mptcp: add support for changing the backup flag

Linux supports 'MPTCP_PM_CMD_SET_FLAGS' since v5.12, and this control has
recently been extended to allow setting flags for a given endpoint id.
Although there is no use for changing 'signal' or 'subflow' flags, it can
be helpful to set/clear the backup bit on existing endpoints: add the 'ip
mptcp endpoint change <...>' command for this purpose.

Link: https://github.com/multipath-tcp/mptcp_net-next/issues/158
Acked-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Signed-off-by: David Ahern <dsahern@kernel.org>

diff --git a/ip/ipmptcp.c b/ip/ipmptcp.c
index 433fa68d2c6f6a6d570a8b62315dd881e97c29d0..10dcb1ea14cfd9e82153a1ba6f2a7858aea5385d 100644 (file)
--- a/ip/ipmptcp.c
+++ b/ip/ipmptcp.c
@@ -25,6 +25,7 @@ static void usage(void)
                "Usage: ip mptcp endpoint add ADDRESS [ dev NAME ] [ id ID ]\n"
                "                                     [ port NR ] [ FLAG-LIST ]\n"
                "       ip mptcp endpoint delete id ID\n"
+               "       ip mptcp endpoint change id ID [ backup | nobackup ]\n"
                "       ip mptcp endpoint show [ id ID ]\n"
                "       ip mptcp endpoint flush\n"
                "       ip mptcp limits set [ subflows NR ] [ add_addr_accepted NR ]\n"
@@ -45,6 +46,8 @@ static int genl_family = -1;
        GENL_REQUEST(_req, MPTCP_BUFLEN, genl_family, 0,        \
                     MPTCP_PM_VER, _cmd, _flags)
 
+#define MPTCP_PM_ADDR_FLAG_NOBACKUP 0x0
+
 /* Mapping from argument to address flag mask */
 static const struct {
        const char *name;
@@ -54,6 +57,7 @@ static const struct {
        { "subflow",            MPTCP_PM_ADDR_FLAG_SUBFLOW },
        { "backup",             MPTCP_PM_ADDR_FLAG_BACKUP },
        { "fullmesh",           MPTCP_PM_ADDR_FLAG_FULLMESH },
+       { "nobackup",           MPTCP_PM_ADDR_FLAG_NOBACKUP }
 };
 
 static void print_mptcp_addr_flags(unsigned int flags)
@@ -96,9 +100,9 @@ static int get_flags(const char *arg, __u32 *flags)
        return -1;
 }
 
-static int mptcp_parse_opt(int argc, char **argv, struct nlmsghdr *n,
-                        bool adding)
+static int mptcp_parse_opt(int argc, char **argv, struct nlmsghdr *n, int cmd)
 {
+       bool adding = cmd == MPTCP_PM_CMD_ADD_ADDR;
        struct rtattr *attr_addr;
        bool addr_set = false;
        inet_prefix address;
@@ -111,6 +115,11 @@ static int mptcp_parse_opt(int argc, char **argv, struct nlmsghdr *n,
        ll_init_map(&rth);
        while (argc > 0) {
                if (get_flags(*argv, &flags) == 0) {
+                       /* allow changing the 'backup' flag only */
+                       if (cmd == MPTCP_PM_CMD_SET_FLAGS &&
+                           (flags & ~MPTCP_PM_ADDR_FLAG_BACKUP))
+                               invarg("invalid flags\n", *argv);
+
                } else if (matches(*argv, "id") == 0) {
                        NEXT_ARG();
 
@@ -183,7 +192,7 @@ static int mptcp_addr_modify(int argc, char **argv, int cmd)
        MPTCP_REQUEST(req, cmd, NLM_F_REQUEST);
        int ret;
 
-       ret = mptcp_parse_opt(argc, argv, &req.n, cmd == MPTCP_PM_CMD_ADD_ADDR);
+       ret = mptcp_parse_opt(argc, argv, &req.n, cmd);
        if (ret)
                return ret;
 
@@ -299,7 +308,7 @@ static int mptcp_addr_show(int argc, char **argv)
        if (argc <= 0)
                return mptcp_addr_dump();
 
-       ret = mptcp_parse_opt(argc, argv, &req.n, false);
+       ret = mptcp_parse_opt(argc, argv, &req.n, MPTCP_PM_CMD_GET_ADDR);
        if (ret)
                return ret;
 
@@ -531,6 +540,9 @@ int do_mptcp(int argc, char **argv)
                if (matches(*argv, "add") == 0)
                        return mptcp_addr_modify(argc-1, argv+1,
                                                 MPTCP_PM_CMD_ADD_ADDR);
+               if (matches(*argv, "change") == 0)
+                       return mptcp_addr_modify(argc-1, argv+1,
+                                                MPTCP_PM_CMD_SET_FLAGS);
                if (matches(*argv, "delete") == 0)
                        return mptcp_addr_modify(argc-1, argv+1,
                                                 MPTCP_PM_CMD_DEL_ADDR);

diff --git a/man/man8/ip-mptcp.8 b/man/man8/ip-mptcp.8
index 019debe2f4d55fb5ee2dcc9f8e56f3cd5f7dbff0..0e6e153215c1259faf27ac314c8e5e8d5611026e 100644 (file)
--- a/man/man8/ip-mptcp.8
+++ b/man/man8/ip-mptcp.8
@@ -34,6 +34,13 @@ ip-mptcp \- MPTCP path manager configuration
 .BR "ip mptcp endpoint del id "
 .I ID
 
+.ti -8
+.BR "ip mptcp endpoint change id "
+.I ID
+.RB "[ "
+.I BACKUP-OPT
+.RB "] "
+
 .ti -8
 .BR "ip mptcp endpoint show "
 .RB "[ " id
@@ -57,6 +64,13 @@ ip-mptcp \- MPTCP path manager configuration
 .B fullmesh
 .RB  "]"
 
+.ti -8
+.IR BACKUP-OPT " := ["
+.B backup
+.RB "|"
+.B nobackup
+.RB  "]"
+
 .ti -8
 .BR "ip mptcp limits set "
 .RB "[ "