mseal_all()

Posted Jan 23, 2024 1:24 UTC (Tue) by NYKevin (subscriber, #129325)
In reply to: mseal_all() by itsmycpu
Parent article: mseal() gets closer

> This would mean the mappings internally receive a timestamp, and any attempt to change a restricted mapping involves comparing the code's seal-timestamp to the mappings seal-timestamp.

While I agree that in principle a mechanism like this might prove useful, it is far more complex than the mechanism which is currently proposed, and I'm not sure it would make sense to tie it to this particular API (especially seeing as they just got finished *removing* the concept of different "types" of sealing).

One thing I do feel obligated to point out, as said by the immortal James Mickens[1]: "Gadgets are eternal. There will always be gadgets, there were gadgets before we got here, there'll be gadgets after we're dead." In other words, you really can't say "this was executed by read-only code, therefore it must be non-malicious," because of ROP-style attacks. No matter how many control flow invariants you try to enforce, sooner or later somebody is going to invent another way of fiddling the instruction pointer into a clever position and exploiting code that already exists.

[1]: https://youtu.be/ajGX7odA87k?si=y0eIv5UAtcv28-Zd&t=1874

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mseal_all()

Posted Jan 23, 2024 2:00 UTC (Tue) by itsmycpu (guest, #139639) [Link]

> While I agree that in principle a mechanism like this might prove useful, it is far more complex than the mechanism which is currently proposed, and I'm not sure it would make sense to tie it to this particular API (especially seeing as they just got finished *removing* the concept of different "types" of sealing).

Yes, of course this would be a separate step. And thanks, I guess.

> One thing I do feel obligated to point out, as said by the immortal James Mickens[1]: "Gadgets are eternal. There will always be gadgets, there were gadgets before we got here, there'll be gadgets after we're dead." In other words, you really can't say "this was executed by read-only code, therefore it must be non-malicious," because of ROP-style attacks. No matter how many control flow invariants you try to enforce, sooner or later somebody is going to invent another way of fiddling the instruction pointer into a clever position and exploiting code that already exists.

Sure, a high bar which probably can't be reached by any single measure. Any sealing, automatic or explicit, be it from libc, the kernel, the loader, or otherwise, that doesn't require (potentially simple) apps to figure out address ranges, would be another separate step in this sense.