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/*
* Main daemon code: invokes the actual POP handling routines. Most calls
* to functions in other source files are done as a non-root user (either
* POP_USER or the authenticated user). Depending on compile-time options
* in params.h, the following files may contain code executed as root:
*
* standalone.c if not running via an inetd clone (POP_STANDALONE)
* virtual.c if supporting virtual domains (POP_VIRTUAL)
* auth_passwd.c if using passwd or *BSD (AUTH_PASSWD && !VIRTUAL_ONLY)
* auth_shadow.c if using shadow (AUTH_SHADOW && !VIRTUAL_ONLY)
* auth_pam.c if using PAM (AUTH_PAM || AUTH_PAM_USERPASS)
*/
#include <unistd.h>
#include <signal.h>
#include <string.h>
#include <stdlib.h>
#include <syslog.h>
#include <errno.h>
#include <grp.h>
#include <pwd.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <sys/types.h>
#include "params.h"
#include "protocol.h"
#include "pop_auth.h"
#include "pop_trans.h"
#if POP_VIRTUAL
#include "virtual.h"
#endif
#if !VIRTUAL_ONLY
extern struct passwd *auth_userpass(char *user, char *pass, char **mailbox);
#endif
static struct passwd pop_pw;
static char *mailbox;
int log_error(char *s)
{
syslog(SYSLOG_PRIORITY, "%s: %m", s);
return 1;
}
static int set_user(struct passwd *pw)
{
gid_t groups[2];
if (!pw->pw_uid) return 1;
groups[0] = groups[1] = pw->pw_gid;
if (setgroups(1, groups)) return log_error("setgroups");
if (setgid(pw->pw_gid)) return log_error("setgid");
if (setuid(pw->pw_uid)) return log_error("setuid");
return 0;
}
/*
* Attempts to read until EOF, and returns the number of bytes read.
* We don't expect any signals, so even EINTR is considered an error.
*/
static int read_loop(int fd, char *buffer, int count)
{
int offset, block;
offset = 0;
while (count > 0) {
block = read(fd, &buffer[offset], count);
if (block < 0) return block;
if (!block) return offset;
offset += block;
count -= block;
}
return offset;
}
/*
* The root-privileged part of the AUTHORIZATION state handling: reads
* the authentication data obtained over POP from its end of the pipe,
* attempts authentication, and, if successful, drops privilege to the
* authenticated user. Returns one of the AUTH_* result codes.
*/
static int do_root_auth(int channel)
{
static char auth[AUTH_BUFFER_SIZE + 2];
char *user, *pass;
struct passwd *pw;
mailbox = NULL;
#if POP_VIRTUAL
virtual_domain = NULL;
#endif
/* The POP client could have sent extra commands without waiting for
* successful authentication. We're passing them into the TRANSACTION
* state if we ever get there. */
if (read_loop(channel, (char *)&pop_buffer, sizeof(pop_buffer)) !=
sizeof(pop_buffer)) return AUTH_NONE;
/* Now, the authentication data. */
memset(auth, 0, sizeof(auth)); /* Ensure the NUL termination */
if (read_loop(channel, auth, AUTH_BUFFER_SIZE) < 0) return AUTH_NONE;
user = auth;
pass = &user[strlen(user) + 1];
pw = NULL;
#if POP_VIRTUAL
if (!(pw = virtual_userpass(user, pass, &mailbox)) && virtual_domain)
return AUTH_FAILED;
#endif
#if VIRTUAL_ONLY
if (!pw)
return AUTH_FAILED;
#else
if (!pw && !(pw = auth_userpass(user, pass, &mailbox)))
return AUTH_FAILED;
#endif
if (!*user || !*pass) return AUTH_FAILED;
memset(pass, 0, strlen(pass));
if (set_user(pw)) return AUTH_FAILED;
return AUTH_OK;
}
int do_pop_startup(void)
{
struct passwd *pw;
umask(077);
signal(SIGPIPE, SIG_IGN);
openlog(SYSLOG_IDENT, SYSLOG_OPTIONS, SYSLOG_FACILITY);
errno = 0;
if (!(pw = getpwnam(POP_USER))) {
syslog(SYSLOG_PRIORITY, "getpwnam(\"" POP_USER "\"): %s",
errno ? strerror(errno) : "No such user");
return 1;
}
memcpy(&pop_pw, pw, sizeof(pop_pw));
#if POP_VIRTUAL
if (virtual_startup()) return 1;
#endif
return 0;
}
int do_pop_session(void)
{
int channel[2];
int result, status;
signal(SIGCHLD, SIG_IGN);
if (pipe(channel)) return log_error("pipe");
switch (fork()) {
case -1:
return log_error("fork");
case 0:
if (close(channel[0])) return log_error("close");
if (set_user(&pop_pw)) return 1;
return do_pop_auth(channel[1]);
}
if (close(channel[1]))
result = AUTH_NONE;
else
result = do_root_auth(channel[0]);
if (wait(&status) < 0)
status = 1;
else
if (WIFEXITED(status))
status = WEXITSTATUS(status);
else
status = 1;
if (result == AUTH_OK) {
if (close(channel[0])) return log_error("close");
log_pop_auth(result, mailbox);
#if POP_VIRTUAL
if (virtual_domain)
return do_pop_trans(virtual_spool, mailbox);
#endif
#if !VIRTUAL_ONLY
return do_pop_trans(MAIL_SPOOL_PATH, mailbox);
#endif
}
if (set_user(&pop_pw)) return 1;
log_pop_auth(result, mailbox);
#ifdef AUTH_FAILED_MESSAGE
if (result == AUTH_FAILED) pop_reply("-ERR %s", AUTH_FAILED_MESSAGE);
#else
if (result == AUTH_FAILED) pop_reply_error();
#endif
return status;
}
#if !POP_STANDALONE
int main(void)
{
if (do_pop_startup()) return 1;
return do_pop_session();
}
#endif
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