audit: clean up AUDIT_GET/SET local variables and future-proof API

Re-named confusing local variable names (status_set and status_get didn't agree
with their command type name) and reduced their scope.

Future-proof API changes by not depending on the exact size of the audit_status
struct and by adding an API version field.

Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Eric Paris <eparis@redhat.com>

diff --git a/include/uapi/linux/audit.h b/include/uapi/linux/audit.h
index e2f0d99..4fdedd4 100644 (file)
--- a/include/uapi/linux/audit.h
+++ b/include/uapi/linux/audit.h
@@ -376,6 +376,7 @@ struct audit_status {
        __u32           backlog_limit;  /* waiting messages limit */
        __u32           lost;           /* messages lost */
        __u32           backlog;        /* messages waiting in queue */
+       __u32           version;        /* audit api version number */
 };
 
 struct audit_features {

diff --git a/kernel/audit.c b/kernel/audit.c
index 833f8e2..80b7de0 100644 (file)
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -743,7 +743,6 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
 {
        u32                     seq;
        void                    *data;
-       struct audit_status     *status_get, status_set;
        int                     err;
        struct audit_buffer     *ab;
        u16                     msg_type = nlh->nlmsg_type;
@@ -769,34 +768,38 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
        data = nlmsg_data(nlh);
 
        switch (msg_type) {
-       case AUDIT_GET:
-               memset(&status_set, 0, sizeof(status_set));
-               status_set.enabled       = audit_enabled;
-               status_set.failure       = audit_failure;
-               status_set.pid           = audit_pid;
-               status_set.rate_limit    = audit_rate_limit;
-               status_set.backlog_limit = audit_backlog_limit;
-               status_set.lost          = atomic_read(&audit_lost);
-               status_set.backlog       = skb_queue_len(&audit_skb_queue);
+       case AUDIT_GET: {
+               struct audit_status     s;
+               memset(&s, 0, sizeof(s));
+               s.enabled               = audit_enabled;
+               s.failure               = audit_failure;
+               s.pid                   = audit_pid;
+               s.rate_limit            = audit_rate_limit;
+               s.backlog_limit         = audit_backlog_limit;
+               s.lost                  = atomic_read(&audit_lost);
+               s.backlog               = skb_queue_len(&audit_skb_queue);
+               s.version               = 1;
                audit_send_reply(NETLINK_CB(skb).portid, seq, AUDIT_GET, 0, 0,
-                                &status_set, sizeof(status_set));
+                                &s, sizeof(s));
                break;
-       case AUDIT_SET:
-               if (nlmsg_len(nlh) < sizeof(struct audit_status))
-                       return -EINVAL;
-               status_get   = (struct audit_status *)data;
-               if (status_get->mask & AUDIT_STATUS_ENABLED) {
-                       err = audit_set_enabled(status_get->enabled);
+       }
+       case AUDIT_SET: {
+               struct audit_status     s;
+               memset(&s, 0, sizeof(s));
+               /* guard against past and future API changes */
+               memcpy(&s, data, min_t(size_t, sizeof(s), nlmsg_len(nlh)));
+               if (s.mask & AUDIT_STATUS_ENABLED) {
+                       err = audit_set_enabled(s.enabled);
                        if (err < 0)
                                return err;
                }
-               if (status_get->mask & AUDIT_STATUS_FAILURE) {
-                       err = audit_set_failure(status_get->failure);
+               if (s.mask & AUDIT_STATUS_FAILURE) {
+                       err = audit_set_failure(s.failure);
                        if (err < 0)
                                return err;
                }
-               if (status_get->mask & AUDIT_STATUS_PID) {
-                       int new_pid = status_get->pid;
+               if (s.mask & AUDIT_STATUS_PID) {
+                       int new_pid = s.pid;
 
                        if (audit_enabled != AUDIT_OFF)
                                audit_log_config_change("audit_pid", new_pid, audit_pid, 1);
@@ -804,14 +807,15 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
                        audit_nlk_portid = NETLINK_CB(skb).portid;
                        audit_sock = NETLINK_CB(skb).sk;
                }
-               if (status_get->mask & AUDIT_STATUS_RATE_LIMIT) {
-                       err = audit_set_rate_limit(status_get->rate_limit);
+               if (s.mask & AUDIT_STATUS_RATE_LIMIT) {
+                       err = audit_set_rate_limit(s.rate_limit);
                        if (err < 0)
                                return err;
                }
-               if (status_get->mask & AUDIT_STATUS_BACKLOG_LIMIT)
-                       err = audit_set_backlog_limit(status_get->backlog_limit);
+               if (s.mask & AUDIT_STATUS_BACKLOG_LIMIT)
+                       err = audit_set_backlog_limit(s.backlog_limit);
                break;
+       }
        case AUDIT_GET_FEATURE:
                err = audit_get_feature(skb);
                if (err)