Alistair Delva | beaee83 | 2021-02-24 11:27:23 -0800 | [diff] [blame] | 1 | /* Copyright 1997,1999,2001,2002,2007,2009 Alain Knaff. |
| 2 | * This file is part of mtools. |
| 3 | * |
| 4 | * Mtools is free software: you can redistribute it and/or modify |
| 5 | * it under the terms of the GNU General Public License as published by |
| 6 | * the Free Software Foundation, either version 3 of the License, or |
| 7 | * (at your option) any later version. |
| 8 | * |
| 9 | * Mtools is distributed in the hope that it will be useful, |
| 10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 12 | * GNU General Public License for more details. |
| 13 | * |
| 14 | * You should have received a copy of the GNU General Public License |
| 15 | * along with Mtools. If not, see <http://www.gnu.org/licenses/>. |
| 16 | */ |
| 17 | |
| 18 | #include "sysincludes.h" |
| 19 | #include "msdos.h" |
| 20 | #include "mtools.h" |
| 21 | |
| 22 | int noPrivileges=0; |
| 23 | |
| 24 | #ifdef OS_mingw32msvc |
| 25 | void reclaim_privs(void) |
| 26 | { |
| 27 | } |
| 28 | |
| 29 | void drop_privs(void) |
| 30 | { |
| 31 | } |
| 32 | |
| 33 | void destroy_privs(void) |
| 34 | { |
| 35 | } |
| 36 | |
| 37 | uid_t get_real_uid(void) |
| 38 | { |
| 39 | return 0; |
| 40 | } |
| 41 | |
| 42 | void init_privs(void) |
| 43 | { |
| 44 | } |
| 45 | |
| 46 | void closeExec(int fd) |
| 47 | { |
| 48 | } |
| 49 | |
| 50 | #else |
| 51 | /*#define PRIV_DEBUG*/ |
| 52 | |
| 53 | #if 0 |
| 54 | #undef HAVE_SETEUID |
| 55 | #define HAVE_SETRESUID |
| 56 | #include <asm/unistd.h> |
| 57 | int setresuid(int a, int b, int c) |
| 58 | { |
| 59 | syscall(164, a, b, c); |
| 60 | |
| 61 | } |
| 62 | #endif |
| 63 | |
| 64 | static __inline__ void print_privs(const char *message UNUSEDP) |
| 65 | { |
| 66 | #ifdef PRIV_DEBUG |
| 67 | /* for debugging purposes only */ |
| 68 | fprintf(stderr,"%s egid=%d rgid=%d\n", message, getegid(), getgid()); |
| 69 | fprintf(stderr,"%s euid=%d ruid=%d\n", message, geteuid(), getuid()); |
| 70 | #endif |
| 71 | } |
| 72 | |
| 73 | |
| 74 | static gid_t rgid, egid; |
| 75 | static uid_t ruid, euid; |
| 76 | |
| 77 | /* privilege management routines for SunOS and Solaris. These are |
| 78 | * needed in order to issue raw SCSI read/write ioctls. Mtools drops |
| 79 | * its privileges at the beginning, and reclaims them just for the |
| 80 | * above-mentioned ioctl's. Before popen(), exec() or system, it |
| 81 | * drops its privileges completely, and issues a warning. |
| 82 | */ |
| 83 | |
| 84 | |
| 85 | /* group id handling is lots easier, as long as we don't use group 0. |
| 86 | * If you want to use group id's, create a *new* group mtools or |
| 87 | * floppy. Chgrp any devices that you only want to be accessible to |
| 88 | * mtools to this group, and give them the appropriate privs. Make |
| 89 | * sure this group doesn't own any other files: be aware that any user |
| 90 | * with access to mtools may mformat these files! |
| 91 | */ |
| 92 | |
| 93 | |
| 94 | static __inline__ void Setuid(uid_t uid) |
| 95 | { |
| 96 | #if defined HAVE_SETEUID || defined HAVE_SETRESUID |
| 97 | if(euid == 0) { |
| 98 | #ifdef HAVE_SETEUID |
| 99 | seteuid(uid); |
| 100 | #else |
| 101 | setresuid(ruid, uid, euid); |
| 102 | #endif |
| 103 | } else |
| 104 | #endif |
| 105 | setuid(uid); |
| 106 | } |
| 107 | |
| 108 | /* In reclaim_privs and drop privs, we have to manipulate group privileges |
| 109 | * when having no root privileges, else we might lose them */ |
| 110 | |
| 111 | void reclaim_privs(void) |
| 112 | { |
| 113 | if(noPrivileges) |
| 114 | return; |
| 115 | setgid(egid); |
| 116 | Setuid(euid); |
| 117 | print_privs("after reclaim privs, both uids should be 0 "); |
| 118 | } |
| 119 | |
| 120 | void drop_privs(void) |
| 121 | { |
| 122 | Setuid(ruid); |
| 123 | setgid(rgid); |
| 124 | print_privs("after drop_privs, real should be 0, effective should not "); |
| 125 | } |
| 126 | |
| 127 | void destroy_privs(void) |
| 128 | { |
| 129 | |
| 130 | #if defined HAVE_SETEUID || defined HAVE_SETRESUID |
| 131 | if(euid == 0) { |
| 132 | #ifdef HAVE_SETEUID |
| 133 | setuid(0); /* get the necessary privs to drop real root id */ |
| 134 | setuid(ruid); /* this should be enough to get rid of the three |
| 135 | * ids */ |
| 136 | seteuid(ruid); /* for good measure... just in case we came |
| 137 | * across a system which implemented sane |
| 138 | * semantics instead of POSIXly broken |
| 139 | * semantics for setuid */ |
| 140 | #else |
| 141 | setresuid(ruid, ruid, ruid); |
| 142 | #endif |
| 143 | } |
| 144 | #endif |
| 145 | |
| 146 | /* we also destroy group privileges */ |
| 147 | drop_privs(); |
| 148 | |
| 149 | /* saved set [ug]id will go away by itself on exec */ |
| 150 | |
| 151 | print_privs("destroy_privs, no uid should be zero "); |
| 152 | } |
| 153 | |
| 154 | |
| 155 | uid_t get_real_uid(void) |
| 156 | { |
| 157 | return ruid; |
| 158 | } |
| 159 | |
| 160 | void init_privs(void) |
| 161 | { |
| 162 | euid = geteuid(); |
| 163 | ruid = getuid(); |
| 164 | egid = getegid(); |
| 165 | rgid = getgid(); |
| 166 | |
| 167 | #ifndef F_SETFD |
| 168 | if(euid != ruid) { |
| 169 | fprintf(stderr, |
| 170 | "Setuid installation not supported on this platform\n"); |
| 171 | fprintf(stderr, |
| 172 | "Missing F_SETFD"); |
| 173 | exit(1); |
| 174 | } |
| 175 | #endif |
| 176 | |
| 177 | if(euid != ruid) { |
| 178 | unsetenv("SOURCE_DATE_EPOCH"); |
| 179 | } |
| 180 | if(euid == 0 && ruid != 0) { |
| 181 | #ifdef HAVE_SETEUID |
| 182 | setuid(0); /* set real uid to 0 */ |
| 183 | #else |
| 184 | #ifndef HAVE_SETRESUID |
| 185 | /* on this machine, it is not possible to reversibly drop |
| 186 | * root privileges. We print an error and quit */ |
| 187 | |
| 188 | /* BEOS is no longer a special case, as both euid and ruid |
| 189 | * return 0, and thus we do not get any longer into this |
| 190 | * branch */ |
| 191 | fprintf(stderr, |
| 192 | "Seteuid call not supported on this architecture.\n"); |
| 193 | fprintf(stderr, |
| 194 | "Mtools cannot be installed setuid root.\n"); |
| 195 | fprintf(stderr, |
| 196 | "However, it can be installed setuid to a non root"); |
| 197 | fprintf(stderr, |
| 198 | "user or setgid to any id.\n"); |
| 199 | exit(1); |
| 200 | #endif |
| 201 | #endif |
| 202 | } |
Yi Kong | 39bbd96 | 2022-01-09 19:41:38 +0800 | [diff] [blame^] | 203 | |
Alistair Delva | beaee83 | 2021-02-24 11:27:23 -0800 | [diff] [blame] | 204 | drop_privs(); |
| 205 | print_privs("after init, real should be 0, effective should not "); |
| 206 | } |
| 207 | |
| 208 | void closeExec(int fd) |
| 209 | { |
| 210 | #ifdef F_SETFD |
| 211 | fcntl(fd, F_SETFD, 1); |
| 212 | #endif |
| 213 | } |
| 214 | #endif |