audit: implement audit by executable

This adds the ability audit the actions of a not-yet-running process.

This patch implements the ability to filter on the executable path.  Instead of
just hard coding the ino and dev of the executable we care about at the moment
the rule is inserted into the kernel, use the new audit_fsnotify
infrastructure to manage this dynamically.  This means that if the filename
does not yet exist but the containing directory does, or if the inode in
question is unlinked and creat'd (aka updated) the rule will just continue to
work.  If the containing directory is moved or deleted or the filesystem is
unmounted, the rule is deleted automatically.  A future enhancement would be to
have the rule survive across directory disruptions.

This is a heavily modified version of a patch originally submitted by Eric
Paris with some ideas from Peter Moody.

Cc: Peter Moody <peter@hda3.com>
Cc: Eric Paris <eparis@redhat.com>
Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
[PM: minor whitespace clean to satisfy ./scripts/checkpatch]
Signed-off-by: Paul Moore <pmoore@redhat.com>

1 files changed, 52 insertions, 1 deletions

diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c
index b4d8c366ec30..7714d93edb85 100644
--- a/kernel/auditfilter.c
+++ b/kernel/auditfilter.c
@@ -405,6 +405,12 @@ static int audit_field_valid(struct audit_entry *entry, struct audit_field *f)
 		if (f->val > AUDIT_MAX_FIELD_COMPARE)
 			return -EINVAL;
 		break;
+	case AUDIT_EXE:
+		if (f->op != Audit_equal)
+			return -EINVAL;
+		if (entry->rule.listnr != AUDIT_FILTER_EXIT)
+			return -EINVAL;
+		break;
 	};
 	return 0;
 }
@@ -419,6 +425,7 @@ static struct audit_entry *audit_data_to_entry(struct audit_rule_data *data,
 	size_t remain = datasz - sizeof(struct audit_rule_data);
 	int i;
 	char *str;
+	struct audit_fsnotify_mark *audit_mark;
 
 	entry = audit_to_entry_common(data);
 	if (IS_ERR(entry))
@@ -539,6 +546,24 @@ static struct audit_entry *audit_data_to_entry(struct audit_rule_data *data,
 			entry->rule.buflen += f->val;
 			entry->rule.filterkey = str;
 			break;
+		case AUDIT_EXE:
+			if (entry->rule.exe || f->val > PATH_MAX)
+				goto exit_free;
+			str = audit_unpack_string(&bufp, &remain, f->val);
+			if (IS_ERR(str)) {
+				err = PTR_ERR(str);
+				goto exit_free;
+			}
+			entry->rule.buflen += f->val;
+
+			audit_mark = audit_alloc_mark(&entry->rule, str, f->val);
+			if (IS_ERR(audit_mark)) {
+				kfree(str);
+				err = PTR_ERR(audit_mark);
+				goto exit_free;
+			}
+			entry->rule.exe = audit_mark;
+			break;
 		}
 	}
 
@@ -551,6 +576,8 @@ exit_nofree:
 exit_free:
 	if (entry->rule.tree)
 		audit_put_tree(entry->rule.tree); /* that's the temporary one */
+	if (entry->rule.exe)
+		audit_remove_mark(entry->rule.exe); /* that's the template one */
 	audit_free_rule(entry);
 	return ERR_PTR(err);
 }
@@ -615,6 +642,10 @@ static struct audit_rule_data *audit_krule_to_data(struct audit_krule *krule)
 			data->buflen += data->values[i] =
 				audit_pack_string(&bufp, krule->filterkey);
 			break;
+		case AUDIT_EXE:
+			data->buflen += data->values[i] =
+				audit_pack_string(&bufp, audit_mark_path(krule->exe));
+			break;
 		case AUDIT_LOGINUID_SET:
 			if (krule->pflags & AUDIT_LOGINUID_LEGACY && !f->val) {
 				data->fields[i] = AUDIT_LOGINUID;
@@ -678,6 +709,12 @@ static int audit_compare_rule(struct audit_krule *a, struct audit_krule *b)
 			if (strcmp(a->filterkey, b->filterkey))
 				return 1;
 			break;
+		case AUDIT_EXE:
+			/* both paths exist based on above type compare */
+			if (strcmp(audit_mark_path(a->exe),
+				   audit_mark_path(b->exe)))
+				return 1;
+			break;
 		case AUDIT_UID:
 		case AUDIT_EUID:
 		case AUDIT_SUID:
@@ -799,8 +836,14 @@ struct audit_entry *audit_dupe_rule(struct audit_krule *old)
 				err = -ENOMEM;
 			else
 				new->filterkey = fk;
+			break;
+		case AUDIT_EXE:
+			err = audit_dupe_exe(new, old);
+			break;
 		}
 		if (err) {
+			if (new->exe)
+				audit_remove_mark(new->exe);
 			audit_free_rule(entry);
 			return ERR_PTR(err);
 		}
@@ -963,6 +1006,9 @@ int audit_del_rule(struct audit_entry *entry)
 	if (e->rule.tree)
 		audit_remove_tree_rule(&e->rule);
 
+	if (e->rule.exe)
+		audit_remove_mark_rule(&e->rule);
+
 #ifdef CONFIG_AUDITSYSCALL
 	if (!dont_count)
 		audit_n_rules--;
@@ -1067,8 +1113,11 @@ int audit_rule_change(int type, __u32 portid, int seq, void *data,
 		WARN_ON(1);
 	}
 
-	if (err || type == AUDIT_DEL_RULE)
+	if (err || type == AUDIT_DEL_RULE) {
+		if (entry->rule.exe)
+			audit_remove_mark(entry->rule.exe);
 		audit_free_rule(entry);
+	}
 
 	return err;
 }
@@ -1360,6 +1409,8 @@ static int update_lsm_rule(struct audit_krule *r)
 		return 0;
 
 	nentry = audit_dupe_rule(r);
+	if (entry->rule.exe)
+		audit_remove_mark(entry->rule.exe);
 	if (IS_ERR(nentry)) {
 		/* save the first error encountered for the
 		 * return value */