@@ -74,6 +74,7 @@ struct common_audit_data {
#define LSM_AUDIT_DATA_FILE 12
#define LSM_AUDIT_DATA_IBPKEY 13
#define LSM_AUDIT_DATA_IBENDPORT 14
+#define LSM_AUDIT_DATA_LOCKDOWN 15
union {
struct path path;
struct dentry *dentry;
@@ -93,6 +94,7 @@ struct common_audit_data {
struct file *file;
struct lsm_ibpkey_audit *ibpkey;
struct lsm_ibendport_audit *ibendport;
+ int reason;
} u;
/* this union contains LSM specific data */
union {
@@ -125,6 +125,8 @@ enum lockdown_reason {
LOCKDOWN_CONFIDENTIALITY_MAX,
};
+extern const char *const lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1];
+
/* These functions are in security/commoncap.c */
extern int cap_capable(const struct cred *cred, struct user_namespace *ns,
int cap, unsigned int opts);
@@ -16,30 +16,6 @@
static enum lockdown_reason kernel_locked_down;
-static 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_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_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_CONFIDENTIALITY_MAX] = "confidentiality",
-};
-
static const enum lockdown_reason lockdown_levels[] = {LOCKDOWN_NONE,
LOCKDOWN_INTEGRITY_MAX,
LOCKDOWN_CONFIDENTIALITY_MAX};
@@ -27,6 +27,7 @@
#include <linux/dccp.h>
#include <linux/sctp.h>
#include <linux/lsm_audit.h>
+#include <linux/security.h>
/**
* ipv4_skb_to_auditdata : fill auditdata from skb
@@ -425,6 +426,10 @@ static void dump_common_audit_data(struct audit_buffer *ab,
a->u.ibendport->dev_name,
a->u.ibendport->port);
break;
+ case LSM_AUDIT_DATA_LOCKDOWN:
+ audit_log_format(ab, " lockdown_reason=");
+ audit_log_string(ab, lockdown_reasons[a->u.reason]);
+ break;
} /* switch (a->type) */
}
@@ -35,6 +35,36 @@
#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_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_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_CONFIDENTIALITY_MAX] = "confidentiality",
+};
+
struct security_hook_heads security_hook_heads __lsm_ro_after_init;
static BLOCKING_NOTIFIER_HEAD(blocking_lsm_notifier_chain);
@@ -6799,6 +6799,34 @@ static void selinux_bpf_prog_free(struct bpf_prog_aux *aux)
}
#endif
+static int selinux_lockdown(enum lockdown_reason what)
+{
+ struct common_audit_data ad;
+ u32 sid = current_sid();
+ int invalid_reason = (what <= LOCKDOWN_NONE) ||
+ (what == LOCKDOWN_INTEGRITY_MAX) ||
+ (what >= LOCKDOWN_CONFIDENTIALITY_MAX);
+
+ if (WARN(invalid_reason, "Invalid lockdown reason")) {
+ audit_log(audit_context(),
+ GFP_ATOMIC, AUDIT_SELINUX_ERR,
+ "lockdown_reason=invalid");
+ return -EINVAL;
+ }
+
+ ad.type = LSM_AUDIT_DATA_LOCKDOWN;
+ ad.u.reason = what;
+
+ if (what <= LOCKDOWN_INTEGRITY_MAX)
+ return avc_has_perm(&selinux_state,
+ sid, sid, SECCLASS_LOCKDOWN,
+ LOCKDOWN__INTEGRITY, &ad);
+ else
+ return avc_has_perm(&selinux_state,
+ sid, sid, SECCLASS_LOCKDOWN,
+ LOCKDOWN__CONFIDENTIALITY, &ad);
+}
+
struct lsm_blob_sizes selinux_blob_sizes __lsm_ro_after_init = {
.lbs_cred = sizeof(struct task_security_struct),
.lbs_file = sizeof(struct file_security_struct),
@@ -7042,6 +7070,8 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = {
LSM_HOOK_INIT(bpf_map_free_security, selinux_bpf_map_free),
LSM_HOOK_INIT(bpf_prog_free_security, selinux_bpf_prog_free),
#endif
+
+ LSM_HOOK_INIT(locked_down, selinux_lockdown),
};
static __init int selinux_init(void)
@@ -244,6 +244,8 @@ struct security_class_mapping secclass_map[] = {
{"map_create", "map_read", "map_write", "prog_load", "prog_run"} },
{ "xdp_socket",
{ COMMON_SOCK_PERMS, NULL } },
+ { "lockdown",
+ { "integrity", "confidentiality", NULL } },
{ NULL }
};
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> --- include/linux/lsm_audit.h | 2 ++ include/linux/security.h | 2 ++ security/lockdown/lockdown.c | 24 ----------------------- security/lsm_audit.c | 5 +++++ security/security.c | 30 +++++++++++++++++++++++++++++ security/selinux/hooks.c | 30 +++++++++++++++++++++++++++++ security/selinux/include/classmap.h | 2 ++ 7 files changed, 71 insertions(+), 24 deletions(-)