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> An externally imposed sandboxing feature can be useful for namespacing, but is necessarily less restrictive than pledge and unveil. An externally imposed san

> An externally imposed sandboxing feature can be useful for namespacing, but is necessarily less restrictive than pledge and unveil. An externally imposed sandboxing feature isn't necessarily less restrictive than pledge and unveil at all, although I'm curious why you think that is the case. To say nothing of the fact that pledge and unveil are wholly dependent on developer opt-in. A good sandboxing solution should be robust and not require the cooperation of the programs that require sandboxing.

0x457 2y ago
Those are two different kinds of sandboxing. One protects application from itself - "here is what I use, if I try anything else, then it's a bug". Sandboxing you're talking about protects system from the application. You really need both. re: restrictiveness With external sandboxing, you need to restrict to a common denominator of all application states you see youself observing that application. Internal sandbox can adjust itself as it goes.
- ruthmarx 2y ago
  > Those are two different kinds of sandboxing. I'm arguing that only one example is sandboxing, the other is imposing limitations but doesn't meet the definition of sandboxing.
yjftsjthsd-h 2y ago
> An externally imposed sandboxing feature isn't necessarily less restrictive than pledge and unveil at all, although I'm curious why you think that is the case. With pledge, you can read config files, open a file handle to your logs, and then completely drop the ability to open() files at all for the remaining lifetime of the program. How would you do that from outside the program?
- ruthmarx 2y ago
  By monitoring and intercepting what the program is doing?
  - yjftsjthsd-h 2y ago
    I guess technically you could write a dynamic policy that... I guess you'd give it a list of files that the program can access exactly once? But that seems difficult and brittle. Is anyone actually doing that?
    - ruthmarx 2y ago
      No, I suppose not, but then, is there really an advantage to doing so? I'm much more concerned with blocking write and execute access than I am about a potential hacker being able to read the config files of the program they leveraged to get a shell. I think it's a good approach and part of defense in depth, but if we're comparing approaches I'll tale the former every time.
      - ori_b 2y ago
        > No, I suppose not, but then, is there really an advantage to doing so? A massive one; not reading the config is just a consequence of dropping all file system access once you're done with the initial program setup. You can also set up listening sockets, and then stop the program from making any new network connections, even after a compromise. And so on, with most resources. There are a lot of resources that tend to be needed to set up a program. There tend to be very few needed once the program is running. How would you block all file system access after a program is finished reading its config files, the files they include, and the shared libraries and plugins scattered around the file system? How would you turn off all network access after the listening socket is established? With Pledge, it's trivial: load_config(); load_plugins(); open_sockets(); pledge(NULL, NULL); run(); Pledge makes everything you're talking about work trivially, the only thing that's needed is for the program to opt in to security with one line of code. You don't need to micromanage the permissions and what the program is doing to drop privileges from the outside, with all of the race conditions and fragility that implies.
        ruthmarx 2y ago
        > There are a lot of resources that tend to be needed to set up a program. There tend to be very few needed once the program is running. I think this is true for simple programs, and less true the more complex a program is. What about programs that due to their nature need to frequently make new network connections, or to periodically check config files? > How would you block all file system access after a program is finished reading its config files, the files they include, and the shared libraries and plugins scattered around the file system? How would you turn off all network access after the listening socket is established? This could be done with seccomp, although it would be more work than it is to use pledge (although a pledge 'port' also exists), it could also be done with things like SELinux. > Pledge makes everything you're talking about work trivially, I was talking about more complete sandboxing, and pledge doesn't allow for that. Pledge is substantially more limited in scope. > the only thing that's needed is for the program to opt in That's actually a pretty big issue. If all the software you want to use is in the ports tree I guess it's fine, but what about for untrusted or complex code? Say, running an instance of Oracle, or a torrent program that by it's nature constantly needs to make network connections and write/read different files? Pledge is little help in these cases, and especially ineffective as any attempt at sandboxing such applications.

0x457 2y ago

Those are two different kinds of sandboxing. One protects application from itself - "here is what I use, if I try anything else, then it's a bug". Sandboxing you're talking about protects system from the application. You really need both. re: restrictiveness With external sandboxing, you need to restrict to a common denominator of all application states you see youself observing that application. Internal sandbox can adjust itself as it goes.

ruthmarx 2y ago
> Those are two different kinds of sandboxing. I'm arguing that only one example is sandboxing, the other is imposing limitations but doesn't meet the definition of sandboxing.

yjftsjthsd-h 2y ago

> An externally imposed sandboxing feature isn't necessarily less restrictive than pledge and unveil at all, although I'm curious why you think that is the case. With pledge, you can read config files, open a file handle to your logs, and then completely drop the ability to open() files at all for the remaining lifetime of the program. How would you do that from outside the program?

ruthmarx 2y ago
By monitoring and intercepting what the program is doing?
- yjftsjthsd-h 2y ago
  I guess technically you could write a dynamic policy that... I guess you'd give it a list of files that the program can access exactly once? But that seems difficult and brittle. Is anyone actually doing that?
  - ruthmarx 2y ago
    No, I suppose not, but then, is there really an advantage to doing so? I'm much more concerned with blocking write and execute access than I am about a potential hacker being able to read the config files of the program they leveraged to get a shell. I think it's a good approach and part of defense in depth, but if we're comparing approaches I'll tale the former every time.
    - ori_b 2y ago
      > No, I suppose not, but then, is there really an advantage to doing so? A massive one; not reading the config is just a consequence of dropping all file system access once you're done with the initial program setup. You can also set up listening sockets, and then stop the program from making any new network connections, even after a compromise. And so on, with most resources. There are a lot of resources that tend to be needed to set up a program. There tend to be very few needed once the program is running. How would you block all file system access after a program is finished reading its config files, the files they include, and the shared libraries and plugins scattered around the file system? How would you turn off all network access after the listening socket is established? With Pledge, it's trivial: load_config(); load_plugins(); open_sockets(); pledge(NULL, NULL); run(); Pledge makes everything you're talking about work trivially, the only thing that's needed is for the program to opt in to security with one line of code. You don't need to micromanage the permissions and what the program is doing to drop privileges from the outside, with all of the race conditions and fragility that implies.
      - ruthmarx 2y ago
        > There are a lot of resources that tend to be needed to set up a program. There tend to be very few needed once the program is running. I think this is true for simple programs, and less true the more complex a program is. What about programs that due to their nature need to frequently make new network connections, or to periodically check config files? > How would you block all file system access after a program is finished reading its config files, the files they include, and the shared libraries and plugins scattered around the file system? How would you turn off all network access after the listening socket is established? This could be done with seccomp, although it would be more work than it is to use pledge (although a pledge 'port' also exists), it could also be done with things like SELinux. > Pledge makes everything you're talking about work trivially, I was talking about more complete sandboxing, and pledge doesn't allow for that. Pledge is substantially more limited in scope. > the only thing that's needed is for the program to opt in That's actually a pretty big issue. If all the software you want to use is in the ports tree I guess it's fine, but what about for untrusted or complex code? Say, running an instance of Oracle, or a torrent program that by it's nature constantly needs to make network connections and write/read different files? Pledge is little help in these cases, and especially ineffective as any attempt at sandboxing such applications.