Hiyall, I have created a seccomp white list filter for a program that launches other less trustworthy programs. It's working great so far, but I have run into a little roadblock. the launcher program needs to call execve as it's final step, but that may not be present in the white list. I am wondering if there is any way to use some sort of global variable that will be preserved between syscall filter calls so that I can allow only one execve, if not present in white list by incrementing a counter variable.
I see that in Documentation/networking/filter.txt one of the registers is documented as being a pointer to struct sk_buff, in the seccomp context this is a pointer to struct seccomp_data instead, right? and the line about callee saved registers R6-R9 probably refers to them being saved across calls within that filter, and not calls between filters? My apologies if this is not the appropriate place to ask for help, but it is difficult to find useful information on how eBPF works, and is a bit confusing trying to figure out the differences between seccomp and net filters, and the old bpf code kicking around short of spending countless hours reading through all of it. If anybody has a some links to share I would be very grateful. the only way I can think to make this work otherwise is to mount everything as MS_NOEXEC in the new namespace, but that just feels wrong. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
