On Tue, 30 Jan 2024 10:47:22 GMT, Sebastian Lövdahl <d...@openjdk.org> wrote:
> 8307977: jcmd and jstack broken for target processes running with elevated > capabilities src/jdk.attach/linux/classes/sun/tools/attach/VirtualMachineImpl.java line 217: > 215: // Instead, attach relative to the target root filesystem as > exposed by > 216: // procfs regardless of namespaces. > 217: String root = "/proc/" + pid + "/root/" + tmpdir; Helping myself and other future readers understand this: the problem with the previous implementation is that the code _assumed_ that the tmpdir could be accessed this way (`/proc/<pid>/root/<tmpdir>`). In other words: * The code for creating the socket would correctly check if `pid != ns_pid` and then act accordingly (`/proc/<pid>/root/<tmpdir>` or just plain `<tmpdir>`) * The code for reading the socket would not have the check the above. It would resort to always use `/proc/<pid>/root/<tmpdir>`. * For certain scenarios (`CAP_NET_BIND_SERVICE`-processes, as described in https://github.com/openjdk/jdk/pull/17628#issuecomment-1916589081) would get a `Permission denied` when trying to access the temporary directory like this. What this PR does is to ensure that the same `pid != ns_pid` check is used both when creating and reading the socket, and fall back to `<tmpdir>` when no namespacing is being used. This seems to work better for these processes with elevated permissions. ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/17628#discussion_r1471105891
