shithub: ext4srv

Info  •  Files  •  Log

better permission checking and simple file writing

--- a/ext4srv.c

+++ b/ext4srv.c

@@ -12,6 +12,7 @@

 struct Aux {

 	Part *p;

+	u32int uid;

 	char *path;

 	union {

 		ext4_file *file;

@@ -23,6 +24,8 @@

 enum {

 	Adir,

 	Afile,

+

+	Root = 0,

 };

 static Opts opts = {

@@ -29,6 +32,95 @@

 	.cachewb = 0,

 };

+static char *

+linkresolve(Aux *a, char *s)

+{

+	char *q;

+	char buf[4096+1];

+	ulong sz;

+

+	if(ext4_readlink(s, buf, sizeof(buf)-1, &sz) == 0){

+		buf[sz] = 0;

+		cleanname(buf);

+		if(buf[0] == '/'){

+			free(s);

+			s = smprint("%M%s", a->p, buf);

+		}else{

+			q = strrchr(s, '/');

+			*q = 0;

+			q = s;

+			s = smprint("%s/%s", q, buf);

+			cleanname(s);

+			free(q);

+		}

+	}

+

+	return s;

+}

+

+static char *

+fullpath(Aux *a)

+{

+	return linkresolve(a, smprint("%M/%s", a->p, a->path));

+}

+

+static int

+haveperm(Aux *a, int p)

+{

+	struct ext4_inode inode;

+	u32int ino;

+	Group *g;

+	char *s;

+	int m, fm, r;

+

+	switch(p & 3){

+	case OREAD:

+		p = AREAD;	

+		break;

+	case OWRITE:

+		p = AWRITE;

+		break;

+	case ORDWR:

+		p = AREAD|AWRITE;

+		break;

+	case OEXEC:

+		p = AEXEC;	

+		break;

+	default:

+		return 0;

+	}

+

+	s = fullpath(a);

+	if((r = ext4_raw_inode_fill(s, &ino, &inode)) != 0){

+		fprint(2, "inode: %s: %s\n", s, errno2s(r));

+		return 0;

+	}

+	free(s);

+

+	fm = ext4_inode_get_mode(a->p->sb, &inode);

+

+	/* other */

+	m = fm & 7;

+	if((p & m) == p)

+		return 1;

+

+	/* owner */

+	if(a->uid == Root || ((g = findgroupid(&a->p->groups, ext4_inode_get_uid(&inode))) != nil && g->id == a->uid)){

+		m |= (fm >> 6) & 7;

+		if((p & m) == p)

+			return 1;

+	}

+

+	/* group */

+	if(a->uid == Root || ((g = findgroupid(&a->p->groups, ext4_inode_get_gid(&inode))) != nil && g->id == a->uid)){

+		m |= (fm >> 3) & 7;

+		if((p & m) == p)

+			return 1;

+	}

+

+	return 0;

+}

+

 static void

 rattach(Req *r)

 {

@@ -42,6 +134,9 @@

 		rerrstr(err, sizeof(err));

 		respond(r, err);

 	}else{

+		if(findgroup(&a->p->groups, r->ifcall.uname, &a->uid) == nil)

+			a->uid = Root; /* FIXME need external mapping */

+

 		incref(a->p);

 		a->type = Adir;

 		a->path = strdup("");

@@ -52,6 +147,34 @@

 	}

 }

+static u32int

+toext4mode(u32int mode, u32int perm, int creat)

+{

+	u32int e;

+

+	e = 0;

+	mode &= ~OCEXEC;

+

+	if(mode & OTRUNC){

+		mode &= ~OTRUNC;

+		e |= O_TRUNC;

+	}

+	if(mode == OWRITE)

+		e |= O_WRONLY;

+	else if(mode == ORDWR)

+		e |= O_RDWR;

+

+	if(creat)

+		e |= O_CREAT;

+

+	if(perm & DMEXCL)

+		e |= O_EXCL;

+	if(perm & DMAPPEND)

+		e |= O_APPEND;

+

+	return e;

+}

+

 static void

 ropen(Req *r)

 {

@@ -62,7 +185,7 @@

 	a = r->fid->aux;

 	switch(a->type){

 	case Adir:

-		if(r->ifcall.mode != OREAD){

+		if(r->ifcall.mode != OREAD || !haveperm(a, r->ifcall.mode)){

 			respond(r, "permission denied");

 			return;

 		}

@@ -88,7 +211,7 @@

 		break;

 	case Afile:

-		if(r->ifcall.mode != OREAD){

+		if(!haveperm(a, r->ifcall.mode)){

 			respond(r, "permission denied");

 			return;

 		}

@@ -103,7 +226,7 @@

 			a->file = nil;

 			goto Nomem;

 		}

-		res = ext4_fopen2(a->file, path, O_RDONLY);

+		res = ext4_fopen2(a->file, path, toext4mode(r->ifcall.mode, 0, 0));

 		free(path);

 		if(res != 0){

 			free(a->file);

@@ -127,40 +250,14 @@

 	respond(r, "nope");

 }

-static char *

-linkresolve(Aux *a, char *s)

-{

-	char *q;

-	char buf[4096+1];

-	ulong sz;

-

-	if(ext4_readlink(s, buf, sizeof(buf)-1, &sz) == 0){

-		buf[sz] = 0;

-		cleanname(buf);

-		if(buf[0] == '/'){

-			free(s);

-			s = smprint("%M%s", a->p, buf);

-		}else{

-			q = strrchr(s, '/');

-			*q = 0;

-			q = s;

-			s = smprint("%s/%s", q, buf);

-			cleanname(s);

-			free(q);

-		}

-	}

-

-	return s;

-}

-

 static int

 dirfill(Dir *dir, Aux *a, char *path)

 {

 	struct ext4_inode inode;

-	Group *g;

+	u32int t, ino;

 	char *s, *q;

-	int r, i;

-	u32int uid, gid, t, ino;

+	Group *g;

+	int r;

 	memset(dir, 0, sizeof(*dir));

@@ -196,14 +293,10 @@

 	dir->atime = ext4_inode_get_access_time(&inode);

 	dir->mtime = ext4_inode_get_modif_time(&inode);

-	uid = ext4_inode_get_uid(&inode);

-	gid = ext4_inode_get_gid(&inode);

-	for(i = 0, g = a->p->groups.g; i < a->p->groups.ng && (dir->uid == nil || dir->gid == nil); i++, g++){

-		if(g->id == uid)

-			dir->uid = estrdup9p(g->name);

-		if(g->id == gid)

-			dir->gid = estrdup9p(g->name);

-	}

+	if((g = findgroupid(&a->p->groups, ext4_inode_get_uid(&inode))) != nil)

+		dir->uid = estrdup9p(g->name);

+	if((g = findgroupid(&a->p->groups, ext4_inode_get_gid(&inode))) != nil)

+		dir->gid = estrdup9p(g->name);

 	free(s);

@@ -255,7 +348,26 @@

 static void

 rwrite(Req *r)

 {

-	respond(r, "nope");

+	Aux *a;

+	ulong n;

+	int res;

+

+	a = r->fid->aux;

+	if(a->type == Adir){

+		respond(r, "can't write to dir");

+		return;

+	}else if(a->type == Afile){

+		ext4_fseek(a->file, r->ifcall.offset, SEEK_SET);

+		if((res = ext4_fwrite(a->file, r->ifcall.data, r->ifcall.count, &n)) != 0)

+			respond(r, errno2s(res));

+		else{

+			r->ofcall.count = n;

+			respond(r, nil);

+		}

+		return;

+	}

+

+	respond(r, "eh?");

 }

 static void

--- a/group.c

+++ b/group.c

@@ -69,3 +69,39 @@

 	free(gs->g);

 	free(gs->raw);

 }

+

+Group *

+findgroup(Groups *gs, char *name, u32int *id)

+{

+	int i;

+	Group *g;

+

+	g = gs->g;

+	for(i = 0; i < gs->ng; i++, g++){

+		if(strcmp(g->name, name) == 0){

+			if(id != nil)

+				*id = g->id;

+			return g;

+		}

+	}

+

+	if(id != nil)

+		*id = ~0;

+

+	return nil;

+}

+

+Group *

+findgroupid(Groups *gs, u32int id)

+{

+	int i;

+	Group *g;

+

+	g = gs->g;

+	for(i = 0; i < gs->ng; i++, g++){

+		if(g->id == id)

+			return g;

+	}

+

+	return nil;

+}

--- a/group.h

+++ b/group.h

@@ -16,3 +16,5 @@

 int loadgroups(Groups *gs, char *raw);

 void freegroups(Groups *gs);

+Group *findgroup(Groups *gs, char *name, u32int *id);

+Group *findgroupid(Groups *gs, u32int id);