git.gag.com Git - debian/sudo/blob - plugins/sudoers/prompt.c

   1 /*
   2  * Copyright (c) 1993-1996,1998-2005, 2007-2013
   3  *      Todd C. Miller <Todd.Miller@courtesan.com>
   4  *
   5  * Permission to use, copy, modify, and distribute this software for any
   6  * purpose with or without fee is hereby granted, provided that the above
   7  * copyright notice and this permission notice appear in all copies.
   8  *
   9  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  10  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  11  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  12  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  13  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  14  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  15  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  16  *
  17  * Sponsored in part by the Defense Advanced Research Projects
  18  * Agency (DARPA) and Air Force Research Laboratory, Air Force
  19  * Materiel Command, USAF, under agreement number F39502-99-1-0512.
  20  */
  21
  22 #include <config.h>
  23
  24 #include <sys/types.h>
  25 #include <stdio.h>
  26 #ifdef STDC_HEADERS
  27 # include <stdlib.h>
  28 # include <stddef.h>
  29 #else
  30 # ifdef HAVE_STDLIB_H
  31 #  include <stdlib.h>
  32 # endif
  33 #endif /* STDC_HEADERS */
  34 #ifdef HAVE_STRING_H
  35 # include <string.h>
  36 #endif /* HAVE_STRING_H */
  37 #ifdef HAVE_STRINGS_H
  38 # include <strings.h>
  39 #endif /* HAVE_STRINGS_H */
  40 #include <pwd.h>
  41 #include <grp.h>
  42
  43 #include "sudoers.h"
  44
  45 /*
  46  * Expand %h and %u escapes in the prompt and pass back the dynamically
  47  * allocated result.  Returns the same string if there are no escapes.
  48  */
  49 char *
  50 expand_prompt(const char *old_prompt, const char *user, const char *host)
  51 {
  52     size_t len, n;
  53     int subst;
  54     const char *p;
  55     char *np, *new_prompt, *endp;
  56     debug_decl(expand_prompt, SUDO_DEBUG_AUTH)
  57
  58     /* How much space do we need to malloc for the prompt? */
  59     subst = 0;
  60     for (p = old_prompt, len = strlen(old_prompt); *p; p++) {
  61         if (p[0] =='%') {
  62             switch (p[1]) {
  63                 case 'h':
  64                     p++;
  65                     len += strlen(user_shost) - 2;
  66                     subst = 1;
  67                     break;
  68                 case 'H':
  69                     p++;
  70                     len += strlen(user_host) - 2;
  71                     subst = 1;
  72                     break;
  73                 case 'p':
  74                     p++;
  75                     if (def_rootpw)
  76                             len += 2;
  77                     else if (def_targetpw || def_runaspw)
  78                             len += strlen(runas_pw->pw_name) - 2;
  79                     else
  80                             len += strlen(user_name) - 2;
  81                     subst = 1;
  82                     break;
  83                 case 'u':
  84                     p++;
  85                     len += strlen(user_name) - 2;
  86                     subst = 1;
  87                     break;
  88                 case 'U':
  89                     p++;
  90                     len += strlen(runas_pw->pw_name) - 2;
  91                     subst = 1;
  92                     break;
  93                 case '%':
  94                     p++;
  95                     len--;
  96                     subst = 1;
  97                     break;
  98                 default:
  99                     break;
 100             }
 101         }
 102     }
 103
 104     if (subst) {
 105         new_prompt = emalloc(++len);
 106         endp = new_prompt + len;
 107         for (p = old_prompt, np = new_prompt; *p; p++) {
 108             if (p[0] =='%') {
 109                 switch (p[1]) {
 110                     case 'h':
 111                         p++;
 112                         n = strlcpy(np, user_shost, np - endp);
 113                         if (n >= np - endp)
 114                             goto oflow;
 115                         np += n;
 116                         continue;
 117                     case 'H':
 118                         p++;
 119                         n = strlcpy(np, user_host, np - endp);
 120                         if (n >= np - endp)
 121                             goto oflow;
 122                         np += n;
 123                         continue;
 124                     case 'p':
 125                         p++;
 126                         if (def_rootpw)
 127                                 n = strlcpy(np, "root", np - endp);
 128                         else if (def_targetpw || def_runaspw)
 129                                 n = strlcpy(np, runas_pw->pw_name, np - endp);
 130                         else
 131                                 n = strlcpy(np, user_name, np - endp);
 132                         if (n >= np - endp)
 133                                 goto oflow;
 134                         np += n;
 135                         continue;
 136                     case 'u':
 137                         p++;
 138                         n = strlcpy(np, user_name, np - endp);
 139                         if (n >= np - endp)
 140                             goto oflow;
 141                         np += n;
 142                         continue;
 143                     case 'U':
 144                         p++;
 145                         n = strlcpy(np,  runas_pw->pw_name, np - endp);
 146                         if (n >= np - endp)
 147                             goto oflow;
 148                         np += n;
 149                         continue;
 150                     case '%':
 151                         /* convert %% -> % */
 152                         p++;
 153                         break;
 154                     default:
 155                         /* no conversion */
 156                         break;
 157                 }
 158             }
 159             *np++ = *p;
 160             if (np >= endp)
 161                 goto oflow;
 162         }
 163         *np = '\0';
 164     } else
 165         new_prompt = estrdup(old_prompt);
 166
 167     debug_return_str(new_prompt);
 168
 169 oflow:
 170     /* We pre-allocate enough space, so this should never happen. */
 171     fatalx(_("internal error, %s overflow"), "expand_prompt()");
 172 }