[Click] Trouble linking MD5 hash functions against Linux kernel module

[Daniel Pall]

I'm trying to compile the Linux kernel module with an additional
element included.  That element uses MD5 hashing, so it uses function
calls like MD5_Init, MD5_Update, and MD5_Final as defined in
openssl/md5.h.  I'm #include'ing this file in my code, and I'm also
trying to link with the -lssl flag in the Makefile, but it does not
appear to be working.  Check out this failed compilation:

[root at sw0.dan11.chang.emulab.net:/proj/Chang/tmp/click-1.6.0/linuxmodule
107 ]make
make -C /lib/modules/2.6.19.2-1.2944.fc6.emulab-1/build
M=/proj/Chang/tmp/click-1.6.0/linuxmodule modules
make[1]: Entering directory `/usr/src/linux-2.6.19.2'
  Building modules, stage 2.
  MODPOST 2 modules
WARNING: "MD5_Update"
[/proj/Chang/tmp/click-1.6.0/linuxmodule/click.ko] undefined!
WARNING: "MD5_Final"
[/proj/Chang/tmp/click-1.6.0/linuxmodule/click.ko] undefined!
WARNING: "MD5_Init" [/proj/Chang/tmp/click-1.6.0/linuxmodule/click.ko]
undefined!
make[1]: Leaving directory `/usr/src/linux-2.6.19.2'
[root at sw0.dan11.chang.emulab.net:/proj/Chang/tmp/click-1.6.0/linuxmodule 108 ]

So, this does make a click.ko kernel module, but it's incomplete and I
can't insert it into the kernel, because it can't resolve these MD5
functions (it complains about the MD5* functions as unknown symbols).

Some details: I'm running Linux kernel 2.6.19.2, and on my machine,
libssl.a is contained in /usr/lib.  I noticed in the FAQ there was a
question that seems close to what I want to know:
One of my elements must be linked against another library. How can I
make userlevel Click link with that library?

Basically, I want to know the answer to that question, but for the
Linux kernel module instead of userlevel Click.  Any suggestions?

Thanks for your time,
Dan