mirror of
https://github.com/RsyncProject/rsync.git
synced 2026-09-16 15:17:41 -04:00
Andrew Tridgell
b33571a1df
Route the daemon's operator-supplied path opens through safe_open_no_attacker_symlinks() / a pinned parent dir so a local attacker cannot plant a symlink at one and redirect the daemon's privileged read/write: motd, --early-input, lock and --config paths (clientserver/connection/params); the --password-file and daemon secrets file, fstat'ing the opened fd (authenticate); and the pid-file parent dir. Tests: daemon-config-symlink, early-input-symlink, daemon-secrets-file-symlink, password-file-symlink, daemon-module-chdir-symlink.
50 lines
1.5 KiB
C
50 lines
1.5 KiB
C
/*
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* Support the max connections option.
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*
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* Copyright (C) 1998 Andrew Tridgell
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* Copyright (C) 2006-2020 Wayne Davison
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, visit the http://fsf.org website.
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*/
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#include "rsync.h"
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/* A simple routine to do connection counting. This returns 1 on success
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* and 0 on failure, with errno also being set if the open() failed (errno
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* will be 0 if the lock request failed). */
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int claim_connection(char *fname, int max_connections)
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{
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int fd, i;
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if (max_connections == 0)
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return 1;
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/* 'lock file = PATH': refuse symlinks not owned by uid 0 or our euid so
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* a planted parent can't redirect the root daemon's O_CREAT open. */
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if ((fd = safe_open_no_attacker_symlinks(fname, O_RDWR|O_CREAT, 0600)) < 0)
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return 0;
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/* Find a free spot. */
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for (i = 0; i < max_connections; i++) {
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if (lock_range(fd, i*4, 4))
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return 1;
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}
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close(fd);
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/* A lock failure needs to return an errno of 0. */
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errno = 0;
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return 0;
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}
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