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/*
* virt-login-shell.c: a setuid shell to connect to a container
*
* Copyright (C) 2019 Red Hat, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library. If not, see
* <http://www.gnu.org/licenses/>.
*/
#include <config.h>
#include <unistd.h>
#include <sys/types.h>
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include "configmake.h"
#define G_N_ELEMENTS(Array) (sizeof(Array) / sizeof(*(Array)))
#define VIR_INT64_STR_BUFLEN 21
int main(int argc, char **argv) {
char uidstr[VIR_INT64_STR_BUFLEN];
char gidstr[VIR_INT64_STR_BUFLEN];
const char * newargv[6];
size_t nargs = 0;
char *newenv[] = {
NULL,
NULL,
};
char *term = getenv("TERM");
if (getuid() == 0 || getgid() == 0) {
fprintf(stderr, "%s: must not be run as root\n", argv[0]);
exit(EXIT_FAILURE);
}
if (geteuid() != 0) {
fprintf(stderr, "%s: must be run as setuid root\n", argv[0]);
exit(EXIT_FAILURE);
}
newargv[nargs++] = LIBEXECDIR "/virt-login-shell-helper";
if (argc == 3) {
if (strcmp(argv[1], "-c") != 0) {
fprintf(stderr, "%s: syntax: %s [-c CMDSTR]\n", argv[0], argv[0]);
exit(EXIT_FAILURE);
}
newargv[nargs++] = argv[1];
newargv[nargs++] = argv[2];
} else if (argc != 1) {
fprintf(stderr, "%s: syntax: %s [-c CMDSTR]\n", argv[0], argv[0]);
exit(EXIT_FAILURE);
}
newargv[nargs++] = uidstr;
newargv[nargs++] = gidstr;
newargv[nargs++] = NULL;
assert(nargs <= G_N_ELEMENTS(newargv));
if (term &&
asprintf(&(newenv[0]), "TERM=%s", term) < 0) {
fprintf(stderr, "%s: cannot set TERM env variable: %s\n",
argv[0], strerror(errno));
exit(EXIT_FAILURE);
}
assert(snprintf(uidstr, sizeof(uidstr), "%d", getuid()) < sizeof(uidstr));
assert(snprintf(gidstr, sizeof(gidstr), "%d", getgid()) < sizeof(gidstr));
if (setuid(0) < 0) {
fprintf(stderr, "%s: unable to set real UID to root: %s\n",
argv[0], strerror(errno));
exit(EXIT_FAILURE);
}
execve(newargv[0], (char *const*)newargv, newenv);
fprintf(stderr, "%s: failed to run %s/virt-login-shell-helper: %s\n",
argv[0], LIBEXECDIR, strerror(errno));
exit(EXIT_FAILURE);
}
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