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    Subject[PATCH 4.14 185/293] ipv4: dont set IPv6 only flags to IPv4 addresses
    Date
    From: Matteo Croce <mcroce@redhat.com>

    [ Upstream commit 2e60546368165c2449564d71f6005dda9205b5fb ]

    Avoid the situation where an IPV6 only flag is applied to an IPv4 address:

    # ip addr add 192.0.2.1/24 dev dummy0 nodad home mngtmpaddr noprefixroute
    # ip -4 addr show dev dummy0
    2: dummy0: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN group default qlen 1000
    inet 192.0.2.1/24 scope global noprefixroute dummy0
    valid_lft forever preferred_lft forever

    Or worse, by sending a malicious netlink command:

    # ip -4 addr show dev dummy0
    2: dummy0: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN group default qlen 1000
    inet 192.0.2.1/24 scope global nodad optimistic dadfailed home tentative mngtmpaddr noprefixroute stable-privacy dummy0
    valid_lft forever preferred_lft forever

    Signed-off-by: Matteo Croce <mcroce@redhat.com>
    Reviewed-by: David Ahern <dsahern@gmail.com>
    Signed-off-by: David S. Miller <davem@davemloft.net>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    net/ipv4/devinet.c | 8 ++++++++
    1 file changed, 8 insertions(+)

    --- a/net/ipv4/devinet.c
    +++ b/net/ipv4/devinet.c
    @@ -66,6 +66,11 @@
    #include <net/net_namespace.h>
    #include <net/addrconf.h>

    +#define IPV6ONLY_FLAGS \
    + (IFA_F_NODAD | IFA_F_OPTIMISTIC | IFA_F_DADFAILED | \
    + IFA_F_HOMEADDRESS | IFA_F_TENTATIVE | \
    + IFA_F_MANAGETEMPADDR | IFA_F_STABLE_PRIVACY)
    +
    static struct ipv4_devconf ipv4_devconf = {
    .data = {
    [IPV4_DEVCONF_ACCEPT_REDIRECTS - 1] = 1,
    @@ -455,6 +460,9 @@ static int __inet_insert_ifa(struct in_i
    ifa->ifa_flags &= ~IFA_F_SECONDARY;
    last_primary = &in_dev->ifa_list;

    + /* Don't set IPv6 only flags to IPv4 addresses */
    + ifa->ifa_flags &= ~IPV6ONLY_FLAGS;
    +
    for (ifap = &in_dev->ifa_list; (ifa1 = *ifap) != NULL;
    ifap = &ifa1->ifa_next) {
    if (!(ifa1->ifa_flags & IFA_F_SECONDARY) &&

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