sun-src/os/dtlogin.c

/*
 * Copyright (c) 1996, 2015, Oracle and/or its affiliates. All rights reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 */


/* Implementation of Display Manager (dtlogin/gdm/xdm/etc.) to X server
 * communication pipe. The Display Manager process will start
 * the X window server at system boot time before any user
 * has logged into the system.  The X server is by default
 * started as the root UID "0".
 *
 * At login time the Xserver local communication pipe is provided
 * by the Xserver for user specific configuration data supplied
 * by the display manager.  It notifies the Xserver it needs to change
 * over to the user's credentials (UID, GID, GID_LIST) and
 * also switch CWD (current working directory) of to match
 * the user's CWD home.
 *
 * When shutting down, the Xserver restores it's original uid/gid as
 * needed by the cleanup/teardown actions in several drivers.
 *
 * For the original definition, see Sun ASARC case 1995/390
 */

#ifdef HAVE_DIX_CONFIG_H
#include <dix-config.h>
#endif

#include <X11/Xos.h>
#include <sys/param.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <stdio.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <errno.h>
#include <X11/X.h>
#include <X11/Xmd.h>
#include "misc.h"
#include <X11/Xpoll.h>
#include "osdep.h"
#include "input.h"
#include "dixstruct.h"
#include "dixfont.h"
#include "opaque.h"
#include <pwd.h>
#include <project.h>
#include <sys/task.h>
#include <ctype.h>
#include "scrnintstr.h"
#include <sys/vt.h>

#define DTLOGIN_PATH "/var/dt/sdtlogin"

#define BUFLEN 1024

int xf86ConsoleFd = -1;

/* in Xserver/os/auth.c */
extern const char *GetAuthFilename(void);

/* Data about the user we need to switch to */
struct dmuser {
    uid_t   uid;
    gid_t   gid;            /* Primary group */
    gid_t   groupids[NGROUPS_UMAX]; /* Supplementary groups */
    int     groupid_cnt;
    char *  homedir;
    projid_t    projid;
};

/* Data passed to block/wakeup handlers */
struct dmdata {
    int     pipeFD;
    char *  pipename;   /* path to pipe */
    char *  buf;        /* contains characters to be processed */
    int     bufsize;    /* size allocated for buf */
    struct dmuser user;     /* target user, to switch to on login */
};


/* Data stored in screen privates */
struct dmScreenPriv {
    CloseScreenProcPtr  CloseScreen;
};
static DevPrivateKeyRec dmScreenKeyRec;
#define dmScreenKey (&dmScreenKeyRec)
static struct dmdata *dmHandlerData;
static struct dmuser originalUser; /* user to switch back to in CloseDown */

static Bool DtloginCloseScreen(ScreenPtr pScreen);
static void DtloginBlockHandler(void *, struct timeval **, void *);
static void DtloginWakeupHandler(void *, int, void *);
static int  dtlogin_create_pipe(int, struct dmdata *);
static void dtlogin_receive_packet(struct dmdata *);
static int  dtlogin_parse_packet(struct dmdata *, char *);
static void dtlogin_process(struct dmuser *user, int user_logged_in);
static void dtlogin_close_pipe(struct dmdata *);

#define DtloginError(fmt, arg)  LogMessageVerb(X_ERROR, 1, fmt ": %s\n", \
                        arg, strerror(errno))
#define DtloginInfo(fmt, arg)   LogMessageVerb(X_INFO, 5, fmt, arg)

/*
 * initialize DTLOGIN: create pipe; set handlers.
 * Called from main loop in os/main.c
 */

_X_HIDDEN void
DtloginInit(void)
{
    int displayNumber = 0;
    struct dmdata *dmd;

    if (serverGeneration != 1) return;

    originalUser.uid = geteuid();
    originalUser.gid = getegid();
    getgroups(NGROUPS_UMAX, originalUser.groupids);
    originalUser.homedir = getcwd(NULL, 0);
    originalUser.projid = getprojid();

    if (getuid() != 0)  return;

    dmd = calloc(1, sizeof(struct dmdata));
    if (dmd == NULL) {
    DtloginError("Failed to allocate %d bytes for display manager pipe",
             (int) sizeof(struct dmdata));
    return;
    }

    dmd->user.uid = (uid_t) -1;
    dmd->user.gid = (gid_t) -1;
    dmd->user.projid = (projid_t) -1;

    displayNumber = atoi(display); /* Assigned in dix/main.c */

    dmd->pipeFD = dtlogin_create_pipe(displayNumber, dmd);

    if (dmd->pipeFD == -1) {
    free(dmd);
    return;
    }

    dmHandlerData = dmd;

    RegisterBlockAndWakeupHandlers (DtloginBlockHandler,
                    DtloginWakeupHandler,
                    (void *) dmd);
}

/*
 * cleanup dtlogin pipe at exit if still running, reset privs back to
 * root as needed for various cleanup tasks.
 * Called from main loop in os/main.c & CloseScreen wrappers
 */
_X_HIDDEN void
DtloginCloseDown(void)
{
    if (geteuid() != 0) {       /* reset privs back to root */
    if (seteuid(0) < 0) {
        DtloginError("Error in resetting euid to %d", 0);
    }
    dtlogin_process(&originalUser, 0);
    }

    if (dmHandlerData != NULL) {
    dtlogin_close_pipe(dmHandlerData);
    }
}

static Bool
DtloginCloseScreen (ScreenPtr pScreen)
{
    struct dmScreenPriv *pScreenPriv;

    DtloginCloseDown();

    /* Unwrap CloseScreen and call down to further levels */
    pScreenPriv = (struct dmScreenPriv *)
    dixLookupPrivate(&pScreen->devPrivates, dmScreenKey);

    pScreen->CloseScreen = pScreenPriv->CloseScreen;
    free (pScreenPriv);

    return (*pScreen->CloseScreen) (pScreen);
}

static void
DtloginBlockHandler(
    void         *data,
    struct timeval  **wt, /* unused */
    void         *pReadmask)
{
    struct dmdata *dmd = (struct dmdata *) data;
    fd_set *LastSelectMask = (fd_set*)pReadmask;

    FD_SET(dmd->pipeFD, LastSelectMask);
}

static void
DtloginWakeupHandler(
    void   *data,   /* unused */
    int     i,
    void   *pReadmask)
{
    struct dmdata *dmd = (struct dmdata *) data;
    fd_set* LastSelectMask = (fd_set*)pReadmask;

    if (i > 0)
    {
    if (FD_ISSET(dmd->pipeFD, LastSelectMask))
    {
        FD_CLR(dmd->pipeFD, LastSelectMask);
        dtlogin_receive_packet(dmd);
        /* dmd may have been freed in dtlogin_receive_packet, do
           not use after this point */
    }
    }
}

static int
dtlogin_create_pipe(int port, struct dmdata *dmd)
{
    struct stat statbuf;
    char pipename[128];
    int pipeFD = -1;

    if (stat(DTLOGIN_PATH, &statbuf) == -1) {
    if (mkdir(DTLOGIN_PATH, 0700) == -1) {
        DtloginError("Cannot create %s directory for display "
             "manager pipe", DTLOGIN_PATH);
        return -1;
    }
    } else if (!S_ISDIR(statbuf.st_mode)) {
    DtloginError("Cannot create display manager pipe: "
             "%s is not a directory", DTLOGIN_PATH);
    return -1;
    }

    snprintf(pipename, sizeof(pipename), "%s/%d", DTLOGIN_PATH, port);

    if (mkfifo(pipename, S_IRUSR | S_IWUSR) < 0)
    return -1;

    if ((pipeFD = open(pipename, O_RDONLY | O_NONBLOCK)) < 0) {
    remove(pipename);
    return -1;
    }

    dmd->pipename = xstrdup(pipename);

    /* To make sure root has rw permissions. */
    (void) fchmod(pipeFD, 0600);

    return pipeFD;
}

static void dtlogin_close_pipe(struct dmdata *dmd)
{
    RemoveBlockAndWakeupHandlers (DtloginBlockHandler,
                  DtloginWakeupHandler, dmd);

    close(dmd->pipeFD);
    remove(dmd->pipename);
    free(dmd->pipename);
    free(dmd->buf);
    free(dmd->user.homedir);
    free(dmd);

    if (dmHandlerData == dmd) {
    dmHandlerData = NULL;
    }
}

static void
dtlogin_receive_packet(struct dmdata *dmd)
{
    int bufLen, nbRead;
    char *p, *n;
    int done = 0;

    if (dmd->buf == NULL) {
    dmd->bufsize = BUFLEN;
    dmd->buf = malloc(dmd->bufsize);
    dmd->buf[0] = '\0';
    }

    /* Read data from pipe and split into tokens, buffering the rest */
    while (!done) {
    bufLen = strlen(dmd->buf);

    /*
     * Realloc only if buf has filled up and we don't have a record
     * delimiter yet. Keep track of alloced size.
     */
    if (bufLen > (dmd->bufsize/2)) {
        dmd->bufsize += BUFLEN;
        dmd->buf = realloc(dmd->buf, dmd->bufsize);
    }

    nbRead = read(dmd->pipeFD, dmd->buf + bufLen,
              dmd->bufsize - bufLen - 1);

    if (nbRead == -1) {
        if (errno == EINTR) {
        continue;
        } else if (errno == EAGAIN) {
        return;     /* return to WaitFor, wait for select() */
        } else {
        dtlogin_close_pipe(dmd);
        return;
        }
    }

    if (nbRead == 0) { /* End of file */
        dtlogin_close_pipe(dmd);
        return;
    }

    bufLen += nbRead;
    dmd->buf[bufLen] = '\0';

    DtloginInfo("Data buffer: %s\n", dmd->buf);

    p = dmd->buf;
    while ((n = strchr(p, ';')) != NULL) { /* Next complete packet */
        *n = '\0';
        DtloginInfo("Next packet: %s\n", p);
        done = dtlogin_parse_packet(dmd, p);
        if (done) {
        dtlogin_close_pipe(dmd);    /* free's dmd */
        return;
        }
        p = n+1;
    }

    /* save the rest for the next iteration */
    if (p < (dmd->buf + bufLen)) {
        DtloginInfo("Left over: %s\n", p);
        strcpy(dmd->buf, p);
    }
    }
}

/* Parse data from packet
 *
 * Example Record:
 *      UID="xxx" GID="yyy";
 *      G_LIST_ID="aaa" G_LIST_ID="bbb" G_LIST_ID="ccc";
 *      HOME="/nn/mmm/ooo" EOF="";
 */
static int
dtlogin_parse_packet(struct dmdata *dmd, char *s)
{
    char *k, *v, *p;

    while (s < (dmd->buf + dmd->bufsize)) {
    /* format is key="value" - split into key & value pair */

    for (k = s ; (*k != '\0') && isspace(*k); k++) {
        /* Skip over whitespace */
    }

    if (*k == '\0') {
        break;
    }

    p = strchr(k, '=');

    if (p == NULL) {
        DtloginInfo("Malformed key \'%s\'\n", k);
        return 0;
    }

    *p = '\0'; /* end of key string */
    p++;

    if (*p != '\"') {
        DtloginInfo("Bad delimiter at \'%s\'\n", p);
        return 0;
    }

    v = p + 1; /* start of value string */

    p = strchr(v, '\"');

    if (p == NULL) {
        DtloginInfo("Missing quote after value \'%s\'\n", v);
        break;
    }

    *p = '\0'; /* end of value string */

    s = p + 1; /* start of next pair */

    DtloginInfo("Received key \"%s\" =>", k);
    DtloginInfo(" value \"%s\"\n", v);

    /* Found key & value, now process & put into dmd */
    if (strcmp(k, "EOF") == 0) {
        /* End of transmission, process & close */
        dtlogin_process(&(dmd->user), 1);
        return 1;
    }
    else if (strcmp(k, "HOME") == 0) {
        dmd->user.homedir = xstrdup(v);
    }
    else if ( (strcmp(k, "UID") == 0) || (strcmp(k, "GID") == 0)
          || (strcmp(k, "G_LIST_ID") == 0) ) {
        /* Value is numeric, convert to int */
        long val;

        errno = 0;
        val = strtol(v, NULL, 10);

        if ((val == 0) && (strcmp(v, "0") != 0)) {
        /* strtol couldn't parse the results */
        DtloginInfo("Invalid number \"%s\"\n", v);
        continue;
        }

        if ( ((val == LONG_MAX) || (val == LONG_MIN))
         && (errno == ERANGE) ) {
        /* Value out of range */
        DtloginInfo("Out of range number \"%s\"\n", v);
        continue;
        }

        if (strcmp(k, "UID") == 0) {
        dmd->user.uid = (uid_t) val;
        }
        else if (strcmp(k, "GID") == 0) {
        dmd->user.gid = (gid_t) val;
        }
        else if (strcmp(k, "G_LIST_ID") == 0) {
        if (dmd->user.groupid_cnt < NGROUPS_UMAX) {
            dmd->user.groupids[dmd->user.groupid_cnt++] = (gid_t) val;
        }
        }
    }
    else {
        DtloginInfo("Unrecognized key \"%s\"\n", k);
    }
    }

    return 0;
}


static void
dtlogin_process(struct dmuser *user, int user_logged_in)
{
    struct project proj;
    char proj_buf[PROJECT_BUFSZ];
    struct passwd *ppasswd;
    const char *auth_file = NULL;

    auth_file = GetAuthFilename();

    if (auth_file) {
    if (chown(auth_file, user->uid, user->gid) < 0)
        DtloginError("Error in changing owner to %d", user->uid);
    }

    /* This gid dance is necessary in order to make sure
       our "saved-set-gid" is 0 so that we can regain gid
       0 when necessary for priocntl & power management.
       The first step sets rgid to the user's gid and
       makes the egid & saved-gid be 0.  The second then
       sets the egid to the users gid, but leaves the
       saved-gid as 0.  */

    if (user->gid != (gid_t) -1) {
    DtloginInfo("Setting gid to %d\n", user->gid);

    if (setregid(user->gid, 0) < 0)
        DtloginError("Error in setting regid to %d\n", user->gid);

    if (setegid(user->gid) < 0)
        DtloginError("Error in setting egid to %d\n", user->gid);
    }

    if (user->groupid_cnt >= 0) {
    if (setgroups(user->groupid_cnt, user->groupids) < 0)
        DtloginError("Error in setting supplemental (%d) groups",
             user->groupid_cnt);
    }


    /*
     * BUG: 4462531: Set project ID for Xserver
     *               Get user name and default project.
     *           Set before the uid value is set.
     */
    if (user->projid != (uid_t) -1) {
    if (settaskid(user->projid, TASK_NORMAL) == (taskid_t) -1) {
        DtloginError("Error in setting project id to %d", user->projid);
    }
    } else if (user->uid != (uid_t) -1) {
    ppasswd = getpwuid(user->uid);

    if (ppasswd == NULL) {
        DtloginError("Error in getting user name for %d", user->uid);
    } else {
        if (getdefaultproj(ppasswd->pw_name, &proj,
                   (void *)&proj_buf, PROJECT_BUFSZ) == NULL) {
        DtloginError("Error in getting project id for %s",
                 ppasswd->pw_name);
        } else {
        DtloginInfo("Setting project to %s\n", proj.pj_name);

        if (setproject(proj.pj_name, ppasswd->pw_name,
                   TASK_NORMAL) == -1) {
            DtloginError("Error in setting project to %s",
                 proj.pj_name);
        }
        }
    }
    }

    if (user->uid != (uid_t) -1) {
    DtloginInfo("Setting uid to %d\n", user->uid);

    if (setreuid(user->uid, -1) < 0)
        DtloginError("Error in setting ruid to %d", user->uid);

    if (setreuid(-1, user->uid) < 0)
        DtloginError("Error in setting euid to %d", user->uid);

    /* Wrap closeScreen to allow resetting uid on closedown */
    if ((user->uid != 0) && (user != &originalUser)) {
        int i;

        if (dixRegisterPrivateKey(dmScreenKey, PRIVATE_SCREEN, 0)) {
        for (i = 0; i < screenInfo.numScreens; i++)
        {
            ScreenPtr pScreen = screenInfo.screens[i];
            struct dmScreenPriv *pScreenPriv
            = calloc(1, sizeof(struct dmScreenPriv));

            dixSetPrivate(&pScreen->devPrivates, dmScreenKey,
                  pScreenPriv);

            if (pScreenPriv != NULL) {
            pScreenPriv->CloseScreen = pScreen->CloseScreen;
            pScreen->CloseScreen = DtloginCloseScreen;
            } else {
            DtloginError("Failed to allocate %d bytes"
                     " for uid reset info",
                     (int) sizeof(struct dmScreenPriv));
            }
        }
        } else {
        DtloginError("Failed to register screen private %s",
                 "for uid reset info");
        }
    }
    }

    if (user->homedir != NULL) {
    char *env_str = Xprintf("HOME=%s", user->homedir);

    if (env_str == NULL) {
        DtloginError("Not enough memory to setenv HOME=%s", user->homedir);
    } else {
        DtloginInfo("Setting %s\n",env_str);

        if (putenv(env_str) < 0)
        DtloginError("Failed to setenv %s", env_str);
    }

    if (chdir(user->homedir) < 0)
        DtloginError("Error in changing working directory to %s",
             user->homedir);
    }

    /* Inform the kernel whether a user has logged in on this VT device */
    if (xf86ConsoleFd != -1)
    ioctl(xf86ConsoleFd, VT_SETDISPLOGIN, user_logged_in);
}