1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
|
#include <stdio.h>
#include <stdlib.h>
#include <security/pam_appl.h>
#include <security/pam_modules.h>
#include <sys/wait.h>
#include <unistd.h>
#include <sched.h>
#include <dlfcn.h>
#define countof(_x) ((int)((sizeof((_x)) / sizeof((_x)[0]))))
struct module_args_t {
int (*callback)(pam_handle_t *, int, int, const char **);
pam_handle_t *handler;
int flags;
int argc;
const char **argv;
};
struct auth_module_t {
const char *name;
const char *path;
const char *symbol;
struct module_args_t args;
void *dl_handler;
pid_t pid;
};
static
struct auth_module_t modules_g[] = {
{
.name = "unix",
.path = "/usr/lib/security/pam_unix.so",
.symbol = "pam_sm_authenticate",
}, {
.name = "other",
.path = "/home/camel_case/dev/fingerprint/pam_other.so",
.symbol = "pam_sm_authenticate",
},
};
static int multi_auth_init(pam_handle_t *pamh, int flags,
int argc, const char **argv)
{
for (int i = 0; i < countof(modules_g); ++i) {
struct auth_module_t *mod = &modules_g[i];
mod->dl_handler = dlopen(mod->path, RTLD_NOW);
if (mod->dl_handler == NULL) {
fprintf(stderr, "%s: %m\n", mod->path);
return PAM_SYSTEM_ERR;
}
mod->args.callback = dlsym(mod->dl_handler, mod->symbol);
mod->args.handler = pamh;
mod->args.flags = flags;
mod->args.argc = argc;
mod->args.argv = argv;
if (mod->args.callback == NULL) {
return PAM_SYSTEM_ERR;
}
}
return 0;
}
static void multi_auth_fini(void)
{
for (int i = 0; i < countof(modules_g); ++i) {
dlclose(modules_g[i].dl_handler);
}
}
static int module_auth_main(void *_args)
{
struct module_args_t *args = _args;
/* the child is supposed to close after returning from this function */
return args->callback(args->handler, args->flags, args->argc, args->argv);
}
static int perform_auth(void)
{
for (int i = 0; i < countof(modules_g); ++i) {
#define STACK_SIZE (1000 * 1000)
struct auth_module_t *mod = &modules_g[i];
void *stack = malloc(STACK_SIZE);
if (stack == NULL) {
return PAM_AUTH_ERR;
}
int clone_flags = CLONE_NEWUTS|SIGCHLD;
modules_g[i].pid = clone(module_auth_main, stack + STACK_SIZE, clone_flags, &mod->args);
if (modules_g[i].pid == -1) {
return PAM_SYSTEM_ERR;
}
#undef STACK_SIZE
}
for (int i = 0; i < countof(modules_g); ++i) {
int status;
do {
waitpid(-1, &status, 0);
} while (!WIFEXITED(status) && !WIFSIGNALED(status));
if (WIFEXITED(status)) {
for (int j = 0; j < countof(modules_g); ++j) {
kill(modules_g[j].pid, SIGKILL);
}
return (WEXITSTATUS(status) == 0) ? PAM_SUCCESS : PAM_AUTH_ERR;
}
}
return PAM_AUTH_ERR;
}
PAM_EXTERN
int pam_sm_setcred(pam_handle_t *pamh, int flags, int argc, const char **argv)
{
(void)pamh;
(void)flags;
(void)argc;
(void)argv;
return PAM_SUCCESS;
}
PAM_EXTERN
int pam_sm_authenticate(pam_handle_t *pamh, int flags,
int argc, const char **argv)
{
int ret = multi_auth_init(pamh, flags, argc, argv);
if (ret == 0) {
ret = perform_auth();
}
multi_auth_fini();
return ret;
}
|
