| bigbiff bigbiff | e60683a | 2013-02-22 20:55:50 -0500 | [diff] [blame] | 1 | /* |
| 2 | * Security checks of environment |
| 3 | * Added from shadow-utils package |
| 4 | * by Arkadiusz Miśkiewicz <misiek@pld.ORG.PL> |
| 5 | * |
| 6 | */ |
| 7 | |
| 8 | #include <stdio.h> |
| 9 | #include <stdlib.h> |
| 10 | #include <string.h> |
| 11 | #ifdef HAVE_SYS_PRCTL_H |
| 12 | #include <sys/prctl.h> |
| 13 | #else |
| 14 | #define PR_GET_DUMPABLE 3 |
| 15 | #endif |
| 16 | #if (!defined(HAVE_PRCTL) && defined(linux)) |
| 17 | #include <sys/syscall.h> |
| 18 | #endif |
| 19 | #include <unistd.h> |
| 20 | #include <sys/types.h> |
| 21 | |
| 22 | #include "env.h" |
| 23 | |
| 24 | #ifndef HAVE_ENVIRON_DECL |
| 25 | extern char **environ; |
| 26 | #endif |
| 27 | |
| 28 | static char * const forbid[] = { |
| 29 | "_RLD_=", |
| 30 | "BASH_ENV=", /* GNU creeping featurism strikes again... */ |
| 31 | "ENV=", |
| 32 | "HOME=", |
| 33 | "IFS=", |
| 34 | "KRB_CONF=", |
| 35 | "LD_", /* anything with the LD_ prefix */ |
| 36 | "LIBPATH=", |
| 37 | "MAIL=", |
| 38 | "NLSPATH=", |
| 39 | "PATH=", |
| 40 | "SHELL=", |
| 41 | "SHLIB_PATH=", |
| 42 | (char *) 0 |
| 43 | }; |
| 44 | |
| 45 | /* these are allowed, but with no slashes inside |
| 46 | (to work around security problems in GNU gettext) */ |
| 47 | static char * const noslash[] = { |
| 48 | "LANG=", |
| 49 | "LANGUAGE=", |
| 50 | "LC_", /* anything with the LC_ prefix */ |
| 51 | (char *) 0 |
| 52 | }; |
| 53 | |
| 54 | void |
| 55 | sanitize_env(void) |
| 56 | { |
| 57 | char **envp = environ; |
| 58 | char * const *bad; |
| 59 | char **cur; |
| 60 | char **move; |
| 61 | |
| 62 | for (cur = envp; *cur; cur++) { |
| 63 | for (bad = forbid; *bad; bad++) { |
| 64 | if (strncmp(*cur, *bad, strlen(*bad)) == 0) { |
| 65 | for (move = cur; *move; move++) |
| 66 | *move = *(move + 1); |
| 67 | cur--; |
| 68 | break; |
| 69 | } |
| 70 | } |
| 71 | } |
| 72 | |
| 73 | for (cur = envp; *cur; cur++) { |
| 74 | for (bad = noslash; *bad; bad++) { |
| 75 | if (strncmp(*cur, *bad, strlen(*bad)) != 0) |
| 76 | continue; |
| 77 | if (!strchr(*cur, '/')) |
| 78 | continue; /* OK */ |
| 79 | for (move = cur; *move; move++) |
| 80 | *move = *(move + 1); |
| 81 | cur--; |
| 82 | break; |
| 83 | } |
| 84 | } |
| 85 | } |
| 86 | |
| 87 | |
| 88 | char *safe_getenv(const char *arg) |
| 89 | { |
| 90 | uid_t ruid = getuid(); |
| 91 | |
| 92 | if (ruid != 0 || (ruid != geteuid()) || (getgid() != getegid())) |
| 93 | return NULL; |
| 94 | #ifdef HAVE_PRCTL |
| 95 | if (prctl(PR_GET_DUMPABLE, 0, 0, 0, 0) == 0) |
| 96 | return NULL; |
| 97 | #else |
| 98 | #if (defined(linux) && defined(SYS_prctl)) |
| 99 | if (syscall(SYS_prctl, PR_GET_DUMPABLE, 0, 0, 0, 0) == 0) |
| 100 | return NULL; |
| 101 | #endif |
| 102 | #endif |
| 103 | #ifdef HAVE_SECURE_GETENV |
| 104 | return secure_getenv(arg); |
| 105 | #elif HAVE___SECURE_GETENV |
| 106 | return __secure_getenv(arg); |
| 107 | #else |
| 108 | return getenv(arg); |
| 109 | #endif |
| 110 | } |