sys/unix/unixres.c

   1 /* aNetHack 0.0.1       unixres.c       $ANH-Date: 1432512788 2015/05/25 00:13:08 $  $ANH-Branch: master $:$ANH-Revision: 1.12 $ */
   2 /* Copyright (c) Slash'EM development team, 2001. */
   3 /* aNetHack may be freely redistributed.  See license for details. */
   4
   5 /* [ALI] This module defines nh_xxx functions to replace getuid etc which
   6  * will hide privileges from the caller if so desired.
   7  *
   8  * Currently supported UNIX variants:
   9  *      Linux version 2.1.44 and above
  10  *      FreeBSD (versions unknown)
  11  *
  12  * Note: SunOS and Solaris have no mechanism for retrieving the saved id,
  13  * so temporarily dropping privileges on these systems is sufficient to
  14  * hide them.
  15  */
  16
  17 #include "config.h"
  18
  19 #ifdef GETRES_SUPPORT
  20
  21 #if defined(LINUX)
  22
  23 /* requires dynamic linking with libc */
  24 #include <dlfcn.h>
  25
  26 static int
  27 real_getresuid(ruid, euid, suid)
  28 uid_t *ruid, *euid, *suid;
  29 {
  30     int (*f)(uid_t *, uid_t *, uid_t *); /* getresuid signature */
  31
  32     f = dlsym(RTLD_NEXT, "getresuid");
  33     if (!f)
  34         return -1;
  35
  36     return f(ruid, euid, suid);
  37 }
  38
  39 static int
  40 real_getresgid(rgid, egid, sgid)
  41 gid_t *rgid, *egid, *sgid;
  42 {
  43     int (*f)(gid_t *, gid_t *, gid_t *); /* getresgid signature */
  44
  45     f = dlsym(RTLD_NEXT, "getresgid");
  46     if (!f)
  47         return -1;
  48
  49     return f(rgid, egid, sgid);
  50 }
  51
  52 #else
  53 #if defined(BSD) || defined(SVR4)
  54
  55 #ifdef SYS_getresuid
  56
  57 static int
  58 real_getresuid(ruid, euid, suid)
  59 uid_t *ruid, *euid, *suid;
  60 {
  61     return syscall(SYS_getresuid, ruid, euid, suid);
  62 }
  63
  64 #else /* SYS_getresuid */
  65
  66 #ifdef SVR4
  67 #include <sys/stat.h>
  68 #endif /* SVR4 */
  69
  70 static int
  71 real_getresuid(ruid, euid, suid)
  72 uid_t *ruid, *euid, *suid;
  73 {
  74     int retval;
  75     int pfd[2];
  76     struct stat st;
  77     if (pipe(pfd))
  78         return -1;
  79     retval = fstat(pfd[0], &st);
  80     close(pfd[0]);
  81     close(pfd[1]);
  82     if (!retval) {
  83         *euid = st.st_uid;
  84         *ruid = syscall(SYS_getuid);
  85         *suid = *ruid; /* Not supported under SVR4 */
  86     }
  87     return retval;
  88 }
  89
  90 #endif /* SYS_getresuid */
  91
  92 #ifdef SYS_getresgid
  93
  94 static int
  95 real_getresgid(rgid, egid, sgid)
  96 gid_t *rgid, *egid, *sgid;
  97 {
  98     return syscall(SYS_getresgid, rgid, egid, sgid);
  99 }
 100
 101 #else /* SYS_getresgid */
 102
 103 static int
 104 real_getresgid(rgid, egid, sgid)
 105 gid_t *rgid, *egid, *sgid;
 106 {
 107     int retval;
 108     int pfd[2];
 109     struct stat st;
 110     if (pipe(pfd))
 111         return -1;
 112     retval = fstat(pfd[0], &st);
 113     close(pfd[0]);
 114     close(pfd[1]);
 115     if (!retval) {
 116         *egid = st.st_gid;
 117         *rgid = syscall(SYS_getgid);
 118         *sgid = *rgid; /* Not supported under SVR4 */
 119     }
 120     return retval;
 121 }
 122
 123 #endif /* SYS_getresgid */
 124 #endif /* BSD || SVR4 */
 125 #endif /* LINUX */
 126
 127 static unsigned int hiding_privileges = 0;
 128
 129 /*
 130  * Note: returns the value _after_ action.
 131  */
 132
 133 int
 134 hide_privileges(flag)
 135 boolean flag;
 136 {
 137     if (flag)
 138         hiding_privileges++;
 139     else if (hiding_privileges)
 140         hiding_privileges--;
 141     return hiding_privileges;
 142 }
 143
 144 int
 145 nh_getresuid(ruid, euid, suid)
 146 uid_t *ruid, *euid, *suid;
 147 {
 148     int retval = real_getresuid(ruid, euid, suid);
 149     if (!retval && hiding_privileges)
 150         *euid = *suid = *ruid;
 151     return retval;
 152 }
 153
 154 uid_t
 155 nh_getuid()
 156 {
 157     uid_t ruid, euid, suid;
 158     (void) real_getresuid(&ruid, &euid, &suid);
 159     return ruid;
 160 }
 161
 162 uid_t
 163 nh_geteuid()
 164 {
 165     uid_t ruid, euid, suid;
 166     (void) real_getresuid(&ruid, &euid, &suid);
 167     if (hiding_privileges)
 168         euid = ruid;
 169     return euid;
 170 }
 171
 172 int
 173 nh_getresgid(rgid, egid, sgid)
 174 gid_t *rgid, *egid, *sgid;
 175 {
 176     int retval = real_getresgid(rgid, egid, sgid);
 177     if (!retval && hiding_privileges)
 178         *egid = *sgid = *rgid;
 179     return retval;
 180 }
 181
 182 gid_t
 183 nh_getgid()
 184 {
 185     gid_t rgid, egid, sgid;
 186     (void) real_getresgid(&rgid, &egid, &sgid);
 187     return rgid;
 188 }
 189
 190 gid_t
 191 nh_getegid()
 192 {
 193     gid_t rgid, egid, sgid;
 194     (void) real_getresgid(&rgid, &egid, &sgid);
 195     if (hiding_privileges)
 196         egid = rgid;
 197     return egid;
 198 }
 199
 200 #else /* GETRES_SUPPORT */
 201
 202 #ifdef GNOME_GRAPHICS
 203 int
 204 hide_privileges(flag)
 205 boolean flag;
 206 {
 207     return 0;
 208 }
 209 #endif
 210
 211 #endif /* GETRES_SUPPORT */