drbd: Also need to check for DRBD_GENLA_F_MANDATORY flags before nla_find_nested()

This is done by introducing drbd_nla_find_nested() which handles the flag
before calling nla_find_nested().

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>

1 files changed, 76 insertions, 20 deletions

diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c
index 5b4090f52f5a..24187f1c93d5 100644
--- a/drivers/block/drbd/drbd_nl.c
+++ b/drivers/block/drbd/drbd_nl.c
@@ -92,7 +92,7 @@ static struct drbd_config_context {
 #define VOLUME_UNSPECIFIED              (-1U)
         /* pointer into the request skb,
          * limited lifetime! */
-        char *conn_name;
+        char *resource_name;
 
         /* reply buffer */
         struct sk_buff *reply_skb;
@@ -191,15 +191,15 @@ static int drbd_adm_prepare(struct sk_buff *skb, struct genl_info *info,
                 /* and assign stuff to the global adm_ctx */
                 nla = nested_attr_tb[__nla_type(T_ctx_volume)];
                 adm_ctx.volume = nla ? nla_get_u32(nla) : VOLUME_UNSPECIFIED;
-                nla = nested_attr_tb[__nla_type(T_ctx_conn_name)];
+                nla = nested_attr_tb[__nla_type(T_ctx_resource_name)];
                 if (nla)
-                        adm_ctx.conn_name = nla_data(nla);
+                        adm_ctx.resource_name = nla_data(nla);
         } else
                 adm_ctx.volume = VOLUME_UNSPECIFIED;
 
         adm_ctx.minor = d_in->minor;
         adm_ctx.mdev = minor_to_mdev(d_in->minor);
-        adm_ctx.tconn = conn_get_by_name(adm_ctx.conn_name);
+        adm_ctx.tconn = conn_get_by_name(adm_ctx.resource_name);
 
         if (!adm_ctx.mdev && (flags & DRBD_ADM_NEED_MINOR)) {
                 drbd_msg_put_info("unknown minor");
@@ -214,7 +214,8 @@ static int drbd_adm_prepare(struct sk_buff *skb, struct genl_info *info,
         if (adm_ctx.mdev && adm_ctx.tconn &&
             adm_ctx.mdev->tconn != adm_ctx.tconn) {
                 pr_warning("request: minor=%u, conn=%s; but that minor belongs to connection %s\n",
-                                adm_ctx.minor, adm_ctx.conn_name, adm_ctx.mdev->tconn->name);
+                                adm_ctx.minor, adm_ctx.resource_name,
+                                adm_ctx.mdev->tconn->name);
                 drbd_msg_put_info("minor exists in different connection");
                 return ERR_INVALID_REQUEST;
         }
@@ -239,7 +240,7 @@ fail:
 static int drbd_adm_finish(struct genl_info *info, int retcode)
 {
         struct nlattr *nla;
-        const char *conn_name = NULL;
+        const char *resource_name = NULL;
 
         if (adm_ctx.tconn) {
                 kref_put(&adm_ctx.tconn->kref, &conn_destroy);
@@ -253,9 +254,10 @@ static int drbd_adm_finish(struct genl_info *info, int retcode)
 
         nla = info->attrs[DRBD_NLA_CFG_CONTEXT];
         if (nla) {
-                nla = nla_find_nested(nla, __nla_type(T_ctx_conn_name));
-                if (nla)
-                        conn_name = nla_data(nla);
+                int maxtype = ARRAY_SIZE(drbd_cfg_context_nl_policy) - 1;
+                nla = drbd_nla_find_nested(maxtype, nla, __nla_type(T_ctx_resource_name));
+                if (nla && !IS_ERR(nla))
+                        resource_name = nla_data(nla);
         }
 
         drbd_adm_send_reply(adm_ctx.reply_skb, info);
@@ -2526,7 +2528,7 @@ int drbd_adm_outdate(struct sk_buff *skb, struct genl_info *info)
         return drbd_adm_simple_request_state(skb, info, NS(disk, D_OUTDATED));
 }
 
-int nla_put_drbd_cfg_context(struct sk_buff *skb, const char *conn_name, unsigned vnr)
+int nla_put_drbd_cfg_context(struct sk_buff *skb, const char *resource_name, unsigned vnr)
 {
         struct nlattr *nla;
         nla = nla_nest_start(skb, DRBD_NLA_CFG_CONTEXT);
@@ -2534,7 +2536,7 @@ int nla_put_drbd_cfg_context(struct sk_buff *skb, const char *conn_name, unsigne
                 goto nla_put_failure;
         if (vnr != VOLUME_UNSPECIFIED)
                 NLA_PUT_U32(skb, T_ctx_volume, vnr);
-        NLA_PUT_STRING(skb, T_ctx_conn_name, conn_name);
+        NLA_PUT_STRING(skb, T_ctx_resource_name, resource_name);
         nla_nest_end(skb, nla);
         return 0;
 
@@ -2778,8 +2780,9 @@ int drbd_adm_get_status_all(struct sk_buff *skb, struct netlink_callback *cb)
 {
         const unsigned hdrlen = GENL_HDRLEN + GENL_MAGIC_FAMILY_HDRSZ;
         struct nlattr *nla;
-        const char *conn_name;
+        const char *resource_name;
         struct drbd_tconn *tconn;
+        int maxtype;
 
         /* Is this a followup call? */
         if (cb->args[0]) {
@@ -2799,12 +2802,15 @@ int drbd_adm_get_status_all(struct sk_buff *skb, struct netlink_callback *cb)
         /* No explicit context given.  Dump all. */
         if (!nla)
                 goto dump;
-        nla = nla_find_nested(nla, __nla_type(T_ctx_conn_name));
+        maxtype = ARRAY_SIZE(drbd_cfg_context_nl_policy) - 1;
+        nla = drbd_nla_find_nested(maxtype, nla, __nla_type(T_ctx_resource_name));
+        if (IS_ERR(nla))
+                return PTR_ERR(nla);
         /* context given, but no name present? */
         if (!nla)
                 return -EINVAL;
-        conn_name = nla_data(nla);
-        tconn = conn_get_by_name(conn_name);
+        resource_name = nla_data(nla);
+        tconn = conn_get_by_name(resource_name);
 
         if (!tconn)
                 return -ENODEV;
@@ -2957,16 +2963,16 @@ out_nolock:
 }
 
 static enum drbd_ret_code
-drbd_check_conn_name(const char *name)
+drbd_check_resource_name(const char *name)
 {
         if (!name || !name[0]) {
-                drbd_msg_put_info("connection name missing");
+                drbd_msg_put_info("resource name missing");
                 return ERR_MANDATORY_TAG;
         }
         /* if we want to use these in sysfs/configfs/debugfs some day,
          * we must not allow slashes */
         if (strchr(name, '/')) {
-                drbd_msg_put_info("invalid connection name");
+                drbd_msg_put_info("invalid resource name");
                 return ERR_INVALID_REQUEST;
         }
         return NO_ERROR;
@@ -2982,7 +2988,7 @@ int drbd_adm_new_resource(struct sk_buff *skb, struct genl_info *info)
         if (retcode != NO_ERROR)
                 goto out;
 
-        retcode = drbd_check_conn_name(adm_ctx.conn_name);
+        retcode = drbd_check_resource_name(adm_ctx.resource_name);
         if (retcode != NO_ERROR)
                 goto out;
 
@@ -2995,7 +3001,7 @@ int drbd_adm_new_resource(struct sk_buff *skb, struct genl_info *info)
                 goto out;
         }
 
-        if (!conn_create(adm_ctx.conn_name))
+        if (!conn_create(adm_ctx.resource_name))
                 retcode = ERR_NOMEM;
 out:
         drbd_adm_finish(info, retcode);
@@ -3213,3 +3219,53 @@ failed:
                         "Event seq:%u sib_reason:%u\n",
                         err, seq, sib->sib_reason);
 }
+
+int drbd_nla_check_mandatory(int maxtype, struct nlattr *nla)
+{
+        struct nlattr *head = nla_data(nla);
+        int len = nla_len(nla);
+        int rem;
+
+        /*
+         * validate_nla (called from nla_parse_nested) ignores attributes
+         * beyond maxtype, and does not understand the DRBD_GENLA_F_MANDATORY flag.
+         * In order to have it validate attributes with the DRBD_GENLA_F_MANDATORY
+         * flag set also, check and remove that flag before calling
+         * nla_parse_nested.
+         */
+
+        nla_for_each_attr(nla, head, len, rem) {
+                if (nla->nla_type & DRBD_GENLA_F_MANDATORY) {
+                        nla->nla_type &= ~DRBD_GENLA_F_MANDATORY;
+                        if (nla_type(nla) > maxtype)
+                                return -EOPNOTSUPP;
+                }
+        }
+        return 0;
+}
+
+int drbd_nla_parse_nested(struct nlattr *tb[], int maxtype, struct nlattr *nla,
+                          const struct nla_policy *policy)
+{
+        int err;
+
+        err = drbd_nla_check_mandatory(maxtype, nla);
+        if (!err)
+                err = nla_parse_nested(tb, maxtype, nla, policy);
+
+        return err;
+}
+
+struct nlattr *drbd_nla_find_nested(int maxtype, struct nlattr *nla, int attrtype)
+{
+        int err;
+        /*
+         * If any nested attribute has the DRBD_GENLA_F_MANDATORY flag set and
+         * we don't know about that attribute, reject all the nested
+         * attributes.
+         */
+        err = drbd_nla_check_mandatory(maxtype, nla);
+        if (err)
+                return ERR_PTR(err);
+        return nla_find_nested(nla, attrtype);
+}