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Prevent Make from talking to public Internet

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This change introduces the nointernet() function which may be called to
prevent a process and its descendants from communicating with publicly
routable Internet addresses. GNU Make has been modified to always call
this function. In the future Landlock Make will have a way to whitelist
subnets to override this behavior, or disable it entirely. Support is
available for Linux only. Our firewall does not require root access.

Calling nointernet() will return control to the caller inside a new
process that has a SECCOMP BPF filter installed, which traps network
related system calls. Your original process then becomes a permanent
ptrace() supervisor that monitors all processes and threads descending
from the returned child. Whenever a networking system call happens the
kernel will stop the process and wakes up the monitor, which then peeks
into the child memory to read the sockaddr_in to determine if it's ok.

The downside to doing this is that there can be only one supervisor at a
time using ptrace() on a process. So this firewall won't be enabled if
you run make under strace or inside gdb. It also makes testing tricky.
This commit is contained in:
Justine Tunney 2022-08-12 05:17:06 -07:00
parent 8a0a2c0c36
commit 7cf66bc161
48 changed files with 4924 additions and 2046 deletions
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2
libc/sysv/calls/__sys_ptrace.s Normal file
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@ -0,0 +1,2 @@
.include "o/libc/sysv/macros.internal.inc"
.scall __sys_ptrace,0x01a01a01a201a065,globl,hidden

2
libc/sysv/calls/sys_ptrace.s
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@ -1,2 +0,0 @@
.include "o/libc/sysv/macros.internal.inc"
.scall sys_ptrace,0x01a01a01a201a065,globl,hidden

2
libc/sysv/syscalls.sh
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@ -139,7 +139,7 @@ scall sys_getrlimit 0x0c20c20c220c2061 globl hidden
scall __sys_getrusage 0x1bd0130752075062 globl hidden
scall sys_sysinfo 0xfffffffffffff063 globl hidden
scall sys_times 0xfffffffffffff064 globl hidden
scall sys_ptrace 0x01a01a01a201a065 globl hidden
scall __sys_ptrace 0x01a01a01a201a065 globl hidden # ptrace() wrapper api is terrible
scall sys_syslog 0xfffffffffffff067 globl hidden
scall sys_getuid 0x0180180182018066 globl hidden
scall sys_getgid 0x02f02f02f202f068 globl hidden