Systems code should be written in something higher level than assembler but lower level than the symbolic execution system that C claims to provide currently. “Just use assembly” or “just use a type safe language” aren’t useful answers.
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Systems code benefits from memory and type safety even more than most other code because it's often in a position of trust and privilege. Using a language where unsafety can be contained and quickly wrapped into safe APIs is certainly useful advice for newly written systems code.
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The expectations of software robustness and security have increased a lot, and it's simply not realistic to achieve it while using unsafe tools making it much more difficult to write safe code. Writing something complex like an safe ext4 implementation is C is not very realistic.
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i.e. writing the entire thing with zero memory corruption bugs for an attacker to exploit either via an attacker controlled filesystem or an application. Drivers similarly have to be written treating the hardware and code using them as adversarial. Choice of tools is important.
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FS drivers do not belong in privileged contexts. The FS driver for an untrusted FS should be executing in a context where it can do nothing worse than store or retrieve wrong data.
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No, that's not what he means. He's saying that an external file system should have a sandboxed filesystem driver, so that exploiting a bug inside it doesn't immediately grant complete control over the entire system and at least requires privesc to escape (likely via the kernel).
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Try reading the overview in events.linuxfoundation.org/wp-content/upl. Finding a Linux kernel vulnerability is not hard. Literally hundreds of bugs are found by syszkiller every month and many are not fixed. Most are memory corruption. There are simply too many to even fix all discovered bugs.
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yes, we don't need to debate the question "can people write memory safe code in C" the answer is overwhelmingly obvious to almost all of us
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If you look through grep's commits, you can see fixes like git.savannah.gnu.org/cgit/grep.git/ and git.savannah.gnu.org/cgit/grep.git/ which did not get a CVE assigned, because it's rare to seek out CVE assignments for each security relevant bug fix. Most projects don't do much of that, or don't at all.
CVE databases just aren't usable for determining most of the vulnerability fixes going into a project. Linux distributions like Debian relying on CVEs to determine which fixes need to be backported have serious security issues. Greg KH spells this out again and again for Linux.
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Also, the Linux kernel having far more CVE assignments than say the FreeBSD kernel doesn't mean it's less secure or had more vulnerabilities. In fact, the lack of security research / fuzzing / dynamic analysis being done to find these bugs in other kernels is a very bad thing.
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