open: add Open(at)InRoot and Reopen #15
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In order to add a reopen primitive, it'll be necessary to do very similar checks to procSelfFdReadlink but with slightly different types. By refactoring procSelfFdReadlink with generics we can use the same codepath for both operations. Signed-off-by: Aleksa Sarai <cyphar@cyphar.com>
These are very thin wrappers around the existing partialLookupInRoot and doProcSelfMagiclink infrastructure to allow user to get a much safer API for operating on paths than SecureJoin. In principle, with very careful usage, these operations should be sufficient to make any program safe against races. In theory we could disable the symlink stack when doing OpenInRoot (because the symlink stack is only relevant for partial lookups), but for now we'll just keep the codepaths the same. Also, add a note to SecureJoin to tell users that you should probably use OpenInRoot if you can. This API is based on the libpathrs base API. Signed-off-by: Aleksa Sarai <cyphar@cyphar.com>
These are mostly based on the partialOpen tests, but making sure we don't return any partial resolutions. Signed-off-by: Aleksa Sarai <cyphar@cyphar.com>
We need to read the list of dirents during the loop, and re-opening and closing the fd each time doesn't really make much sense. O_DIRECTORY should stop us from opening any "bad" inodes, so we might as well make MkdirAllHandle always return an O_DIRECTORY and we can eliminate all of the unneeded reopens. We need to duplicate the handle at the start to make sure we return a non-O_PATH even if we are asked to MkdirAll an existing directory. We can just re-use Reopen now that we have it. Signed-off-by: Aleksa Sarai <cyphar@cyphar.com>
Signed-off-by: Aleksa Sarai <cyphar@cyphar.com>
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These are very thin wrappers around the existing partialLookupInRoot and
doProcSelfMagiclink infrastructure to allow user to get a much safer API
for operating on paths than SecureJoin. In principle, with very careful
usage, these operations should be sufficient to make any program safe
against races.
In theory we could disable the symlink stack when doing OpenInRoot
(because the symlink stack is only relevant for partial lookups), but
for now we'll just keep the codepaths the same. Also, add a note to
SecureJoin to tell users that you should probably use OpenInRoot if you
can.
This API is based on the libpathrs base API.
Closes #12
Signed-off-by: Aleksa Sarai cyphar@cyphar.com