6.18-stable review patch. If anyone has any objections, please let me know.
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From: Matthieu Baerts (NGI0) matttbe@kernel.org
commit 0ace3297a7301911e52d8195cb1006414897c859 upstream.
Before this patch, the kernel was saving any flags set by the userspace, even unknown ones. This doesn't cause critical issues because the kernel is only looking at specific ones. But on the other hand, endpoints dumps could tell the userspace some recent flags seem to be supported on older kernel versions.
Instead, ignore all unknown flags when parsing them. By doing that, the userspace can continue to set unsupported flags, but it has a way to verify what is supported by the kernel.
Note that it sounds better to continue accepting unsupported flags not to change the behaviour, but also that eases things on the userspace side by adding "optional" endpoint types only supported by newer kernel versions without having to deal with the different kernel versions.
A note for the backports: there will be conflicts in mptcp.h on older versions not having the mentioned flags, the new line should still be added last, and the '5' needs to be adapted to have the same value as the last entry.
Fixes: 01cacb00b35c ("mptcp: add netlink-based PM") Cc: stable@vger.kernel.org Reviewed-by: Mat Martineau martineau@kernel.org Signed-off-by: Matthieu Baerts (NGI0) matttbe@kernel.org Link: https://patch.msgid.link/20251205-net-mptcp-misc-fixes-6-19-rc1-v1-1-9e4781a... Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- include/uapi/linux/mptcp.h | 1 + net/mptcp/pm_netlink.c | 3 ++- 2 files changed, 3 insertions(+), 1 deletion(-)
--- a/include/uapi/linux/mptcp.h +++ b/include/uapi/linux/mptcp.h @@ -40,6 +40,7 @@ #define MPTCP_PM_ADDR_FLAG_FULLMESH _BITUL(3) #define MPTCP_PM_ADDR_FLAG_IMPLICIT _BITUL(4) #define MPTCP_PM_ADDR_FLAG_LAMINAR _BITUL(5) +#define MPTCP_PM_ADDR_FLAGS_MASK GENMASK(5, 0)
struct mptcp_info { __u8 mptcpi_subflows; --- a/net/mptcp/pm_netlink.c +++ b/net/mptcp/pm_netlink.c @@ -119,7 +119,8 @@ int mptcp_pm_parse_entry(struct nlattr * }
if (tb[MPTCP_PM_ADDR_ATTR_FLAGS]) - entry->flags = nla_get_u32(tb[MPTCP_PM_ADDR_ATTR_FLAGS]); + entry->flags = nla_get_u32(tb[MPTCP_PM_ADDR_ATTR_FLAGS]) & + MPTCP_PM_ADDR_FLAGS_MASK;
if (tb[MPTCP_PM_ADDR_ATTR_PORT]) entry->addr.port = htons(nla_get_u16(tb[MPTCP_PM_ADDR_ATTR_PORT]));