shithub: ext4srv

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fix truncation permission check; fix writing beyond file end

--- a/ext4srv.c

+++ b/ext4srv.c

@@ -6,6 +6,8 @@

 #include "group.h"

 #include "common.h"

+#define MIN(a,b) ((a)<(b)?(a):(b))

+

 int mainstacksize = 65536;

 typedef struct Aux Aux;

@@ -29,7 +31,7 @@

 };

 static Opts opts;

-

+static u8int zero[65536];

 static char Eperm[] = "permission denied";

 static char *

@@ -103,6 +105,8 @@

 	default:

 		return 0;

 	}

+	if(p & OTRUNC)

+		p |= AWRITE;

 	if((s = fullpath(a)) == nil)

 		return -1;

@@ -343,6 +347,7 @@

 		goto ext4errorrm;

 	ext4_owner_set(s, a->uid, ext4_inode_get_gid(&inode));

+	free(a->path);

 	a->path = strdup(strchr(s+1, '/')+1);

 	free(s);

 	r->ofcall.iounit = 0;

@@ -445,25 +450,24 @@

 rread(Req *r)

 {

 	ulong n;

+	int res;

 	Aux *a;

 	a = r->fid->aux;

 	if(a->type == Adir && a->dir != nil){

 		dirread9p(r, dirgen, a);

-		respond(r, nil);

-		return;

 	}else if(a->type == Afile && a->file != nil){

-		ext4_fseek(a->file, r->ifcall.offset, 0);

-		if(ext4_fread(a->file, r->ofcall.data, r->ifcall.count, &n) != 0){

-			respond(r, "i/o error");

-		}else{

-			r->ofcall.count = n;

-			respond(r, nil);

+		if(ext4_fseek(a->file, r->ifcall.offset, SEEK_SET) != 0)

+			n = 0;

+		else if((res = ext4_fread(a->file, r->ofcall.data, r->ifcall.count, &n)) != 0){

+			respond(r, errno2s(res));

+			return;

 		}

-		return;

+

+		r->ofcall.count = n;

 	}

-	respond(r, "eh?");

+	respond(r, nil);

 }

 static void

@@ -476,19 +480,25 @@

 	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);

+		while(ext4_fsize(a->file) < r->ifcall.offset){

+			ext4_fseek(a->file, 0, SEEK_END);

+			if((res = ext4_fwrite(a->file, zero, MIN(r->ifcall.offset-ext4_fsize(a->file), sizeof(zero)), &n)) != 0)

+				goto ext4error;

 		}

-		return;

+		if((res = ext4_fseek(a->file, r->ifcall.offset, SEEK_SET)) != 0)

+			goto ext4error;

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

+			goto ext4error;

+

+		r->ofcall.count = n;

+		respond(r, nil);

 	}

-	respond(r, "eh?");

+	return;

+

+ext4error:

+	respond(r, errno2s(res));

 }

 static void

@@ -758,20 +768,14 @@

 	Aux *a, *c;

 	a = oldfid->aux;

-	switch(a->type){

-	case Afile:

-	case Adir:

-		if((c = calloc(1, sizeof(*c))) == nil)

-			return "memory";

-		memmove(c, a, sizeof(*c));

-		c->path = strdup(a->path);

-		c->file = nil;

-		c->dir = nil;

-		break;

-	default:

-		return "unknown aux type";

-	}

+	if((c = calloc(1, sizeof(*c))) == nil)

+		return "memory";

+	memmove(c, a, sizeof(*c));

+	c->path = strdup(a->path);

+	c->file = nil;

+	c->dir = nil;

+

 	incref(c->p);

 	newfid->aux = c;

@@ -798,12 +802,9 @@

 			ext4_fclose(a->file);

 			free(a->file);

 		}

-	}else{

-		/* that would be a BUG */

-		return;

 	}

-	if(decref(a->p) == 0)

+	if(decref(a->p) < 1)

 		closepart(a->p);

 	free(a->path);

 	free(a);