/* * Zebra privileges. * * Copyright (C) 2003 Paul Jakma. * Copyright (C) 2005 Sun Microsystems, Inc. * * This file is part of GNU Zebra. * * GNU Zebra 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 2, or (at your option) any * later version. * * GNU Zebra 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 GNU Zebra; see the file COPYING. If not, write to the Free * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA * 02111-1307, USA. */ #include #include "log.h" #include "privs.h" #include "memory.h" #ifdef HAVE_CAPABILITIES /* sort out some generic internal types for: * * privilege values (cap_value_t, priv_t) -> pvalue_t * privilege set (..., priv_set_t) -> pset_t * privilege working storage (cap_t, ...) -> pstorage_t * * values we think of as numeric (they're ints really, but we dont know) * sets are mostly opaque, to hold a set of privileges, related in some way. * storage binds together a set of sets we're interested in. * (in reality: cap_value_t and priv_t are ints) */ #ifdef HAVE_LCAPS /* Linux doesn't have a 'set' type: a set of related privileges */ struct _pset { int num; cap_value_t *caps; }; typedef cap_value_t pvalue_t; typedef struct _pset pset_t; typedef cap_t pstorage_t; #elif defined (HAVE_SOLARIS_CAPABILITIES) typedef priv_t pvalue_t; typedef priv_set_t pset_t; typedef priv_set_t *pstorage_t; #else /* neither LCAPS nor SOLARIS_CAPABILITIES */ #error "HAVE_CAPABILITIES defined, but neither LCAPS nor Solaris Capabilties!" #endif /* HAVE_LCAPS */ #endif /* HAVE_CAPABILITIES */ /* the default NULL state we report is RAISED, but could be LOWERED if * zprivs_terminate is called and the NULL handler is installed. */ static zebra_privs_current_t zprivs_null_state = ZPRIVS_RAISED; /* internal privileges state */ static struct _zprivs_t { #ifdef HAVE_CAPABILITIES pstorage_t caps; /* working storage */ pset_t *syscaps_p; /* system-type requested permitted caps */ pset_t *syscaps_i; /* system-type requested inheritable caps */ #endif /* HAVE_CAPABILITIES */ uid_t zuid, /* uid to run as */ zsuid; /* saved uid */ gid_t zgid; /* gid to run as */ gid_t vtygrp; /* gid for vty sockets */ } zprivs_state; /* externally exported but not directly accessed functions */ #ifdef HAVE_CAPABILITIES int zprivs_change_caps (zebra_privs_ops_t); zebra_privs_current_t zprivs_state_caps (void); #endif /* HAVE_CAPABILITIES */ int zprivs_change_uid (zebra_privs_ops_t); zebra_privs_current_t zprivs_state_uid (void); int zprivs_change_null (zebra_privs_ops_t); zebra_privs_current_t zprivs_state_null (void); #ifdef HAVE_CAPABILITIES /* internal capability API */ static pset_t *zcaps2sys (zebra_capabilities_t *, int); static void zprivs_caps_init (struct zebra_privs_t *); static void zprivs_caps_terminate (void); /* Map of Quagga abstract capabilities to system capabilities */ static struct { int num; pvalue_t *system_caps; } cap_map [ZCAP_MAX] = { #ifdef HAVE_LCAPS /* Quagga -> Linux capabilities mappings */ [ZCAP_SETID] = { 2, (pvalue_t []) { CAP_SETGID, CAP_SETUID }, }, [ZCAP_BIND] = { 2, (pvalue_t []) { CAP_NET_BIND_SERVICE, CAP_NET_BROADCAST }, }, [ZCAP_NET_ADMIN] = { 1, (pvalue_t []) { CAP_NET_ADMIN }, }, [ZCAP_NET_RAW] = { 1, (pvalue_t []) { CAP_NET_RAW }, }, [ZCAP_CHROOT] = { 1, (pvalue_t []) { CAP_SYS_CHROOT, }, }, [ZCAP_NICE] = { 1, (pvalue_t []) { CAP_SYS_NICE }, }, [ZCAP_PTRACE] = { 1, (pvalue_t []) { CAP_SYS_PTRACE }, }, [ZCAP_DAC_OVERRIDE] = { 1, (pvalue_t []) { CAP_DAC_OVERRIDE }, }, [ZCAP_READ_SEARCH] = { 1, (pvalue_t []) { CAP_DAC_READ_SEARCH }, }, [ZCAP_SYS_ADMIN] = { 1, (pvalue_t []) { CAP_SYS_ADMIN }, }, [ZCAP_FOWNER] = { 1, (pvalue_t []) { CAP_FOWNER }, }, #elif defined(HAVE_SOLARIS_CAPABILITIES) /* HAVE_LCAPS */ /* Quagga -> Solaris privilege mappings */ [ZCAP_SETID] = { 1, (pvalue_t []) { PRIV_PROC_SETID }, }, [ZCAP_BIND] = { 1, (pvalue_t []) { PRIV_NET_PRIVADDR }, }, /* IP_CONFIG is a subset of NET_CONFIG and is allowed in zones */ #ifdef PRIV_SYS_IP_CONFIG [ZCAP_NET_ADMIN] = { 1, (pvalue_t []) { PRIV_SYS_IP_CONFIG }, }, #else [ZCAP_NET_ADMIN] = { 1, (pvalue_t []) { PRIV_SYS_NET_CONFIG }, }, #endif [ZCAP_NET_RAW] = { 2, (pvalue_t []) { PRIV_NET_RAWACCESS, PRIV_NET_ICMPACCESS }, }, [ZCAP_CHROOT] = { 1, (pvalue_t []) { PRIV_PROC_CHROOT }, }, [ZCAP_NICE] = { 1, (pvalue_t []) { PRIV_PROC_PRIOCNTL }, }, [ZCAP_PTRACE] = { 1, (pvalue_t []) { PRIV_PROC_SESSION }, }, [ZCAP_DAC_OVERRIDE] = { 2, (pvalue_t []) { PRIV_FILE_DAC_EXECUTE, PRIV_FILE_DAC_READ, PRIV_FILE_DAC_SEARCH, PRIV_FILE_DAC_WRITE, PRIV_FILE_DAC_SEARCH }, }, [ZCAP_READ_SEARCH] = { 2, (pvalue_t []) { PRIV_FILE_DAC_SEARCH, PRIV_FILE_DAC_READ }, }, [ZCAP_SYS_ADMIN] = { 1, (pvalue_t []) { PRIV_SYS_ADMIN }, }, [ZCAP_FOWNER] = { 1, (pvalue_t []) { PRIV_FILE_OWNER }, }, #endif /* HAVE_SOLARIS_CAPABILITIES */ }; #ifdef HAVE_LCAPS /* Linux forms of capabilities methods */ /* convert zebras privileges to system capabilities */ static pset_t * zcaps2sys (zebra_capabilities_t *zcaps, int num) { pset_t *syscaps; int i, j = 0, count = 0; if (!num) return NULL; /* first count up how many system caps we have */ for (i= 0; i < num; i++) count += cap_map[zcaps[i]].num; if ( (syscaps = XCALLOC (MTYPE_PRIVS, (sizeof(pset_t) * num))) == NULL) { fprintf (stderr, "%s: could not allocate syscaps!", __func__); return NULL; } syscaps->caps = XCALLOC (MTYPE_PRIVS, (sizeof (pvalue_t) * count)); if (!syscaps->caps) { fprintf (stderr, "%s: could not XCALLOC caps!", __func__); return NULL; } /* copy the capabilities over */ count = 0; for (i=0; i < num; i++) for (j = 0; j < cap_map[zcaps[i]].num; j++) syscaps->caps[count++] = cap_map[zcaps[i]].system_caps[j]; /* iterations above should be exact same as previous count, obviously.. */ syscaps->num = count; return syscaps; } /* set or clear the effective capabilities to/from permitted */ int zprivs_change_caps (zebra_privs_ops_t op) { cap_flag_value_t cflag; /* should be no possibility of being called without valid caps */ assert (zprivs_state.syscaps_p && zprivs_state.caps); if (! (zprivs_state.syscaps_p && zprivs_state.caps)) exit (1); if (op == ZPRIVS_RAISE) cflag = CAP_SET; else if (op == ZPRIVS_LOWER) cflag = CAP_CLEAR; else return -1; if ( !cap_set_flag (zprivs_state.caps, CAP_EFFECTIVE, zprivs_state.syscaps_p->num, zprivs_state.syscaps_p->caps, cflag)) return cap_set_proc (zprivs_state.caps); return -1; } zebra_privs_current_t zprivs_state_caps (void) { int i; cap_flag_value_t val; /* should be no possibility of being called without valid caps */ assert (zprivs_state.syscaps_p && zprivs_state.caps); if (! (zprivs_state.syscaps_p && zprivs_state.caps)) exit (1); for (i=0; i < zprivs_state.syscaps_p->num; i++) { if ( cap_get_flag (zprivs_state.caps, zprivs_state.syscaps_p->caps[i], CAP_EFFECTIVE, &val) ) { zlog_warn ("zprivs_state_caps: could not cap_get_flag, %s", safe_strerror (errno) ); return ZPRIVS_UNKNOWN; } if (val == CAP_SET) return ZPRIVS_RAISED; } return ZPRIVS_LOWERED; } static void zprivs_caps_init (struct zebra_privs_t *zprivs) { zprivs_state.syscaps_p = zcaps2sys (zprivs->caps_p, zprivs->cap_num_p); zprivs_state.syscaps_i = zcaps2sys (zprivs->caps_i, zprivs->cap_num_i); /* Tell kernel we want caps maintained across uid changes */ if ( prctl(PR_SET_KEEPCAPS, 1, 0, 0, 0) == -1 ) { fprintf (stderr, "privs_init: could not set PR_SET_KEEPCAPS, %s\n", safe_strerror (errno) ); exit(1); } if ( !zprivs_state.syscaps_p ) { fprintf (stderr, "privs_init: capabilities enabled, " "but no capabilities supplied\n"); } /* we have caps, we have no need to ever change back the original user */ if (zprivs_state.zuid) { if ( setreuid (zprivs_state.zuid, zprivs_state.zuid) ) { fprintf (stderr, "zprivs_init (cap): could not setreuid, %s\n", safe_strerror (errno)); exit (1); } } if ( !(zprivs_state.caps = cap_init()) ) { fprintf (stderr, "privs_init: failed to cap_init, %s\n", safe_strerror (errno)); exit (1); } if ( cap_clear (zprivs_state.caps) ) { fprintf (stderr, "privs_init: failed to cap_clear, %s\n", safe_strerror (errno)); exit (1); } /* set permitted caps */ cap_set_flag(zprivs_state.caps, CAP_PERMITTED, zprivs_state.syscaps_p->num, zprivs_state.syscaps_p->caps, CAP_SET); /* set inheritable caps, if any */ if (zprivs_state.syscaps_i && zprivs_state.syscaps_i->num) { cap_set_flag(zprivs_state.caps, CAP_INHERITABLE, zprivs_state.syscaps_i->num, zprivs_state.syscaps_i->caps, CAP_SET); } /* apply caps. CAP_EFFECTIVE is cleared. we'll raise the caps as * and when, and only when, they are needed. */ if ( cap_set_proc (zprivs_state.caps) ) { fprintf (stderr, "privs_init: initial cap_set_proc failed\n"); exit (1); } /* set methods for the caller to use */ zprivs->change = zprivs_change_caps; zprivs->current_state = zprivs_state_caps; } static void zprivs_caps_terminate (void) { /* clear all capabilities */ if (zprivs_state.caps) cap_clear (zprivs_state.caps); /* and boom, capabilities are gone forever */ if ( cap_set_proc (zprivs_state.caps) ) { fprintf (stderr, "privs_terminate: cap_set_proc failed, %s", safe_strerror (errno) ); exit (1); } /* free up private state */ if (zprivs_state.syscaps_p->num) { XFREE (MTYPE_PRIVS, zprivs_state.syscaps_p->caps); XFREE (MTYPE_PRIVS, zprivs_state.syscaps_p); } if (zprivs_state.syscaps_i && zprivs_state.syscaps_i->num) { XFREE (MTYPE_PRIVS, zprivs_state.syscaps_i->caps); XFREE (MTYPE_PRIVS, zprivs_state.syscaps_i); } cap_free (zprivs_state.caps); } #elif defined (HAVE_SOLARIS_CAPABILITIES) /* !HAVE_LCAPS */ /* Solaris specific capability/privilege methods * * Resources: * - the 'privileges' man page * - http://cvs.opensolaris.org * - http://blogs.sun.com/roller/page/gbrunett?entry=privilege_enabling_set_id_programs1 */ /* convert zebras privileges to system capabilities */ static pset_t * zcaps2sys (zebra_capabilities_t *zcaps, int num) { pset_t *syscaps; int i, j = 0; if ((syscaps = priv_allocset()) == NULL) { fprintf (stderr, "%s: could not allocate syscaps!\n", __func__); exit (1); } priv_emptyset (syscaps); for (i=0; i < num; i++) for (j = 0; j < cap_map[zcaps[i]].num; j++) priv_addset (syscaps, cap_map[zcaps[i]].system_caps[j]); return syscaps; } /* callback exported to users to RAISE and LOWER effective privileges * from nothing to the given permitted set and back down */ int zprivs_change_caps (zebra_privs_ops_t op) { /* should be no possibility of being called without valid caps */ assert (zprivs_state.syscaps_p); if (!zprivs_state.syscaps_p) { fprintf (stderr, "%s: Eek, missing caps!", __func__); exit (1); } /* to raise: copy original permitted into our working effective set * to lower: just clear the working effective set */ if (op == ZPRIVS_RAISE) priv_copyset (zprivs_state.syscaps_p, zprivs_state.caps); else if (op == ZPRIVS_LOWER) priv_emptyset (zprivs_state.caps); else return -1; if (setppriv (PRIV_SET, PRIV_EFFECTIVE, zprivs_state.caps) != 0) return -1; return 0; } /* Retrieve current privilege state, is it RAISED or LOWERED? */ zebra_privs_current_t zprivs_state_caps (void) { zebra_privs_current_t result; pset_t *effective; if ( (effective = priv_allocset()) == NULL) { fprintf (stderr, "%s: failed to get priv_allocset! %s\n", __func__, safe_strerror (errno)); return ZPRIVS_UNKNOWN; } if (getppriv (PRIV_EFFECTIVE, effective)) { fprintf (stderr, "%s: failed to get state! %s\n", __func__, safe_strerror (errno)); result = ZPRIVS_UNKNOWN; } else { if (priv_isemptyset (effective) == B_TRUE) result = ZPRIVS_LOWERED; else result = ZPRIVS_RAISED; } if (effective) priv_freeset (effective); return result; } static void zprivs_caps_init (struct zebra_privs_t *zprivs) { pset_t *basic; pset_t *empty; /* the specified sets */ zprivs_state.syscaps_p = zcaps2sys (zprivs->caps_p, zprivs->cap_num_p); zprivs_state.syscaps_i = zcaps2sys (zprivs->caps_i, zprivs->cap_num_i); /* nonsensical to have gotten here but not have capabilities */ if (!zprivs_state.syscaps_p) { fprintf (stderr, "%s: capabilities enabled, " "but no valid capabilities supplied\n", __func__); } /* We retain the basic set in our permitted set, as Linux has no * equivalent. The basic set on Linux hence is implicit, always * there. */ if ((basic = priv_str_to_set("basic", ",", NULL)) == NULL) { fprintf (stderr, "%s: couldn't get basic set!\n", __func__); exit (1); } /* Add the basic set to the permitted set */ priv_union (basic, zprivs_state.syscaps_p); priv_freeset (basic); /* we need an empty set for 'effective', potentially for inheritable too */ if ( (empty = priv_allocset()) == NULL) { fprintf (stderr, "%s: couldn't get empty set!\n", __func__); exit (1); } priv_emptyset (empty); /* Hey kernel, we know about privileges! * this isn't strictly required, use of setppriv should have same effect */ if (setpflags (PRIV_AWARE, 1)) { fprintf (stderr, "%s: error setting PRIV_AWARE!, %s\n", __func__, safe_strerror (errno) ); exit (1); } /* need either valid or empty sets for both p and i.. */ assert (zprivs_state.syscaps_i && zprivs_state.syscaps_p); /* we have caps, we have no need to ever change back the original user * change real, effective and saved to the specified user. */ if (zprivs_state.zuid) { if ( setreuid (zprivs_state.zuid, zprivs_state.zuid) ) { fprintf (stderr, "%s: could not setreuid, %s\n", __func__, safe_strerror (errno)); exit (1); } } /* set the permitted set */ if (setppriv (PRIV_SET, PRIV_PERMITTED, zprivs_state.syscaps_p)) { fprintf (stderr, "%s: error setting permitted set!, %s\n", __func__, safe_strerror (errno) ); exit (1); } /* set the inheritable set */ if (setppriv (PRIV_SET, PRIV_INHERITABLE, zprivs_state.syscaps_i)) { fprintf (stderr, "%s: error setting inheritable set!, %s\n", __func__, safe_strerror (errno) ); exit (1); } /* now clear the effective set and we're ready to go */ if (setppriv (PRIV_SET, PRIV_EFFECTIVE, empty)) { fprintf (stderr, "%s: error setting effective set!, %s\n", __func__, safe_strerror (errno) ); exit (1); } /* we'll use this as our working-storage privset */ zprivs_state.caps = empty; /* set methods for the caller to use */ zprivs->change = zprivs_change_caps; zprivs->current_state = zprivs_state_caps; } static void zprivs_caps_terminate (void) { assert (zprivs_state.caps); /* clear all capabilities */ priv_emptyset (zprivs_state.caps); setppriv (PRIV_SET, PRIV_EFFECTIVE, zprivs_state.caps); setppriv (PRIV_SET, PRIV_PERMITTED, zprivs_state.caps); setppriv (PRIV_SET, PRIV_INHERITABLE, zprivs_state.caps); /* free up private state */ if (zprivs_state.syscaps_p) priv_freeset (zprivs_state.syscaps_p); if (zprivs_state.syscaps_i) priv_freeset (zprivs_state.syscaps_i); priv_freeset (zprivs_state.caps); } #else /* !HAVE_LCAPS && ! HAVE_SOLARIS_CAPABILITIES */ #error "Neither Solaris nor Linux capabilities, dazed and confused..." #endif /* HAVE_LCAPS */ #endif /* HAVE_CAPABILITIES */ int zprivs_change_uid (zebra_privs_ops_t op) { if (op == ZPRIVS_RAISE) return seteuid (zprivs_state.zsuid); else if (op == ZPRIVS_LOWER) return seteuid (zprivs_state.zuid); else return -1; } zebra_privs_current_t zprivs_state_uid (void) { return ( (zprivs_state.zuid == geteuid()) ? ZPRIVS_LOWERED : ZPRIVS_RAISED); } int zprivs_change_null (zebra_privs_ops_t op) { return 0; } zebra_privs_current_t zprivs_state_null (void) { return zprivs_null_state; } void zprivs_init(struct zebra_privs_t *zprivs) { struct passwd *pwentry = NULL; struct group *grentry = NULL; if (!zprivs) { fprintf (stderr, "zprivs_init: called with NULL arg!\n"); exit (1); } /* NULL privs */ if (! (zprivs->user || zprivs->group || zprivs->cap_num_p || zprivs->cap_num_i) ) { zprivs->change = zprivs_change_null; zprivs->current_state = zprivs_state_null; return; } if (zprivs->user) { if ( (pwentry = getpwnam (zprivs->user)) ) { zprivs_state.zuid = pwentry->pw_uid; } else { /* cant use log.h here as it depends on vty */ fprintf (stderr, "privs_init: could not lookup user %s\n", zprivs->user); exit (1); } } grentry = NULL; if (zprivs->vty_group) /* Add the vty_group to the supplementary groups so it can be chowned to */ { if ( (grentry = getgrnam (zprivs->vty_group)) ) { zprivs_state.vtygrp = grentry->gr_gid; if ( setgroups (1, &zprivs_state.vtygrp) ) { fprintf (stderr, "privs_init: could not setgroups, %s\n", safe_strerror (errno) ); exit (1); } } else { fprintf (stderr, "privs_init: could not lookup vty group %s\n", zprivs->vty_group); exit (1); } } if (zprivs->group) { if ( (grentry = getgrnam (zprivs->group)) ) { zprivs_state.zgid = grentry->gr_gid; } else { fprintf (stderr, "privs_init: could not lookup group %s\n", zprivs->group); exit (1); } /* change group now, forever. uid we do later */ if ( setregid (zprivs_state.zgid, zprivs_state.zgid) ) { fprintf (stderr, "zprivs_init: could not setregid, %s\n", safe_strerror (errno) ); exit (1); } } #ifdef HAVE_CAPABILITIES zprivs_caps_init (zprivs); #else /* !HAVE_CAPABILITIES */ /* we dont have caps. we'll need to maintain rid and saved uid * and change euid back to saved uid (who we presume has all neccessary * privileges) whenever we are asked to raise our privileges. * * This is not worth that much security wise, but all we can do. */ zprivs_state.zsuid = geteuid(); if ( zprivs_state.zuid ) { if ( setreuid (-1, zprivs_state.zuid) ) { fprintf (stderr, "privs_init (uid): could not setreuid, %s\n", safe_strerror (errno)); exit (1); } } zprivs->change = zprivs_change_uid; zprivs->current_state = zprivs_state_uid; #endif /* HAVE_CAPABILITIES */ } void zprivs_terminate (struct zebra_privs_t *zprivs) { if (!zprivs) { fprintf (stderr, "%s: no privs struct given, terminating", __func__); exit (0); } #ifdef HAVE_CAPABILITIES zprivs_caps_terminate(); #else /* !HAVE_CAPABILITIES */ if (zprivs_state.zuid) { if ( setreuid (zprivs_state.zuid, zprivs_state.zuid) ) { fprintf (stderr, "privs_terminate: could not setreuid, %s", safe_strerror (errno) ); exit (1); } } #endif /* HAVE_LCAPS */ zprivs->change = zprivs_change_null; zprivs->current_state = zprivs_state_null; zprivs_null_state = ZPRIVS_LOWERED; return; } void zprivs_get_ids(struct zprivs_ids_t *ids) { ids->uid_priv = getuid(); (zprivs_state.zuid) ? (ids->uid_normal = zprivs_state.zuid) : (ids->uid_normal = -1); (zprivs_state.zgid) ? (ids->gid_normal = zprivs_state.zgid) : (ids->gid_normal = -1); (zprivs_state.vtygrp) ? (ids->gid_vty = zprivs_state.vtygrp) : (ids->gid_vty = -1); return; }