[CentOS] Where is source address info of a route kept?

I have an ethernet device in my lan with a primary address 192.168.5.205
and a secondary address .217.  I added the secondary address after network
startup established the primary address by an ip addr add command:

# ip addr add 192.168.5.217/24 broadcast 192.168.5.255 dev eth0

# ip addr show
...
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast qlen 1000
    link/ether 78:2b:cb:23:21:4c brd ff:ff:ff:ff:ff:ff
    inet 192.168.5.205/24 brd 192.168.5.255 scope global eth0
    inet 192.168.5.217/24 brd 192.168.5.255 scope global secondary eth0
    inet6 fe80::7a2b:cbff:fe23:214c/64 scope link
       valid_lft forever preferred_lft forever
...

Then I add a new route via a network gateway but I want the route to use
the secondary address as a source.

# ip route add 11.11.11.11 via 192.168.5.148 src 192.168.5.217

And the ip route show command shows that it knows the source.

# ip route show
11.11.11.11 via 192.168.5.148 dev eth0  src 192.168.5.217

But where is the source address kept?  If I look at /proc/net/route,
it shows the route (0B0B0B0B = 11.11.11.11), but not the source
address.

# cat /proc/net/route
Iface Destination Gateway  Flags RefCnt Use Metric Mask     MTU Window IRTT
eth0  0B0B0B0B    9405A8C0 0007  0      0   0      FFFFFFFF 0   0      0
...

Where is the source address kept?

-- 
Dale Dellutri