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Try to make sudo less vulnerable to Rowhammer attacks

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Re: Try to make sudo less vulnerable to Rowhammer attacks

#51

Post by randomdata »

IshKebab wrote: post #21
delusional wrote: post #16

Earlier quoted context omitted.

What about the Non-experienced Rust programmer? A lot of open source code are written by inexperienced people who understand the nuances of computer science primarily through hype. I think those are the kinds of people OP was asking about.

I don't think there are going to be a large number of inexperienced Rust programmers. Inexperienced programmers write Javascript or Python, not Rust.

Yet the vocal majority of Rust users present themselves as being inexperienced programmers. I expect it is not just an act – that the vocal majority truly are inexperienced, and I expect the segment of users who are novices is much larger than you suggest.

The fact of the matter is that the novices have always been drawn to the 'hot new technology' and it is unlikely that Rust, being today's 'hot new technology', is the exception. Indeed, Python and Javascript had time in the sun when they were considered hot, and novices were attracted in that direction at that time, but time continues to march forward.

Re: Try to make sudo less vulnerable to Rowhammer attacks

#53

Post by HankB99 »

dist-epoch wrote: post #50
HankB99 wrote: post #19

I thought that Rowhammer was a thing of the past. Out of curiosity I found code to test for this and ran it on some of my hosts. My old desktop - I7-4770K/DDR3 - was susceptible. My old server - Xeon X3460/DDR3+ECC - was not. I upgraded the desktop with components based on a Ryzen 7 7700X/DDR5. It tested not susceptible. I'm not sure if that's a result of RAM designed not to be susceptible or that (I think) DDR5 RAM…

Are you running the Ryzen DDR5 at stock speeds (4800 MT/s) or at some XMP profile.

Everything is at stock speed.

Re: Try to make sudo less vulnerable to Rowhammer attacks

#54

Post by HankB99 »

thijsr wrote: post #27
HankB99 wrote: post #19

I thought that Rowhammer was a thing of the past. Out of curiosity I found code to test for this and ran it on some of my hosts. My old desktop - I7-4770K/DDR3 - was susceptible. My old server - Xeon X3460/DDR3+ECC - was not. I upgraded the desktop with components based on a Ryzen 7 7700X/DDR5. It tested not susceptible. I'm not sure if that's a result of RAM designed not to be susceptible or that (I think) DDR5 RAM…

RowHammer is not a thing of the past. In fact, modern DRAM chips are significantly more susceptible to RowHammer due to their increased chip density [1]. [1] https://arxiv.org/abs/2005.13121

Thanks for the link. I guess I thought wrong. But I have more questions.

> with RowHammer protection mechanisms disabled

I wonder what this means. Is it S/W mitigations or does it include H/W factors like disabling on-die ECC.

It makes sense to me that with all other things being equal that higher density would lead to more susceptibility to Rowhammer. But as always, other things are not equal. I expect that on-die ECC would reduce susceptibility to Rowhammer and AFAIK that is used for DDR4 and DDR5 RAM, but perhaps not exclusively. Or did disabling "protection mechanisms" include disabling that (if it is even possible.)

Re: Try to make sudo less vulnerable to Rowhammer attacks

#55

Post by HankB99 »

trebligdivad wrote: post #20
HankB99 wrote: post #19

I thought that Rowhammer was a thing of the past. Out of curiosity I found code to test for this and ran it on some of my hosts. My old desktop - I7-4770K/DDR3 - was susceptible. My old server - Xeon X3460/DDR3+ECC - was not. I upgraded the desktop with components based on a Ryzen 7 7700X/DDR5. It tested not susceptible. I'm not sure if that's a result of RAM designed not to be susceptible or that (I think) DDR5 RAM…

Rowhammer is not architecture specific, since it's the DRAM rather than the CPU. The paper linked in the patch references other works showing every defence at rowhammer can be bypassed somehow (I've not followed them all) - e.g. it specifically says that ECC and the like can be bypassed.

Interesting. I did not expect that Rowhammer was architecture specific, only that the test I found was.

I also did not expect that the various defenses, including ECC, could be bypassed.

Re: Try to make sudo less vulnerable to Rowhammer attacks

#57

Post by IshKebab »

loeg wrote: post #39
stressinduktion wrote: post #32

Related, hardbool, it seems gcc can automatically handle this soon. https://blog.adacore.com/adacore-enhances-gcc-security-with-... and https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.ht...

Not exactly; these constants in sudo are an enum of sorts (actually preprocessor macros). It's not just bool (and won't just be bool in many situations). It is cool to see GCC exploring automatic protection in this space; I just don't think it is relevant to what sudo did here.

Hardbool lets you use custom true and false representations with higher hamming distances. The sudo patch uses custom representations for their enum that have higher hamming distances. The only difference is that hardbool is for true/false and this patch is for AUTH_SUCCESS/AUTH_FAILURE/AUTH_ERROR etc. But that's irrelevant. It's the exact same technique.

Re: Try to make sudo less vulnerable to Rowhammer attacks

#58

Post by nuccy »

dist-epoch wrote: post #49
TacticalCoder wrote: post #43

Earlier quoted context omitted.

> I enjoyed this part Very nice indeed. Such a simple mitigation and it makes evil people sad, which makes me happy.

This is for local sudo privilege escalation. If the attacker is already running code on your system, you kind of lost anyway.

Not really. An example out of top of my head, where this still might be useful are login nodes (used in many research clusters to allow users to enter and sumbit jobs) or shared web-hosting servers (few of those definitely still exist). There legitimate non-privileged users can run their programs and the end goal is to prevent them from getting root.

Re: Try to make sudo less vulnerable to Rowhammer attacks

#59

Post by omoikane »

thijsr wrote: post #27
HankB99 wrote: post #19

I thought that Rowhammer was a thing of the past. Out of curiosity I found code to test for this and ran it on some of my hosts. My old desktop - I7-4770K/DDR3 - was susceptible. My old server - Xeon X3460/DDR3+ECC - was not. I upgraded the desktop with components based on a Ryzen 7 7700X/DDR5. It tested not susceptible. I'm not sure if that's a result of RAM designed not to be susceptible or that (I think) DDR5 RAM…

RowHammer is not a thing of the past. In fact, modern DRAM chips are significantly more susceptible to RowHammer due to their increased chip density [1]. [1] https://arxiv.org/abs/2005.13121

In the "countermeasures" section of the linked paper[1], it mentioned that there are some new techniques available, but repeatedly mentioned that they are not yet available in consumer systems. Maybe rowhammer will eventually be a thing of the past despite the increasing chip density.

[1] https://arxiv.org/abs/2309.02545

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