shithub: git9

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git/serve: restrict namespace

Use our auth and namespace code to drop access
to anything other than our repository early on.

This should make git serving more secure.

While we're here, fix a few bugs.

--- a/serve.c

+++ b/serve.c

@@ -1,11 +1,13 @@

 #include <u.h>

 #include <libc.h>

 #include <ctype.h>

+#include <auth.h>

 #include "git.h"

-char *pathpfx = "";

-int allowwrite;

+char	*pathpfx = "/usr/git";

+char	*namespace = nil;

+int	allowwrite;

 int

 fmtpkt(Conn *c, char *fmt, ...)

@@ -277,14 +279,40 @@

 }

 int

+mkdir(char *dir)

+{

+	char buf[ERRMAX];

+	int f;

+

+	if(access(dir, AEXIST) == 0)

+		return 0;

+	if((f = create(dir, OREAD, DMDIR | 0755)) == -1){

+		rerrstr(buf, sizeof(buf));

+		if(strstr(buf, "exist") == nil)

+			return -1;

+	}

+	close(f);

+	return 0;

+}

+

+int

 updatepack(Conn *c)

 {

-	char buf[Pktmax], packtmp[128], idxtmp[128];

+	char buf[Pktmax], packtmp[128], idxtmp[128], ebuf[ERRMAX];

 	int n, pfd, packsz;

 	Hash h;

+	/* make sure the needed dirs exist */

+	if(mkdir(".git/objects") == -1)

+		return -1;

+	if(mkdir(".git/objects/pack") == -1)

+		return -1;

+	if(mkdir(".git/refs") == -1)

+		return -1;

+	if(mkdir(".git/refs/heads") == -1)

+		return -1;

 	snprint(packtmp, sizeof(packtmp), ".git/objects/pack/recv-%d.pack.tmp", getpid());

-	snprint(idxtmp, sizeof(idxtmp), ".git/objects/idx/recv-%d.idx.tmp", getpid());

+	snprint(idxtmp, sizeof(idxtmp), ".git/objects/pack/recv-%d.idx.tmp", getpid());

 	if((pfd = create(packtmp, ORDWR, 0644)) == -1)

 		return -1;

 	packsz = 0;

@@ -292,7 +320,13 @@

 		n = read(c->rfd, buf, sizeof(buf));

 		if(n == 0)

 			break;

-		if(n == -1 || write(pfd, buf, n) != n)

+		if(n == -1){

+			rerrstr(ebuf, sizeof(ebuf));

+			if(strstr(ebuf, "hungup") == nil)

+				return -1;

+			break;

+		}

+		if(write(pfd, buf, n) != n)

 			return -1;

 		packsz += n;

 	}

@@ -301,7 +335,7 @@

 		goto error1;

 	}

 	if(indexpack(packtmp, idxtmp, h) == -1){

-		dprint(1, "indexing failed\n");

+		dprint(1, "indexing failed: %r\n");

 		goto error1;

 	}

 	if(rename(packtmp, idxtmp, h) == -1){

@@ -321,7 +355,7 @@

 	int fd, i;

 	for(i = 0; i < 10; i++) {

-		if((fd = create(".git/index9/lock", ORDWR|OEXCL, 0644))!= -1)

+		if((fd = create(".git/_lock", ORDWR|OTRUNC|OEXCL, 0644))!= -1)

 			return fd;

 		sleep(250);

 	}

@@ -374,7 +408,6 @@

 	ret = 0;

 error:

 	close(lockfd);

-	remove(".git/index9/lock");

 	return ret;

 }

@@ -422,7 +455,8 @@

 void

 main(int argc, char **argv)

 {

-	char *p, cmd[32], buf[512], path[512];

+	char *repo, cmd[32], buf[512];

+	char *user;

 	Conn c;

 	ARGBEGIN{

@@ -434,6 +468,9 @@

 		if(*pathpfx != '/')

 			sysfatal("path prefix must begin with '/'");

 		break;

+	case 'n':

+		namespace=EARGF(usage());

+		break;

 	case 'w':

 		allowwrite++;

 		break;

@@ -443,18 +480,27 @@

 	}ARGEND;

 	gitinit();

-	initconn(&c, 0, 1);

+	user = "none";

+	if(allowwrite)

+		user = getuser();

+	if(newns(user, namespace) == -1)

+		sysfatal("addns: %r");

+	if(bind(pathpfx, "/", MREPL) == -1)

+		sysfatal("bind: %r");

+	if(rfork(RFNOMNT) == -1)

+		sysfatal("rfork: %r");

+	initconn(&c, 0, 1);

 	if(readpkt(&c, buf, sizeof(buf)) == -1)

 		sysfatal("readpkt: %r");

-	p = parsecmd(buf, cmd, sizeof(cmd));

-	if(snprint(path, sizeof(path), "%s/%s", pathpfx, p) == sizeof(path))

-		sysfatal("%s: path too long\n", p);

-	cleanname(path);

-	if(strncmp(pathpfx, path, strlen(pathpfx)) != 0)

-		sysfatal("%s: path escapes prefix", p);

-	if(chdir(path) == -1)

-		sysfatal("cd %s: %r", path);

+	repo = parsecmd(buf, cmd, sizeof(cmd));

+	cleanname(repo);

+	if(strncmp(repo, "../", 3) == 0)

+		sysfatal("invalid path %s\n", repo);

+	if(bind(repo, "/", MREPL) == -1)

+		sysfatal("enter %s: %r", repo);

+	if(chdir("/") == -1)

+		sysfatal("chdir: %r");

 	if(access(".git", AREAD) == -1)

 		sysfatal("no git repository");

 	if(strcmp(cmd, "git-receive-pack") == 0 && allowwrite)