diff options
Diffstat (limited to 'nscd')
| -rw-r--r-- | nscd/selinux.c | 107 |
1 files changed, 68 insertions, 39 deletions
diff --git a/nscd/selinux.c b/nscd/selinux.c index 46b0ea9779..9a8a5a86d3 100644 --- a/nscd/selinux.c +++ b/nscd/selinux.c @@ -28,7 +28,6 @@ #include <syslog.h> #include <unistd.h> #include <sys/prctl.h> -#include <selinux/av_permissions.h> #include <selinux/avc.h> #include <selinux/flask.h> #include <selinux/selinux.h> @@ -44,35 +43,31 @@ /* Global variable to tell if the kernel has SELinux support. */ int selinux_enabled; -/* Define mappings of access vector permissions to request types. */ -static const access_vector_t perms[LASTREQ] = +/* Define mappings of request type to AVC permission name. */ +static const char *perms[LASTREQ] = { - [GETPWBYNAME] = NSCD__GETPWD, - [GETPWBYUID] = NSCD__GETPWD, - [GETGRBYNAME] = NSCD__GETGRP, - [GETGRBYGID] = NSCD__GETGRP, - [GETHOSTBYNAME] = NSCD__GETHOST, - [GETHOSTBYNAMEv6] = NSCD__GETHOST, - [GETHOSTBYADDR] = NSCD__GETHOST, - [GETHOSTBYADDRv6] = NSCD__GETHOST, - [GETSTAT] = NSCD__GETSTAT, - [SHUTDOWN] = NSCD__ADMIN, - [INVALIDATE] = NSCD__ADMIN, - [GETFDPW] = NSCD__SHMEMPWD, - [GETFDGR] = NSCD__SHMEMGRP, - [GETFDHST] = NSCD__SHMEMHOST, - [GETAI] = NSCD__GETHOST, - [INITGROUPS] = NSCD__GETGRP, -#ifdef NSCD__GETSERV - [GETSERVBYNAME] = NSCD__GETSERV, - [GETSERVBYPORT] = NSCD__GETSERV, - [GETFDSERV] = NSCD__SHMEMSERV, -#endif -#ifdef NSCD__GETNETGRP - [GETNETGRENT] = NSCD__GETNETGRP, - [INNETGR] = NSCD__GETNETGRP, - [GETFDNETGR] = NSCD__SHMEMNETGRP, -#endif + [GETPWBYNAME] = "getpwd", + [GETPWBYUID] = "getpwd", + [GETGRBYNAME] = "getgrp", + [GETGRBYGID] = "getgrp", + [GETHOSTBYNAME] = "gethost", + [GETHOSTBYNAMEv6] = "gethost", + [GETHOSTBYADDR] = "gethost", + [GETHOSTBYADDRv6] = "gethost", + [SHUTDOWN] = "admin", + [GETSTAT] = "getstat", + [INVALIDATE] = "admin", + [GETFDPW] = "shmempwd", + [GETFDGR] = "shmemgrp", + [GETFDHST] = "shmemhost", + [GETAI] = "gethost", + [INITGROUPS] = "getgrp", + [GETSERVBYNAME] = "getserv", + [GETSERVBYPORT] = "getserv", + [GETFDSERV] = "shmemserv", + [GETNETGRENT] = "getnetgrp", + [INNETGR] = "getnetgrp", + [GETFDNETGR] = "shmemnetgrp", }; /* Store an entry ref to speed AVC decisions. */ @@ -344,7 +339,16 @@ nscd_avc_init (void) /* Check the permission from the caller (via getpeercon) to nscd. - Returns 0 if access is allowed, 1 if denied, and -1 on error. */ + Returns 0 if access is allowed, 1 if denied, and -1 on error. + + The SELinux policy, enablement, and permission bits are all dynamic and the + caching done by glibc is not entirely correct. This nscd support should be + rewritten to use selinux_check_permission. A rewrite is risky though and + requires some refactoring. Currently we use symbolic mappings instead of + compile time constants (which SELinux upstream says are going away), and we + use security_deny_unknown to determine what to do if selinux-policy* doesn't + have a definition for the the permission or object class we are looking + up. */ int nscd_request_avc_has_perm (int fd, request_type req) { @@ -354,6 +358,33 @@ nscd_request_avc_has_perm (int fd, request_type req) security_id_t ssid = NULL; security_id_t tsid = NULL; int rc = -1; + security_class_t sc_nscd; + access_vector_t perm; + int avc_deny_unknown; + + /* Check if SELinux denys or allows unknown object classes + and permissions. It is 0 if they are allowed, 1 if they + are not allowed and -1 on error. */ + if ((avc_deny_unknown = security_deny_unknown ()) == -1) + dbg_log (_("Error querying policy for undefined object classes " + "or permissions.")); + + /* Get the security class for nscd. If this fails we will likely be + unable to do anything unless avc_deny_unknown is 0. */ + sc_nscd = string_to_security_class ("nscd"); + if (perm == 0 && avc_deny_unknown == 1) + dbg_log (_("Error getting security class for nscd.")); + + /* Convert permission to AVC bits. */ + perm = string_to_av_perm (sc_nscd, perms[req]); + if (perm == 0 && avc_deny_unknown == 1) + dbg_log (_("Error translating permission name " + "\"%s\" to access vector bit."), perms[req]); + + /* If the nscd security class was not found or perms were not + found and AVC does not deny unknown values then allow it. */ + if ((sc_nscd == 0 || perm == 0) && avc_deny_unknown == 0) + return 0; if (getpeercon (fd, &scon) < 0) { @@ -372,15 +403,13 @@ nscd_request_avc_has_perm (int fd, request_type req) goto out; } -#ifndef NSCD__GETSERV - if (perms[req] == 0) - { - dbg_log (_("compile-time support for database policy missing")); - goto out; - } -#endif - - rc = avc_has_perm (ssid, tsid, SECCLASS_NSCD, perms[req], &aeref, NULL) < 0; + /* The SELinux API for avc_has_perm conflates access denied and error into + the return code -1, while nscd_request_avs_has_perm has distinct error + (-1) and denied (1) return codes. We map the avc_has_perm access denied or + error into an access denied at the nscd interface level (we do accurately + report error for the getpeercon, getcon, and avc_context_to_sid interfaces + used above). */ + rc = avc_has_perm (ssid, tsid, sc_nscd, perm, &aeref, NULL) < 0; out: if (scon) |