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libtdevnc/x11vnc/user.c

931 lines
17 KiB

/* -- user.c -- */
#include "x11vnc.h"
#include "solid.h"
#include "cleanup.h"
#include "scan.h"
#include "screen.h"
void check_switched_user(void);
void lurk_loop(char *str);
int switch_user(char *user, int fb_mode);
int read_passwds(char *passfile);
void install_passwds(void);
void check_new_passwds(void);
static void switch_user_task_dummy(void);
static void switch_user_task_solid_bg(void);
static char *get_login_list(int with_display);
static char **user_list(char *user_str);
static void user2uid(char *user, uid_t *uid, char **name, char **home);
static int lurk(char **users);
static int guess_user_and_switch(char *str, int fb_mode);
static int try_user_and_display(uid_t uid, char *dpystr);
static int switch_user_env(uid_t uid, char *name, char *home, int fb_mode);
static void try_to_switch_users(void);
/* tasks for after we switch */
static void switch_user_task_dummy(void) {
; /* dummy does nothing */
}
static void switch_user_task_solid_bg(void) {
/* we have switched users, some things to do. */
if (use_solid_bg && client_count) {
solid_bg(0);
}
}
void check_switched_user(void) {
static time_t sched_switched_user = 0;
static int did_solid = 0;
static int did_dummy = 0;
int delay = 15;
time_t now = time(0);
if (started_as_root == 1 && users_list) {
try_to_switch_users();
if (started_as_root == 2) {
/*
* schedule the switch_user_tasks() call
* 15 secs is for piggy desktops to start up.
* might not be enough for slow machines...
*/
sched_switched_user = now;
did_dummy = 0;
did_solid = 0;
/* add other activities */
}
}
if (! sched_switched_user) {
return;
}
if (! did_dummy) {
switch_user_task_dummy();
did_dummy = 1;
}
if (! did_solid) {
int doit = 0;
char *ss = solid_str;
if (now >= sched_switched_user + delay) {
doit = 1;
} else if (ss && strstr(ss, "root:") == ss) {
if (now >= sched_switched_user + 3) {
doit = 1;
}
} else if (strcmp("root", guess_desktop())) {
usleep(1000 * 1000);
doit = 1;
}
if (doit) {
switch_user_task_solid_bg();
did_solid = 1;
}
}
if (did_dummy && did_solid) {
sched_switched_user = 0;
}
}
/* utilities for switching users */
static char *get_login_list(int with_display) {
char *out;
#if LIBVNCSERVER_HAVE_UTMPX_H
int i, cnt, max = 200, ut_namesize = 32;
int dpymax = 1000, sawdpy[1000];
struct utmpx *utx;
/* size based on "username:999," * max */
out = (char *) malloc(max * (ut_namesize+1+3+1) + 1);
out[0] = '\0';
for (i=0; i<dpymax; i++) {
sawdpy[i] = 0;
}
setutxent();
cnt = 0;
while (1) {
char *user, *line, *host, *id;
char tmp[10];
int d = -1;
utx = getutxent();
if (! utx) {
break;
}
if (utx->ut_type != USER_PROCESS) {
continue;
}
user = lblanks(utx->ut_user);
if (*user == '\0') {
continue;
}
if (strchr(user, ',')) {
continue; /* unlikely, but comma is our sep. */
}
line = lblanks(utx->ut_line);
host = lblanks(utx->ut_host);
id = lblanks(utx->ut_id);
if (with_display) {
if (0 && line[0] != ':' && strcmp(line, "dtlocal")) {
/* XXX useful? */
continue;
}
if (line[0] == ':') {
if (sscanf(line, ":%d", &d) != 1) {
d = -1;
}
}
if (d < 0 && host[0] == ':') {
if (sscanf(host, ":%d", &d) != 1) {
d = -1;
}
}
if (d < 0 && id[0] == ':') {
if (sscanf(id, ":%d", &d) != 1) {
d = -1;
}
}
if (d < 0 || d >= dpymax || sawdpy[d]) {
continue;
}
sawdpy[d] = 1;
sprintf(tmp, ":%d", d);
} else {
/* try to eliminate repeats */
int repeat = 0;
char *q;
q = out;
while ((q = strstr(q, user)) != NULL) {
char *p = q + strlen(user) + strlen(":DPY");
if (q == out || *(q-1) == ',') {
/* bounded on left. */
if (*p == ',' || *p == '\0') {
/* bounded on right. */
repeat = 1;
break;
}
}
q = p;
}
if (repeat) {
continue;
}
sprintf(tmp, ":DPY");
}
if (*out) {
strcat(out, ",");
}
strcat(out, user);
strcat(out, tmp);
cnt++;
if (cnt >= max) {
break;
}
}
endutxent();
#else
out = strdup("");
#endif
return out;
}
static char **user_list(char *user_str) {
int n, i;
char *p, **list;
p = user_str;
n = 1;
while (*p++) {
if (*p == ',') {
n++;
}
}
list = (char **) malloc((n+1)*sizeof(char *));
p = strtok(user_str, ",");
i = 0;
while (p) {
list[i++] = p;
p = strtok(NULL, ",");
}
list[i] = NULL;
return list;
}
static void user2uid(char *user, uid_t *uid, char **name, char **home) {
int numerical = 1;
char *q;
*uid = (uid_t) -1;
*name = NULL;
*home = NULL;
q = user;
while (*q) {
if (! isdigit(*q++)) {
numerical = 0;
break;
}
}
if (numerical) {
int u = atoi(user);
if (u < 0) {
return;
}
*uid = (uid_t) u;
}
#if LIBVNCSERVER_HAVE_PWD_H
if (1) {
struct passwd *pw;
if (numerical) {
pw = getpwuid(*uid);
} else {
pw = getpwnam(user);
}
if (pw) {
*uid = pw->pw_uid;
*name = pw->pw_name; /* n.b. use immediately */
*home = pw->pw_dir;
}
}
#endif
}
static int lurk(char **users) {
uid_t uid;
int success = 0, dmin = -1, dmax = -1;
char *p, *logins, **u;
if ((u = users) != NULL && *u != NULL && *(*u) == ':') {
int len;
char *tmp;
/* extract min and max display numbers */
tmp = *u;
if (strchr(tmp, '-')) {
if (sscanf(tmp, ":%d-%d", &dmin, &dmax) != 2) {
dmin = -1;
dmax = -1;
}
}
if (dmin < 0) {
if (sscanf(tmp, ":%d", &dmin) != 1) {
dmin = -1;
dmax = -1;
} else {
dmax = dmin;
}
}
if ((dmin < 0 || dmax < 0) || dmin > dmax || dmax > 10000) {
dmin = -1;
dmax = -1;
}
/* get user logins regardless of having a display: */
logins = get_login_list(0);
/*
* now we append the list in users (might as well try
* them) this will probably allow weird ways of starting
* xservers to work.
*/
len = strlen(logins);
u++;
while (*u != NULL) {
len += strlen(*u) + strlen(":DPY,");
u++;
}
tmp = (char *) malloc(len+1);
strcpy(tmp, logins);
/* now concatenate them: */
u = users+1;
while (*u != NULL) {
char *q, chk[100];
snprintf(chk, 100, "%s:DPY", *u);
q = strstr(tmp, chk);
if (q) {
char *p = q + strlen(chk);
if (q == tmp || *(q-1) == ',') {
/* bounded on left. */
if (*p == ',' || *p == '\0') {
/* bounded on right. */
u++;
continue;
}
}
}
if (*tmp) {
strcat(tmp, ",");
}
strcat(tmp, *u);
strcat(tmp, ":DPY");
u++;
}
free(logins);
logins = tmp;
} else {
logins = get_login_list(1);
}
p = strtok(logins, ",");
while (p) {
char *user, *name, *home, dpystr[10];
char *q, *t;
int ok = 1, dn;
t = strdup(p); /* bob:0 */
q = strchr(t, ':');
if (! q) {
free(t);
break;
}
*q = '\0';
user = t;
snprintf(dpystr, 10, ":%s", q+1);
if (users) {
u = users;
ok = 0;
while (*u != NULL) {
if (*(*u) == ':') {
u++;
continue;
}
if (!strcmp(user, *u++)) {
ok = 1;
break;
}
}
}
user2uid(user, &uid, &name, &home);
free(t);
if (! uid) {
ok = 0;
}
if (! ok) {
p = strtok(NULL, ",");
continue;
}
for (dn = dmin; dn <= dmax; dn++) {
if (dn >= 0) {
sprintf(dpystr, ":%d", dn);
}
if (try_user_and_display(uid, dpystr)) {
if (switch_user_env(uid, name, home, 0)) {
rfbLog("lurk: now user: %s @ %s\n",
name, dpystr);
started_as_root = 2;
success = 1;
}
set_env("DISPLAY", dpystr);
break;
}
}
if (success) {
break;
}
p = strtok(NULL, ",");
}
free(logins);
return success;
}
void lurk_loop(char *str) {
char *tstr = NULL, **users = NULL;
if (strstr(str, "lurk=") != str) {
exit(1);
}
rfbLog("lurking for logins using: '%s'\n", str);
if (strlen(str) > strlen("lurk=")) {
char *q = strchr(str, '=');
tstr = strdup(q+1);
users = user_list(tstr);
}
while (1) {
if (lurk(users)) {
break;
}
sleep(3);
}
if (tstr) {
free(tstr);
}
if (users) {
free(users);
}
}
static int guess_user_and_switch(char *str, int fb_mode) {
char *dstr, *d = DisplayString(dpy);
char *p, *tstr = NULL, *allowed = NULL, *logins, **users = NULL;
int dpy1, ret = 0;
/* pick out ":N" */
dstr = strchr(d, ':');
if (! dstr) {
return 0;
}
if (sscanf(dstr, ":%d", &dpy1) != 1) {
return 0;
}
if (dpy1 < 0) {
return 0;
}
if (strstr(str, "guess=") == str && strlen(str) > strlen("guess=")) {
allowed = strchr(str, '=');
allowed++;
tstr = strdup(allowed);
users = user_list(tstr);
}
/* loop over the utmpx entries looking for this display */
logins = get_login_list(1);
p = strtok(logins, ",");
while (p) {
char *user, *q, *t;
int dpy2, ok = 1;
t = strdup(p);
q = strchr(t, ':');
if (! q) {
free(t);
break;
}
*q = '\0';
user = t;
dpy2 = atoi(q+1);
if (users) {
char **u = users;
ok = 0;
while (*u != NULL) {
if (!strcmp(user, *u++)) {
ok = 1;
break;
}
}
}
if (dpy1 != dpy2) {
ok = 0;
}
if (! ok) {
free(t);
p = strtok(NULL, ",");
continue;
}
if (switch_user(user, fb_mode)) {
rfbLog("switched to guessed user: %s\n", user);
free(t);
ret = 1;
break;
}
p = strtok(NULL, ",");
}
if (tstr) {
free(tstr);
}
if (users) {
free(users);
}
if (logins) {
free(logins);
}
return ret;
}
static int try_user_and_display(uid_t uid, char *dpystr) {
/* NO strtoks */
#if LIBVNCSERVER_HAVE_FORK && LIBVNCSERVER_HAVE_SYS_WAIT_H && LIBVNCSERVER_HAVE_PWD_H
pid_t pid, pidw;
char *home, *name;
int st;
struct passwd *pw;
pw = getpwuid(uid);
if (pw) {
name = pw->pw_name;
home = pw->pw_dir;
} else {
return 0;
}
/*
* We fork here and try to open the display again as the
* new user. Unreadable XAUTHORITY could be a problem...
* This is not really needed since we have DISPLAY open but:
* 1) is a good indicator this user owns the session and 2)
* some activities do spawn new X apps, e.g. xmessage(1), etc.
*/
if ((pid = fork()) > 0) {
;
} else if (pid == -1) {
fprintf(stderr, "could not fork\n");
rfbLogPerror("fork");
return 0;
} else {
/* child */
Display *dpy2 = NULL;
int rc;
rc = switch_user_env(uid, name, home, 0);
if (! rc) {
exit(1);
}
fclose(stderr);
dpy2 = XOpenDisplay(dpystr);
if (dpy2) {
XCloseDisplay(dpy2);
exit(0); /* success */
} else {
exit(2); /* fail */
}
}
/* see what the child says: */
pidw = waitpid(pid, &st, 0);
if (pidw == pid && WIFEXITED(st) && WEXITSTATUS(st) == 0) {
return 1;
}
#endif /* LIBVNCSERVER_HAVE_FORK ... */
return 0;
}
int switch_user(char *user, int fb_mode) {
/* NO strtoks */
int doit = 0;
uid_t uid = 0;
char *name, *home;
if (*user == '+') {
doit = 1;
user++;
}
if (strstr(user, "guess=") == user) {
return guess_user_and_switch(user, fb_mode);
}
user2uid(user, &uid, &name, &home);
if (uid == (uid_t) -1 || uid == 0) {
return 0;
}
if (! doit && dpy) {
/* see if this display works: */
char *dstr = DisplayString(dpy);
doit = try_user_and_display(uid, dstr);
}
if (doit) {
int rc = switch_user_env(uid, name, home, fb_mode);
if (rc) {
started_as_root = 2;
}
return rc;
} else {
return 0;
}
}
static int switch_user_env(uid_t uid, char *name, char *home, int fb_mode) {
/* NO strtoks */
char *xauth;
int reset_fb = 0;
#if !LIBVNCSERVER_HAVE_SETUID
return 0;
#else
/*
* OK tricky here, we need to free the shm... otherwise
* we won't be able to delete it as the other user...
*/
if (fb_mode == 1 && using_shm) {
reset_fb = 1;
clean_shm(0);
free_tiles();
}
if (setuid(uid) != 0) {
if (reset_fb) {
/* 2 means we did clean_shm and free_tiles */
do_new_fb(2);
}
return 0;
}
#endif
if (reset_fb) {
do_new_fb(2);
}
xauth = getenv("XAUTHORITY");
if (xauth && access(xauth, R_OK) != 0) {
*(xauth-2) = '_'; /* yow */
}
set_env("USER", name);
set_env("LOGNAME", name);
set_env("HOME", home);
return 1;
}
static void try_to_switch_users(void) {
static time_t last_try = 0;
time_t now = time(0);
char *users, *p;
if (getuid() && geteuid()) {
rfbLog("try_to_switch_users: not root\n");
started_as_root = 2;
return;
}
if (!last_try) {
last_try = now;
} else if (now <= last_try + 2) {
/* try every 3 secs or so */
return;
}
last_try = now;
users = strdup(users_list);
if (strstr(users, "guess=") == users) {
if (switch_user(users, 1)) {
started_as_root = 2;
}
free(users);
return;
}
p = strtok(users, ",");
while (p) {
if (switch_user(p, 1)) {
started_as_root = 2;
rfbLog("try_to_switch_users: now %s\n", p);
break;
}
p = strtok(NULL, ",");
}
free(users);
}
int read_passwds(char *passfile) {
char line[1024];
char *filename;
char **old_passwd_list = passwd_list;
int remove = 0;
int read_mode = 0;
int begin_vo = -1;
struct stat sbuf;
int linecount = 0, i, max;
FILE *in;
static time_t last_read = 0;
static int read_cnt = 0;
int db_passwd = 0;
filename = passfile;
if (strstr(filename, "rm:") == filename) {
filename += strlen("rm:");
remove = 1;
} else if (strstr(filename, "read:") == filename) {
filename += strlen("read:");
read_mode = 1;
if (stat(filename, &sbuf) == 0) {
if (sbuf.st_mtime <= last_read) {
return 0;
}
last_read = sbuf.st_mtime;
}
}
if (stat(filename, &sbuf) == 0) {
/* (poor...) upper bound to number of lines */
max = (int) sbuf.st_size;
last_read = sbuf.st_mtime;
} else {
max = 64;
}
/* create 1 more than max to have it be the ending NULL */
passwd_list = (char **) malloc( (max+1) * (sizeof(char *)) );
for (i=0; i<max+1; i++) {
passwd_list[i] = NULL;
}
in = fopen(filename, "r");
if (in == NULL) {
rfbLog("cannot open passwdfile: %s\n", passfile);
rfbLogPerror("fopen");
if (remove) {
unlink(filename);
}
clean_up_exit(1);
}
if (getenv("DEBUG_PASSWDFILE") != NULL) {
db_passwd = 1;
}
while (fgets(line, 1024, in) != NULL) {
char *p;
int blank = 1;
int len = strlen(line);
if (db_passwd) {
fprintf(stderr, "read_passwds: raw line: %s\n", line);
}
if (len == 0) {
continue;
} else if (line[len-1] == '\n') {
line[len-1] = '\0';
}
if (line[0] == '\0') {
continue;
}
if (strstr(line, "__SKIP__") != NULL) {
continue;
}
if (strstr(line, "__COMM__") == line) {
continue;
}
if (!strcmp(line, "__BEGIN_VIEWONLY__")) {
if (begin_vo < 0) {
begin_vo = linecount;
}
continue;
}
if (line[0] == '#') {
/* commented out, cannot have password beginning with # */
continue;
}
p = line;
while (*p != '\0') {
if (! isspace(*p)) {
blank = 0;
break;
}
p++;
}
if (blank) {
continue;
}
passwd_list[linecount++] = strdup(line);
if (db_passwd) {
fprintf(stderr, "read_passwds: keepline: %s\n", line);
fprintf(stderr, "read_passwds: begin_vo: %d\n", begin_vo);
}
if (linecount >= max) {
break;
}
}
fclose(in);
for (i=0; i<1024; i++) {
line[i] = '\0';
}
if (remove) {
unlink(filename);
}
if (! linecount) {
rfbLog("cannot read a valid line from passwdfile: %s\n",
passfile);
if (read_cnt == 0) {
clean_up_exit(1);
} else {
return 0;
}
}
read_cnt++;
for (i=0; i<linecount; i++) {
char *q, *p = passwd_list[i];
if (!strcmp(p, "__EMPTY__")) {
*p = '\0';
} else if ((q = strstr(p, "__COMM__")) != NULL) {
*q = '\0';
}
passwd_list[i] = strdup(p);
if (db_passwd) {
fprintf(stderr, "read_passwds: trimline: %s\n", p);
}
strzero(p);
}
begin_viewonly = begin_vo;
if (read_mode && read_cnt > 1) {
if (viewonly_passwd) {
free(viewonly_passwd);
viewonly_passwd = NULL;
}
}
if (begin_viewonly < 0 && linecount == 2) {
/* for compatibility with previous 2-line usage: */
viewonly_passwd = strdup(passwd_list[1]);
if (db_passwd) {
fprintf(stderr, "read_passwds: linecount is 2.\n");
}
if (screen) {
char **apd = (char **) screen->authPasswdData;
if (apd) {
if (apd[0] != NULL) {
strzero(apd[0]);
}
apd[0] = strdup(passwd_list[0]);
}
}
begin_viewonly = 1;
}
if (old_passwd_list != NULL) {
char *p;
i = 0;
while (old_passwd_list[i] != NULL) {
p = old_passwd_list[i];
strzero(p);
free(old_passwd_list[i]);
i++;
}
free(old_passwd_list);
}
return 1;
}
void install_passwds(void) {
if (viewonly_passwd) {
/* append the view only passwd after the normal passwd */
char **passwds_new = (char **) malloc(3*sizeof(char *));
char **passwds_old = (char **) screen->authPasswdData;
passwds_new[0] = passwds_old[0];
passwds_new[1] = viewonly_passwd;
passwds_new[2] = NULL;
screen->authPasswdData = (void*) passwds_new;
} else if (passwd_list) {
int i = 0;
while(passwd_list[i] != NULL) {
i++;
}
if (begin_viewonly < 0) {
begin_viewonly = i+1;
}
screen->authPasswdData = (void*) passwd_list;
screen->authPasswdFirstViewOnly = begin_viewonly;
}
}
void check_new_passwds(void) {
static time_t last_check = 0;
time_t now;
if (! passwdfile) {
return;
}
if (strstr(passwdfile, "read:") != passwdfile) {
return;
}
now = time(0);
if (now > last_check + 1) {
if (read_passwds(passwdfile)) {
install_passwds();
}
last_check = now;
}
}