[9front] [PATCH] Permissions for child boards in /srv

[Jacob Moody <moody@mail.posixcafe.org>]

This patch allows board stats to be mutated. It also changes
the default child board permissions to 0550.

This results in child service directories being
"private" to just the user who created them by
default.


Thanks,
moody

diff 5ee86cf824c5591aa92118c0cd9d71b005e789d0 uncommitted
--- a/sys/src/9/port/devsrv.c
+++ b/sys/src/9/port/devsrv.c
@@ -13,6 +13,8 @@
 	void 	*link;
 	char 	*name;
 	ulong 	path;
+	char	*owner;
+	ulong	perm;
 };

 typedef struct Srv Srv;
@@ -19,9 +21,6 @@
 struct Srv
 {
 	Link;
-
-	char	*owner;
-	ulong	perm;
 	Chan	*chan;
 };

@@ -140,6 +139,7 @@

 		b = ch->parent;
 		free(ch->name);
+		free(ch->owner);
 		wunlock(ch);
 		free(ch);
 	}
@@ -162,14 +162,17 @@
 	rlock(b);
 	if(waserror()){
 		runlock(b);
-		return -1;
+		nexterror();
 	}
-	if(s == DEVDOTDOT){
+	switch(s){
+	case -2: /* dot */
+		ch = b;
+		goto Child;
+	case DEVDOTDOT:
 		ch = b->parent;
 		if(ch == nil)
 			ch = &root;
 		goto Child;
-		
 	}
 	if(name != nil){
 		if(strcmp("clone", name) == 0)
@@ -194,21 +197,25 @@
 		devdir(c, q, up->genbuf, 0, sp->owner, sp->perm, dp);
 	} else if(ch != nil){
 Child:
+		if(name != nil || s == DEVDOTDOT){
+			devpermcheck(ch->owner, ch->perm, OEXEC);
+			c->aux = ch;
+		}
 		kstrcpy(up->genbuf, ch->name, sizeof up->genbuf);
 		q.vers = ch->id;
 		q.path = NETQID(q.vers, ch->path);
 		q.type = QTDIR;
-		devdir(c, q, up->genbuf, 0, eve, 0555|DMDIR, dp);
-		/* dirread's and stats shouldn't alter c->aux */
-		if(name != nil)
-			c->aux = ch;
+		devdir(c, q, up->genbuf, 0, ch->owner, ch->perm|DMDIR, dp);
 	} else if(0){
 Clone:
 		q.vers = NETID(c->qid.path);
 		q.path = NETQID(q.vers, Qclone);
 		devdir(c, q, "clone", 0, eve, 0444, dp);
-	} else
-		error(Enonexist);
+	} else {
+		runlock(b);
+		poperror();
+		return -1;
+	}

 	runlock(b);
 	poperror();
@@ -220,6 +227,8 @@
 {
 	root.qidpath = Qend;
 	root.name = "#s";
+	root.owner = eve;
+	root.perm = 0555;
 }

 static Chan*
@@ -253,6 +262,17 @@
 static int
 srvstat(Chan *c, uchar *db, int n)
 {
+	Dir d;
+
+	/* devstat cheats for dir stats, we care about our dir perms */
+	if(c->qid.type == QTDIR){
+		srvgen(c, nil, nil, 0, -2, &d);
+		n = convD2M(&d, db, n);
+		if(n == 0)
+			error(Ebadarg);
+		return n;
+	}
+
 	return devstat(c, db, n, 0, 0, srvgen);
 }

@@ -286,16 +306,6 @@
 	Chan *nc;
 	char buf[64];

-	if(c->qid.type == QTDIR){
-		if(omode & ORCLOSE)
-			error(Eperm);
-		if(omode != OREAD)
-			error(Eisdir);
-		c->mode = omode;
-		c->flag |= COPEN;
-		c->offset = 0;
-		return c;
-	}
 	if(omode&OTRUNC)
 		error(Eexist);
 	if(omode&ORCLOSE)
@@ -311,6 +321,8 @@
 		ch = smalloc(sizeof *ch);
 		ch->qidpath = Qend;
 		ch->ref = 1;
+		ch->perm = 0550;
+		kstrdup(&ch->owner, up->user);
 		do {
 			qlock(&boards);
 			ch->id = ++boards.path;
@@ -336,6 +348,19 @@
 		runlock(b);
 		nexterror();
 	}
+	if(c->qid.type == QTDIR){
+		if(omode & ORCLOSE)
+			error(Eperm);
+		if(omode != OREAD)
+			error(Eisdir);
+		devpermcheck(b->owner, b->perm, omode);
+		c->mode = omode;
+		c->flag |= COPEN;
+		c->offset = 0;
+		runlock(b);
+		poperror();
+		return c;
+	}
 	if(b->closed)
 		error(Eexpired);

@@ -459,18 +484,18 @@
 static int
 srvwstat(Chan *c, uchar *dp, int n)
 {
-	Board *b;
+	Board *b, *s;
 	char *strs;
-	Srv *sp;
 	Dir d;
+	Link *lp;

-	if(c->qid.type & QTDIR)
-		error(Eperm);
 	switch(NETTYPE(c->qid.path)){
 	case Qlease:
 	case Qclone:
 		error(Eperm);
 	}
+	if(c->qid.type == QTDIR && c->aux == &root)
+		error(Eperm);

 	strs = smalloc(n);
 	if(waserror()){
@@ -490,28 +515,49 @@
 	if(b->closed)
 		error(Eexpired);

-	sp = lookup(b->srv, nil, c->qid.path);
-	if(sp == nil)
+	if(c->qid.type == QTDIR){
+		lp = b;
+		/* we share ownership of our stats with our parent */
+		assert(b->parent != nil);
+		wlock(b->parent);
+		if(waserror()){
+			wunlock(b->parent);
+			nexterror();
+		}
+	} else
+		lp = lookup(b->srv, nil, c->qid.path);
+	if(lp == nil)
 		error(Enonexist);

-	if(strcmp(sp->owner, up->user) != 0 && !iseve())
+	if(strcmp(lp->owner, up->user) != 0 && !iseve())
 		error(Eperm);

-	if(d.name != nil && *d.name && strcmp(sp->name, d.name) != 0) {
+	if(d.name != nil && *d.name && strcmp(lp->name, d.name) != 0) {
 		if(strchr(d.name, '/') != nil)
 			error(Ebadchar);
 		if(strlen(d.name) >= sizeof(up->genbuf))
 			error(Etoolong);
-		if(lookup(b->srv, d.name, ~0UL) != nil)
+
+		//Ensure new name doesn't conflict with old names
+		if(c->qid.type == QTDIR)
+			s = b->parent;
+		else
+			s = b;
+		if(lookup(s->srv, d.name, ~0UL) != nil)
 			error(Eexist);
-		if(lookup(b->child, d.name, ~0UL) != nil)
+		if(lookup(s->child, d.name, ~0UL) != nil)
 			error(Eexist);
-		kstrdup(&sp->name, d.name);
+		kstrdup(&lp->name, d.name);
 	}
 	if(d.uid != nil && *d.uid)
-		kstrdup(&sp->owner, d.uid);
+		kstrdup(&lp->owner, d.uid);
 	if(d.mode != ~0UL)
-		sp->perm = d.mode & 0777;
+		lp->perm = d.mode & 0777;
+
+	if(c->qid.type == QTDIR){
+		wunlock(b->parent);
+		poperror();
+	}

 	wunlock(b);
 	poperror();