969715 - WebRTC creates a PF_NETLINK socket in the content process

Status: RESOLVED FIXED

(Core :: WebRTC: Signaling, defect, P2)

Description

[Jed Davis [:jld] ⟨⏰|UTC-7⟩ ⟦he/him⟧]

0  libc.so + 0xcf00
 1  libxul.so!getifaddrs [ifaddrs_android.cpp : 119 + 0x7]
 2  libxul.so!sctp_init_vrf_list [sctp_bsd_addr.c : 460 + 0x9]
 3  libxul.so!sctp_pcb_init [sctp_pcb.c : 6745 + 0x5]
 4  libxul.so!sctp_init [sctp_usrreq.c : 162 + 0x3]
 5  libxul.so!usrsctp_init [user_socket.c : 81 + 0x3]
 6  libxul.so!mozilla::DataChannelConnection::Init(unsigned short, unsigned short, bool) [DataChannel.cpp : 343 + 0xb]
 7  libxul.so!sipcc::PeerConnectionImpl::EnsureDataConnection(unsigned short) [PeerConnectionImpl.cpp : 952 + 0xf]
 8  libxul.so!sipcc::PeerConnectionImpl::CreateDataChannel(nsAString_internal const&, nsAString_internal const&, unsigned short, bool, unsigned short, unsigned short, bool, unsigned short, nsDOMDataChannel**) [PeerConnectionImpl.cpp : 1030 + 0x3]
 9  libxul.so!sipcc::PeerConnectionImpl::CreateDataChannel(nsAString_internal const&, nsAString_internal const&, unsigned short, bool, unsigned short, unsigned short, bool, unsigned short, mozilla::ErrorResult&) [PeerConnectionImpl.cpp : 1004 + 0x13]
10  libxul.so!mozilla::dom::PeerConnectionImplBinding::createDataChannel [PeerConnectionImplBinding.cpp : 917 + 0x2d]

This should be remoted to the parent process at some point in this stack.

Comment 1

[Randell Jesup [:jesup] (needinfo me)]

Bug 916427 and changes to the config we use should eliminate any external socket creation.

Comment 2

[Jed Davis [:jld] ⟨⏰|UTC-7⟩ ⟦he/him⟧]

Should this be marked as depending on bug 916427?

Comment 3

[Jed Davis [:jld] ⟨⏰|UTC-7⟩ ⟦he/him⟧]

A relevant fact: our content processes already can't create AF_INET or AF_INET6 sockets — they aren't in the AID_NET group and the kernel has CONFIG_ANDROID_PARANOID_NETWORK=y.  So if usrsctp is trying to do any of that in the content process, then it's already broken on b2g.

Comment 4

[Jed Davis [:jld] ⟨⏰|UTC-7⟩ ⟦he/him⟧]

If I modify the syscall filter to reject all socket()s with EACCES, then the mochitests in gecko/dom/media/tests all pass and the test at http://mozilla.github.io/webrtc-landing/data_test.html appears to work.  So that seems to also be possible as a workaround (and indicates that whatever is going on in sctp_pcb_init isn't actually necessary).

Comment 5

[Jed Davis [:jld] ⟨⏰|UTC-7⟩ ⟦he/him⟧]

This is no longer a seccomp blocker, as of bug 974230; clearing needinfo.

Comment 6

[Randell Jesup [:jesup] (needinfo me)]

Since we landed Bug 916427 I should look at this again - the dependency was missing

Comment 7

[Randell Jesup [:jesup] (needinfo me)]

Michael - FYI.  I'll look at this soon

Comment 8

[Michael Tüxen]

The call is needed if you want to support SCTP/IPv4 or SCTP/IPv6 or SCTP/UDP/IPv4 or SCTP/UDP/IPv6. However, for SCTP/DTLS/UDP/IPv4 or SCTP/DTLS/UDP/IPv6 as used by WebRTC this is not needed.
You can disable the support of SCTP/IPv4 or SCTP/IPv6 or SCTP/UDP/IPv4 or SCTP/UDP/IPv6 by NOT defining INET and INET6 when compiling the usrsctp stack and in all files which include usrsctp.h.

You can remove INET from
https://dxr.mozilla.org/mozilla-central/source/netwerk/sctp/src/moz.build#56
https://dxr.mozilla.org/mozilla-central/source/netwerk/sctp/datachannel/moz.build#26
and INET6 from
https://dxr.mozilla.org/mozilla-central/source/netwerk/sctp/src/moz.build#64
https://dxr.mozilla.org/mozilla-central/source/netwerk/sctp/datachannel/moz.build#30

There should be no change for WebRTC.

Comment 9

[Nils Ohlmeier [:drno]]

Attachment: Bug 969715: remove INET and INET6 from sctp build env.

Review commit: https://reviewboard.mozilla.org/r/97824/diff/#index_header
See other reviews: https://reviewboard.mozilla.org/r/97824/

Comment 10

[Randell Jesup [:jesup] (needinfo me)]

Comment on attachment 8817593 [details]
Bug 969715: remove INET and INET6 from sctp build env.

https://reviewboard.mozilla.org/r/97824/#review98194

Comment 11

[Nils Ohlmeier [:drno]]

Comment on attachment 8817593 [details]
Bug 969715: remove INET and INET6 from sctp build env.

Review request updated; see interdiff: https://reviewboard.mozilla.org/r/97824/diff/1-2/

Comment 12

[Nils Ohlmeier [:drno]]

Comment on attachment 8817593 [details]
Bug 969715: remove INET and INET6 from sctp build env.

Review request updated; see interdiff: https://reviewboard.mozilla.org/r/97824/diff/2-3/

Comment 13

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/572fdb501218
remove INET and INET6 from sctp build env. r=jesup

Comment 14

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/572fdb501218