git: f2a4eed3e13b - main - netlink: underscore snl_get_genl_family_info() to discourage its use

The branch main has been updated by glebius:

URL: https://cgit.FreeBSD.org/src/commit/?id=f2a4eed3e13b6aeb9ddeef580d3b931cf22a14e3

commit f2a4eed3e13b6aeb9ddeef580d3b931cf22a14e3
Author:     Gleb Smirnoff <glebius@FreeBSD.org>
AuthorDate: 2025-01-20 20:53:37 +0000
Commit:     Gleb Smirnoff <glebius@FreeBSD.org>
CommitDate: 2025-01-20 20:53:37 +0000

    netlink: underscore snl_get_genl_family_info() to discourage its use
    
    This function uses already supposedly opaque struct _getfamily_attrs as
    the argument and it fills it with pointers to volatile memory, which makes
    it is unsafe for general use.  While here also underscore structures that
    hang off the struct _getfamily_attrs.
    
    Small programs like powerd(8) and RPC daemons are converted to use
    snl_get_genl_mcast_group() and/or snl_get_genl_family().  The genl(1)
    utility was fixed not to mix its own parsers with parsers declared in
    netlink_snl_generic.h.
    
    Reviewed by:            melifaro
    Differential Revision:  https://reviews.freebsd.org/D48480
---
 sys/netlink/netlink_snl_generic.h    | 36 +++++++++++++++++++++++-------------
 tests/sys/netlink/test_snl_generic.c |  2 +-
 2 files changed, 24 insertions(+), 14 deletions(-)

diff --git a/sys/netlink/netlink_snl_generic.h b/sys/netlink/netlink_snl_generic.h
index bdbefb914259..7dc8980e1c5c 100644
--- a/sys/netlink/netlink_snl_generic.h
+++ b/sys/netlink/netlink_snl_generic.h
@@ -60,17 +60,17 @@ static struct snl_field_parser snl_fp_genl[] = {};
 #define	SNL_DECLARE_GENL_PARSER(_name, _np)	SNL_DECLARE_PARSER(_name,\
     struct genlmsghdr, snl_fp_genl, _np)
 
-struct snl_genl_ctrl_mcast_group {
+struct _snl_genl_ctrl_mcast_group {
 	uint32_t mcast_grp_id;
 	const char *mcast_grp_name;
 };
 
-struct snl_genl_ctrl_mcast_groups {
+struct _snl_genl_ctrl_mcast_groups {
 	uint32_t num_groups;
-	struct snl_genl_ctrl_mcast_group **groups;
+	struct _snl_genl_ctrl_mcast_group **groups;
 };
 
-#define	_OUT(_field)	offsetof(struct snl_genl_ctrl_mcast_group, _field)
+#define	_OUT(_field)	offsetof(struct _snl_genl_ctrl_mcast_group, _field)
 static struct snl_attr_parser _nla_p_getmc[] = {
 	{
 		.type = CTRL_ATTR_MCAST_GRP_NAME,
@@ -85,12 +85,12 @@ static struct snl_attr_parser _nla_p_getmc[] = {
 };
 #undef _OUT
 SNL_DECLARE_ATTR_PARSER_EXT(_genl_ctrl_mc_parser,
-    sizeof(struct snl_genl_ctrl_mcast_group), _nla_p_getmc, NULL);
+    sizeof(struct _snl_genl_ctrl_mcast_group), _nla_p_getmc, NULL);
 
 struct _getfamily_attrs {
 	uint16_t family_id;
 	const char *family_name;
-	struct snl_genl_ctrl_mcast_groups mcast_groups;
+	struct _snl_genl_ctrl_mcast_groups mcast_groups;
 };
 
 #define	_IN(_field)	offsetof(struct genlmsghdr, _field)
@@ -118,7 +118,7 @@ static struct snl_attr_parser _nla_p_getfam[] = {
 SNL_DECLARE_GENL_PARSER(_genl_ctrl_getfam_parser, _nla_p_getfam);
 
 static bool
-snl_get_genl_family_info(struct snl_state *ss, const char *family_name,
+_snl_get_genl_family_info(struct snl_state *ss, const char *family_name,
     struct _getfamily_attrs *attrs)
 {
 	struct snl_writer nw;
@@ -126,10 +126,16 @@ snl_get_genl_family_info(struct snl_state *ss, const char *family_name,
 
 	memset(attrs, 0, sizeof(*attrs));
 
-	snl_init_writer(ss, &nw);
-	hdr = snl_create_genl_msg_request(&nw, GENL_ID_CTRL, CTRL_CMD_GETFAMILY);
-	snl_add_msg_attr_string(&nw, CTRL_ATTR_FAMILY_NAME, family_name);
-	if ((hdr = snl_finalize_msg(&nw)) == NULL || !snl_send_message(ss, hdr))
+	if (__predict_false(!snl_init_writer(ss, &nw)))
+		return (false);
+	if (__predict_false(snl_create_genl_msg_request(&nw, GENL_ID_CTRL,
+	    CTRL_CMD_GETFAMILY) == NULL))
+		return (false);
+	if (__predict_false(!snl_add_msg_attr_string(&nw,
+	    CTRL_ATTR_FAMILY_NAME, family_name)))
+		return (false);
+	hdr = snl_finalize_msg(&nw);
+	if (!snl_send_message(ss, hdr))
 		return (false);
 
 	hdr = snl_read_reply(ss, hdr->nlmsg_seq);
@@ -146,7 +152,9 @@ snl_get_genl_family(struct snl_state *ss, const char *family_name)
 {
 	struct _getfamily_attrs attrs = {};
 
-	snl_get_genl_family_info(ss, family_name, &attrs);
+	if (__predict_false(!_snl_get_genl_family_info(ss, family_name,
+	    &attrs)))
+		return (0);
 	return (attrs.family_id);
 }
 
@@ -156,7 +164,9 @@ snl_get_genl_mcast_group(struct snl_state *ss, const char *family_name,
 {
 	struct _getfamily_attrs attrs = {};
 
-	snl_get_genl_family_info(ss, family_name, &attrs);
+	if (__predict_false(!_snl_get_genl_family_info(ss, family_name,
+	    &attrs)))
+		return (0);
 	if (attrs.family_id == 0)
 		return (0);
 	if (family_id != NULL)
diff --git a/tests/sys/netlink/test_snl_generic.c b/tests/sys/netlink/test_snl_generic.c
index d84d3f88f487..839127fe5232 100644
--- a/tests/sys/netlink/test_snl_generic.c
+++ b/tests/sys/netlink/test_snl_generic.c
@@ -98,7 +98,7 @@ ATF_TC_BODY(test_snl_get_genl_family_groups, tc)
 	ATF_CHECK(snl_parse_nlmsg(&ss, hdr, &_genl_ctrl_getfam_parser, &attrs));
 	ATF_CHECK_EQ(attrs.mcast_groups.num_groups, 1);
 
-	struct snl_genl_ctrl_mcast_group *group = attrs.mcast_groups.groups[0];
+	struct _snl_genl_ctrl_mcast_group *group = attrs.mcast_groups.groups[0];
 
 	ATF_CHECK(group->mcast_grp_id > 0);
 	ATF_CHECK(!strcmp(group->mcast_grp_name, "notify"));