Linux unprivileged ping support #173
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On Linux, when running with an unprivileged process, the kernel does not respect the assigned "id" field. So in that scenario we need to ask the kernel what assignment it has given us instead. Signed-off-by: Steven Noonan <steven@uplinklabs.net>
Linux doesn't include an IP header in the payload when using an unprivileged SOCK_DGRAM socket. Signed-off-by: Steven Noonan <steven@uplinklabs.net>
Signed-off-by: Steven Noonan <steven@uplinklabs.net>
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Right now if you try to use unprivileged ping (i.e. via
SOCK_DGRAM) on the "develop" branch, it doesn't see the response packets.There are a few problems this PR fixes:
getsockname. This change is necessary in order for it to see the ident fields line up and accept the responses.SOCK_DGRAMfor IPv4 unprivileged ping on Linux, there is nostruct ipat the beginning of the message read byrecvmsg. So we have to handle that situation specially. First, we need to account for the size of the missing header when logging the responses (since it is data sent/received over the wire, but it's not visible to the userspace process). Second, we need to avoid treating the start of the buffer asstruct ip.test-11-noprivtest will fail on Linux if the user is allowed to do unprivileged pings. We can check if the effective GID is within the range specified in the sysctlnet.ipv4.ping_group_rangeand know in advance whether the ping is expected to work or not. If it is expected to work, then we should skip thetest-11-noprivtest.