On Sat, Jan 19, 2019 at 12:43:35PM -0500, Daniel Colascione wrote: > On Sat, Jan 19, 2019 at 11:27 AM Joel Fernandes <joel@xxxxxxxxxxxxxxxxx> wrote: > > > > On Sat, Jan 19, 2019 at 09:25:32AM +0100, Greg KH wrote: > > > On Fri, Jan 18, 2019 at 05:55:43PM -0500, Joel Fernandes wrote: > > > > --- /dev/null > > > > +++ b/kernel/kheaders.c > > Thanks a ton for this work. It'll make it much easier to do cool > things with BPF. You're welcome, thanks. > One question: I can imagine wanting to probe > structures that are defined, not in headers, but in random > implementation files. Would it be possible to optionally include *all* > kernel source files? That would be prohibitively too large to justify keeping it in memory, even compressed. Arguably, such structures should be moved into include/ if modules or whatever is extending the kernel like eBPF needs them. > If not, what about a hash, so we could at least > do precise correlation between a candidate local tree and what's > actually on device? That would make a tool too difficult to write wouldn't it, since they you have to correlate every possible hash and keep updating eBPF tools with new hashes - probably not scalable. I think what you want is to use the kernel version to assume what such internal structures look like although that's still not robust. > BTW, I'm not sure that the magic constants you've defined are long > enough. I'd feel more comfortable with two UUIDs (16 bytes each). Ok, I'll expand it. > I'd also strongly consider LZMA compression: xz -9 on the kernel > headers (with comments) brings the size down to 5MB, compared to the > 7MB I get for gzip -9. Considering that this feature is optional, I > think it's okay to introduce a dependency on widespread modern > compression tools. (For comparison, bzip2 -9 gets us 6MB.) Ok, I'll look into LZMA. Thanks for checking the compression sizes. - Joel
