Allow setdevname, setspeed and setipaddr to return a fatal error

Add check_prot argument to options_from_file; check permissions
on ~/.ppprc and argument of file option
Process options for tty port (/etc/ppp/options.<ttyname>)
Don't allow loopback or multicast addresses for local or remote
IP address, and don't use these for default local IP address
Don't allow netmask option to reduce the network part of the mask

diff --git a/pppd/options.c b/pppd/options.c
index b7e517a1272a93829d55bd115acf277f43e489c8..a87bb78a0c66ccb1128fc25da37bd3a45e14e440 100644 (file)
--- a/pppd/options.c
+++ b/pppd/options.c
@@ -18,19 +18,22 @@
  */
 
 #ifndef lint
-static char rcsid[] = "$Id: options.c,v 1.6 1994/05/01 11:45:53 paulus Exp $";
+static char rcsid[] = "$Id: options.c,v 1.7 1994/05/18 06:34:15 paulus Exp $";
 #endif
 
 #include <stdio.h>
 #include <errno.h>
 #include <unistd.h>
 #include <stdlib.h>
+#include <limits.h>
 #include <termios.h>
 #include <syslog.h>
 #include <string.h>
 #include <netdb.h>
+#include <pwd.h>
 #include <sys/types.h>
 #include <sys/stat.h>
+#include <netinet/in.h>
 
 #include "ppp.h"
 #include "pppd.h"
@@ -49,6 +52,12 @@ static char rcsid[] = "$Id: options.c,v 1.6 1994/05/01 11:45:53 paulus Exp $";
 char *strdup __ARGS((char *));
 #endif
 
+#if defined(ultrix) || defined(sun)
+#define GETGROUPS_TYPE int
+#else
+#define GETGROUPS_TYPE gid_t
+#endif
+
 /*
  * Prototypes
  */
@@ -111,7 +120,7 @@ static int setipcpaccl __ARGS((void));
 static int setipcpaccr __ARGS((void));
 
 static int number_option __ARGS((char *, long *, int));
-
+static int readable __ARGS((int fd));
 
 /*
  * Option variables
@@ -243,6 +252,7 @@ parse_args(argc, argv)
 {
     char *arg, *val;
     struct cmd *cmdp;
+    int ret;
 
     while (argc > 0) {
        arg = *argv++;
@@ -269,11 +279,15 @@ parse_args(argc, argv)
            /*
             * Maybe a tty name, speed or IP address?
             */
-           if (!setdevname(arg) && !setspeed(arg) && !setipaddr(arg)) {
+           if ((ret = setdevname(arg)) == 0
+               && (ret = setspeed(arg)) == 0
+               && (ret = setipaddr(arg)) == 0) {
                fprintf(stderr, "%s: unrecognized command\n", arg);
                usage();
                return 0;
            }
+           if (ret < 0)        /* error */
+               return 0;
        }
     }
     return 1;
@@ -292,12 +306,13 @@ usage()
  * and interpret them.
  */
 int
-options_from_file(filename, must_exist)
+options_from_file(filename, must_exist, check_prot)
     char *filename;
     int must_exist;
+    int check_prot;
 {
     FILE *f;
-    int i, newline;
+    int i, newline, ret;
     struct cmd *cmdp;
     char *argv[MAXARGS];
     char args[MAXARGS][MAXWORDLEN];
@@ -309,6 +324,12 @@ options_from_file(filename, must_exist)
        perror(filename);
        return 0;
     }
+    if (check_prot && !readable(fileno(f))) {
+       fprintf(stderr, "%s: access denied\n", filename);
+       fclose(f);
+       return 0;
+    }
+
     while (getword(f, cmd, &newline, filename)) {
        /*
         * First see if it's a command.
@@ -337,12 +358,16 @@ options_from_file(filename, must_exist)
            /*
             * Maybe a tty name, speed or IP address?
             */
-           if (!setdevname(cmd) && !setspeed(cmd) && !setipaddr(cmd)) {
+           if ((ret = setdevname(cmd)) == 0
+               && (ret = setspeed(cmd)) == 0
+               && (ret = setipaddr(cmd)) == 0) {
                fprintf(stderr, "In file %s: unrecognized command %s\n",
                        filename, cmd);
                fclose(f);
                return 0;
            }
+           if (ret < 0)        /* error */
+               return 0;
        }
     }
     return 1;
@@ -357,20 +382,78 @@ options_from_user()
 {
     char *user, *path, *file;
     int ret;
+    struct passwd *pw;
 
-    if ((user = getenv("HOME")) == NULL)
+    pw = getpwuid(getuid());
+    if (pw == NULL || (user = pw->pw_dir) == NULL || user[0] == 0)
        return;
-    file = "/.ppprc";
-    path = malloc(strlen(user) + strlen(file) + 1);
+    file = _PATH_USEROPT;
+    path = malloc(strlen(user) + strlen(file) + 2);
     if (path == NULL)
        novm("init file name");
     strcpy(path, user);
+    strcat(path, "/");
     strcat(path, file);
-    ret = options_from_file(path, 0);
+    ret = options_from_file(path, 0, 1);
+    free(path);
+    return ret;
+}
+
+/*
+ * options_for_tty - See if an options file exists for the serial
+ * device, and if so, interpret options from it.
+ */
+int
+options_for_tty()
+{
+    char *dev, *path;
+    int ret;
+
+    dev = strrchr(devname, '/');
+    if (dev == NULL)
+       dev = devname;
+    else
+       ++dev;
+    if (strcmp(dev, "tty") == 0)
+       return 1;               /* don't look for /etc/ppp/options.tty */
+    path = malloc(strlen(_PATH_TTYOPT) + strlen(dev) + 1);
+    if (path == NULL)
+       novm("tty init file name");
+    strcpy(path, _PATH_TTYOPT);
+    strcat(path, dev);
+    ret = options_from_file(path, 0, 0);
     free(path);
     return ret;
 }
 
+/*
+ * readable - check if a file is readable by the real user.
+ */
+static int
+readable(fd)
+    int fd;
+{
+    uid_t uid;
+    int ngroups, i;
+    struct stat sbuf;
+    GETGROUPS_TYPE groups[NGROUPS_MAX];
+
+    uid = getuid();
+    if (uid == 0)
+       return 1;
+    if (fstat(fd, &sbuf) != 0)
+       return 0;
+    if (sbuf.st_uid == uid)
+       return sbuf.st_mode & S_IRUSR;
+    if (sbuf.st_gid == getgid())
+       return sbuf.st_mode & S_IRGRP;
+    ngroups = getgroups(NGROUPS_MAX, groups);
+    for (i = 0; i < ngroups; ++i)
+       if (sbuf.st_gid == groups[i])
+           return sbuf.st_mode & S_IRGRP;
+    return sbuf.st_mode & S_IROTH;
+}
+
 /*
  * Read a word from a file.
  * Words are delimited by white-space or by quotes (").
@@ -527,7 +610,7 @@ static int
 readfile(argv)
     char **argv;
 {
-    return options_from_file(*argv, 1);
+    return options_from_file(*argv, 1, 1);
 }
 
 /*
@@ -923,16 +1006,16 @@ setdevname(cp)
      */
     if (stat(cp, &statbuf) < 0) {
        if (errno == ENOENT)
-           return (0);
+           return 0;
        syslog(LOG_ERR, cp);
-       return 0;
+       return -1;
     }
   
     (void) strncpy(devname, cp, MAXPATHLEN);
     devname[MAXPATHLEN-1] = 0;
     default_device = FALSE;
   
-    return (1);
+    return 1;
 }
 
 
@@ -952,7 +1035,7 @@ setipaddr(arg)
      * IP address pair separated by ":".
      */
     if ((colon = index(arg, ':')) == NULL)
-       return (0);
+       return 0;
   
     /*
      * If colon first character, then no local addr.
@@ -961,8 +1044,8 @@ setipaddr(arg)
        *colon = '\0';
        if ((local = inet_addr(arg)) == -1) {
            if ((hp = gethostbyname(arg)) == NULL) {
-               fprintf(stderr, "unknown host: %s", arg);
-               local = 0;
+               fprintf(stderr, "unknown host: %s\n", arg);
+               return -1;
            } else {
                local = *(long *)hp->h_addr;
                if (our_name[0] == 0) {
@@ -971,6 +1054,10 @@ setipaddr(arg)
                }
            }
        }
+       if (bad_ip_adrs(local)) {
+           fprintf(stderr, "bad local IP address %s\n", ip_ntoa(local));
+           return -1;
+       }
        if (local != 0)
            wo->ouraddr = local;
        *colon = ':';
@@ -982,8 +1069,8 @@ setipaddr(arg)
     if (*++colon != '\0') {
        if ((remote = inet_addr(colon)) == -1) {
            if ((hp = gethostbyname(colon)) == NULL) {
-               fprintf(stderr, "unknown host: %s", colon);
-               remote = 0;
+               fprintf(stderr, "unknown host: %s\n", colon);
+               return -1;
            } else {
                remote = *(long *)hp->h_addr;
                if (remote_name[0] == 0) {
@@ -992,11 +1079,15 @@ setipaddr(arg)
                }
            }
        }
+       if (bad_ip_adrs(remote)) {
+           fprintf(stderr, "bad remote IP address %s\n", ip_ntoa(remote));
+           return -1;
+       }
        if (remote != 0)
            wo->hisaddr = remote;
     }
 
-    return (1);
+    return 1;
 }
 
 
@@ -1058,7 +1149,7 @@ setipdefault()
     if ((hp = gethostbyname(hostname)) == NULL)
        return;
     local = *(long *)hp->h_addr;
-    if (local != 0)
+    if (local != 0 && !bad_ip_adrs(local))
        wo->ouraddr = local;
 }
 
@@ -1071,8 +1162,8 @@ setnetmask(argv)
     char **argv;
 {
     u_long mask;
-       
-    if ((mask = inet_addr(*argv)) == -1) {
+
+    if ((mask = inet_addr(*argv)) == -1 || (netmask & ~mask) != 0) {
        fprintf(stderr, "Invalid netmask %s\n", *argv);
        return 0;
     }