[refpolicy] [PATCH 1/1] Interface to read /run/systemd/resolve/resolv.conf

[refpolicy] [PATCH 1/1] Interface to read /run/systemd/resolve/resolv.conf

[Dave Sugar]

With systemd /etc/resolv.conf is a symlink to /run/systemd/resolve/resolv.conf allow domains with access to DNS lookup to read this file.

I was seeing the following denials when using DNS.  This should resolve the problem on the whole system.
type=AVC msg=audit(1523455881.596:214): avc:  denied  { search } for  pid=944 comm="chronyd" name="resolve" dev="tmpfs" ino=14267 scontext=system_u:system_r:chronyd_t:s0 tcontext=system_u:object_r:systemd_resolved_var_run_t:s0 tclass=dir
type=AVC msg=audit(1523455881.596:214): avc:  denied  { read } for  pid=944 comm="chronyd" name="resolv.conf" dev="tmpfs" ino=14277 scontext=system_u:system_r:chronyd_t:s0 tcontext=system_u:object_r:systemd_resolved_var_run_t:s0 tclass=file
type=AVC msg=audit(1523455881.596:214): avc:  denied  { open } for  pid=944 comm="chronyd" path="/run/systemd/resolve/resolv.conf" dev="tmpfs" ino=14277 scontext=system_u:system_r:chronyd_t:s0 tcontext=system_u:object_r:systemd_resolved_var_run_t:s0 tclass=file
type=AVC msg=audit(1523455881.596:215): avc:  denied  { getattr } for  pid=944 comm="chronyd" path="/run/systemd/resolve/resolv.conf" dev="tmpfs" ino=14277 scontext=system_u:system_r:chronyd_t:s0 tcontext=system_u:object_r:systemd_resolved_var_run_t:s0 tclass=file

Signed-off-by: Dave Sugar <dsugar@tresys.com>
---
 policy/modules/system/sysnetwork.if |  1 +
 policy/modules/system/systemd.if    | 18 ++++++++++++++++++
 2 files changed, 19 insertions(+)

diff --git a/policy/modules/system/sysnetwork.if b/policy/modules/system/sysnetwork.if
index a53122b1..d7cef330 100644
--- a/policy/modules/system/sysnetwork.if
+++ b/policy/modules/system/sysnetwork.if
@@ -755,6 +755,7 @@ interface(`sysnet_dns_name_resolve',`
 	# This seems needed when the mymachines NSS module is used
 	optional_policy(`
 		systemd_read_machines($1)
+		systemd_resolved_read_resolv($1)
 	')
 ')
 
diff --git a/policy/modules/system/systemd.if b/policy/modules/system/systemd.if
index f6e34102..e0065ef5 100644
--- a/policy/modules/system/systemd.if
+++ b/policy/modules/system/systemd.if
@@ -715,3 +715,21 @@ interface(`systemd_tmpfilesd_managed',`
 
 	allow systemd_tmpfiles_t $1:$2 { setattr relabelfrom relabelto create };
 ')
+
+#######################################
+## <summary>
+##  Allow domain to read resolv.conf file generated by systemd_resolved
+## </summary>
+## <param name="domain">
+## <summary>
+##  domain allowed access
+## </summary>
+## </param>
+#
+interface(`systemd_resolved_read_resolv',`
+	gen_require(`
+		type systemd_resolved_var_run_t;
+	')
+
+	read_files_pattern($1, systemd_resolved_var_run_t, systemd_resolved_var_run_t)
+')
-- 
2.14.3

[refpolicy] [PATCH 1/1] Interface to read /run/systemd/resolve/resolv.conf

[Chris PeBenito]

On 04/11/2018 05:35 PM, Dave Sugar via refpolicy wrote:
> With systemd /etc/resolv.conf is a symlink to /run/systemd/resolve/resolv.conf allow domains with access to DNS lookup to read this file.
> 
> I was seeing the following denials when using DNS.  This should resolve the problem on the whole system.
> type=AVC msg=audit(1523455881.596:214): avc:  denied  { search } for  pid=944 comm="chronyd" name="resolve" dev="tmpfs" ino=14267 scontext=system_u:system_r:chronyd_t:s0 tcontext=system_u:object_r:systemd_resolved_var_run_t:s0 tclass=dir
> type=AVC msg=audit(1523455881.596:214): avc:  denied  { read } for  pid=944 comm="chronyd" name="resolv.conf" dev="tmpfs" ino=14277 scontext=system_u:system_r:chronyd_t:s0 tcontext=system_u:object_r:systemd_resolved_var_run_t:s0 tclass=file
> type=AVC msg=audit(1523455881.596:214): avc:  denied  { open } for  pid=944 comm="chronyd" path="/run/systemd/resolve/resolv.conf" dev="tmpfs" ino=14277 scontext=system_u:system_r:chronyd_t:s0 tcontext=system_u:object_r:systemd_resolved_var_run_t:s0 tclass=file
> type=AVC msg=audit(1523455881.596:215): avc:  denied  { getattr } for  pid=944 comm="chronyd" path="/run/systemd/resolve/resolv.conf" dev="tmpfs" ino=14277 scontext=system_u:system_r:chronyd_t:s0 tcontext=system_u:object_r:systemd_resolved_var_run_t:s0 tclass=file
> 
> Signed-off-by: Dave Sugar <dsugar@tresys.com>
> ---
>   policy/modules/system/sysnetwork.if |  1 +
>   policy/modules/system/systemd.if    | 18 ++++++++++++++++++
>   2 files changed, 19 insertions(+)
> 
> diff --git a/policy/modules/system/sysnetwork.if b/policy/modules/system/sysnetwork.if
> index a53122b1..d7cef330 100644
> --- a/policy/modules/system/sysnetwork.if
> +++ b/policy/modules/system/sysnetwork.if
> @@ -755,6 +755,7 @@ interface(`sysnet_dns_name_resolve',`
>   	# This seems needed when the mymachines NSS module is used
>   	optional_policy(`
>   		systemd_read_machines($1)
> +		systemd_resolved_read_resolv($1)

This should probably be part of sysnet_read_config instead.

>   	')
>   ')
>   
> diff --git a/policy/modules/system/systemd.if b/policy/modules/system/systemd.if
> index f6e34102..e0065ef5 100644
> --- a/policy/modules/system/systemd.if
> +++ b/policy/modules/system/systemd.if
> @@ -715,3 +715,21 @@ interface(`systemd_tmpfilesd_managed',`
>   
>   	allow systemd_tmpfiles_t $1:$2 { setattr relabelfrom relabelto create };
>   ')
> +
> +#######################################
> +## <summary>
> +##  Allow domain to read resolv.conf file generated by systemd_resolved
> +## </summary>
> +## <param name="domain">
> +## <summary>
> +##  domain allowed access
> +## </summary>
> +## </param>
> +#
> +interface(`systemd_resolved_read_resolv',`

systemd_read_resolved_runtime()


> +	gen_require(`
> +		type systemd_resolved_var_run_t;
> +	')
> +
> +	read_files_pattern($1, systemd_resolved_var_run_t, systemd_resolved_var_run_t)
> +')
> 


-- 
Chris PeBenito