| Message ID | 20211126134311.920808-1-alexander.mikhalitsyn@virtuozzo.com (mailing list archive) |
|---|---|
| State | New, archived |
| Delegated to: | David Ahern |
| Headers | show |
| Series | [iproute2] ip route: save: exclude rtnh_flags which can't be set | expand |
| Context | Check | Description |
|---|---|---|
| netdev/tree_selection | success | Not a local patch |
On Fri, Nov 26, 2021 at 04:43:10PM +0300, Alexander Mikhalitsyn wrote: > + /* > + * Exclude flags which can't be set directly > + * by the userspace from the rtmsg dump. > + */ I believe iproute2 is following netdev style comments [1] so this should be: /* Exclude flags which can't be set directly * by the userspace from the rtmsg dump. */ At least it's consistent with other comments in the file. [1] https://www.kernel.org/doc/html/v5.12/networking/netdev-FAQ.html#is-the-comment-style-convention-different-for-the-networking-content > + r->rtm_flags &= ~RTNH_REJECT_MASK; > + > ret = write(STDOUT_FILENO, n, n->nlmsg_len); > if ((ret > 0) && (ret != n->nlmsg_len)) { > fprintf(stderr, "Short write while saving nlmsg\n"); > -- > 2.31.1 >
diff --git a/include/uapi/linux/rtnetlink.h b/include/uapi/linux/rtnetlink.h index e01efa28..6de83c62 100644 --- a/include/uapi/linux/rtnetlink.h +++ b/include/uapi/linux/rtnetlink.h @@ -417,6 +417,9 @@ struct rtnexthop { #define RTNH_COMPARE_MASK (RTNH_F_DEAD | RTNH_F_LINKDOWN | \ RTNH_F_OFFLOAD | RTNH_F_TRAP) +/* these flags can't be set by the userspace */ +#define RTNH_REJECT_MASK (RTNH_F_DEAD | RTNH_F_LINKDOWN) + /* Macros to handle hexthops */ #define RTNH_ALIGNTO 4 diff --git a/ip/iproute.c b/ip/iproute.c index 1447a5f7..a72b652b 100644 --- a/ip/iproute.c +++ b/ip/iproute.c @@ -1632,6 +1632,12 @@ static int save_route(struct nlmsghdr *n, void *arg) if (!filter_nlmsg(n, tb, host_len)) return 0; + /* + * Exclude flags which can't be set directly + * by the userspace from the rtmsg dump. + */ + r->rtm_flags &= ~RTNH_REJECT_MASK; + ret = write(STDOUT_FILENO, n, n->nlmsg_len); if ((ret > 0) && (ret != n->nlmsg_len)) { fprintf(stderr, "Short write while saving nlmsg\n");
During "ip route save" we preserve all rtnh_flags, even those that can't be set directly by the userspace. This looks like a bug because a user can't restore route dump which was generated by "ip route save" back. This also prevents CRIU from correct restore of the containers with some route configurations inside. Reproducer: $ ip link add type veth $ ip addr add 10.0.0.1/24 dev veth0 $ ip link set veth0 up $ ip route add default via 10.0.0.1 $ ip route save > route_dump $ ip route restore < route_dump Error: Invalid rtm_flags - can not contain DEAD or LINKDOWN. Let's just omit non-settable rtnh_flags from the dump image. According to the check in the fib_create_info() kernel function it looks like we can't restore back only RTNH_F_DEAD and RTNH_F_LINKDOWN flags, so RTNH_REJECT_MASK contains this flags for now. See also linux kernel patch: [PATCH net-next] rtnetlink: add RTNH_REJECT_MASK Cc: David Miller <davem@davemloft.net> Cc: David Ahern <dsahern@gmail.com> Cc: Stephen Hemminger <stephen@networkplumber.org> Cc: Ido Schimmel <idosch@nvidia.com> Cc: Jakub Kicinski <kuba@kernel.org> Cc: Roopa Prabhu <roopa@nvidia.com> Cc: Andrei Vagin <avagin@gmail.com> Cc: Pavel Tikhomirov <ptikhomirov@virtuozzo.com> Cc: Alexander Mikhalitsyn <alexander@mihalicyn.com> Signed-off-by: Alexander Mikhalitsyn <alexander.mikhalitsyn@virtuozzo.com> --- include/uapi/linux/rtnetlink.h | 3 +++ ip/iproute.c | 6 ++++++ 2 files changed, 9 insertions(+)