Date: Tue, 16 Jul 2019 15:58:50 +0000 From: bugzilla-noreply@freebsd.org To: bugs@FreeBSD.org Subject: [Bug 239250] need to define limits on unix socket control messages Message-ID: <bug-239250-227@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D239250 Bug ID: 239250 Summary: need to define limits on unix socket control messages Product: Base System Version: CURRENT Hardware: Any OS: Any Status: New Severity: Affects Only Me Priority: --- Component: kern Assignee: bugs@FreeBSD.org Reporter: markj@FreeBSD.org There are some undocumented limits that apply to control messages over unix domain sockets, and SCM_RIGHTS messages in particular. - Control messages must fit in an mbuf cluster, which is MCLBYTES (2KB) in size. - Control message data must be natively aligned, so 64-bit kernels are limi= ted to fewer rights per message than 32-bit kernels. This can be problematic w= hen running 32-bit applications on a 64-bit kernel. - SCM_RIGHTS message contents must be translated to an internalized format before they can be transmitted. Specifically, a 4-byte file descriptor is converted to a pointer, and internalized messages must fit in an mbuf clust= er as well. So even though we can pack (2048-16)/sizeof(int) FDs in a single SCM_RIGHTS message on amd64, the kernel can only handle (2048-16)/sizeof(vo= id *) FDs. --=20 You are receiving this mail because: You are the assignee for the bug.=
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