Fix possible buffer overflow: buflen (a size_t*) was being used

[hcoop/debian/libnss-afs.git] / nss_afs.c

diff --git a/nss_afs.c b/nss_afs.c
index 2d6eaf4..126b5c5 100644 (file)
--- a/nss_afs.c
+++ b/nss_afs.c
@@ -52,10 +52,10 @@
 #include <string.h>
 #include <sys/select.h>
 #include <sys/socket.h>
+#include <sys/stat.h>
 #include <sys/time.h>
 #include <sys/types.h>
 #include <unistd.h>
-#include <afs/afs.h>
 #include <afs/afsutil.h>
 #include <afs/cellconfig.h>
 #include <afs/com_err.h>
@@ -87,6 +87,7 @@ extern struct ubik_client *pruclient;
 int  afs_initialized = 0;
 char cellname[MAXCELLNAMELEN];
 char homedir_prefix[MAXPATHLEN];
+char cell_root[MAXPATHLEN];
 int  homedir_prefix_len=0;
 char homedirs_method=0;
 char shells_method=0;
@@ -114,7 +115,7 @@ enum nss_status ptsid2name(int uid, char **buffer, int *buflen) {
   idlist lid;
   namelist lnames;
 
-  init_afs();
+  if (init_afs()) return NSS_STATUS_UNAVAIL;
 
   if (uid==AFS_MAGIC_ANONYMOUS_USERID) {
     if (!cpstr("anonymous", buffer, buflen)) return NSS_STATUS_UNAVAIL;
@@ -129,6 +130,7 @@ enum nss_status ptsid2name(int uid, char **buffer, int *buflen) {
   lnames.namelist_len = 0;
 
   if (ubik_Call(PR_IDToName,pruclient,0,&lid,&lnames) != PRSUCCESS) {
+    perror("ubik_Call() in ptsid2name() failed\n");
     pthread_mutex_unlock(&mutex);
     return NSS_STATUS_UNAVAIL;
   }
@@ -136,7 +138,7 @@ enum nss_status ptsid2name(int uid, char **buffer, int *buflen) {
   ret = NSS_STATUS_NOTFOUND;
   for (i=0;i<lnames.namelist_len;i++) {
     int delta = strlen(lnames.namelist_val[i]);
-    if ( (delta < buflen) && islower(*(lnames.namelist_val[i])) ) {
+    if ( (delta < *buflen) && islower(*(lnames.namelist_val[i])) ) {
       cpstr(lnames.namelist_val[i], buffer, buflen);
       ret = NSS_STATUS_SUCCESS;
     }
@@ -159,7 +161,7 @@ enum nss_status ptsname2id(char *name, uid_t* uid) {
   namelist lnames;
   char uname[MAXUSERNAMELEN];
 
-  init_afs();
+  if (init_afs()) return NSS_STATUS_UNAVAIL;
   
   if (!strcmp(name,"anonymous")) {
     *uid = AFS_MAGIC_ANONYMOUS_USERID;
@@ -176,6 +178,7 @@ enum nss_status ptsname2id(char *name, uid_t* uid) {
   lnames.namelist_len = 1;
 
   if (ubik_Call(PR_NameToID,pruclient,0,&lnames,&lid) != PRSUCCESS) {
+    perror("ubik_Call() in ptsname2id() failed\n");
     pthread_mutex_unlock(&mutex);
     return NSS_STATUS_UNAVAIL;
   }
@@ -193,9 +196,38 @@ enum nss_status ptsname2id(char *name, uid_t* uid) {
 int init_afs() {
   FILE *thiscell;
   int len;
+  struct stat statbuf;
+
+  char buf[6];
+  int fd;
+  int pos;
 
-  if (afs_initialized) return 0;
+  if (afs_initialized) {
+    /* wait until /afs/@cell/ appears as a proxy for "the network is up" */
+    if (stat(cell_root, &statbuf)) return -1;
+    return 0;
+  }
 
+  // check to make sure that we are running inside nscd
+  pos = 0;
+  fd = open("/proc/self/cmdline", O_RDONLY);
+  if (fd==-1) return -1;
+  while(1) {
+    int numread;
+    numread = read(fd, buf+pos, 1);
+    if (buf[ (pos+5)%6 ] == 'd' &&
+        buf[ (pos+4)%6 ] == 'c' &&
+        buf[ (pos+3)%6 ] == 's' &&
+        buf[ (pos+2)%6 ] == 'n' &&
+        (buf[(pos+1)%6 ] == '/' || pos==4) &&
+        (buf[(pos+0)%6 ] ==  0  || numread==-1)
+        )
+      break;
+    pos = (pos+1)%6;
+    if (numread==0) { close(fd); return -1; }
+  }
+  close(fd);
+  
   if (pthread_mutex_lock(&mutex)) return -1;
   do {
     homedirs_method=HOMEDIR_PREFIX;
@@ -219,10 +251,21 @@ int init_afs() {
 
     if (cellname[len-1] == '\n') len--;
     cellname[len]='\0';
+
+    /* wait until /afs/@cell/ appears as a proxy for "the network is up" */
+    sprintf(cell_root,"/afs/%s/",cellname);
+    if (stat(cell_root, &statbuf)) break;
+
     sprintf(homedir_prefix,"/afs/%s/user/",cellname);
     homedir_prefix_len=strlen(homedir_prefix);
-    
-    if (pr_Initialize(0L,AFSDIR_CLIENT_ETC_DIRPATH, 0)) break;
+
+    /* time out requests after 5 seconds to avoid hanging things */
+    rx_SetRxDeadTime(5);    
+
+    if (pr_Initialize(0L,AFSDIR_CLIENT_ETC_DIRPATH, 0)) {
+      perror("pr_Initialize() failed\n");
+      break;
+    }
     
     afs_initialized = 1;
     pthread_mutex_unlock(&mutex);
@@ -344,7 +387,7 @@ enum nss_status _nss_afs_getgrgid_r (gid_t gid,
 
     result->gr_passwd=buffer;
 
-    if (!cpstr("x",&buffer,&buflen)) break;
+    if (!cpstr("z",&buffer,&buflen)) break;
 
     if (buflen < sizeof(char*)) break;
     result->gr_mem=buffer;
@@ -370,9 +413,9 @@ enum nss_status fill_result_buf(uid_t uid,
                                 int *errnop) {
   result_buf->pw_name = name;
   do {
-    /* set the password to "x" */
+    /* set the password to "z"; we can't use "x" because of pam_unix.so */
     result_buf->pw_passwd = buffer;
-    if ( ! cpstr("x",&buffer, &buflen) ) break;
+    if ( ! cpstr("z",&buffer, &buflen) ) break;
 
     /* the uid and gid are both the uid passed in */
     result_buf->pw_uid = uid;
@@ -390,6 +433,14 @@ enum nss_status fill_result_buf(uid_t uid,
     result_buf->pw_shell = buffer;
     if ( get_shell(result_buf->pw_name,&buffer,&buflen) ) break;
 
+#ifdef LIMIT_USERNAME_CHARS
+    if ( strlen(result_buf->pw_name) > LIMIT_USERNAME_CHARS ) {
+      result_buf->pw_name[LIMIT_USERNAME_CHARS] = '\0';
+      buflen = buflen + ( buffer - &result_buf->pw_name[LIMIT_USERNAME_CHARS+1] );
+      buffer = &result_buf->pw_name[LIMIT_USERNAME_CHARS+1];
+    }
+#endif
+
     *errnop = errno;
     return NSS_STATUS_SUCCESS;
   } while(0);
@@ -421,14 +472,6 @@ enum nss_status _nss_afs_getpwuid_r (uid_t uid,
     return temp;
   }
 
-#ifdef LIMIT_USERNAME_CHARS
-  if ( strlen(result_buf->pw_name) > LIMIT_USERNAME_CHARS ) {
-    result_buf->pw_name[LIMIT_USERNAME_CHARS] = '\0';
-    buflen = buflen + ( buffer - &result_buf->pw_name[LIMIT_USERNAME_CHARS+1] );
-    buffer = &result_buf->pw_name[LIMIT_USERNAME_CHARS+1];
-  }
-#endif
-
   return fill_result_buf(uid, name, result_buf, buffer, buflen, errnop);
 }