On 4/8/19 12:19 PM, Lukas Vrabec wrote:
CRIU can influence the PID of the threads it wants to create.
CRIU uses /proc/sys/kernel/ns_last_pidto tell the kernel which
PID it wants for the next clone().
So it has to write to that file. This feels like a problematic as
it opens up the container writing to all sysctl_kernel_t.
Using new label container_t will just write to
sysctl_kernel_ns_last_pid_t instad writing to more generic
sysctl_kernel_t files.
---
policy/modules/kernel/kernel.if | 60 +++++++++++++++++++++++++++++++++
policy/modules/kernel/kernel.te | 7 ++++
2 files changed, 67 insertions(+)
diff --git a/policy/modules/kernel/kernel.if b/policy/modules/kernel/kernel.if
index 1ad282aa..3f0a2dbe 100644
--- a/policy/modules/kernel/kernel.if
+++ b/policy/modules/kernel/kernel.if
@@ -2150,6 +2150,66 @@ interface(`kernel_mounton_kernel_sysctl_files',`
allow $1 sysctl_kernel_t:file { getattr mounton };
')
+########################################
+## <summary>
+## Read kernel ns lastpid sysctls.
+## </summary>
+## <param name="domain">
+## <summary>
+## Domain allowed access.
+## </summary>
+## </param>
+## <rolecap/>
+#
+interface(`kernel_read_kernel_ns_lastpid_sysctls',`
+ gen_require(`
+ type proc_t, sysctl_t, sysctl_kernel_ns_last_pid_t;
+ ')
+
+ read_files_pattern($1, { proc_t sysctl_t sysctl_kernel_ns_last_pid_t }, sysctl_kernel_ns_last_pid_t)
+
+ list_dirs_pattern($1, { proc_t sysctl_t }, sysctl_kernel_ns_last_pid_t)
+')
+
+########################################
+## <summary>
+## Do not audit attempts to write kernel ns lastpid sysctls.
+## </summary>
+## <param name="domain">
+## <summary>
+## Domain to not audit.
+## </summary>
+## </param>
+#
+interface(`kernel_dontaudit_write_kernel_ns_lastpid_sysctl',`
+ gen_require(`
+ type sysctl_kernel_ns_last_pid_t;
+ ')
+
+ dontaudit $1 sysctl_kernel_ns_last_pid_t:file write;
+')
+
+########################################
+## <summary>
+## Read and write kernel ns lastpid sysctls.
+## </summary>
+## <param name="domain">
+## <summary>
+## Domain allowed access.
+## </summary>
+## </param>
+## <rolecap/>
+#
+interface(`kernel_rw_kernel_ns_lastpid_sysctl',`
+ gen_require(`
+ type proc_t, sysctl_t, sysctl_kernel_ns_last_pid_t;
+ ')
+
+ rw_files_pattern($1, { proc_t sysctl_t sysctl_kernel_ns_last_pid_t }, sysctl_kernel_ns_last_pid_t)
+
+ list_dirs_pattern($1, { proc_t sysctl_t }, sysctl_kernel_ns_last_pid_t)
+')
+
########################################
## <summary>
## Search filesystem sysctl directories.
diff --git a/policy/modules/kernel/kernel.te b/policy/modules/kernel/kernel.te
index 8e958074..f5ec1c22 100644
--- a/policy/modules/kernel/kernel.te
+++ b/policy/modules/kernel/kernel.te
@@ -132,6 +132,11 @@ genfscon proc /sys/fs gen_context(system_u:object_r:sysctl_fs_t,s0)
type sysctl_kernel_t, sysctl_type;
genfscon proc /sys/kernel gen_context(system_u:object_r:sysctl_kernel_t,s0)
+# /sys/kernel/ns_last_pid file
+type sysctl_kernel_ns_last_pid_t, sysctl_type;
+fs_associate(sysctl_kernel_ns_last_pid_t)
Is this associate really necessary? It's not used for any other sysctls.
+genfscon proc /sys/kernel/ns_last_pid gen_context(system_u:object_r:sysctl_kernel_ns_last_pid_t,s0)
+
# /proc/sys/kernel/modprobe file
type sysctl_modprobe_t, sysctl_type;
genfscon proc /sys/kernel/modprobe gen_context(system_u:object_r:sysctl_modprobe_t,s0)
@@ -232,6 +237,8 @@ allow kernel_t sysctl_kernel_t:dir list_dir_perms;
allow kernel_t sysctl_kernel_t:file read_file_perms;
allow kernel_t sysctl_t:dir list_dir_perms;
+allow kernel_t sysctl_kernel_ns_last_pid_t:file read_file_perms;
+
# Other possible mount points for the root fs are in files
allow kernel_t unlabeled_t:dir mounton;
# Kernel-generated traffic e.g., TCP resets on
--
Chris PeBenito
