/*-
 * Copyright (c) 1996 by
 * Sean Eric Fagan <sef@kithrup.com>
 * David Nugent <davidn@blaze.net.au>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, is permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice immediately at the beginning of the file, without modification,
 *    this list of conditions, and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. This work was done expressly for inclusion into FreeBSD.  Other use
 *    is permitted provided this notation is included.
 * 4. Absolutely no warranty of function or purpose is made by the authors.
 * 5. Modifications may be freely made to this file providing the above
 *    conditions are met.
 *
 * High-level routines relating to use of the user capabilities database
 */

#include <sys/param.h>
#include <sys/cpuset.h>
#include <sys/mac.h>
#include <sys/resource.h>
#include <sys/rtprio.h>
#include <sys/stat.h>
#include <sys/time.h>

#include <ctype.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <login_cap.h>
#include <paths.h>
#include <pwd.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <unistd.h>


static struct login_res {
    const char *what;
    rlim_t (*who)(login_cap_t *, const char *, rlim_t, rlim_t);
    int why;
} resources[] = {
    { "cputime",         login_getcaptime, RLIMIT_CPU     },
    { "filesize",        login_getcapsize, RLIMIT_FSIZE   },
    { "datasize",        login_getcapsize, RLIMIT_DATA    },
    { "stacksize",       login_getcapsize, RLIMIT_STACK   },
    { "memoryuse",       login_getcapsize, RLIMIT_RSS     },
    { "memorylocked",    login_getcapsize, RLIMIT_MEMLOCK },
    { "maxproc",         login_getcapnum,  RLIMIT_NPROC   },
    { "openfiles",       login_getcapnum,  RLIMIT_NOFILE  },
    { "coredumpsize",    login_getcapsize, RLIMIT_CORE    },
    { "sbsize",          login_getcapsize, RLIMIT_SBSIZE  },
    { "vmemoryuse",      login_getcapsize, RLIMIT_VMEM    },
    { "pseudoterminals", login_getcapnum,  RLIMIT_NPTS    },
    { "swapuse",         login_getcapsize, RLIMIT_SWAP    },
    { "kqueues",         login_getcapsize, RLIMIT_KQUEUES },
    { "umtxp",           login_getcapnum,  RLIMIT_UMTXP   },
    { "pipebuf",         login_getcapnum,  RLIMIT_PIPEBUF },
    { NULL,              0,                0              }
};


void
setclassresources(login_cap_t *lc)
{
    struct login_res *lr;

    if (lc == NULL)
        return;

    for (lr = resources; lr->what != NULL; ++lr) {
        struct rlimit   rlim;

        /*
         * The login.conf file can have <limit>, <limit>-max, and
         * <limit>-cur entries.
         * What we do is get the current current- and maximum- limits.
         * Then, we try to get an entry for <limit> from the capability,
         * using the current and max limits we just got as the
         * default/error values.
         * *Then*, we try looking for <limit>-cur and <limit>-max,
         * again using the appropriate values as the default/error
         * conditions.
         */

        if (getrlimit(lr->why, &rlim) != 0)
            syslog(LOG_ERR, "getting %s resource limit: %m", lr->what);
        else {
            char        name_cur[40];
            char        name_max[40];
            rlim_t      rcur = rlim.rlim_cur;
            rlim_t      rmax = rlim.rlim_max;

            sprintf(name_cur, "%s-cur", lr->what);
            sprintf(name_max, "%s-max", lr->what);

            rcur = (*lr->who)(lc, lr->what, rcur, rcur);
            rmax = (*lr->who)(lc, lr->what, rmax, rmax);
            rlim.rlim_cur = (*lr->who)(lc, name_cur, rcur, rcur);
            rlim.rlim_max = (*lr->who)(lc, name_max, rmax, rmax);

            if (setrlimit(lr->why, &rlim) == -1)
                syslog(LOG_WARNING, "set class '%s' resource limit %s: %m", lc->lc_class, lr->what);
        }
    }
}



static struct login_vars {
    const char *tag;
    const char *var;
    const char *def;
    int overwrite;
} pathvars[] = {
    { "path",           "PATH",       NULL, 1},
    { "cdpath",         "CDPATH",     NULL, 1},
    { "manpath",        "MANPATH",    NULL, 1},
    { NULL,             NULL,         NULL, 0}
}, envars[] = {
    { "lang",           "LANG",       NULL, 1},
    { "charset",        "MM_CHARSET", NULL, 1},
    { "mail",           "MAIL",       NULL, 1},
    { "timezone",       "TZ",         NULL, 1},
    { "term",           "TERM",       NULL, 0},
    { NULL,             NULL,         NULL, 0}
};

static char *
substvar(const char * var, const struct passwd * pwd, int hlen, int pch, int nlen)
{
    char    *np = NULL;

    if (var != NULL) {
        int     tildes = 0;
        int     dollas = 0;
        char    *p;
        const char *q;

        if (pwd != NULL) {
            for (q = var; *q != '\0'; ++q) {
                tildes += (*q == '~');
                dollas += (*q == '$');
            }
        }

        np = malloc(strlen(var) + (dollas * nlen)
                    - dollas + (tildes * (pch+hlen))
                    - tildes + 1);

        if (np != NULL) {
            p = strcpy(np, var);

            if (pwd != NULL) {
                /*
                 * This loop does user username and homedir substitutions
                 * for unescaped $ (username) and ~ (homedir)
                 */
                while (*(p += strcspn(p, "~$")) != '\0') {
                    int l = strlen(p);

                    if (p > np && *(p-1) == '\\')  /* Escaped: */
                        memmove(p - 1, p, l + 1); /* Slide-out the backslash */
                    else if (*p == '~') {
                        int     v = pch && *(p+1) != '/'; /* Avoid double // */
                        memmove(p + hlen + v, p + 1, l);  /* Subst homedir */
                        memmove(p, pwd->pw_dir, hlen);
                        if (v)
                            p[hlen] = '/';
                        p += hlen + v;
                    }
                    else /* if (*p == '$') */ {
                        memmove(p + nlen, p + 1, l);    /* Subst username */
                        memmove(p, pwd->pw_name, nlen);
                        p += nlen;
                    }
                }
            }
        }
    }

    return (np);
}


void
setclassenvironment(login_cap_t *lc, const struct passwd * pwd, int paths)
{
    struct login_vars   *vars = paths ? pathvars : envars;
    int                 hlen = pwd ? strlen(pwd->pw_dir) : 0;
    int                 nlen = pwd ? strlen(pwd->pw_name) : 0;
    char pch = 0;

    if (hlen && pwd->pw_dir[hlen-1] != '/')
        ++pch;

    while (vars->tag != NULL) {
        const char * var = paths ? login_getpath(lc, vars->tag, NULL)
                                 : login_getcapstr(lc, vars->tag, NULL, NULL);

        char * np  = substvar(var, pwd, hlen, pch, nlen);

        if (np != NULL) {
            setenv(vars->var, np, vars->overwrite);
            free(np);
        } else if (vars->def != NULL) {
            setenv(vars->var, vars->def, 0);
        }
        ++vars;
    }

    /*
     * If we're not processing paths, then see if there is a setenv list by
     * which the admin and/or user may set an arbitrary set of env vars.
     */
    if (!paths) {
        const char      **set_env = login_getcaplist(lc, "setenv", ",");

        if (set_env != NULL) {
            while (*set_env != NULL) {
                char    *p = strchr(*set_env, '=');

                if (p != NULL && p != *set_env) {  /* Discard invalid entries */
                    const char  *ep;
                    char        *np;

                    *p++ = '\0';
                    /* Strip leading spaces from variable name */
                    ep = *set_env;
                    while (*ep == ' ' || *ep == '\t')
                        ep++;
                    if ((np = substvar(p, pwd, hlen, pch, nlen)) != NULL) {
                        setenv(ep, np, 1);
                        free(np);
                    }
                }
                ++set_env;
            }
        }
    }
}


static int
list2cpuset(const char *list, cpuset_t *mask)
{
        enum { NONE, NUM, DASH } state;
        int lastnum;
        int curnum;
        const char *l;

        state = NONE;
        curnum = lastnum = 0;
        for (l = list; *l != '\0';) {
                if (isdigit(*l)) {
                        curnum = atoi(l);
                        if (curnum > CPU_SETSIZE)
                                errx(EXIT_FAILURE,
                                    "Only %d cpus supported", CPU_SETSIZE);
                        while (isdigit(*l))
                                l++;
                        switch (state) {
                        case NONE:
                                lastnum = curnum;
                                state = NUM;
                                break;
                        case DASH:
                                for (; lastnum <= curnum; lastnum++)
                                        CPU_SET(lastnum, mask);
                                state = NONE;
                                break;
                        case NUM:
                        default:
                                return (0);
                        }
                        continue;
                }
                switch (*l) {
                case ',':
                        switch (state) {
                        case NONE:
                                break;
                        case NUM:
                                CPU_SET(curnum, mask);
                                state = NONE;
                                break;
                        case DASH:
                                return (0);
                                break;
                        }
                        break;
                case '-':
                        if (state != NUM)
                                return (0);
                        state = DASH;
                        break;
                default:
                        return (0);
                }
                l++;
        }
        switch (state) {
                case NONE:
                        break;
                case NUM:
                        CPU_SET(curnum, mask);
                        break;
                case DASH:
                        return (0);
        }
        return (1);
}


void
setclasscpumask(login_cap_t *lc)
{
        const char *maskstr;
        cpuset_t maskset;
        cpusetid_t setid;

        maskstr = login_getcapstr(lc, "cpumask", NULL, NULL);
        CPU_ZERO(&maskset);
        if (maskstr == NULL)
                return;
        if (strcasecmp("default", maskstr) == 0)
                return;
        if (!list2cpuset(maskstr, &maskset)) {
                syslog(LOG_WARNING,
                    "list2cpuset(%s) invalid mask specification", maskstr);
                return;
        }

        if (cpuset(&setid) != 0) {
                syslog(LOG_ERR, "cpuset(): %s", strerror(errno));
                return;
        }

        if (cpuset_setaffinity(CPU_LEVEL_CPUSET, CPU_WHICH_PID, -1,
            sizeof(maskset), &maskset) != 0)
                syslog(LOG_ERR, "cpuset_setaffinity(%s): %s", maskstr,
                    strerror(errno));
}


/*
 * setclasscontext()
 *
 * For the login class <class>, set various class context values
 * (limits, mainly) to the values for that class.  Which values are
 * set are controlled by <flags> -- see <login_class.h> for the
 * possible values.
 *
 * setclasscontext() can only set resources, priority, and umask.
 */

int
setclasscontext(const char *classname, unsigned int flags)
{
    int         rc;
    login_cap_t *lc;

    lc = login_getclassbyname(classname, NULL);

    flags &= LOGIN_SETRESOURCES | LOGIN_SETPRIORITY |
            LOGIN_SETUMASK | LOGIN_SETPATH;

    rc = lc ? setusercontext(lc, NULL, 0, flags) : -1;
    login_close(lc);
    return (rc);
}


static const char * const inherit_enum[] = {
    "inherit",
    NULL
};

/*
 * Private function setting umask from the login class.
 */
static void
setclassumask(login_cap_t *lc, const struct passwd *pwd)
{
        /*
         * Make it unlikely that someone would input our default sentinel
         * indicating no specification.
         */
        const rlim_t def_val = INT64_MIN + 1, err_val = INT64_MIN;
        rlim_t val;

        /* If value is "inherit", nothing to change. */
        if (login_getcapenum(lc, "umask", inherit_enum) == 0)
                return;

        val = login_getcapnum(lc, "umask", def_val, err_val);

        if (val != def_val) {
                if (val < 0 || val > UINT16_MAX) {
                        /* We get here also on 'err_val'. */
                        syslog(LOG_WARNING,
                            "%s%s%sLogin class '%s': "
                            "Invalid umask specification: '%s'",
                            pwd ? "Login '" : "",
                            pwd ? pwd->pw_name : "",
                            pwd ? "': " : "",
                            lc->lc_class,
                            login_getcapstr(lc, "umask", "", ""));
                } else {
                        const mode_t mode = val;

                        umask(mode);
                }
        }
}

/*
 * Private function which takes care of processing
 */

static void
setlogincontext(login_cap_t *lc, const struct passwd *pwd, unsigned long flags)
{
        if (lc == NULL)
                return;

        /* Set resources. */
        if ((flags & LOGIN_SETRESOURCES) != 0)
                setclassresources(lc);

        /* See if there's a umask override. */
        if ((flags & LOGIN_SETUMASK) != 0)
                setclassumask(lc, pwd);

        /* Set paths. */
        if ((flags & LOGIN_SETPATH) != 0)
                setclassenvironment(lc, pwd, 1);

        /* Set environment. */
        if ((flags & LOGIN_SETENV) != 0)
                setclassenvironment(lc, pwd, 0);

        /* Set cpu affinity. */
        if ((flags & LOGIN_SETCPUMASK) != 0)
                setclasscpumask(lc);
}


/*
 * Private function to set process priority.
 */
static void
setclasspriority(login_cap_t * const lc, struct passwd const * const pwd)
{
        const rlim_t def_val = 0, err_val = INT64_MIN;
        rlim_t p;
        int rc;

        /* If value is "inherit", nothing to change. */
        if (login_getcapenum(lc, "priority", inherit_enum) == 0)
                return;

        p = login_getcapnum(lc, "priority", def_val, err_val);

        if (p == err_val) {
                /* Invariant: 'lc' != NULL. */
                syslog(LOG_WARNING,
                    "%s%s%sLogin class '%s': "
                    "Invalid priority specification: '%s'",
                    pwd ? "Login '" : "",
                    pwd ? pwd->pw_name : "",
                    pwd ? "': " : "",
                    lc->lc_class,
                    login_getcapstr(lc, "priority", "", ""));
                /* Reset the priority, as if the capability was not present. */
                p = def_val;
        }

        if (p > PRIO_MAX) {
                struct rtprio rtp;

                rtp.type = RTP_PRIO_IDLE;
                p += RTP_PRIO_MIN - (PRIO_MAX + 1);
                rtp.prio = p > RTP_PRIO_MAX ? RTP_PRIO_MAX : p;
                rc = rtprio(RTP_SET, 0, &rtp);
        } else if (p < PRIO_MIN) {
                struct rtprio rtp;

                rtp.type = RTP_PRIO_REALTIME;
                p += RTP_PRIO_MAX - (PRIO_MIN - 1);
                rtp.prio = p < RTP_PRIO_MIN ? RTP_PRIO_MIN : p;
                rc = rtprio(RTP_SET, 0, &rtp);
        } else
                rc = setpriority(PRIO_PROCESS, 0, (int)p);

        if (rc != 0)
                syslog(LOG_WARNING,
                    "%s%s%sLogin class '%s': "
                    "Setting priority failed: %m",
                    pwd ? "Login '" : "",
                    pwd ? pwd->pw_name : "",
                    pwd ? "': " : "",
                    lc ? lc->lc_class : "<none>");
}

/*
 * setusercontext()
 *
 * Given a login class <lc> and a user in <pwd>, with a uid <uid>,
 * set the context as in setclasscontext().  <flags> controls which
 * values are set.
 *
 * The difference between setclasscontext() and setusercontext() is
 * that the former sets things up for an already-existing process,
 * while the latter sets things up from a root context.  Such as might
 * be called from login(1).
 *
 */

int
setusercontext(login_cap_t *lc, const struct passwd *pwd, uid_t uid, unsigned int flags)
{
    login_cap_t *llc = NULL;
    int error;

    if (lc == NULL) {
        if (pwd != NULL && (lc = login_getpwclass(pwd)) != NULL)
            llc = lc; /* free this when we're done */
    }

    if (flags & LOGIN_SETPATH)
        pathvars[0].def = uid ? _PATH_DEFPATH : _PATH_STDPATH;

    /* we need a passwd entry to set these */
    if (pwd == NULL)
        flags &= ~(LOGIN_SETGROUP | LOGIN_SETLOGIN);

    /* Set the process priority */
    if (flags & LOGIN_SETPRIORITY)
        setclasspriority(lc, pwd);

    /* Setup the user's group permissions */
    if (flags & LOGIN_SETGROUP) {
        if (setgid(pwd->pw_gid) != 0) {
            syslog(LOG_ERR, "setgid(%lu): %m", (u_long)pwd->pw_gid);
            login_close(llc);
            return (-1);
        }
        if (initgroups(pwd->pw_name, pwd->pw_gid) == -1) {
            syslog(LOG_ERR, "initgroups(%s,%lu): %m", pwd->pw_name,
                   (u_long)pwd->pw_gid);
            login_close(llc);
            return (-1);
        }
    }

    /* Set the sessions login */
    if ((flags & LOGIN_SETLOGIN) && setlogin(pwd->pw_name) != 0) {
        syslog(LOG_ERR, "setlogin(%s): %m", pwd->pw_name);
        login_close(llc);
        return (-1);
    }

    /* Inform the kernel about current login class */
    if (lc != NULL && lc->lc_class != NULL && (flags & LOGIN_SETLOGINCLASS)) {
        error = setloginclass(lc->lc_class);
        if (error != 0) {
            syslog(LOG_ERR, "setloginclass(%s): %m", lc->lc_class);
#ifdef notyet
            login_close(llc);
            return (-1);
#endif
        }
    }

    setlogincontext(lc, pwd, flags);

    /* Set up the user's MAC label. */
    if ((flags & LOGIN_SETMAC) && mac_is_present(NULL) == 1) {
        const char *label_string;
        mac_t label;

        label_string = login_getcapstr(lc, "label", NULL, NULL);
        if (label_string != NULL) {
            if (mac_from_text(&label, label_string) == -1) {
                syslog(LOG_ERR, "mac_from_text('%s') for %s %s: %m",
                    label_string, pwd != NULL ? "user" : "class",
                    pwd != NULL ? pwd->pw_name : lc->lc_class);
                login_close(llc);
                return (-1);
            }
            if (mac_set_proc(label) == -1)
                error = errno;
            else
                error = 0;
            mac_free(label);
            if (error != 0) {
                syslog(LOG_ERR, "mac_set_proc('%s') for %s %s: %s",
                    label_string, pwd != NULL ? "user" : "class",
                    pwd != NULL ? pwd->pw_name : lc->lc_class, strerror(error));
                login_close(llc);
                return (-1);
            }
        }
    }

    login_close(llc);

    /* This needs to be done after anything that needs root privs */
    if ((flags & LOGIN_SETUSER) && setuid(uid) != 0) {
        syslog(LOG_ERR, "setuid(%lu): %m", (u_long)uid);
        return (-1);    /* Paranoia again */
    }

    /*
     * Now, we repeat some of the above for the user's private entries
     */
    if (geteuid() == uid && (lc = login_getuserclass(pwd)) != NULL) {
        setlogincontext(lc, pwd, flags);
        if (flags & LOGIN_SETPRIORITY)
            setclasspriority(lc, pwd);
        login_close(lc);
    }

    return (0);
}