1 /* $OpenBSD: setresuid.c,v 1.3 2021/12/15 18:42:38 anton Exp $ */ 2 /* 3 * Written by Bret Stephen Lambert <blambert@openbsd.org> 2014 4 * Public Domain. 5 */ 6 7 #include <sys/types.h> 8 #include <sys/signal.h> 9 #include <sys/proc.h> 10 #include <sys/sysctl.h> 11 #include <sys/wait.h> 12 13 #include <err.h> 14 #include <stdio.h> 15 #include <stdlib.h> 16 #include <pwd.h> 17 #include <unistd.h> 18 19 #include "setuid_regress.h" 20 21 int 22 main(int argc, const char *argv[]) 23 { 24 struct kinfo_proc kproc; 25 struct passwd *pw; 26 uid_t uid; 27 28 if ((pw = getpwnam(_SETUID_REGRESS_USER)) == NULL) 29 err(1, "unknown user \"%s\"", _SETUID_REGRESS_USER); 30 31 uid = getuid(); 32 33 if (setresuid(pw->pw_uid, -1, -1) == -1) 34 err(1, "setuid 0"); 35 checkuids(pw->pw_uid, uid, uid, "0"); 36 37 /* should only respond to setuid upon exec */ 38 if (issetugid()) 39 errx(1, "process incorrectly marked as issetugid()"); 40 41 if (read_kproc_pid(&kproc, getpid()) == -1) 42 err(1, "kproc read failed"); 43 44 if (!(kproc.p_psflags & PS_SUGID)) 45 errx(1, "PS_SUGID not set"); 46 if (kproc.p_psflags & PS_SUGIDEXEC) 47 errx(1, "PS_SUGIDEXEC incorrectly set"); 48 49 /* we should be able to roll back our uids for now */ 50 if (setresuid(uid, -1, -1) == -1) 51 err(1, "setuid 1"); 52 checkuids(uid, uid, uid, "1"); 53 54 if (setresuid(-1, pw->pw_uid, -1) == -1) 55 err(1, "setuid 2"); 56 checkuids(uid, pw->pw_uid, uid, "2"); 57 58 /* we should be able to roll back our uids for now */ 59 if (setresuid(-1, uid, -1) == -1) 60 err(1, "setuid 3"); 61 checkuids(uid, uid, uid, "3"); 62 63 /* 64 * after changing our saved uid, we should be able to change 65 * our real and effective uids to that of our saved uid, 66 * but not to anything else 67 */ 68 69 if (setresuid(-1, -1, pw->pw_uid) == -1) 70 err(1, "setuid 4"); 71 checkuids(uid, uid, pw->pw_uid, "4"); 72 73 if (setresuid(pw->pw_uid, -1, -1) == -1) 74 err(1, "setuid 5"); 75 checkuids(pw->pw_uid, uid, pw->pw_uid, "5"); 76 77 if (setresuid(-1, pw->pw_uid, -1) == -1) 78 err(1, "setuid 6"); 79 checkuids(pw->pw_uid, pw->pw_uid, pw->pw_uid, "6"); 80 81 if (setresuid(uid, -1, -1) != -1) 82 errx(1, "incorrectly capable of setting real uid"); 83 checkuids(pw->pw_uid, pw->pw_uid, pw->pw_uid, "7"); 84 85 if (setresuid(-1, uid, -1) != -1) 86 errx(1, "incorrectly capable of setting effective uid"); 87 checkuids(pw->pw_uid, pw->pw_uid, pw->pw_uid, "9"); 88 89 if (setresuid(-1, -1, uid) != -1) 90 errx(1, "incorrectly capable of setting saved uid"); 91 checkuids(pw->pw_uid, pw->pw_uid, pw->pw_uid, "9"); 92 93 /* sanity-check use of -1 as noop */ 94 if (setresuid(-1, -1, -1) == -1) 95 errx(1, "-1 not properly recognized as noop"); 96 checkuids(pw->pw_uid, pw->pw_uid, pw->pw_uid, "9"); 97 98 exit(0); 99 } 100