open(2): update ENOTCAPABLE error for ..

[emaste]

Summary

After rS308212 Capsicum permits .. lookups in capability mode, as long as path component traversal does not escape the directory corresponding to the provided file descriptor.

[kib]

Perhaps also mention that dotdot is not allowed on non-local fs, unless vfs.lookup_cap_dotdot ise set.

[bjk]

Please bump .Dd when committing.

lib/libc/sys/open.2

493 ↗

(On Diff #32976)

I might even drop the "file descriptor" part, as fd must be a file descriptor as covered previously in the document.

[emaste]

In D12343#255946, @kib wrote:

Perhaps also mention that dotdot is not allowed on non-local fs, unless vfs.lookup_cap_dotdot ise set.

Good point; perhaps we need to explain both of the sysctls, although I'm not sure how far we'd like to go in covering non-default options.

lib/libc/sys/open.2

493 ↗

(On Diff #32976)

Thanks for the reminder, I would indeed have forgotten. And will make the suggested amendment too.