module Process::UID

The Process::UID module contains a collection of module functions which can be used to portably get, set, and switch the current process's real, effective, and saved user IDs.

Public Class Methods

Process::UID.change_privilege(user) → integer Show source

static VALUE
p_uid_change_privilege(VALUE obj, VALUE id)
{
    rb_uid_t uid;

    check_uid_switch();

    uid = OBJ2UID(id);

    if (geteuid() == 0) { /* root-user */
#if defined(HAVE_SETRESUID)
        if (setresuid(uid, uid, uid) < 0) rb_sys_fail(0);
        SAVED_USER_ID = uid;
#elif defined(HAVE_SETUID)
        if (setuid(uid) < 0) rb_sys_fail(0);
        SAVED_USER_ID = uid;
#elif defined(HAVE_SETREUID) && !defined(OBSOLETE_SETREUID)
        if (getuid() == uid) {
            if (SAVED_USER_ID == uid) {
                if (setreuid(-1, uid) < 0) rb_sys_fail(0);
            }
            else {
                if (uid == 0) { /* (r,e,s) == (root, root, x) */
                    if (setreuid(-1, SAVED_USER_ID) < 0) rb_sys_fail(0);
                    if (setreuid(SAVED_USER_ID, 0) < 0) rb_sys_fail(0);
                    SAVED_USER_ID = 0; /* (r,e,s) == (x, root, root) */
                    if (setreuid(uid, uid) < 0) rb_sys_fail(0);
                    SAVED_USER_ID = uid;
                }
                else {
                    if (setreuid(0, -1) < 0) rb_sys_fail(0);
                    SAVED_USER_ID = 0;
                    if (setreuid(uid, uid) < 0) rb_sys_fail(0);
                    SAVED_USER_ID = uid;
                }
            }
        }
        else {
            if (setreuid(uid, uid) < 0) rb_sys_fail(0);
            SAVED_USER_ID = uid;
        }
#elif defined(HAVE_SETRUID) && defined(HAVE_SETEUID)
        if (getuid() == uid) {
            if (SAVED_USER_ID == uid) {
                if (seteuid(uid) < 0) rb_sys_fail(0);
            }
            else {
                if (uid == 0) {
                    if (setruid(SAVED_USER_ID) < 0) rb_sys_fail(0);
                    SAVED_USER_ID = 0;
                    if (setruid(0) < 0) rb_sys_fail(0);
                }
                else {
                    if (setruid(0) < 0) rb_sys_fail(0);
                    SAVED_USER_ID = 0;
                    if (seteuid(uid) < 0) rb_sys_fail(0);
                    if (setruid(uid) < 0) rb_sys_fail(0);
                    SAVED_USER_ID = uid;
                }
            }
        }
        else {
            if (seteuid(uid) < 0) rb_sys_fail(0);
            if (setruid(uid) < 0) rb_sys_fail(0);
            SAVED_USER_ID = uid;
        }
#else
        (void)uid;
        rb_notimplement();
#endif
    }
    else { /* unprivileged user */
#if defined(HAVE_SETRESUID)
        if (setresuid((getuid() == uid)? (rb_uid_t)-1: uid,
                      (geteuid() == uid)? (rb_uid_t)-1: uid,
                      (SAVED_USER_ID == uid)? (rb_uid_t)-1: uid) < 0) rb_sys_fail(0);
        SAVED_USER_ID = uid;
#elif defined(HAVE_SETREUID) && !defined(OBSOLETE_SETREUID)
        if (SAVED_USER_ID == uid) {
            if (setreuid((getuid() == uid)? (rb_uid_t)-1: uid,
                         (geteuid() == uid)? (rb_uid_t)-1: uid) < 0)
                rb_sys_fail(0);
        }
        else if (getuid() != uid) {
            if (setreuid(uid, (geteuid() == uid)? (rb_uid_t)-1: uid) < 0)
                rb_sys_fail(0);
            SAVED_USER_ID = uid;
        }
        else if (/* getuid() == uid && */ geteuid() != uid) {
            if (setreuid(geteuid(), uid) < 0) rb_sys_fail(0);
            SAVED_USER_ID = uid;
            if (setreuid(uid, -1) < 0) rb_sys_fail(0);
        }
        else { /* getuid() == uid && geteuid() == uid */
            if (setreuid(-1, SAVED_USER_ID) < 0) rb_sys_fail(0);
            if (setreuid(SAVED_USER_ID, uid) < 0) rb_sys_fail(0);
            SAVED_USER_ID = uid;
            if (setreuid(uid, -1) < 0) rb_sys_fail(0);
        }
#elif defined(HAVE_SETRUID) && defined(HAVE_SETEUID)
        if (SAVED_USER_ID == uid) {
            if (geteuid() != uid && seteuid(uid) < 0) rb_sys_fail(0);
            if (getuid() != uid && setruid(uid) < 0) rb_sys_fail(0);
        }
        else if (/* SAVED_USER_ID != uid && */ geteuid() == uid) {
            if (getuid() != uid) {
                if (setruid(uid) < 0) rb_sys_fail(0);
                SAVED_USER_ID = uid;
            }
            else {
                if (setruid(SAVED_USER_ID) < 0) rb_sys_fail(0);
                SAVED_USER_ID = uid;
                if (setruid(uid) < 0) rb_sys_fail(0);
            }
        }
        else if (/* geteuid() != uid && */ getuid() == uid) {
            if (seteuid(uid) < 0) rb_sys_fail(0);
            if (setruid(SAVED_USER_ID) < 0) rb_sys_fail(0);
            SAVED_USER_ID = uid;
            if (setruid(uid) < 0) rb_sys_fail(0);
        }
        else {
            rb_syserr_fail(EPERM, 0);
        }
#elif defined HAVE_44BSD_SETUID
        if (getuid() == uid) {
            /* (r,e,s)==(uid,?,?) ==> (uid,uid,uid) */
            if (setuid(uid) < 0) rb_sys_fail(0);
            SAVED_USER_ID = uid;
        }
        else {
            rb_syserr_fail(EPERM, 0);
        }
#elif defined HAVE_SETEUID
        if (getuid() == uid && SAVED_USER_ID == uid) {
            if (seteuid(uid) < 0) rb_sys_fail(0);
        }
        else {
            rb_syserr_fail(EPERM, 0);
        }
#elif defined HAVE_SETUID
        if (getuid() == uid && SAVED_USER_ID == uid) {
            if (setuid(uid) < 0) rb_sys_fail(0);
        }
        else {
            rb_syserr_fail(EPERM, 0);
        }
#else
        rb_notimplement();
#endif
    }
    return id;
}

Change the current process's real and effective user ID to that specified by user. Returns the new user ID. Not available on all platforms.

[Process.uid, Process.euid]          #=> [0, 0]
Process::UID.change_privilege(31)    #=> 31
[Process.uid, Process.euid]          #=> [31, 31]

euid → integer Show source

Process::UID.eid → integer

Process::Sys.geteuid → integer

static VALUE
proc_geteuid(VALUE obj)
{
    rb_uid_t euid = geteuid();
    return UIDT2NUM(euid);
}

Returns the effective user ID for this process.

Process.euid   #=> 501

Process::UID.from_name(name) → uid Show source

static VALUE
p_uid_from_name(VALUE self, VALUE id)
{
    return UIDT2NUM(OBJ2UID(id));
}

Get the user ID by the name. If the user is not found, ArgumentError will be raised.

Process::UID.from_name("root") #=> 0
Process::UID.from_name("nosuchuser") #=> can't find user for nosuchuser (ArgumentError)

Process::UID.grant_privilege(user) → integer Show source

Process::UID.eid= user → integer

static VALUE
p_uid_grant_privilege(VALUE obj, VALUE id)
{
    rb_seteuid_core(OBJ2UID(id));
    return id;
}

Set the effective user ID, and if possible, the saved user ID of the process to the given user. Returns the new effective user ID. Not available on all platforms.

[Process.uid, Process.euid]          #=> [0, 0]
Process::UID.grant_privilege(31)     #=> 31
[Process.uid, Process.euid]          #=> [0, 31]

Process::UID.re_exchange → integer Show source

static VALUE
p_uid_exchange(VALUE obj)
{
    rb_uid_t uid;
#if defined(HAVE_SETRESUID) || (defined(HAVE_SETREUID) && !defined(OBSOLETE_SETREUID))
    rb_uid_t euid;
#endif

    check_uid_switch();

    uid = getuid();
#if defined(HAVE_SETRESUID) || (defined(HAVE_SETREUID) && !defined(OBSOLETE_SETREUID))
    euid = geteuid();
#endif

#if defined(HAVE_SETRESUID)
    if (setresuid(euid, uid, uid) < 0) rb_sys_fail(0);
    SAVED_USER_ID = uid;
#elif defined(HAVE_SETREUID) && !defined(OBSOLETE_SETREUID)
    if (setreuid(euid,uid) < 0) rb_sys_fail(0);
    SAVED_USER_ID = uid;
#else
    rb_notimplement();
#endif
    return UIDT2NUM(uid);
}

Exchange real and effective user IDs and return the new effective user ID. Not available on all platforms.

[Process.uid, Process.euid]   #=> [0, 31]
Process::UID.re_exchange      #=> 0
[Process.uid, Process.euid]   #=> [31, 0]

Process::UID.re_exchangeable? → true or false Show source

static VALUE
p_uid_exchangeable(VALUE _)
{
#if defined(HAVE_SETRESUID)
    return Qtrue;
#elif defined(HAVE_SETREUID) && !defined(OBSOLETE_SETREUID)
    return Qtrue;
#else
    return Qfalse;
#endif
}

Returns true if the real and effective user IDs of a process may be exchanged on the current platform.

uid → integer Show source

Process::UID.rid → integer

Process::Sys.getuid → integer

static VALUE
proc_getuid(VALUE obj)
{
    rb_uid_t uid = getuid();
    return UIDT2NUM(uid);
}

Returns the (real) user ID of this process.

Process.uid   #=> 501

Process::UID.sid_available? → true or false Show source

static VALUE
p_uid_have_saved_id(VALUE _)
{
#if defined(HAVE_SETRESUID) || defined(HAVE_SETEUID) || defined(_POSIX_SAVED_IDS)
    return Qtrue;
#else
    return Qfalse;
#endif
}

Returns true if the current platform has saved user ID functionality.

Process::UID.switch → integer Show source

Process::UID.switch {|| block} → object

static VALUE
p_uid_switch(VALUE obj)
{
    rb_uid_t uid, euid;

    check_uid_switch();

    uid = getuid();
    euid = geteuid();

    if (uid != euid) {
        proc_seteuid(uid);
        if (rb_block_given_p()) {
            under_uid_switch = 1;
            return rb_ensure(rb_yield, Qnil, p_uid_sw_ensure, SAVED_USER_ID);
        }
        else {
            return UIDT2NUM(euid);
        }
    }
    else if (euid != SAVED_USER_ID) {
        proc_seteuid(SAVED_USER_ID);
        if (rb_block_given_p()) {
            under_uid_switch = 1;
            return rb_ensure(rb_yield, Qnil, p_uid_sw_ensure, euid);
        }
        else {
            return UIDT2NUM(uid);
        }
    }
    else {
        rb_syserr_fail(EPERM, 0);
    }

    UNREACHABLE_RETURN(Qnil);
}

Switch the effective and real user IDs of the current process. If a block is given, the user IDs will be switched back after the block is executed. Returns the new effective user ID if called without a block, and the return value of the block if one is given.

Ruby Core © 1993–2020 Yukihiro Matsumoto
Licensed under the Ruby License.
Ruby Standard Library © contributors
Licensed under their own licenses.