[PATCH v24 23/25] Audit: Add a new record for multiple object LSM attributes

Casey Schaufler
2021-01-27T00:20:38Z

Create a new audit record type to contain the object information
when there are multiple security modules that may require such data.
This record is linked with the same timestamp and serial number.

An example of the MAC_OBJ_CONTEXTS (1421) record is:

type=UNKNOWN[1421]
msg=audit(1601152467.009:1050):
obj_selinux=unconfined_u:object_r:user_home_t:s0

Not all security modules that can provide object information
do so in all cases. It is possible that a security module won't
apply an object attribute in all cases.

Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Cc: linux-audit@redhat.com
To: Paul Moore <paul@paul-moore.com>
---
include/linux/audit.h | 7 ++++
include/uapi/linux/audit.h | 1 +
kernel/audit.c | 53 +++++++++++++++++++++++++++
kernel/audit.h | 4 +--
kernel/auditsc.c | 73 +++++++-------------------------------
5 files changed, 75 insertions(+), 63 deletions(-)

diff --git a/include/linux/audit.h b/include/linux/audit.h
index 229cd71fbf09..b92ad58bc97d 100644
--- a/include/linux/audit.h
+++ b/include/linux/audit.h
@@ -189,6 +189,8 @@ extern void audit_log_path_denied(int type,
extern void audit_log_lost(const char *message);

extern int audit_log_task_context(struct audit_buffer *ab);
+extern int audit_log_object_context(struct audit_buffer *ab,
+ struct lsmblob *blob);
extern void audit_log_task_info(struct audit_buffer *ab);
extern void audit_log_lsm(struct audit_context *context);

@@ -256,6 +258,11 @@ static inline int audit_log_task_context(struct audit_buffer *ab)
{
return 0;
}
+static inline int audit_log_object_context(struct audit_buffer *ab,
+ struct lsmblob *blob)
+{
+ return 0;
+}
static inline void audit_log_task_info(struct audit_buffer *ab)
{ }
static void audit_log_lsm(struct audit_context *context)
diff --git a/include/uapi/linux/audit.h b/include/uapi/linux/audit.h
index 2a63720e56f6..dbb1dce16962 100644
--- a/include/uapi/linux/audit.h
+++ b/include/uapi/linux/audit.h
@@ -140,6 +140,7 @@
#define AUDIT_MAC_CALIPSO_ADD 1418 /* NetLabel: add CALIPSO DOI entry */
#define AUDIT_MAC_CALIPSO_DEL 1419 /* NetLabel: del CALIPSO DOI entry */
#define AUDIT_MAC_TASK_CONTEXTS 1420 /* Multiple LSM contexts */
+#define AUDIT_MAC_OBJ_CONTEXTS 1421 /* Multiple LSM object contexts */

#define AUDIT_FIRST_KERN_ANOM_MSG 1700
#define AUDIT_LAST_KERN_ANOM_MSG 1799
diff --git a/kernel/audit.c b/kernel/audit.c
index 732ce576ed89..357b652339cf 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -2171,6 +2171,59 @@ int audit_log_task_context(struct audit_buffer *ab)
}
EXPORT_SYMBOL(audit_log_task_context);

+int audit_log_object_context(struct audit_buffer *ab,
+ struct lsmblob *blob)
+{
+ int i;
+ int error;
+ bool sep = false;
+ struct lsmcontext lsmdata;
+ struct audit_buffer *lsmab = NULL;
+ struct audit_context *context = NULL;
+
+ /*
+ * If there is more than one security module that has a
+ * object "context" it's necessary to put the object data
+ * into a separate record to maintain compatibility.
+ */
+ if (lsm_multiple_contexts()) {
+ audit_log_format(ab, " obj=?");
+ context = ab->ctx;
+ if (context)
+ lsmab = audit_log_start(context, GFP_KERNEL,
+ AUDIT_MAC_OBJ_CONTEXTS);
+ }
+
+ for (i = 0; i < LSMBLOB_ENTRIES; i++) {
+ if (blob->secid[i] == 0)
+ continue;
+ error = security_secid_to_secctx(blob, &lsmdata, i);
+ if (error && error != -EINVAL) {
+ audit_panic("error in audit_log_object_context");
+ return error;
+ }
+
+ if (context) {
+ audit_log_format(lsmab, "%sobj_%s=%s",
+ sep ? " " : "",
+ lsm_slot_to_name(i),
+ lsmdata.context);
+ sep = true;
+ } else
+ audit_log_format(ab, " obj=%s", lsmdata.context);
+
+ security_release_secctx(&lsmdata);
+ if (!context)
+ break;
+ }
+
+ if (context)
+ audit_log_end(lsmab);
+
+ return 0;
+}
+EXPORT_SYMBOL(audit_log_object_context);
+
void audit_log_d_path_exe(struct audit_buffer *ab,
struct mm_struct *mm)
{
diff --git a/kernel/audit.h b/kernel/audit.h
index 4f245c3dac0c..c65f40a1d308 100644
--- a/kernel/audit.h
+++ b/kernel/audit.h
@@ -78,7 +78,7 @@ struct audit_names {
kuid_t uid;
kgid_t gid;
dev_t rdev;
- u32 osid;
+ struct lsmblob oblob;
struct audit_cap_data fcap;
unsigned int fcap_ver;
unsigned char type; /* record type */
@@ -155,7 +155,7 @@ struct audit_context {
kuid_t uid;
kgid_t gid;
umode_t mode;
- u32 osid;
+ struct lsmblob oblob;
int has_perm;
uid_t perm_uid;
gid_t perm_gid;
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 376adae15a9d..e7c204039264 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -686,14 +686,6 @@ static int audit_filter_rules(struct task_struct *tsk,
if (f->lsm_isset) {
/* Find files that match */
if (name) {
- /*
- * lsmblob_init sets all values in the
- * lsmblob to sid. This is temporary
- * until name->osid is converted to a
- * lsmblob, which happens later in
- * this patch set.
- */
- lsmblob_init(&blob, name->osid);
result = security_audit_rule_match(
&blob,
f->type,
@@ -701,7 +693,6 @@ static int audit_filter_rules(struct task_struct *tsk,
f->lsm_rules);
} else if (ctx) {
list_for_each_entry(n, &ctx->names_list, list) {
- lsmblob_init(&blob, name->osid);
if (security_audit_rule_match(
&blob,
f->type,
@@ -715,8 +706,7 @@ static int audit_filter_rules(struct task_struct *tsk,
/* Find ipc objects that match */
if (!ctx || ctx->type != AUDIT_IPC)
break;
- lsmblob_init(&blob, ctx->ipc.osid);
- if (security_audit_rule_match(&blob,
+ if (security_audit_rule_match(&ctx->ipc.oblob,
f->type, f->op,
f->lsm_rules))
++result;
@@ -1028,7 +1018,6 @@ static int audit_log_pid_context(struct audit_context *context, pid_t pid,
struct lsmblob *blob, char *comm)
{
struct audit_buffer *ab;
- struct lsmcontext lsmctx;
int rc = 0;

ab = audit_log_start(context, GFP_KERNEL, AUDIT_OBJ_PID);
@@ -1038,15 +1027,8 @@ static int audit_log_pid_context(struct audit_context *context, pid_t pid,
audit_log_format(ab, "opid=%d oauid=%d ouid=%d oses=%d", pid,
from_kuid(&init_user_ns, auid),
from_kuid(&init_user_ns, uid), sessionid);
- if (lsmblob_is_set(blob)) {
- if (security_secid_to_secctx(blob, &lsmctx, LSMBLOB_FIRST)) {
- audit_log_format(ab, " obj=(none)");
- rc = 1;
- } else {
- audit_log_format(ab, " obj=%s", lsmctx.context);
- security_release_secctx(&lsmctx);
- }
- }
+ if (lsmblob_is_set(blob))
+ rc = audit_log_object_context(ab, blob);
audit_log_format(ab, " ocomm=");
audit_log_untrustedstring(ab, comm);
audit_log_end(ab);
@@ -1273,26 +1255,15 @@ static void show_special(struct audit_context *context, int *call_panic)
context->socketcall.args[i]);
break; }
case AUDIT_IPC: {
- u32 osid = context->ipc.osid;
+ struct lsmblob *oblob = &context->ipc.oblob;

audit_log_format(ab, "ouid=%u ogid=%u mode=%#ho",
from_kuid(&init_user_ns, context->ipc.uid),
from_kgid(&init_user_ns, context->ipc.gid),
context->ipc.mode);
- if (osid) {
- struct lsmcontext lsmcxt;
- struct lsmblob blob;
-
- lsmblob_init(&blob, osid);
- if (security_secid_to_secctx(&blob, &lsmcxt,
- LSMBLOB_FIRST)) {
- audit_log_format(ab, " osid=%u", osid);
- *call_panic = 1;
- } else {
- audit_log_format(ab, " obj=%s", lsmcxt.context);
- security_release_secctx(&lsmcxt);
- }
- }
+ if (lsmblob_is_set(oblob) &&
+ audit_log_object_context(ab, oblob))
+ *call_panic = 1;
if (context->ipc.has_perm) {
audit_log_end(ab);
ab = audit_log_start(context, GFP_KERNEL,
@@ -1435,20 +1406,9 @@ static void audit_log_name(struct audit_context *context, struct audit_names *n,
from_kgid(&init_user_ns, n->gid),
MAJOR(n->rdev),
MINOR(n->rdev));
- if (n->osid != 0) {
- struct lsmblob blob;
- struct lsmcontext lsmctx;
-
- lsmblob_init(&blob, n->osid);
- if (security_secid_to_secctx(&blob, &lsmctx, LSMBLOB_FIRST)) {
- audit_log_format(ab, " osid=%u", n->osid);
- if (call_panic)
- *call_panic = 2;
- } else {
- audit_log_format(ab, " obj=%s", lsmctx.context);
- security_release_secctx(&lsmctx);
- }
- }
+ if (lsmblob_is_set(&n->oblob) &&
+ audit_log_object_context(ab, &n->oblob) && call_panic)
+ *call_panic = 2;

/* log the audit_names record type */
switch (n->type) {
@@ -2038,17 +1998,13 @@ static void audit_copy_inode(struct audit_names *name,
const struct dentry *dentry,
struct inode *inode, unsigned int flags)
{
- struct lsmblob blob;
-
name->ino = inode->i_ino;
name->dev = inode->i_sb->s_dev;
name->mode = inode->i_mode;
name->uid = inode->i_uid;
name->gid = inode->i_gid;
name->rdev = inode->i_rdev;
- security_inode_getsecid(inode, &blob);
- /* scaffolding until osid is updated */
- name->osid = blob.secid[0];
+ security_inode_getsecid(inode, &name->oblob);
if (flags & AUDIT_INODE_NOEVAL) {
name->fcap_ver = -1;
return;
@@ -2394,16 +2350,11 @@ void __audit_mq_getsetattr(mqd_t mqdes, struct mq_attr *mqstat)
void __audit_ipc_obj(struct kern_ipc_perm *ipcp)
{
struct audit_context *context = audit_context();
- struct lsmblob blob;
context->ipc.uid = ipcp->uid;
context->ipc.gid = ipcp->gid;
context->ipc.mode = ipcp->mode;
context->ipc.has_perm = 0;
- security_ipc_getsecid(ipcp, &blob);
- /* context->ipc.osid will be changed to a lsmblob later in
- * the patch series. This will allow auditing of all the object
- * labels associated with the ipc object. */
- context->ipc.osid = lsmblob_value(&blob);
+ security_ipc_getsecid(ipcp, &context->ipc.oblob);
context->type = AUDIT_IPC;
}

--
2.25.4