child_process: Support setting uid/gid by name

src/node_child_process.cc

@@ -15,6 +15,8 @@
 #include <unistd.h>
 #include <fcntl.h>
 #include <sys/types.h>
+#include <pwd.h> /* getpwnam() */
+#include <grp.h> /* getgrnam() */
 #if defined(__FreeBSD__ ) || defined(__OpenBSD__)
 #include <sys/wait.h>
 #endif
@@ -26,6 +28,8 @@
 extern char **environ;
 # endif
 
+#include <limits.h> /* PATH_MAX */
+
 namespace node {
 
 using namespace v8;
@@ -100,7 +104,11 @@ Handle<Value> ChildProcess::Spawn(const Arguments& args) {
       !args[0]->IsString() ||
       !args[1]->IsArray() ||
       !args[2]->IsString() ||
-      !args[3]->IsArray()) {
+      !args[3]->IsArray() ||
+      !args[4]->IsArray() ||
+      !args[5]->IsBoolean() ||
+      !(args[6]->IsInt32() || args[6]->IsString()) ||
+      !(args[7]->IsInt32() || args[7]->IsString())) {
     return ThrowException(Exception::Error(String::New("Bad argument.")));
   }
 
@@ -158,8 +166,33 @@ Handle<Value> ChildProcess::Spawn(const Arguments& args) {
 
   int fds[3];
 
-  int uid = args[6]->ToInteger()->Value();
-  int gid = args[7]->ToInteger()->Value();
+  char *custom_uname = NULL;
+  int custom_uid = -1;
+  if (args[6]->IsNumber()) {
+    custom_uid = args[6]->Int32Value();
+  } else if (args[6]->IsString()) {
+    String::Utf8Value pwnam(args[6]->ToString());
+    custom_uname = (char *)calloc(sizeof(char), pwnam.length() + 1);
+    strncpy(custom_uname, *pwnam, pwnam.length() + 1);
+  } else {
+    return ThrowException(Exception::Error(
+      String::New("setuid argument must be a number or a string")));
+  }
+
+  char *custom_gname = NULL;
+  int custom_gid = -1;
+  if (args[7]->IsNumber()) {
+    custom_gid = args[7]->Int32Value();
+  } else if (args[7]->IsString()) {
+    String::Utf8Value grnam(args[7]->ToString());
+    custom_gname = (char *)calloc(sizeof(char), grnam.length() + 1);
+    strncpy(custom_gname, *grnam, grnam.length() + 1);
+  } else {
+    return ThrowException(Exception::Error(
+      String::New("setgid argument must be a number or a string")));
+  }
+
+
 
   int r = child->Spawn(argv[0],
                        argv,
@@ -168,8 +201,13 @@ Handle<Value> ChildProcess::Spawn(const Arguments& args) {
                        fds,
                        custom_fds,
                        do_setsid,
-                       uid,
-                       gid);
+                       custom_uid,
+                       custom_uname,
+                       custom_gid,
+                       custom_gname);
+
+  if (custom_uname != NULL) free(custom_uname);
+  if (custom_gname != NULL) free(custom_gname);
 
   for (i = 0; i < argv_length; i++) free(argv[i]);
   delete [] argv;
@@ -246,7 +284,9 @@ int ChildProcess::Spawn(const char *file,
                         int custom_fds[3],
                         bool do_setsid,
                         int custom_uid,
-                        int custom_gid) {
+                        char *custom_uname,
+                        int custom_gid,
+                        char *custom_gname) {
   HandleScope scope;
   assert(pid_ == -1);
   assert(!ev_is_active(&child_watcher_));
@@ -292,16 +332,59 @@ int ChildProcess::Spawn(const char *file,
         _exit(127);
       }
 
-      if (custom_gid != -1 && setgid(custom_gid)) {
+      static char buf[PATH_MAX + 1];
+
+      int gid = -1;
+      if (custom_gid != -1) {
+        gid = custom_gid;
+      } else if (custom_gname != NULL) {
+        struct group grp, *grpp = NULL;
+        int err = getgrnam_r(custom_gname,
+                             &grp,
+                             buf,
+                             PATH_MAX + 1,
+                             &grpp);
+
+        if (err || grpp == NULL) {
+          perror("getgrnam_r()");
+          _exit(127);
+        }
+
+        gid = grpp->gr_gid;
+      }
+
+
+      int uid = -1;
+      if (custom_uid != -1) {
+        uid = custom_uid;
+      } else if (custom_uname != NULL) {
+        struct passwd pwd, *pwdp = NULL;
+        int err = getpwnam_r(custom_uname,
+                             &pwd,
+                             buf,
+                             PATH_MAX + 1,
+                             &pwdp);
+
+        if (err || pwdp == NULL) {
+          perror("getpwnam_r()");
+          _exit(127);
+        }
+
+        uid = pwdp->pw_uid;
+      }
+
+
+      if (gid != -1 && setgid(gid)) {
         perror("setgid()");
         _exit(127);
       }
 
-      if (custom_uid != -1 && setuid(custom_uid)) {
+      if (uid != -1 && setuid(uid)) {
         perror("setuid()");
         _exit(127);
       }
 
+
       if (custom_fds[0] == -1) {
         close(stdin_pipe[1]);  // close write end
         dup2(stdin_pipe[0],  STDIN_FILENO);

src/node_child_process.h

@@ -65,8 +65,10 @@ class ChildProcess : ObjectWrap {
             int stdio_fds[3],
             int custom_fds[3],
             bool do_setsid,
-            int uid,
-            int gid);
+            int custom_uid,
+            char *custom_uname,
+            int custom_gid,
+            char *custom_gname);
 
   // Simple syscall wrapper. Does not disable the watcher. onexit will be
   // called still.

test/disabled/test-child-process-uid-gid.js

@@ -1,13 +1,20 @@
-// must be run as sudo, otherwise the gid/uid setting will fail.
-var child_process = require("child_process"),
-    constants = require("constants"),
-    passwd = require("fs").readFileSync("/etc/passwd", "utf8"),
-    myUid = process.getuid(),
-    myGid = process.getgid();
+var assert = require("assert");
+var spawn = require("child_process").spawn;
+var fs = require('fs');
+
+var myUid = process.getuid();
+var myGid = process.getgid();
+
+if (myUid != 0) {
+  console.error('must be run as root, otherwise the gid/uid setting will fail.');
+  process.exit(1);
+}
 
 // get a different user.
 // don't care who it is, as long as it's not root
+var passwd = fs.readFileSync('/etc/passwd', 'utf8');
 passwd = passwd.trim().split(/\n/);
+
 for (var i = 0, l = passwd.length; i < l; i ++) {
   if (passwd[i].charAt(0) === "#") continue;
   passwd[i] = passwd[i].split(":");
@@ -20,22 +27,31 @@ for (var i = 0, l = passwd.length; i < l; i ++) {
     break;
   }
 }
-if (!otherUid && !otherGid) throw new Error("failed getting passwd info.");
+if (!otherUid && !otherGid) throw new Error('failed getting passwd info.');
 
-console.error("name, id, gid = %j", [otherName, otherUid, otherGid]);
+console.error('name, id, gid = %j', [otherName, otherUid, otherGid]);
 
-var whoNumber = child_process.spawn("id",[], {uid:otherUid,gid:otherGid}),
-    assert = require("assert");
+var whoNumber = spawn('id', [], { uid: otherUid, gid: otherGid });
+var whoName = spawn('id', [], { uid: otherName, gid: otherGid });
 
-whoNumber.stdout.buf = "byNumber:";
-whoNumber.stdout.on("data", onData);
+whoNumber.stdout.buf = 'byNumber:';
+whoName.stdout.buf = 'byName:';
+whoNumber.stdout.on('data', onData);
+whoName.stdout.on('data', onData);
 function onData (c) { this.buf += c; }
 
 whoNumber.on("exit", onExit);
+whoName.on("exit", onExit);
+
 function onExit (code) {
   var buf = this.stdout.buf;
   console.log(buf);
-  var expr = new RegExp("^byNumber:uid="+otherUid+"\\("+
-                        otherName+"\\) gid="+otherGid+"\\(");
+  var expr = new RegExp("^(byName|byNumber):uid=" +
+                        otherUid +
+                        "\\(" +
+                        otherName +
+                        "\\) gid=" +
+                        otherGid +
+                        "\\(");
   assert.ok(buf.match(expr), "uid and gid should match " + otherName);
 }