netdev - [PATCH net] macsec: read MACSEC_SA_ATTR_PN with nla_get

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Message-ID: <1c1df1661b89238caf5beefb84a10ebfd56c66ea.1756459839.git.sd@queasysnail.net>
Date: Fri, 29 Aug 2025 20:55:40 +0200
From: Sabrina Dubroca <sd@...asysnail.net>
To: netdev@...r.kernel.org
Cc: Sabrina Dubroca <sd@...asysnail.net>,
	Era Mayflower <mayflowerera@...il.com>,
	Jakub Kicinski <kuba@...nel.org>
Subject: [PATCH net] macsec: read MACSEC_SA_ATTR_PN with nla_get_uint

The code currently reads both U32 attributes and U64 attributes as
U64, so when a U32 attribute is provided by userspace (ie, when not
using XPN), on big endian systems, we'll load that value into the
upper 32bits of the next_pn field instead of the lower 32bits. This
means that the value that userspace provided is ignored (we only care
about the lower 32bits for non-XPN), and we'll start using PNs from 0.

Switch to nla_get_uint, which will read the value correctly on all
arches, whether it's 32b or 64b.

Fixes: 48ef50fa866a ("macsec: Netlink support of XPN cipher suites (IEEE 802.1AEbw)")
Signed-off-by: Sabrina Dubroca <sd@...asysnail.net>
---
I'm submitting it for net since it fixes the behavior on BE, but I'm
ok if this goes to net-next instead. The patch doesn't conflict with
my policy rework.

 drivers/net/macsec.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/net/macsec.c b/drivers/net/macsec.c
index 4c75d1fea552..01329fe7451a 100644
--- a/drivers/net/macsec.c
+++ b/drivers/net/macsec.c
@@ -1844,7 +1844,7 @@ static int macsec_add_rxsa(struct sk_buff *skb, struct genl_info *info)
 
 	if (tb_sa[MACSEC_SA_ATTR_PN]) {
 		spin_lock_bh(&rx_sa->lock);
-		rx_sa->next_pn = nla_get_u64(tb_sa[MACSEC_SA_ATTR_PN]);
+		rx_sa->next_pn = nla_get_uint(tb_sa[MACSEC_SA_ATTR_PN]);
 		spin_unlock_bh(&rx_sa->lock);
 	}
 
@@ -2086,7 +2086,7 @@ static int macsec_add_txsa(struct sk_buff *skb, struct genl_info *info)
 	}
 
 	spin_lock_bh(&tx_sa->lock);
-	tx_sa->next_pn = nla_get_u64(tb_sa[MACSEC_SA_ATTR_PN]);
+	tx_sa->next_pn = nla_get_uint(tb_sa[MACSEC_SA_ATTR_PN]);
 	spin_unlock_bh(&tx_sa->lock);
 
 	if (tb_sa[MACSEC_SA_ATTR_ACTIVE])
@@ -2398,7 +2398,7 @@ static int macsec_upd_txsa(struct sk_buff *skb, struct genl_info *info)
 
 		spin_lock_bh(&tx_sa->lock);
 		prev_pn = tx_sa->next_pn_halves;
-		tx_sa->next_pn = nla_get_u64(tb_sa[MACSEC_SA_ATTR_PN]);
+		tx_sa->next_pn = nla_get_uint(tb_sa[MACSEC_SA_ATTR_PN]);
 		spin_unlock_bh(&tx_sa->lock);
 	}
 
@@ -2496,7 +2496,7 @@ static int macsec_upd_rxsa(struct sk_buff *skb, struct genl_info *info)
 
 		spin_lock_bh(&rx_sa->lock);
 		prev_pn = rx_sa->next_pn_halves;
-		rx_sa->next_pn = nla_get_u64(tb_sa[MACSEC_SA_ATTR_PN]);
+		rx_sa->next_pn = nla_get_uint(tb_sa[MACSEC_SA_ATTR_PN]);
 		spin_unlock_bh(&rx_sa->lock);
 	}
 
-- 
2.51.0