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Resolves: #1025126

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- Enhance NSCD's SELinux support to use dynamic permission names (#1025126).
This commit is contained in:
Carlos O'Donell 2013-11-09 02:15:56 -05:00
parent 56999f00cc
commit 91f5f14b93
2 changed files with 143 additions and 1 deletions
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135
glibc-rh1025126.patch Normal file
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@ -0,0 +1,135 @@
diff --git a/nscd/selinux.c b/nscd/selinux.c
index 0866c44..ba55b04 100644
--- a/nscd/selinux.c
+++ b/nscd/selinux.c
@@ -44,35 +44,31 @@
/* 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 +340,18 @@ 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.
+
+ Implementation note:
+ 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 fist.
+ Instead we use symbolic mappings instead of compile time
+ constants (which selinux upstream says are going away), and 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 +361,33 @@ 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 = 0;
+ access_vector_t perm = 0;
+ int avc_deny_unknown = 0;
+
+ /* 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. */
+ if ((sc_nscd = string_to_security_class ("nscd")) == 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 +406,7 @@ 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;
+ rc = avc_has_perm (ssid, tsid, sc_nscd, perm, &aeref, NULL) < 0;
out:
if (scon)

9
glibc.spec
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@ -1,6 +1,6 @@
%define glibcsrcdir glibc-2.18-332-gb125d3e %define glibcsrcdir glibc-2.18-332-gb125d3e
%define glibcversion 2.18.90 %define glibcversion 2.18.90
%define glibcrelease 13%{?dist} %define glibcrelease 14%{?dist}
# Pre-release tarballs are pulled in from git using a command that is # Pre-release tarballs are pulled in from git using a command that is
# effectively: # effectively:
# #
@ -211,6 +211,9 @@ Patch2026: %{name}-rh841787.patch
# Upstream BZ 14185 # Upstream BZ 14185
Patch2027: %{name}-rh819430.patch Patch2027: %{name}-rh819430.patch
# Fix nscd to use permission names not constants.
Patch2028: %{name}-rh1025126.patch
############################################################################## ##############################################################################
# End of glibc patches. # End of glibc patches.
############################################################################## ##############################################################################
@ -535,6 +538,7 @@ package or when debugging this package.
%patch0043 -p1 %patch0043 -p1
%patch0044 -p1 %patch0044 -p1
%patch0046 -p1 %patch0046 -p1
%patch2028 -p1
############################################################################## ##############################################################################
# %%prep - Additional prep required... # %%prep - Additional prep required...
@ -1620,6 +1624,9 @@ rm -f *.filelist*
%endif %endif
%changelog %changelog
* Fri Nov 8 2013 Carlos O'Donell <carlos@redhat.com> - 2.18.90-14
- Enhance NSCD's SELinux support to use dynamic permission names (#1025126).
* Mon Oct 28 2013 Siddhesh Poyarekar <siddhesh@redhat.com> - 2.18.90-13 * Mon Oct 28 2013 Siddhesh Poyarekar <siddhesh@redhat.com> - 2.18.90-13
- Sync with upstream master. - Sync with upstream master.
- Skip over unimplemented timezone format specifier in strptime (#947722). - Skip over unimplemented timezone format specifier in strptime (#947722).