Implement command matching without execution. This just extends

functionality of the -C flag, so we are not introducing more garbage.

Input and okay from jmc@ (documentation) and tedu@ (everything).

diff --git a/doas.1 b/doas.1
index 5220eb59e8e4b1002e8e07c8404db2e1af5b2001..63153c618460b8ce63b3c0ef3e7f17176b5fa5ce 100644 (file)
--- a/doas.1
+++ b/doas.1
@@ -1,4 +1,4 @@
-.\" $OpenBSD: doas.1,v 1.9 2015/07/21 16:12:04 tedu Exp $
+.\" $OpenBSD: doas.1,v 1.10 2015/07/21 17:49:33 jmc Exp $
 .\"
 .\"Copyright (c) 2015 Ted Unangst <tedu@openbsd.org>
 .\"
@@ -30,6 +30,13 @@
 The
 .Nm
 utility executes the given command as another user.
+The
+.Ar command
+argument is mandatory unless
+.Fl C
+or
+.Fl s
+is specified.
 .Pp
 The options are as follows:
 .Bl -tag -width tenletters
@@ -37,6 +44,19 @@ The options are as follows:
 Parse and check the configuration file
 .Ar config ,
 then exit.
+If
+.Ar command
+is supplied,
+.Nm
+will also perform command matching.
+In the latter case
+either
+.Sq permit ,
+.Sq permit nopass
+or
+.Sq deny
+will be printed on standard output, depending on command
+matching results.
 No command is executed.
 .It Fl s
 Execute the shell from

diff --git a/doas.c b/doas.c
index 00292e3de3dbd125708e342279b5d28f9258a6a3..79639261f61ded5a007ad820c3c6be7590ea41ef 100644 (file)
--- a/doas.c
+++ b/doas.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: doas.c,v 1.20 2015/07/22 16:35:03 zhuk Exp $ */
+/* $OpenBSD: doas.c,v 1.21 2015/07/24 06:36:42 zhuk Exp $ */
 /*
  * Copyright (c) 2015 Ted Unangst <tedu@openbsd.org>
  *
@@ -152,7 +152,7 @@ permit(uid_t uid, gid_t *groups, int ngroups, struct rule **lastr,
 }
 
 static void
-parseconfig(const char *filename)
+parseconfig(const char *filename, int checkperms)
 {
        extern FILE *yyfp;
        extern int yyparse(void);
@@ -160,16 +160,21 @@ parseconfig(const char *filename)
 
        yyfp = fopen(filename, "r");
        if (!yyfp) {
-               fprintf(stderr, "doas is not enabled.\n");
+               if (checkperms)
+                       fprintf(stderr, "doas is not enabled.\n");
+               else
+                       warn("could not open config file");
                exit(1);
        }
 
-       if (fstat(fileno(yyfp), &sb) != 0)
-               err(1, "fstat(\"%s\")", filename);
-       if ((sb.st_mode & (S_IWGRP|S_IWOTH)) != 0)
-               errx(1, "%s is writable by group or other", filename);
-       if (sb.st_uid != 0)
-               errx(1, "%s is not owned by root", filename);
+       if (checkperms) {
+               if (fstat(fileno(yyfp), &sb) != 0)
+                       err(1, "fstat(\"%s\")", filename);
+               if ((sb.st_mode & (S_IWGRP|S_IWOTH)) != 0)
+                       errx(1, "%s is writable by group or other", filename);
+               if (sb.st_uid != 0)
+                       errx(1, "%s is not owned by root", filename);
+       }
 
        yyparse();
        fclose(yyfp);
@@ -277,11 +282,32 @@ fail(void)
        exit(1);
 }
 
+static int
+checkconfig(const char *confpath, int argc, char **argv,
+    uid_t uid, gid_t *groups, int ngroups, uid_t target) {
+       struct rule *rule;
+
+       setresuid(uid, uid, uid);
+       parseconfig(confpath, 0);
+       if (!argc)
+               exit(0);
+
+       if (permit(uid, groups, ngroups, &rule, target, argv[0],
+           (const char **)argv + 1)) {
+               printf("permit%s\n", (rule->options & NOPASS) ? " nopass" : "");
+               return 1;
+       } else {
+               printf("deny\n");
+               return 0;
+       }
+}
+
 int
 main(int argc, char **argv, char **envp)
 {
        const char *safepath = "/bin:/sbin:/usr/bin:/usr/sbin:"
            "/usr/local/bin:/usr/local/sbin";
+       const char *confpath = NULL;
        char *shargv[] = { NULL, NULL };
        char *sh;
        const char *cmd;
@@ -296,13 +322,11 @@ main(int argc, char **argv, char **envp)
        int i, ch;
        int sflag = 0;
 
-       uid = getuid();
        while ((ch = getopt(argc, argv, "C:su:")) != -1) {
                switch (ch) {
                case 'C':
-                       setresuid(uid, uid, uid);
-                       parseconfig(optarg);
-                       exit(0);
+                       confpath = optarg;
+                       break;
                case 'u':
                        if (parseuid(optarg, &target) != 0)
                                errx(1, "unknown user");
@@ -318,11 +342,13 @@ main(int argc, char **argv, char **envp)
        argv += optind;
        argc -= optind;
 
-       if ((!sflag && !argc) || (sflag && argc))
+       if (confpath) {
+               if (sflag)
+                       usage();
+       } else if ((!sflag && !argc) || (sflag && argc))
                usage();
 
-       parseconfig("/etc/doas.conf");
-
+       uid = getuid();
        pw = getpwuid(uid);
        if (!pw)
                err(1, "getpwuid failed");
@@ -343,6 +369,11 @@ main(int argc, char **argv, char **envp)
                argc = 1;
        }
 
+       if (confpath)
+               exit(!checkconfig(confpath, argc, argv, uid, groups, ngroups,
+                   target));
+       parseconfig("/etc/doas.conf", 1);
+
        cmd = argv[0];
        if (strlcpy(cmdline, argv[0], sizeof(cmdline)) >= sizeof(cmdline))
                errx(1, "command line too long");