Can glibc also give me a good random seed? Take AT_RANDOM, use it to seed some simple PRNG, keep the first chunk of output for a stack canary, and give me the rest. (The PRNG could be as simple as using an MGF or some large-output hash. Something like SHA-3 could be used for this purpose, since Keccak can produce any amount of output, sequentially.)
Currently AFAIR glibc zeros AT_RANDOM after using it for its own nefarious purposes.