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From:   Dominick Grift <dominick.grift@defensec.nl>
To:     Russell Coker <russell@coker.com.au>
Cc:     selinux-refpolicy@vger.kernel.org
Subject: Re: another memlockd patch
References: <20200410060317.GB35896@xev>
Date:   Fri, 10 Apr 2020 10:10:57 +0200
In-Reply-To: <20200410060317.GB35896@xev> (Russell Coker's message of "Fri, 10
        Apr 2020 16:03:17 +1000")
Message-ID: <ypjl369bn4ku.fsf@defensec.nl>
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Russell Coker <russell@coker.com.au> writes:

> Signed-off-by: Russell Coker <russell@coker.com.au>
>
> I think this resolves all issues Chris raised.
>
>
> Index: refpolicy-2.20200410/policy/modules/services/memlockd.fc
> ===================================================================
> --- /dev/null
> +++ refpolicy-2.20200410/policy/modules/services/memlockd.fc
> @@ -0,0 +1 @@
> +/usr/sbin/memlockd	--	gen_context(system_u:object_r:memlockd_exec_t,s0)
> Index: refpolicy-2.20200410/policy/modules/services/memlockd.if
> ===================================================================
> --- /dev/null
> +++ refpolicy-2.20200410/policy/modules/services/memlockd.if
> @@ -0,0 +1,2 @@
> +## <summary>memory lock daemon, keeps important files in RAM.</summary>
> +
> Index: refpolicy-2.20200410/policy/modules/services/memlockd.te
> ===================================================================
> --- /dev/null
> +++ refpolicy-2.20200410/policy/modules/services/memlockd.te
> @@ -0,0 +1,37 @@
> +policy_module(memlockd, 1.0.0)
> +
> +########################################
> +#
> +# Declarations
> +#
> +
> +type memlockd_t;
> +type memlockd_exec_t;
> +init_daemon_domain(memlockd_t, memlockd_exec_t)
> +
> +########################################
> +#
> +# Local policy
> +#
> +
> +allow memlockd_t self:capability { setgid setuid ipc_lock };
> +allow memlockd_t self:fifo_file rw_file_perms;
> +allow memlockd_t self:unix_dgram_socket { create connect };

the unix dgram socket creating is probably redundant and implied with
logging_send_logs_msg() as journald uses dgram_sendto for logging?

> +
> +# cache /etc/shadow too
> +auth_read_shadow(memlockd_t)

Hmm since /etc/shadow is mode 000, how is memlock able to read this
without cap_dac_read_search access. is that implied?

> +auth_map_shadow(memlockd_t)
> +
> +corecmd_exec_all_executables(memlockd_t)
> +corecmd_exec_bin(memlockd_t)
> +corecmd_exec_shell(memlockd_t)
> +corecmd_read_all_executables(memlockd_t)
> +corecmd_search_bin(memlockd_t)
> +files_read_etc_files(memlockd_t)
> +libs_exec_ld_so(memlockd_t)
> +files_map_etc_files(memlockd_t)
> +
> +logging_send_syslog_msg(memlockd_t)
> +miscfiles_read_localization(memlockd_t)
> +
> +sysnet_mmap_read_config(memlockd_t)
> Index: refpolicy-2.20200410/policy/modules/system/sysnetwork.if
> ===================================================================
> --- refpolicy-2.20200410.orig/policy/modules/system/sysnetwork.if
> +++ refpolicy-2.20200410/policy/modules/system/sysnetwork.if
> @@ -391,6 +391,31 @@ interface(`sysnet_mmap_config_files',`
>  
>  #######################################
>  ## <summary>
> +##	map network config files.
> +## </summary>
> +## <desc>
> +##	<p>
> +##	Allow the specified domain to mmap the
> +##	general network configuration files.
> +##	</p>
> +## </desc>
> +## <param name="domain">
> +##	<summary>
> +##	Domain allowed access.
> +##	</summary>
> +## </param>
> +#
> +interface(`sysnet_mmap_read_config',`
> +	gen_require(`
> +		type net_conf_t;
> +	')
> +
> +	files_search_etc($1)
> +	allow $1 net_conf_t:file mmap_read_file_perms;
> +')
> +
> +#######################################
> +## <summary>
>  ##	Do not audit attempts to read network config files.
>  ## </summary>
>  ## <param name="domain">
> Index: refpolicy-2.20200410/policy/modules/system/authlogin.if
> ===================================================================
> --- refpolicy-2.20200410.orig/policy/modules/system/authlogin.if
> +++ refpolicy-2.20200410/policy/modules/system/authlogin.if
> @@ -577,6 +577,23 @@ interface(`auth_read_shadow',`
>  
>  ########################################
>  ## <summary>
> +##	Map the shadow passwords file (/etc/shadow)
> +## </summary>
> +## <param name="domain">
> +##	<summary>
> +##	Domain allowed access.
> +##	</summary>
> +## </param>
> +#
> +interface(`auth_map_shadow',`
> +	gen_require(`
> +		type shadow_t;
> +	')
> +	allow $1 shadow_t:file map;
> +')
> +
> +########################################
> +## <summary>
>  ##	Pass shadow assertion for reading.
>  ## </summary>
>  ## <desc>

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Dominick Grift