X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ian/git?p=userv.git;a=blobdiff_plain;f=process.c;h=c88c3c9bee277d2551f446f2fe7ad22889e2ab38;hp=109c5010dfd6deacd70e3fb68a2074f81890943e;hb=d9cedcfbd2194ff9046d71400cb7878085c26499;hpb=464d71c37246e556de9ec05f7b97af834a5224ee

diff --git a/process.c b/process.c
index 109c501..c88c3c9 100644
--- a/process.c
+++ b/process.c
@@ -19,7 +19,8 @@
  * Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  */
 
-/* We do some horrible asynchronous stuff with signals.
+/*
+ * We do some horrible asynchronous stuff with signals.
  *
  * The following objects &c. are used in signal handlers and so
  * must be protected by calls to blocksignals if they are used in
@@ -40,7 +41,6 @@
 #include <stdio.h>
 #include <stdarg.h>
 #include <unistd.h>
-#include <wait.h>
 #include <assert.h>
 #include <signal.h>
 #include <string.h>
@@ -51,6 +51,7 @@
 #include <grp.h>
 #include <ctype.h>
 #include <limits.h>
+#include <sys/wait.h>
 #include <sys/types.h>
 #include <sys/fcntl.h>
 #include <sys/stat.h>
@@ -178,7 +179,12 @@ static void getevent(struct event_msg *event_r) {
     switch (event_r->type) {
     case et_closereadfd:
       fd= event_r->data.closereadfd.fd;
-      assert(fd<fdarrayused);
+      if (fd >= fdarrayused) {
+	blocksignals();
+	syslog(LOG_ERR,"client sent bad file descriptor %d to close (max %d)",
+	       fd,fdarrayused-1);
+	disconnect(12);
+      }
       if (fdarray[fd].holdfd!=-1) {
 	if (close(fdarray[fd].holdfd)) syscallerror("cannot close holding fd");
 	fdarray[fd].holdfd= -1;
@@ -358,20 +364,6 @@ void senderrmsgstderr(const char *errmsg) {
   xfflush(swfile);
 }
 
-static void getgroupnames(int ngids, gid_t *list, const char ***names_r) {
-  const char **names;
-  struct group *cgrp;
-  int i;
-  
-  names= xmalloc(sizeof(char*)*ngids);
-  for (i=0; i<ngids; i++) {
-    cgrp= getgrgid(list[i]);
-    if (!cgrp) miscerror("get group entry");
-    names[i]= xstrsave(cgrp->gr_name);
-  }
-  *names_r= names;
-}
-  
 /* The per-request main program and its subfunctions. */
 
 static void setup_comms(int sfd) {
@@ -484,6 +476,20 @@ static void establish_pipes(void) {
   }
 }
 
+static void groupnames(int ngids, gid_t *gids, const char ***names_r) {
+  const char **names;
+  struct group *gr;
+  int i;
+  
+  names= xmalloc(sizeof(char*)*ngids);
+  for (i=0; i<ngids; i++) {
+    gr= getgrgid(gids[i]);
+    if (!gr) miscerror("get group entry");
+    names[i]= xstrsave(gr->gr_name);
+  }
+  *names_r= names;
+}
+  
 static void lookup_uidsgids(void) {
   struct passwd *pw;
 
@@ -513,22 +519,55 @@ static void lookup_uidsgids(void) {
   if (getgroups(service_ngids,service_gids+1) != service_ngids)
     syscallerror("getgroups(size,list)");
 
-  getgroupnames(service_ngids,service_gids,&service_groups);
-  getgroupnames(request_mbuf.ngids,calling_gids,&calling_groups);
+  groupnames(request_mbuf.ngids,calling_gids,&calling_groups);
+  groupnames(service_ngids,service_gids,&service_groups);
 }
 
-static void check_find_executable(void) {
-  int r, partsize;
+static void findinpath(char *program) {
   char *part, *exectry;
   const char *string, *delim, *nextstring;
   struct stat stab;
+  int r, partsize;
+  
+  if (strchr(program,'/')) {
+    r= stat(program,&stab);
+    if (r) syscallfailure("failed check for program (containing slash) `%s'",program);
+    execpath= program;
+  } else {
+    string= getenv("PATH");
+    if (!string) string= defaultpath();
+    while (string) {
+      delim= strchr(string,':');
+      if (delim) {
+	if (delim-string > MAX_GENERAL_STRING)
+	  failure("execute-from-path, but PATH component too long");
+	partsize= delim-string;
+	nextstring= delim+1;
+      } else {
+	partsize= strlen(string);
+	nextstring= 0;
+      }
+      part= xstrsubsave(string,partsize);
+      exectry= part[0] ? xstrcat3save(part,"/",program) : xstrsave(program);
+      free(part);
+      r= stat(exectry,&stab);
+      if (!r) { execpath= exectry; break; }
+      free(exectry);
+      string= nextstring;
+    }
+    if (!execpath) failure("program `%s' not found on default PATH",program);
+  }
+}
+  
+static void check_find_executable(void) {
+  struct stat stab;
+  int r;
 
   switch (execute) {
   case tokv_word_reject:
     failure("request rejected");
   case tokv_word_execute:
-    r= stat(execpath,&stab);
-    if (r) syscallfailure("checking for executable `%s'",execpath);
+    findinpath(execpath);
     break;
   case tokv_word_executefromdirectory:
     r= stat(execpath,&stab);
@@ -537,41 +576,37 @@ static void check_find_executable(void) {
   case tokv_word_executebuiltin:
     break;
   case tokv_word_executefrompath:
-    if (strchr(service,'/')) {
-      r= stat(service,&stab);
-      if (r) syscallfailure("execute-from-path (contains slash)"
-			    " cannot check for executable `%s'",service);
-      execpath= service;
-    } else {
-      string= getenv("PATH");
-      if (!string) string= defaultpath();
-      while (string) {
-	delim= strchr(string,':');
-	if (delim) {
-	  if (delim-string > MAX_GENERAL_STRING)
-	    failure("execute-from-path, but PATH component too long");
-	  partsize= delim-string;
-	  nextstring= delim+1;
-	} else {
-	  partsize= strlen(string);
-	  nextstring= 0;
-	}
-	part= xstrsubsave(string,partsize);
-	exectry= part[0] ? xstrcat3save(part,"/",service) : xstrsave(service);
-	free(part);
-	r= stat(exectry,&stab);
-	if (!r) { execpath= exectry; break; }
-	free(exectry);
-	string= nextstring;
-      }
-      if (!execpath) failure("execute-from-path, but program `%s' not found",service);
-    }
+    findinpath(service);
     break;
   default:
     abort();
   }
 }
 
+static void makenonexistentfd(int fd) {
+  if (fdarray[fd].realfd == -1) {
+    assert(fdarray[fd].holdfd == -1);
+  } else {
+    if (close(fdarray[fd].realfd))
+      syscallfailure("close unwanted file descriptor %d",fd);
+    fdarray[fd].realfd= -1;
+  
+    if (fdarray[fd].holdfd != -1) {
+      if (close(fdarray[fd].holdfd))
+	syscallfailure("close unwanted hold descriptor for %d",fd);
+    }
+  }
+}
+
+static void makenullfd(int fd) {
+  fdarray[fd].realfd= open("/dev/null",
+			   fdarray[fd].wantrw == tokv_word_read ? O_RDONLY :
+			   fdarray[fd].wantrw == tokv_word_write ? O_WRONLY :
+			   0);
+  if (fdarray[fd].realfd<0)
+    syscallfailure("cannot open /dev/null for null or allowed, unprovided fd");
+}
+
 static void check_fds(void) {
   int fd;
   
@@ -589,35 +624,27 @@ static void check_fds(void) {
 	failure("file descriptor %d provided but rejected",fd);
       break;
     case tokv_word_ignorefd:
-      if (fdarray[fd].realfd != -1)
-	if (close(fdarray[fd].realfd))
-	  syscallfailure("close unwanted file descriptor %d",fd);
-      fdarray[fd].realfd= -1;
+      makenonexistentfd(fd);
       break;
     case tokv_word_nullfd:
-      if (fdarray[fd].realfd != -1) close(fdarray[fd].realfd);
-      fdarray[fd].realfd= open("/dev/null",
-			       fdarray[fd].iswrite == -1 ? O_RDWR :
-			       fdarray[fd].iswrite ? O_WRONLY : O_RDONLY);
-      if (fdarray[fd].realfd<0)
-	syscallfailure("cannot open /dev/null for null fd");
+      makenonexistentfd(fd);
+      makenullfd(fd);
       break;
     case tokv_word_requirefd:
       if (fdarray[fd].realfd == -1)
-	failure("file descriptor %d not provided but required",fd);
+	failure("file descriptor %d required but not provided",fd);
+      assert(fdarray[fd].holdfd == -1);
       /* fall through */
     case tokv_word_allowfd:
       if (fdarray[fd].realfd == -1) {
-	fdarray[fd].iswrite= (fdarray[fd].wantrw == tokv_word_write);
-	fdarray[fd].realfd= open("/dev/null",fdarray[fd].iswrite ? O_WRONLY : O_RDONLY);
-	if (fdarray[fd].realfd<0)
-	  syscallfailure("cannot open /dev/null for allowed but not provided fd");
+	assert(fdarray[fd].holdfd == -1);
+	makenullfd(fd);
       } else {
 	if (fdarray[fd].iswrite) {
-	  if (fdarray[fd].wantrw != tokv_word_write)
+	  if (fdarray[fd].wantrw == tokv_word_read)
 	    failure("file descriptor %d provided write, wanted read",fd);
 	} else {
-	  if (fdarray[fd].wantrw != tokv_word_read)
+	  if (fdarray[fd].wantrw == tokv_word_write)
 	    failure("file descriptor %d provided read, wanted write",fd);
 	}
       }
@@ -644,6 +671,13 @@ static void fork_service_synch(void) {
   r= socketpair(AF_UNIX,SOCK_STREAM,0,synchsocket);
   if (r) syscallerror("cannot create socket for synch");
 
+  /* Danger here.  Firstly, we start handling signals asynchronously.
+   * Secondly after we fork the service we want it to put
+   * itself in a separate process group so that we can kill it and all
+   * its children - but, we mustn't kill the whole pgrp before it has
+   * done that (or we kill ourselves) and it mustn't fork until it
+   * knows that we are going to kill it the right way ...
+   */
   sig.sa_handler= sighandler_chld;
   sigemptyset(&sig.sa_mask);
   sigaddset(&sig.sa_mask,SIGCHLD);