_NOAUDIT, NULL, NULL);
 	if (error) {
 		vn_lock(vp, locked | LK_RETRY);
 		return (error);
diff --git a/sys/kern/vfs_vnops.c b/sys/kern/vfs_vnops.c
index 9ffb6a6..bef2804 100644
--- a/sys/kern/vfs_vnops.c
+++ b/sys/kern/vfs_vnops.c
@@ -91,7 +91,7 @@ vn_open(ndp, flagp, cmode, fp)
 {
 	struct thread *td = ndp->ni_cnd.cn_thread;
 
-	return (vn_open_cred(ndp, flagp, cmode, td->td_ucred, fp));
+	return (vn_open_cred(ndp, flagp, cmode, 0, td->td_ucred, fp));
 }
 
 /*
@@ -102,11 +102,8 @@ vn_open(ndp, flagp, cmode, fp)
  * due to the NDINIT being done elsewhere.
  */
 int
-vn_open_cred(ndp, flagp, cmode, cred, fp)
-	struct nameidata *ndp;
-	int *flagp, cmode;
-	struct ucred *cred;
-	struct file *fp;
+vn_open_cred(struct nameidata *ndp, int *flagp, int cmode, u_int vn_open_flags,
+    struct ucred *cred, struct file *fp)
 {
 	struct vnode *vp;
 	struct mount *mp;
@@ -124,9 +121,11 @@ restart:
 	if (fmode & O_CREAT) {
 		ndp->ni_cnd.cn_nameiop = CREATE;
 		ndp->ni_cnd.cn_flags = ISOPEN | LOCKPARENT | LOCKLEAF |
-		    MPSAFE | AUDITVNODE1;
+		    MPSAFE;
 		if ((fmode & O_EXCL) == 0 && (fmode & O_NOFOLLOW) == 0)
 			ndp->ni_cnd.cn_flags |= FOLLOW;
+		if (!(vn_open_flags & VN_OPEN_NOAUDIT))
+			ndp->ni_cnd.cn_flags |= AUDITVNODE1;
 		bwillwrite();
 		if ((error = namei(ndp)) != 0)
 			return (error);
@@ -181,9 +180,11 @@ restart:
 		ndp->ni_cnd.cn_nameiop = LOOKUP;
 		ndp->ni_cnd.cn_flags = ISOPEN |
 		    ((fmode & O_NOFOLLOW) ? NOFOLLOW : FOLLOW) |
-		    LOCKLEAF | MPSAFE | AUDITVNODE1;
+		    LOCKLEAF | MPSAFE;
 		if (!(fmode & FWRITE))
 			ndp->ni_cnd.cn_flags |= LOCKSHARED;
+		if (!(vn_open_flags & VN_OPEN_NOAUDIT))
+			ndp->ni_cnd.cn_flags |= AUDITVNODE1;
 		if ((error = namei(ndp)) != 0)
 			return (error);
 		if (!mpsafe)
diff --git a/sys/sys/vnode.h b/sys/sys/vnode.h
index 1e19bb6..7bd1aba 100644
--- a/sys/sys/vnode.h
+++ b/sys/sys/vnode.h
@@ -562,6 +562,9 @@ vn_canvmio(struct vnode *vp)
  */
 #include "vnode_if.h"
 
+/* vn_open_flags */
+#define	VN_OPEN_NOAUDIT		0x00000001
+
 /*
  * Public vnode manipulation functions.
  */
@@ -637,7 +640,7 @@ int	_vn_lock(struct vnode *vp, int flags, char *file, int line);
 #define vn_lock(vp, flags) _vn_lock(vp, flags, __FILE__, __LINE__)
 int	vn_open(struct nameidata *ndp, int *flagp, int cmode, struct file *fp);
 int	vn_open_cred(struct nameidata *ndp, int *flagp, int cmode,
-	    struct ucred *cred, struct file *fp);
+	    u_int vn_open_flags, struct ucred *cred, struct file *fp);
 int	vn_pollrecord(struct vnode *vp, struct thread *p, int events);
 int	vn_rdwr(enum uio_rw rw, struct vnode *vp, void *base,
 	    int len, off_t offset, enum uio_seg segflg, int ioflg,