| 1 |
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| 2 | #include <sys/types.h>
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| 3 |
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| 4 | #include <err.h>
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| 5 | #include <grp.h>
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| 6 | #include <stdio.h>
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| 7 | #include <stdlib.h>
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| 8 | #include <string.h>
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| 9 | #include <unistd.h>
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| 10 |
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| 11 | #ifndef ABUILD_GROUP
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| 12 | #define ABUILD_GROUP "abuild"
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| 13 | #endif
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| 14 |
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| 15 | static const char* valid_cmds[] = {
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| 16 | "/bin/adduser",
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| 17 | "/bin/addgroup",
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| 18 | "/sbin/apk",
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| 19 | NULL
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| 20 | };
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| 21 |
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| 22 | const char *get_command_path(const char *cmd)
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| 23 | {
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| 24 | const char *p;
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| 25 | int i;
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| 26 | for (i = 0; valid_cmds[i] != NULL; i++) {
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| 27 | p = strrchr(valid_cmds[i], '/') + 1;
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| 28 | if (strcmp(p, cmd) == 0)
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| 29 | return valid_cmds[i];
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| 30 | }
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| 31 | return NULL;
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| 32 | }
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| 33 |
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| 34 | int is_in_group(gid_t group)
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| 35 | {
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| 36 | int ngroups_max = sysconf(_SC_NGROUPS_MAX) + 1;
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| 37 | gid_t *buf = malloc(ngroups_max * sizeof(gid_t));
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| 38 | int ngroups, ret = 0;
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| 39 | int i;
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| 40 | if (buf == NULL) {
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| 41 | perror("malloc");
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| 42 | return 0;
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| 43 | }
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| 44 | ngroups = getgroups(ngroups_max, buf);
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| 45 | for (i = 0; i < ngroups; i++) {
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| 46 | if (buf[i] == group)
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| 47 | break;
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| 48 | }
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| 49 | free(buf);
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| 50 | return i < ngroups;
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| 51 | }
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| 52 |
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| 53 |
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| 54 | int main(int argc, const char *argv[])
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| 55 | {
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| 56 | struct group *grent;
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| 57 | const char *cmd;
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| 58 | const char *path;
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| 59 |
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| 60 | grent = getgrnam(ABUILD_GROUP);
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| 61 | if (grent == NULL)
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| 62 | errx(1, "%s: Group not found", ABUILD_GROUP);
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| 63 |
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| 64 | if (!is_in_group(grent->gr_gid))
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| 65 | errx(1, "Not a member of group %s\n", ABUILD_GROUP);
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| 66 |
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| 67 | cmd = strrchr(argv[0], '-');
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| 68 | if (cmd == NULL)
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| 69 | errx(1, "Calling command has no '-'");
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| 70 | cmd++;
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| 71 |
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| 72 | path = get_command_path(cmd);
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| 73 | if (path == NULL)
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| 74 | errx(1, "%s: Not a valid subcommand", cmd);
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| 75 |
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| 76 | argv[0] = path;
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| 77 |
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| 78 | setuid(0);
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| 79 | execv(path, (char * const*)argv);
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| 80 | return 1;
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| 81 | }
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