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f94c11d978
The ape loader now passes the program executable name directly as a register. `x2` is used on aarch64, `%rdx` on x86_64. This is passed as the third argument to `cosmo()` (M1) or `Launch` (non-M1) and is assigned to the global `__program_executable_name`. `GetProgramExecutableName` now returns this global's value, setting it if it is initially null. `InitProgramExecutableName` first tries exotic, secure methods: `KERN_PROC_PATHNAME` on FreeBSD/NetBSD, and `/proc` on Linux. If those produce a reasonable response (i.e., not `"/usr/bin/ape"`, which happens with the loader before this change), that is used. Otherwise, if `issetugid()`, the empty string is used. Otherwise, the old argv/envp parsing code is run. The value returned from the loader is always the full absolute path of the binary to be executed, having passed through `realpath`. For the non-M1 loader, this necessitated writing `RealPath`, which uses `readlinkat` of `"/proc/self/fd/[progfd]"` on Linux, `F_GETPATH` on Xnu, and the `__realpath` syscall on OpenBSD. On FreeBSD/NetBSD, it punts to `GetProgramExecutableName`, which is secure on those OSes. With the loader, all platforms now have a secure program executable name. With no loader or an old loader, everything still works as it did, but setuid/setgid is not supported if the insecure pathfinding code would have been needed. Fixes #991.
22 lines
1.9 KiB
C
22 lines
1.9 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│ vi: set et ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi │
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2023 Justine Alexandra Roberts Tunney │
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│ │
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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above copyright notice and this permission notice appear in all copies. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/runtime/runtime.h"
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char *__program_executable_name;
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