79 lines
1.5 KiB
C
79 lines
1.5 KiB
C
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/*
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* Bind mounts a filesystem mountpoint into the target directory,
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* by using the CAP_SYS_ADMIN capability set on the file.
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*
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* Juan RP - 2010/04/26 - Public Domain.
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <stdbool.h>
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#include <string.h>
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#include <unistd.h>
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#include <errno.h>
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#include <sys/mount.h>
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#include <sys/capability.h>
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void
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usage(void)
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{
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fprintf(stderr, "Usage: xbps-src-capbmount [-w] <orig> <dest>\n");
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exit(EXIT_FAILURE);
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}
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int
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main(int argc, char **argv)
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{
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cap_t cap;
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cap_flag_value_t effective, permitted;
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unsigned long flags;
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int c, rv;
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bool dowrite = false;
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while ((c = getopt(argc, argv, "w")) != -1) {
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switch (c) {
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case 'w':
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dowrite = true;
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break;
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default:
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usage();
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}
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}
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argc -= optind;
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argv += optind;
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if (argc != 2)
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usage();
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cap = cap_get_proc();
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if (cap == NULL) {
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fprintf(stderr, "cap_get_proc() returned %s!\n",
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strerror(errno));
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exit(EXIT_FAILURE);
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}
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cap_get_flag(cap, CAP_SYS_ADMIN, CAP_EFFECTIVE, &effective);
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cap_get_flag(cap, CAP_SYS_ADMIN, CAP_PERMITTED, &permitted);
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if ((effective != CAP_SET) && (permitted != CAP_SET)) {
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fprintf(stderr, "E: missing 'cap_sys_admin' capability!\n"
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"Please set it with: setcap cap_sys_admin=ep %s'\n",
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argv[0]);
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cap_free(cap);
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exit(EXIT_FAILURE);
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}
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cap_free(cap);
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flags = MS_BIND;
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if (!dowrite)
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flags |= MS_RDONLY;
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rv = mount(argv[0], argv[1], "none", flags, NULL);
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if (rv != 0) {
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fprintf(stderr, "E: cannot mount %s into %s: %s\n", argv[0],
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argv[1], strerror(errno));
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exit(EXIT_FAILURE);
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}
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exit(EXIT_SUCCESS);
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}
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