From: Michael Bommarito <michael.bommarito@gmail.com> stable inclusion from stable-v6.6.143 commit 969bc6370334a5b4720c5470783295d6484bbc95 category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/16416 CVE: CVE-2026-64137 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- [ Upstream commit d1ebfce2c1d161186a82e77590bf7da2ea1bce91 ] CIFS_GENL_CMD_SWN_NOTIFY is the userspace witness-notify command. The intended sender is the cifs.witness helper, but the generic-netlink operation currently has no capability flag, so any local process can send RESOURCE_CHANGE or CLIENT_MOVE notifications to the in-kernel witness handler. The same family exposes CIFS_GENL_MCGRP_SWN without multicast-group capability flags. Register messages sent to that group include the witness registration id and, for NTLM-authenticated mounts, the username, domain, and password attributes copied from the CIFS session. An unprivileged local process should not be able to join that group and receive those messages. Require CAP_NET_ADMIN for incoming SWN_NOTIFY commands with GENL_ADMIN_PERM, and require CAP_NET_ADMIN over the network namespace for joining the SWN multicast group with GENL_MCAST_CAP_NET_ADMIN. The cifs.witness service runs with the privileges needed for both operations. Fixes: fed979a7e082 ("cifs: Set witness notification handler for messages from userspace daemon") Cc: stable@vger.kernel.org Signed-off-by: Michael Bommarito <michael.bommarito@gmail.com> Assisted-by: Claude:claude-opus-4-7 Signed-off-by: Steve French <stfrench@microsoft.com> Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Yifan Qiao <qiaoyifan4@huawei.com> --- fs/smb/client/netlink.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/fs/smb/client/netlink.c b/fs/smb/client/netlink.c index 147d9409252c..0dd10913c37a 100644 --- a/fs/smb/client/netlink.c +++ b/fs/smb/client/netlink.c @@ -33,13 +33,17 @@ static const struct nla_policy cifs_genl_policy[CIFS_GENL_ATTR_MAX + 1] = { static const struct genl_ops cifs_genl_ops[] = { { .cmd = CIFS_GENL_CMD_SWN_NOTIFY, + .flags = GENL_ADMIN_PERM, .validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP, .doit = cifs_swn_notify, }, }; static const struct genl_multicast_group cifs_genl_mcgrps[] = { - [CIFS_GENL_MCGRP_SWN] = { .name = CIFS_GENL_MCGRP_SWN_NAME }, + [CIFS_GENL_MCGRP_SWN] = { + .name = CIFS_GENL_MCGRP_SWN_NAME, + .flags = GENL_MCAST_CAP_NET_ADMIN, + }, }; struct genl_family cifs_genl_family = { -- 2.52.0