[PATCH 6.1.y 3/5] sock: add sock_kmemdup helper

[Sasha Levin <sashal@kernel.org>]

From: Geliang Tang <tanggeliang@kylinos.cn>

[ Upstream commit 456cc675b6d4cadd4872a477d8976ff56eef4b6f ]

This patch adds the sock version of kmemdup() helper, named sock_kmemdup(),
to duplicate the input "src" memory block using the socket's option memory
buffer.

Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Acked-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/f828077394c7d1f3560123497348b438c875b510.1740735165.git.tanggeliang@kylinos.cn
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Stable-dep-of: f9f0068e8813 ("mptcp: pm: userspace: fix address ID overflow")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 include/net/sock.h |  2 ++
 net/core/sock.c    | 16 ++++++++++++++++
 2 files changed, 18 insertions(+)

diff --git a/include/net/sock.h b/include/net/sock.h
index 9fe621f985740..d195cddb8559b 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1977,6 +1977,8 @@ static inline struct sk_buff *sock_alloc_send_skb(struct sock *sk,
 }
 
 void *sock_kmalloc(struct sock *sk, int size, gfp_t priority);
+void *sock_kmemdup(struct sock *sk, const void *src,
+		   int size, gfp_t priority);
 void sock_kfree_s(struct sock *sk, void *mem, int size);
 void sock_kzfree_s(struct sock *sk, void *mem, int size);
 void sk_send_sigurg(struct sock *sk);
diff --git a/net/core/sock.c b/net/core/sock.c
index 2a701e0b052b7..7ad32254506ec 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -2670,6 +2670,22 @@ void *sock_kmalloc(struct sock *sk, int size, gfp_t priority)
 }
 EXPORT_SYMBOL(sock_kmalloc);
 
+/*
+ * Duplicate the input "src" memory block using the socket's
+ * option memory buffer.
+ */
+void *sock_kmemdup(struct sock *sk, const void *src,
+		   int size, gfp_t priority)
+{
+	void *mem;
+
+	mem = sock_kmalloc(sk, size, priority);
+	if (mem)
+		memcpy(mem, src, size);
+	return mem;
+}
+EXPORT_SYMBOL(sock_kmemdup);
+
 /* Free an option memory block. Note, we actually want the inline
  * here as this allows gcc to detect the nullify and fold away the
  * condition entirely.
-- 
2.53.0