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usr
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src
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nagios-plugins-2.0.3
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gl
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idpriv-droptemp.c
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/* Dropping uid/gid privileges of the current process temporarily. Copyright (C) 2009-2013 Free Software Foundation, Inc. This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see <http://www.gnu.org/licenses/>. */ #include <config.h> #include "idpriv.h" #include <errno.h> #include <stdlib.h> #include <sys/types.h> #include <unistd.h> /* The privileged uid and gid that the process had earlier. */ #if HAVE_GETUID static int saved_uid = -1; #endif #if HAVE_GETGID static int saved_gid = -1; #endif int idpriv_temp_drop (void) { #if HAVE_GETEUID && HAVE_GETEGID && (HAVE_SETRESUID || HAVE_SETREUID) && (HAVE_SETRESGID || HAVE_SETREGID) int uid = getuid (); int gid = getgid (); /* Find out about the privileged uid and gid at the first call. */ if (saved_uid == -1) saved_uid = geteuid (); if (saved_gid == -1) saved_gid = getegid (); /* Drop the gid privilege first, because in some cases the gid privilege cannot be dropped after the uid privilege has been dropped. */ /* This is for executables that have the setgid bit set. */ # if HAVE_SETRESGID /* glibc, FreeBSD, OpenBSD, HP-UX */ if (setresgid (-1, gid, saved_gid) < 0) return -1; # else /* Mac OS X, NetBSD, AIX, IRIX, Solaris >= 2.5, OSF/1, Cygwin */ if (setregid (-1, gid) < 0) return -1; # endif /* This is for executables that have the setuid bit set. */ # if HAVE_SETRESUID /* glibc, FreeBSD, OpenBSD, HP-UX */ /* See <http://www.usenix.org/events/sec02/full_papers/chen/chen.pdf> figure 14. */ if (setresuid (-1, uid, saved_uid) < 0) return -1; # else /* Mac OS X, NetBSD, AIX, IRIX, Solaris >= 2.5, OSF/1, Cygwin */ if (setreuid (-1, uid) < 0) return -1; # endif /* Verify that the privileges have really been dropped. This verification is here for security reasons. Doesn't matter if it takes a couple of system calls. When the verification fails, it indicates that we need to use different API in the code above. Therefore 'abort ()', not 'return -1'. */ # if HAVE_GETRESUID /* glibc, FreeBSD, OpenBSD, HP-UX */ { uid_t real; uid_t effective; uid_t saved; if (getresuid (&real, &effective, &saved) < 0 || real != uid || effective != uid || saved != saved_uid) abort (); } # else # if HAVE_GETEUID if (geteuid () != uid) abort (); # endif if (getuid () != uid) abort (); # endif # if HAVE_GETRESGID /* glibc, FreeBSD, OpenBSD, HP-UX */ { uid_t real; uid_t effective; uid_t saved; if (getresgid (&real, &effective, &saved) < 0 || real != gid || effective != gid || saved != saved_gid) abort (); } # else # if HAVE_GETEGID if (getegid () != gid) abort (); # endif if (getgid () != gid) abort (); # endif return 0; #else errno = ENOSYS; return -1; #endif } int idpriv_temp_restore (void) { #if HAVE_GETEUID && HAVE_GETEGID && (HAVE_SETRESUID || HAVE_SETREUID) && (HAVE_SETRESGID || HAVE_SETREGID) int uid = getuid (); int gid = getgid (); if (saved_uid == -1 || saved_gid == -1) /* Caller error: idpriv_temp_drop was never invoked. */ abort (); /* Acquire the gid privilege last, because in some cases the gid privilege cannot be acquired before the uid privilege has been acquired. */ /* This is for executables that have the setuid bit set. */ # if HAVE_SETRESUID /* glibc, FreeBSD, OpenBSD, HP-UX */ /* See <http://www.usenix.org/events/sec02/full_papers/chen/chen.pdf> figure 14. */ if (setresuid (-1, saved_uid, -1) < 0) return -1; # else /* Mac OS X, NetBSD, AIX, IRIX, Solaris >= 2.5, OSF/1, Cygwin */ if (setreuid (-1, saved_uid) < 0) return -1; # endif /* This is for executables that have the setgid bit set. */ # if HAVE_SETRESGID /* glibc, FreeBSD, OpenBSD, HP-UX */ if (setresgid (-1, saved_gid, -1) < 0) return -1; # else /* Mac OS X, NetBSD, AIX, IRIX, Solaris >= 2.5, OSF/1, Cygwin */ if (setregid (-1, saved_gid) < 0) return -1; # endif /* Verify that the privileges have really been acquired. This verification is here for security reasons. Doesn't matter if it takes a couple of system calls. When the verification fails, it indicates that we need to use different API in the code above. Therefore 'abort ()', not 'return -1'. */ # if HAVE_GETRESUID /* glibc, FreeBSD, OpenBSD, HP-UX */ { uid_t real; uid_t effective; uid_t saved; if (getresuid (&real, &effective, &saved) < 0 || real != uid || effective != saved_uid || saved != saved_uid) abort (); } # else # if HAVE_GETEUID if (geteuid () != saved_uid) abort (); # endif if (getuid () != uid) abort (); # endif # if HAVE_GETRESGID /* glibc, FreeBSD, OpenBSD, HP-UX */ { uid_t real; uid_t effective; uid_t saved; if (getresgid (&real, &effective, &saved) < 0 || real != gid || effective != saved_gid || saved != saved_gid) abort (); } # else # if HAVE_GETEGID if (getegid () != saved_gid) abort (); # endif if (getgid () != gid) abort (); # endif return 0; #else errno = ENOSYS; return -1; #endif }