6.1-stable review patch. If anyone has any objections, please let me know.
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From: Jakub Kicinski kuba@kernel.org
[ Upstream commit 738136a0e3757a8534df3ad97d6ff6d7f429f6c1 ]
Clean up the use of unsafe_memcpy() by adding a flexible array at the end of netlink message header and splitting up the header and data copies.
Reviewed-by: Kees Cook keescook@chromium.org Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: David S. Miller davem@davemloft.net Stable-dep-of: d0f95894fda7 ("netlink: annotate data-races around sk->sk_err") Signed-off-by: Sasha Levin sashal@kernel.org --- include/net/netlink.h | 21 +++++++++++++++++++++ include/uapi/linux/netlink.h | 2 ++ net/netlink/af_netlink.c | 29 ++++++++++++++++++++--------- 3 files changed, 43 insertions(+), 9 deletions(-)
diff --git a/include/net/netlink.h b/include/net/netlink.h index 6bfa972f2fbf2..a686c9041ddc0 100644 --- a/include/net/netlink.h +++ b/include/net/netlink.h @@ -937,6 +937,27 @@ static inline struct nlmsghdr *nlmsg_put(struct sk_buff *skb, u32 portid, u32 se return __nlmsg_put(skb, portid, seq, type, payload, flags); }
+/** + * nlmsg_append - Add more data to a nlmsg in a skb + * @skb: socket buffer to store message in + * @size: length of message payload + * + * Append data to an existing nlmsg, used when constructing a message + * with multiple fixed-format headers (which is rare). + * Returns NULL if the tailroom of the skb is insufficient to store + * the extra payload. + */ +static inline void *nlmsg_append(struct sk_buff *skb, u32 size) +{ + if (unlikely(skb_tailroom(skb) < NLMSG_ALIGN(size))) + return NULL; + + if (NLMSG_ALIGN(size) - size) + memset(skb_tail_pointer(skb) + size, 0, + NLMSG_ALIGN(size) - size); + return __skb_put(skb, NLMSG_ALIGN(size)); +} + /** * nlmsg_put_answer - Add a new callback based netlink message to an skb * @skb: socket buffer to store message in diff --git a/include/uapi/linux/netlink.h b/include/uapi/linux/netlink.h index e2ae82e3f9f71..5da0da59bf010 100644 --- a/include/uapi/linux/netlink.h +++ b/include/uapi/linux/netlink.h @@ -48,6 +48,7 @@ struct sockaddr_nl { * @nlmsg_flags: Additional flags * @nlmsg_seq: Sequence number * @nlmsg_pid: Sending process port ID + * @nlmsg_data: Message payload */ struct nlmsghdr { __u32 nlmsg_len; @@ -55,6 +56,7 @@ struct nlmsghdr { __u16 nlmsg_flags; __u32 nlmsg_seq; __u32 nlmsg_pid; + __u8 nlmsg_data[]; };
/* Flags values */ diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c index 387e430a35ccc..4ddb2ed7706ad 100644 --- a/net/netlink/af_netlink.c +++ b/net/netlink/af_netlink.c @@ -2443,19 +2443,24 @@ void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err, flags |= NLM_F_ACK_TLVS;
skb = nlmsg_new(payload + tlvlen, GFP_KERNEL); - if (!skb) { - NETLINK_CB(in_skb).sk->sk_err = ENOBUFS; - sk_error_report(NETLINK_CB(in_skb).sk); - return; - } + if (!skb) + goto err_bad_put;
rep = nlmsg_put(skb, NETLINK_CB(in_skb).portid, nlh->nlmsg_seq, - NLMSG_ERROR, payload, flags); + NLMSG_ERROR, sizeof(*errmsg), flags); + if (!rep) + goto err_bad_put; errmsg = nlmsg_data(rep); errmsg->error = err; - unsafe_memcpy(&errmsg->msg, nlh, payload > sizeof(*errmsg) - ? nlh->nlmsg_len : sizeof(*nlh), - /* Bounds checked by the skb layer. */); + errmsg->msg = *nlh; + + if (!(flags & NLM_F_CAPPED)) { + if (!nlmsg_append(skb, nlmsg_len(nlh))) + goto err_bad_put; + + memcpy(errmsg->msg.nlmsg_data, nlh->nlmsg_data, + nlmsg_len(nlh)); + }
if (tlvlen) netlink_ack_tlv_fill(in_skb, skb, nlh, err, extack); @@ -2463,6 +2468,12 @@ void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err, nlmsg_end(skb, rep);
nlmsg_unicast(in_skb->sk, skb, NETLINK_CB(in_skb).portid); + + return; + +err_bad_put: + NETLINK_CB(in_skb).sk->sk_err = ENOBUFS; + sk_error_report(NETLINK_CB(in_skb).sk); } EXPORT_SYMBOL(netlink_ack);