101 lines
3.0 KiB
C
101 lines
3.0 KiB
C
/*
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* Copyright (C) 2023 Red Hat, Inc.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Red Hat designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Red Hat in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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*/
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#include <errno.h>
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#include <libgen.h>
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#include <linux/limits.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/prctl.h>
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#include <unistd.h>
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/* Per task speculation control */
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#ifndef PR_GET_SPECULATION_CTRL
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# define PR_GET_SPECULATION_CTRL 52
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#endif
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#ifndef PR_SET_SPECULATION_CTRL
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# define PR_SET_SPECULATION_CTRL 53
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#endif
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/* Speculation control variants */
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#ifndef PR_SPEC_STORE_BYPASS
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# define PR_SPEC_STORE_BYPASS 0
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#endif
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/* Return and control values for PR_SET/GET_SPECULATION_CTRL */
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#ifndef PR_SPEC_NOT_AFFECTED
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# define PR_SPEC_NOT_AFFECTED 0
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#endif
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#ifndef PR_SPEC_PRCTL
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# define PR_SPEC_PRCTL (1UL << 0)
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#endif
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#ifndef PR_SPEC_ENABLE
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# define PR_SPEC_ENABLE (1UL << 1)
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#endif
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#ifndef PR_SPEC_DISABLE
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# define PR_SPEC_DISABLE (1UL << 2)
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#endif
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#ifndef PR_SPEC_FORCE_DISABLE
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# define PR_SPEC_FORCE_DISABLE (1UL << 3)
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#endif
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#ifndef PR_SPEC_DISABLE_NOEXEC
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# define PR_SPEC_DISABLE_NOEXEC (1UL << 4)
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#endif
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static void set_speculation() {
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#if defined(__linux__) && defined(__x86_64__)
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// PR_SPEC_DISABLE_NOEXEC doesn't survive execve, so we can't use it
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// if ( prctl(PR_SET_SPECULATION_CTRL,
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// PR_SPEC_STORE_BYPASS,
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// PR_SPEC_DISABLE_NOEXEC, 0, 0) == 0 ) {
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// return;
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// }
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prctl(PR_SET_SPECULATION_CTRL, PR_SPEC_STORE_BYPASS, PR_SPEC_DISABLE, 0, 0);
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#else
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#warning alt-java requested but SSB mitigation not available on this platform.
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#endif
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}
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int main(int argc, char **argv) {
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set_speculation();
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char our_name[PATH_MAX], java_name[PATH_MAX];
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ssize_t len = readlink("/proc/self/exe", our_name, PATH_MAX - 1);
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if (len < 0) {
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perror("I can't find myself");
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exit(2);
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}
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our_name[len] = '\0'; // readlink(2) doesn't append a null byte
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char *path = dirname(our_name);
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strncpy(java_name, path, PATH_MAX - 1);
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size_t remaining_bytes = PATH_MAX - strlen(path) - 1;
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strncat(java_name, "/java", remaining_bytes);
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execv(java_name, argv);
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fprintf(stderr, "%s failed to launch: %s\n", java_name, strerror(errno));
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exit(1);
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}
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