Re: smbfs kernel panic

[Matthew Dillon <dillon@xxxxxxxxxxxxxxxxxxxx>]

    Please try this patch set.  I'm not sure whether SMBFS can
    safely use the root creds for file closes, which its
    inactive code has to do, so I cache the cred used in the
    first open and use that for the close.

    When I redid the VFS I wanted it to work from pure threads.
    Most VFSs don't need creds for inactive and choosing which
    cred to use (because multiple user id's might have had the
    file open) is rather non-deterministic... so I simply don't
    make the cred information available.  This means that the
    three filesystems that need it (ntfs, smbfs, nfs) need to do
    their own heuristic which typically involves caching the open
    creds in the auxillary node structure to supply to the close.

    This is mainly due to mistakes made in the protocol 
    specification.  For example, NFS servers should always accept
    root creds to mean 'the greatest access the server allows
    that client to have', but they often don't and instead for user mounts
    only allow that particular user cred.  It's stupid but it's the way
    the cookie crumbles.

						-Matt

Index: smbfs_node.c
===================================================================
RCS file: /cvs/src/sys/vfs/smbfs/smbfs_node.c,v
retrieving revision 1.16
diff -u -r1.16 smbfs_node.c
--- smbfs_node.c	17 Dec 2004 00:18:35 -0000	1.16
+++ smbfs_node.c	4 Jun 2005 17:42:37 -0000
@@ -346,16 +346,16 @@
 	struct smb_cred scred;
 	int error;
 
-	KKASSERT(td->td_proc);
-	cred = td->td_proc->p_ucred;
-
 	SMBVDEBUG("%s: %d\n", VTOSMB(vp)->n_name, vp->v_usecount);
 	if (np->n_opencount) {
 		error = smbfs_vinvalbuf(vp, V_SAVE, td, 1);
+		cred = np->n_cached_cred;
+		np->n_cached_cred = NULL;
 		smb_makescred(&scred, td, cred);
 		error = smbfs_smb_close(np->n_mount->sm_share, np->n_fid, 
 		   &np->n_mtime, &scred);
 		np->n_opencount = 0;
+		crfree(cred);
 	}
 	return (0);
 }
Index: smbfs_node.h
===================================================================
RCS file: /cvs/src/sys/vfs/smbfs/smbfs_node.h,v
retrieving revision 1.4
diff -u -r1.4 smbfs_node.h
--- smbfs_node.h	28 Aug 2004 19:02:28 -0000	1.4
+++ smbfs_node.h	4 Jun 2005 17:35:40 -0000
@@ -61,6 +61,7 @@
 	long			n_ino;
 	int			n_dosattr;
 	int 			n_opencount;
+	struct ucred		*n_cached_cred;	/* cred used to open file */
 	u_int16_t		n_fid;		/* file handle */
 	int			n_rwstate;	/* granted access mode */
 	u_char			n_nmlen;
Index: smbfs_vfsops.c
===================================================================
RCS file: /cvs/src/sys/vfs/smbfs/smbfs_vfsops.c,v
retrieving revision 1.20
diff -u -r1.20 smbfs_vfsops.c
--- smbfs_vfsops.c	20 Apr 2005 17:01:56 -0000	1.20
+++ smbfs_vfsops.c	4 Jun 2005 17:45:16 -0000
@@ -144,8 +144,10 @@
 	int error;
 	char *pc, *pe;
 
-	KKASSERT(td->td_proc);
-	cred = td->td_proc->p_ucred;
+	if (td->td_proc)
+	    cred = td->td_proc->p_ucred;
+	else
+	    cred = proc0.p_ucred;
 
 	if (data == NULL) {
 		printf("missing data argument\n");
@@ -254,8 +256,10 @@
 	struct ucred *cred;
 	int error, flags;
 
-	KKASSERT(td->td_proc);
-	cred = td->td_proc->p_ucred;
+	if (td->td_proc)
+	    cred = td->td_proc->p_ucred;
+	else
+	    cred = proc0.p_ucred;
 
 	SMBVDEBUG("smbfs_unmount: flags=%04x\n", mntflags);
 	flags = 0;
@@ -307,9 +311,6 @@
 	struct smb_cred scred;
 	int error;
 
-	KKASSERT(td->td_proc);
-	cred = td->td_proc->p_ucred;
-
 	if (smp == NULL) {
 		SMBERROR("smp == NULL (bug in umount)\n");
 		return EINVAL;
@@ -318,6 +319,11 @@
 		*vpp = SMBTOV(smp->sm_root);
 		return vget(*vpp, LK_EXCLUSIVE | LK_RETRY, td);
 	}
+	if (td->td_proc)
+		cred = td->td_proc->p_ucred;
+	else
+		cred = proc0.p_ucred;
+
 	smb_makescred(&scred, td, cred);
 	error = smbfs_smb_lookup(NULL, NULL, 0, &fattr, &scred);
 	if (error)
@@ -388,8 +394,10 @@
 	struct ucred *cred;
 	int error = 0;
 
-	KKASSERT(td->td_proc);
-	cred = td->td_proc->p_ucred;
+	if (td->td_proc)
+	    cred = td->td_proc->p_ucred;
+	else
+	    cred = proc0.p_ucred;
 
 	if (np == NULL)
 		return EINVAL;
Index: smbfs_vnops.c
===================================================================
RCS file: /cvs/src/sys/vfs/smbfs/smbfs_vnops.c,v
retrieving revision 1.22
diff -u -r1.22 smbfs_vnops.c
--- smbfs_vnops.c	15 Feb 2005 08:32:18 -0000	1.22
+++ smbfs_vnops.c	4 Jun 2005 17:42:21 -0000
@@ -178,6 +178,8 @@
 		return EACCES;
 	}
 	if (vp->v_type == VDIR) {
+		if (np->n_opencount == 0)
+			np->n_cached_cred = crhold(ap->a_cred);
 		np->n_opencount++;
 		return 0;
 	}
@@ -216,6 +218,7 @@
 		error = smbfs_smb_open(np, accmode, &scred);
 	}
 	if (!error) {
+		np->n_cached_cred = crhold(ap->a_cred);
 		np->n_opencount++;
 	}
 	smbfs_attr_cacheremove(vp);
@@ -258,6 +261,8 @@
 		error = smbfs_smb_close(np->n_mount->sm_share, np->n_fid, 
 			   &np->n_mtime, &scred);
 	}
+	crfree(np->n_cached_cred);
+	np->n_cached_cred = NULL;
 	smbfs_attr_cacheremove(vp);
 	return error;
 }