path: root/security/security.c
diff options
authorStephen Smalley <sds@tycho.nsa.gov>2019-11-27 12:04:36 -0500
committerPaul Moore <paul@paul-moore.com>2019-12-09 17:53:58 -0500
commit59438b46471ae6cdfb761afc8c9beaf1e428a331 (patch)
treebfec7832e21f7704e4ec7a0f5e50b95813c5caa7 /security/security.c
parentselinux: cache the SID -> context string translation (diff)
security,lockdown,selinux: implement SELinux lockdown
Implement a SELinux hook for lockdown. If the lockdown module is also enabled, then a denial by the lockdown module will take precedence over SELinux, so SELinux can only further restrict lockdown decisions. The SELinux hook only distinguishes at the granularity of integrity versus confidentiality similar to the lockdown module, but includes the full lockdown reason as part of the audit record as a hint in diagnosing what triggered the denial. To support this auditing, move the lockdown_reasons[] string array from being private to the lockdown module to the security framework so that it can be used by the lsm audit code and so that it is always available even when the lockdown module is disabled. Note that the SELinux implementation allows the integrity and confidentiality reasons to be controlled independently from one another. Thus, in an SELinux policy, one could allow operations that specify an integrity reason while blocking operations that specify a confidentiality reason. The SELinux hook implementation is stricter than the lockdown module in validating the provided reason value. Sample AVC audit output from denials: avc: denied { integrity } for pid=3402 comm="fwupd" lockdown_reason="/dev/mem,kmem,port" scontext=system_u:system_r:fwupd_t:s0 tcontext=system_u:system_r:fwupd_t:s0 tclass=lockdown permissive=0 avc: denied { confidentiality } for pid=4628 comm="cp" lockdown_reason="/proc/kcore access" scontext=unconfined_u:unconfined_r:test_lockdown_integrity_t:s0-s0:c0.c1023 tcontext=unconfined_u:unconfined_r:test_lockdown_integrity_t:s0-s0:c0.c1023 tclass=lockdown permissive=0 Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov> Reviewed-by: James Morris <jamorris@linux.microsoft.com> [PM: some merge fuzz do the the perf hooks] Signed-off-by: Paul Moore <paul@paul-moore.com>
Diffstat (limited to 'security/security.c')
1 files changed, 33 insertions, 0 deletions
diff --git a/security/security.c b/security/security.c
index cd2d18d2d279..2b5473d92416 100644
--- a/security/security.c
+++ b/security/security.c
@@ -35,6 +35,39 @@
#define LSM_COUNT (__end_lsm_info - __start_lsm_info)
#define EARLY_LSM_COUNT (__end_early_lsm_info - __start_early_lsm_info)
+ * These are descriptions of the reasons that can be passed to the
+ * security_locked_down() LSM hook. Placing this array here allows
+ * all security modules to use the same descriptions for auditing
+ * purposes.
+ */
+const char *const lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
+ [LOCKDOWN_NONE] = "none",
+ [LOCKDOWN_MODULE_SIGNATURE] = "unsigned module loading",
+ [LOCKDOWN_DEV_MEM] = "/dev/mem,kmem,port",
+ [LOCKDOWN_EFI_TEST] = "/dev/efi_test access",
+ [LOCKDOWN_KEXEC] = "kexec of unsigned images",
+ [LOCKDOWN_HIBERNATION] = "hibernation",
+ [LOCKDOWN_PCI_ACCESS] = "direct PCI access",
+ [LOCKDOWN_IOPORT] = "raw io port access",
+ [LOCKDOWN_MSR] = "raw MSR access",
+ [LOCKDOWN_ACPI_TABLES] = "modifying ACPI tables",
+ [LOCKDOWN_PCMCIA_CIS] = "direct PCMCIA CIS storage",
+ [LOCKDOWN_TIOCSSERIAL] = "reconfiguration of serial port IO",
+ [LOCKDOWN_MODULE_PARAMETERS] = "unsafe module parameters",
+ [LOCKDOWN_MMIOTRACE] = "unsafe mmio",
+ [LOCKDOWN_DEBUGFS] = "debugfs access",
+ [LOCKDOWN_XMON_WR] = "xmon write access",
+ [LOCKDOWN_INTEGRITY_MAX] = "integrity",
+ [LOCKDOWN_KCORE] = "/proc/kcore access",
+ [LOCKDOWN_KPROBES] = "use of kprobes",
+ [LOCKDOWN_BPF_READ] = "use of bpf to read kernel RAM",
+ [LOCKDOWN_PERF] = "unsafe use of perf",
+ [LOCKDOWN_TRACEFS] = "use of tracefs",
+ [LOCKDOWN_XMON_RW] = "xmon read and write access",
+ [LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
struct security_hook_heads security_hook_heads __lsm_ro_after_init;
static BLOCKING_NOTIFIER_HEAD(blocking_lsm_notifier_chain);