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January 16, 2021 14:57
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| // Copyright (c) 2021 David Zarzycki | |
| // | |
| // Permission is hereby granted, free of charge, to any person obtaining a copy | |
| // of this software and associated documentation files (the "Software"), to | |
| // deal in the Software without restriction, including without limitation the | |
| // rights to use, copy, modify, merge, publish, distribute, sublicense, and/or | |
| // sell copies of the Software, and to permit persons to whom the Software is | |
| // furnished to do so, subject to the following conditions: | |
| // | |
| // The above copyright notice and this permission notice shall be included in | |
| // all copies or substantial portions of the Software. | |
| // | |
| // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR | |
| // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, | |
| // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE | |
| // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER | |
| // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING | |
| // FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS | |
| // IN THE SOFTWARE. | |
| // | |
| //===----------------------------------------------------------------------===// | |
| // | |
| // This program allows one run a program with a temporary /tmp. | |
| // | |
| //===----------------------------------------------------------------------===// | |
| // Remember: sudo setcap cap_sys_admin+ep tmptmp | |
| // unshare() requres this | |
| #define _GNU_SOURCE | |
| #include <sys/types.h> | |
| #include <sys/mount.h> | |
| #include <unistd.h> | |
| #include <sched.h> | |
| #include <stdio.h> | |
| #include <stdlib.h> | |
| #include <assert.h> | |
| int | |
| main(int argc, char *argv[]) { | |
| if (argc <= 1) { | |
| fprintf(stderr, "usage: %s <program> [args]\n", argv[0]); | |
| return 1; | |
| } | |
| int r; | |
| r = unshare(CLONE_NEWNS); | |
| assert (r == 0); | |
| // Remount the new namespace "private" but do not use MS_REMOUNT because it | |
| // will silently fail. We need to do this, otherwise umount() will affect | |
| // all namespaces. | |
| r = mount("", "/", "", MS_PRIVATE | MS_REC, NULL); | |
| assert (r == 0); | |
| r = umount2("/tmp", MNT_DETACH); | |
| assert(r == 0); | |
| r = mount("", "/tmp", "tmpfs", 0, NULL); | |
| assert (r == 0); | |
| // Is there a way to explicitly drop capabilities? | |
| r = setgid(getgid()); | |
| assert(r == 0); | |
| r = setuid(getuid()); | |
| assert(r == 0); | |
| execvp(argv[1], argv + 1); | |
| perror("execvp"); | |
| return 1; | |
| } |
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