Open tarka opened 1 year ago
Hi,
I believe this is a fundamental problem with the way you are converting from a Vec
to a BTreeMap
.
SeccompFilter::new
clearly expects a BTreeMap
so I don't think there's an issue with the library. You should create the BTreeMap
in the correct manner (by appending to the vector of rules if the key already exists in the map).
I agree though that this could be a quality of life improvement, but I would suggest making this generic over something that implements IntoIterator
.
However I'm not sure it's worth breaking existing users
In the case where the SeccompFilter rules are generated from a list of
(syscall, Vec<SeccompRule)
(as in the doc examples), if a syscall is repeated with different args, the later rule will silently overwrite the earlier one. This is a limitation of the Vec->BTreeMapcollect
implemenation. Given thatrules
is converted into an iterator over(syscall, Vec<SeccompRule)
during try_from the use of a map doesn't seem to add anything.This has implications for ease-of-use of the library. I came across this issue when implementing a port of OpenBSD pledge(). In
pledge()
semantics, promises are additive;cpath
adds the ability to callopen()
withO_CREAT
, andwpath
allowsopen()
withO_WRONLY
; to open and then write a file you would need to specify both.The simplest way to implement this is a separate whitelist for each case, and then chain them together as needed, e.g:
However the use of BTreeMap means the
cpath
rule would be completely overwritten by thewpath
rule, and attempts to create the file would fail.The simplest solution would be to use a Vec for the syscall rule list (i.e. just skip the BTreeMap conversion) and leave the partitioning of the syscall rules up the caller. I've already tried this with v0.3.0 and it works fine; I'm happy to raise a PR. However it would obviously be a breaking change for current users of the lib.