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cosmopolitan/tool/build/lib/ldbl.c

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Initial import
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/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
Prevent Make from talking to public Internet 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.
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│ Copyright 2022 Justine Alexandra Roberts Tunney │
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│ │
Change license
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│ Permission to use, copy, modify, and/or distribute this software for │
│ any purpose with or without fee is hereby granted, provided that the │
│ above copyright notice and this permission notice appear in all copies. │
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│ │
Change license
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
│ PERFORMANCE OF THIS SOFTWARE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
Prevent Make from talking to public Internet 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.
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#include "libc/macros.internal.h"
#include "tool/build/lib/endian.h"
#include "tool/build/lib/ldbl.h"
#include "tool/build/lib/pun.h"
Initial import
2020-06-15 14:18:57 +00:00
Prevent Make from talking to public Internet 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.
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uint8_t *SerializeLdbl(uint8_t b[10], double f) {
int e;
union DoublePun u = {f};
e = (u.i >> 52) & 0x7ff;
if (!e) {
e = 0;
} else if (e == 0x7ff) {
e = 0x7fff;
} else {
e -= 0x3ff;
e += 0x3fff;
}
Write16(b + 8, e | u.i >> 63 << 15);
Write64(b, (u.i & 0x000fffffffffffff) << 11 | (uint64_t) !!u.f << 63);
return b;
}
double DeserializeLdbl(const uint8_t b[10]) {
union DoublePun u;
u.i = (uint64_t)(MAX(-1023, MIN(1024, ((Read16(b + 8) & 0x7fff) - 0x3fff))) +
1023)
<< 52 |
((Read64(b) & 0x7fffffffffffffff) + (1 << (11 - 1))) >> 11 |
(uint64_t)(b[9] >> 7) << 63;
return u.f;
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}
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