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command line options

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added command line options, for now only -u and -g are listed and implemented,
they allow to change user and group target (default is root)
This commit is contained in:
Alessandro Mauri 2021-03-28 16:58:28 +02:00
parent 778168b21a
commit 5ef9bd4200
1 changed files with 46 additions and 29 deletions
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75
us.c
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@ -39,14 +39,55 @@ static struct pam_conv conv = {misc_conv, NULL};
int main (int argc, char *argv[]) int main (int argc, char *argv[])
{ {
// TODO: Add arguments
// FIXME: change the default program to execute SHELL // FIXME: change the default program to execute SHELL
if (argc < 2) { char *t_usr = NULL, *t_grp = NULL;
int opt;
while ((opt = getopt(argc, argv, "A:u:g:C:")) != -1) {
switch (opt) {
case 'A':
printf("-A is not yet implemented\n");
exit(EXIT_FAILURE);
break;
case 'u':
t_usr = optarg;
break;
case 'g':
t_grp = optarg;
break;
case 'C':
printf("-C is not yet implemented\n");
exit(EXIT_FAILURE);
break;
case '?':
usage();
exit(EINVAL);
break;
}
}
// Copy argv and argc
int c_argc = argc - optind;
char **c_argv = malloc((c_argc + 1) * sizeof(char *));
if (!c_argv) {
fprintf(stderr, "malloc: %s\n", strerror(errno));
goto fail_end;
}
for (int i = 0; optind < argc; i++, optind++) {
c_argv[i] = strdup(argv[optind]);
if (!c_argv[i]) {
fprintf(stderr, "getpwid: %s\n", strerror(errno));
exit(errno);
}
}
c_argc[c_argv] = NULL;
if (c_argc == 0) {
usage(); usage();
exit(1); exit(EINVAL);
} }
uid_t ruid = getuid(); uid_t ruid = getuid();
// gid_t rgid = getgid();
struct passwd *pw = getpwuid(ruid); struct passwd *pw = getpwuid(ruid);
if (!pw) { if (!pw) {
fprintf(stderr, "getpwid: %s\n", strerror(errno)); fprintf(stderr, "getpwid: %s\n", strerror(errno));
@ -56,10 +97,6 @@ int main (int argc, char *argv[])
pam_handle_t *pamh; pam_handle_t *pamh;
int pam_err, count = 0; int pam_err, count = 0;
// TODO: Add arguments
// TODO: add PAM authentication
pam_err = pam_start("User Switcher", uname, &conv, &pamh); pam_err = pam_start("User Switcher", uname, &conv, &pamh);
if (pam_err != PAM_SUCCESS) { if (pam_err != PAM_SUCCESS) {
fprintf(stderr, "pam_start: %s\n", pam_strerror(pamh, pam_err)); fprintf(stderr, "pam_start: %s\n", pam_strerror(pamh, pam_err));
@ -85,20 +122,9 @@ int main (int argc, char *argv[])
pam_end(pamh, pam_err); pam_end(pamh, pam_err);
// TODO: clean up env // TODO: clean up env
// Copy argv and argc
int c_argc = argc - 1;
char **c_argv = malloc((c_argc + 1) * sizeof(char *));
if (!c_argv) {
fprintf(stderr, "malloc: %s\n", strerror(errno));
goto fail_end;
}
for (int i = 0; i < c_argc; i++)
c_argv[i] = strdup(argv[i+1]);
c_argc[c_argv] = NULL;
errno = 0; errno = 0;
/* Set permissions */ /* Set permissions */
if (perm_set(NULL, NULL) == -1) { // 0 = root if (perm_set(t_usr, t_grp) == -1) { // 0 = root
fprintf(stderr, "perm_set: %s\n", strerror(errno)); fprintf(stderr, "perm_set: %s\n", strerror(errno));
goto fail_end; goto fail_end;
} }
@ -107,17 +133,8 @@ int main (int argc, char *argv[])
if (execvp(*c_argv, c_argv) == -1) // execvp searches in path if (execvp(*c_argv, c_argv) == -1) // execvp searches in path
fprintf(stderr, "execv: %s\n", strerror(errno)); fprintf(stderr, "execv: %s\n", strerror(errno));
/* We may no longer have permission to reset the permissions
// If exec fails reset the permissions
if (perm_set(pw->pw_name, NULL) == -1) { // 0 = root
fprintf(stderr, "perm_set: %s\n", strerror(errno));
goto fail_end;
} */
/* Cleanup and return */ /* Cleanup and return */
fail_end: fail_end:
/* Free up the copied argv */ /* Free up the copied argv */
for (int i = 0; i < c_argc; i++) for (int i = 0; i < c_argc; i++)
free(c_argv[i]); free(c_argv[i]);
@ -135,7 +152,7 @@ static inline void usage (void)
// -c [file]: manually select config file // -c [file]: manually select config file
// something about environment // something about environment
// something about non interactiveness // something about non interactiveness
printf("usage: us [command]\n"); printf("usage: us [-u user] [-g group] command [args]\n");
} }
static int perm_set (const char *user, const char *group) static int perm_set (const char *user, const char *group)