OpenSolaris_b135/uts/common/io/ptms_conf.c
/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright 2008 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
#pragma ident "%Z%%M% %I% %E% SMI"
/*
* This file contains global data and code shared between master and slave parts
* of the pseudo-terminal driver.
*
* Pseudo terminals (or pt's for short) are allocated dynamically.
* pt's are put in the global ptms_slots array indexed by minor numbers.
*
* The slots array is initially small (of the size NPTY_MIN). When more pt's are
* needed than the slot array size, the larger slot array is allocated and all
* opened pt's move to the new one.
*
* Resource allocation:
*
* pt_ttys structures are allocated via pt_ttys_alloc, which uses
* kmem_cache_alloc().
* Minor number space is allocated via vmem_alloc() interface.
* ptms_slots arrays are allocated via kmem_alloc().
*
* Minors are started from 1 instead of 0 because vmem_alloc returns 0 in case
* of failure. Also, in anticipation of removing clone device interface to
* pseudo-terminal subsystem, minor 0 should not be used. (Potential future
* development).
*
* After the table slot size reaches pt_maxdelta, we stop 2^N extension
* algorithm and start extending the slot table size by pt_maxdelta.
*
* Device entries /dev/pts directory are created dynamically by the
* /dev filesystem. We no longer call ddi_create_minor_node() on
* behalf of the slave driver. The /dev filesystem creates /dev/pts
* nodes based on the pt_ttys array.
*
* Synchronization:
*
* All global data synchronization between ptm/pts is done via global
* ptms_lock mutex which is implicitly initialized by declaring it global.
*
* Individual fields of pt_ttys structure (except ptm_rdq, pts_rdq and
* pt_nullmsg) are protected by pt_ttys.pt_lock mutex.
*
* PT_ENTER_READ/PT_ENTER_WRITE are reference counter based read-write locks
* which allow reader locks to be reacquired by the same thread (usual
* reader/writer locks can't be used for that purpose since it is illegal for
* a thread to acquire a lock it already holds, even as a reader). The sole
* purpose of these macros is to guarantee that the peer queue will not
* disappear (due to closing peer) while it is used. It is safe to use
* PT_ENTER_READ/PT_EXIT_READ brackets across calls like putq/putnext (since
* they are not real locks but reference counts).
*
* PT_ENTER_WRITE/PT_EXIT_WRITE brackets are used ONLY in master/slave
* open/close paths to modify ptm_rdq and pts_rdq fields. These fields should
* be set to appropriate queues *after* qprocson() is called during open (to
* prevent peer from accessing the queue with incomplete plumbing) and set to
* NULL before qprocsoff() is called during close. Put and service procedures
* use PT_ENTER_READ/PT_EXIT_READ to prevent peer closes.
*
* The pt_nullmsg field is only used in open/close routines and is also
* protected by PT_ENTER_WRITE/PT_EXIT_WRITE brackets to avoid extra mutex
* holds.
*
* Lock Ordering:
*
* If both ptms_lock and per-pty lock should be held, ptms_lock should always
* be entered first, followed by per-pty lock.
*
* Global functions:
*
* void ptms_init(void);
*
* Called by pts/ptm _init entry points. It performes one-time
* initialization needed for both pts and ptm. This initialization is done
* here and not in ptms_initspace because all these data structures are not
* needed if pseudo-terminals are not used in the system.
*
* struct pt_ttys *pt_ttys_alloc(void);
*
* Allocate new minor number and pseudo-terminal entry. May sleep.
* New minor number is recorded in pt_minor field of the entry returned.
* This routine also initializes pt_minor and pt_state fields of the new
* pseudo-terminal and puts a pointer to it into ptms_slots array.
*
* struct pt_ttys *ptms_minor2ptty(minor_t minor)
*
* Find pt_ttys structure by minor number.
* Returns NULL when minor is out of range.
*
* int ptms_minor_valid(minor_t minor, uid_t *ruid, gid_t *rgid)
*
* Check if minor refers to an allocated pty in the current zone.
* Returns
* 0 if not allocated or not for this zone.
* 1 if an allocated pty in the current zone.
* Also returns owner of pty.
*
* int ptms_minor_exists(minor_t minor)
* Check if minor refers to an allocated pty (in any zone)
* Returns
* 0 if not an allocated pty
* 1 if an allocated pty
*
* void ptms_set_owner(minor_t minor, uid_t ruid, gid_t rgid)
*
* Sets the owner associated with a pty.
*
* void ptms_close(struct pt_ttys *pt, uint_t flags_to_clear);
*
* Clear flags_to_clear in pt and if no one owns it (PTMOPEN/PTSOPEN not
* set) free pt entry and corresponding slot.
*
* Tuneables and configuration:
*
* pt_cnt: minimum number of pseudo-terminals in the system. The system
* should provide at least this number of ptys (provided sufficient
* memory is available). It is different from the older semantics
* of pt_cnt meaning maximum number of ptys.
* Set to 0 by default.
*
* pt_max_pty: Maximum number of pseudo-terminals in the system. The system
* should not allocate more ptys than pt_max_pty (although, it may
* impose stricter maximum). Zero value means no user-defined
* maximum. This is intended to be used as "denial-of-service"
* protection.
* Set to 0 by default.
*
* Both pt_cnt and pt_max_pty may be modified during system lifetime
* with their semantics preserved.
*
* pt_init_cnt: Initial size of ptms_slots array. Set to NPTY_INITIAL.
*
* pt_ptyofmem: Approximate percentage of system memory that may be
* occupied by pty data structures. Initially set to NPTY_PERCENT.
* This variable is used once during initialization to estimate
* maximum number of ptys in the system. The actual maximum is
* determined as minimum of pt_max_pty and calculated value.
*
* pt_maxdelta: Maximum extension chunk of the slot table.
*/
#include <sys/types.h>
#include <sys/param.h>
#include <sys/termios.h>
#include <sys/stream.h>
#include <sys/stropts.h>
#include <sys/kmem.h>
#include <sys/ptms.h>
#include <sys/stat.h>
#include <sys/sunddi.h>
#include <sys/ddi.h>
#include <sys/bitmap.h>
#include <sys/sysmacros.h>
#include <sys/ddi_impldefs.h>
#include <sys/zone.h>
#ifdef DEBUG
#include <sys/strlog.h>
#endif
/* Initial number of ptms slots */
#define NPTY_INITIAL 16
#define NPTY_PERCENT 5
/* Maximum increment of the slot table size */
#define PTY_MAXDELTA 128
/*
* Tuneable variables.
*/
uint_t pt_cnt = 0; /* Minimum number of ptys */
size_t pt_max_pty = 0; /* Maximum number of ptys */
uint_t pt_init_cnt = NPTY_INITIAL; /* Initial number of ptms slots */
uint_t pt_pctofmem = NPTY_PERCENT; /* Percent of memory to use for ptys */
uint_t pt_maxdelta = PTY_MAXDELTA; /* Max increment for slot table size */
/* Other global variables */
kmutex_t ptms_lock; /* Global data access lock */
/*
* Slot array and its management variables
*/
static struct pt_ttys **ptms_slots = NULL; /* Slots for actual pt structures */
static size_t ptms_nslots = 0; /* Size of slot array */
static size_t ptms_ptymax = 0; /* Maximum number of ptys */
static size_t ptms_inuse = 0; /* # of ptys currently allocated */
dev_info_t *pts_dip = NULL; /* set if slave is attached */
static struct kmem_cache *ptms_cache = NULL; /* pty cache */
static vmem_t *ptms_minor_arena = NULL; /* Arena for device minors */
static uint_t ptms_roundup(uint_t);
static int ptms_constructor(void *, void *, int);
static void ptms_destructor(void *, void *);
static minor_t ptms_grow(void);
/*
* Total size occupied by one pty. Each pty master/slave pair consumes one
* pointer for ptms_slots array, one pt_ttys structure and one empty message
* preallocated for pts close.
*/
#define PTY_SIZE (sizeof (struct pt_ttys) + \
sizeof (struct pt_ttys *) + \
sizeof (dblk_t))
#ifdef DEBUG
int ptms_debug = 0;
#define PTMOD_ID 5
#endif
/*
* Clear all bits of x except the highest bit
*/
#define truncate(x) ((x) <= 2 ? (x) : (1 << (highbit(x) - 1)))
/*
* Roundup the number to the nearest power of 2
*/
static uint_t
ptms_roundup(uint_t x)
{
uint_t p = truncate(x); /* x with non-high bits stripped */
/*
* If x is a power of 2, return x, otherwise roundup.
*/
return (p == x ? p : (p * 2));
}
/*
* Allocate ptms_slots array and kmem cache for pt_ttys. This initialization is
* only called once during system lifetime. Called from ptm or pts _init
* routine.
*/
void
ptms_init(void)
{
mutex_enter(&ptms_lock);
if (ptms_slots == NULL) {
ptms_slots = kmem_zalloc(pt_init_cnt *
sizeof (struct pt_ttys *), KM_SLEEP);
ptms_cache = kmem_cache_create("pty_map",
sizeof (struct pt_ttys), 0, ptms_constructor,
ptms_destructor, NULL, NULL, NULL, 0);
ptms_nslots = pt_init_cnt;
/* Allocate integer space for minor numbers */
ptms_minor_arena = vmem_create("ptms_minor", (void *)1,
ptms_nslots, 1, NULL, NULL, NULL, 0,
VM_SLEEP | VMC_IDENTIFIER);
/*
* Calculate available number of ptys - how many ptys can we
* allocate in pt_pctofmem % of available memory. The value is
* rounded up to the nearest power of 2.
*/
ptms_ptymax = ptms_roundup((pt_pctofmem * kmem_maxavail()) /
(100 * PTY_SIZE));
}
mutex_exit(&ptms_lock);
}
/*
* This routine attaches the pts dip.
*/
int
ptms_attach_slave(void)
{
if (pts_dip == NULL && i_ddi_attach_pseudo_node("pts") == NULL)
return (-1);
ASSERT(pts_dip);
return (0);
}
/*
* Called from /dev fs. Checks if dip is attached,
* and if it is, returns its major number.
*/
major_t
ptms_slave_attached(void)
{
major_t maj = DDI_MAJOR_T_NONE;
mutex_enter(&ptms_lock);
if (pts_dip)
maj = ddi_driver_major(pts_dip);
mutex_exit(&ptms_lock);
return (maj);
}
/*
* Allocate new minor number and pseudo-terminal entry. Returns the new entry or
* NULL if no memory or maximum number of entries reached.
*/
struct pt_ttys *
pt_ttys_alloc(void)
{
minor_t dminor;
struct pt_ttys *pt = NULL;
mutex_enter(&ptms_lock);
/*
* Always try to allocate new pty when pt_cnt minimum limit is not
* achieved. If it is achieved, the maximum is determined by either
* user-specified value (if it is non-zero) or our memory estimations -
* whatever is less.
*/
if (ptms_inuse >= pt_cnt) {
/*
* When system achieved required minimum of ptys, check for the
* denial of service limits.
*
* Since pt_max_pty may be zero, the formula below is used to
* avoid conditional expression. It will equal to pt_max_pty if
* it is not zero and ptms_ptymax otherwise.
*/
size_t user_max = (pt_max_pty == 0 ? ptms_ptymax : pt_max_pty);
/* Do not try to allocate more than allowed */
if (ptms_inuse >= min(ptms_ptymax, user_max)) {
mutex_exit(&ptms_lock);
return (NULL);
}
}
ptms_inuse++;
/*
* Allocate new minor number. If this fails, all slots are busy and
* we need to grow the hash.
*/
dminor = (minor_t)(uintptr_t)
vmem_alloc(ptms_minor_arena, 1, VM_NOSLEEP);
if (dminor == 0) {
/* Grow the cache and retry allocation */
dminor = ptms_grow();
}
if (dminor == 0) {
/* Not enough memory now */
ptms_inuse--;
mutex_exit(&ptms_lock);
return (NULL);
}
pt = kmem_cache_alloc(ptms_cache, KM_NOSLEEP);
if (pt == NULL) {
/* Not enough memory - this entry can't be used now. */
vmem_free(ptms_minor_arena, (void *)(uintptr_t)dminor, 1);
ptms_inuse--;
} else {
pt->pt_minor = dminor;
pt->pt_pid = curproc->p_pid; /* For debugging */
pt->pt_state = (PTMOPEN | PTLOCK);
pt->pt_zoneid = getzoneid();
pt->pt_ruid = 0; /* we don't know uid/gid yet. Report as root */
pt->pt_rgid = 0;
ASSERT(ptms_slots[dminor - 1] == NULL);
ptms_slots[dminor - 1] = pt;
}
mutex_exit(&ptms_lock);
return (pt);
}
/*
* Get pt_ttys structure by minor number.
* Returns NULL when minor is out of range.
*/
struct pt_ttys *
ptms_minor2ptty(minor_t dminor)
{
struct pt_ttys *pt = NULL;
ASSERT(mutex_owned(&ptms_lock));
if ((dminor >= 1) && (dminor <= ptms_nslots) && ptms_slots != NULL)
pt = ptms_slots[dminor - 1];
return (pt);
}
/*
* Invoked in response to chown on /dev/pts nodes to change the
* permission on a pty
*/
void
ptms_set_owner(minor_t dminor, uid_t ruid, gid_t rgid)
{
struct pt_ttys *pt;
ASSERT(ruid >= 0);
ASSERT(rgid >= 0);
if (ruid < 0 || rgid < 0)
return;
/*
* /dev/pts/0 is not used, but some applications may check it. There
* is no pty backing it - so we have nothing to do.
*/
if (dminor == 0)
return;
mutex_enter(&ptms_lock);
pt = ptms_minor2ptty(dminor);
if (pt != NULL && pt->pt_zoneid == getzoneid()) {
pt->pt_ruid = ruid;
pt->pt_rgid = rgid;
}
mutex_exit(&ptms_lock);
}
/*
* Given a ptm/pts minor number
* returns:
* 1 if the pty is allocated to the current zone.
* 0 otherwise
*
* If the pty is allocated to the current zone, it also returns the owner.
*/
int
ptms_minor_valid(minor_t dminor, uid_t *ruid, gid_t *rgid)
{
struct pt_ttys *pt;
int ret;
ASSERT(ruid);
ASSERT(rgid);
*ruid = (uid_t)-1;
*rgid = (gid_t)-1;
/*
* /dev/pts/0 is not used, but some applications may check it, so create
* it also. Report the owner as root. It belongs to all zones.
*/
if (dminor == 0) {
*ruid = 0;
*rgid = 0;
return (1);
}
ret = 0;
mutex_enter(&ptms_lock);
pt = ptms_minor2ptty(dminor);
if (pt != NULL) {
ASSERT(pt->pt_ruid >= 0);
ASSERT(pt->pt_rgid >= 0);
if (pt->pt_zoneid == getzoneid()) {
ret = 1;
*ruid = pt->pt_ruid;
*rgid = pt->pt_rgid;
}
}
mutex_exit(&ptms_lock);
return (ret);
}
/*
* Given a ptm/pts minor number
* returns:
* 0 if the pty is not allocated
* 1 if the pty is allocated
*/
int
ptms_minor_exists(minor_t dminor)
{
int ret;
mutex_enter(&ptms_lock);
ret = ptms_minor2ptty(dminor) ? 1 : 0;
mutex_exit(&ptms_lock);
return (ret);
}
/*
* Close the pt and clear flags_to_clear.
* If pt device is not opened by someone else, free it and clear its slot.
*/
void
ptms_close(struct pt_ttys *pt, uint_t flags_to_clear)
{
uint_t flags;
ASSERT(MUTEX_NOT_HELD(&ptms_lock));
ASSERT(pt != NULL);
mutex_enter(&ptms_lock);
mutex_enter(&pt->pt_lock);
pt->pt_state &= ~flags_to_clear;
flags = pt->pt_state;
mutex_exit(&pt->pt_lock);
if (! (flags & (PTMOPEN | PTSOPEN))) {
/* No one owns the entry - free it */
ASSERT(pt->ptm_rdq == NULL);
ASSERT(pt->pts_rdq == NULL);
ASSERT(pt->pt_nullmsg == NULL);
ASSERT(pt->pt_refcnt == 0);
ASSERT(pt->pt_minor <= ptms_nslots);
ASSERT(ptms_slots[pt->pt_minor - 1] == pt);
ASSERT(ptms_inuse > 0);
ptms_inuse--;
pt->pt_pid = 0;
ptms_slots[pt->pt_minor - 1] = NULL;
/* Return minor number to the pool of minors */
vmem_free(ptms_minor_arena, (void *)(uintptr_t)pt->pt_minor, 1);
/* Return pt to the cache */
kmem_cache_free(ptms_cache, pt);
}
mutex_exit(&ptms_lock);
}
/*
* Allocate another slot table twice as large as the original one (limited to
* global maximum). Migrate all pt to the new slot table and free the original
* one. Create more /devices entries for new devices.
*/
static minor_t
ptms_grow()
{
minor_t old_size = ptms_nslots;
minor_t delta = MIN(pt_maxdelta, old_size);
minor_t new_size = old_size + delta;
struct pt_ttys **ptms_old = ptms_slots;
struct pt_ttys **ptms_new;
void *vaddr; /* vmem_add return value */
ASSERT(MUTEX_HELD(&ptms_lock));
DDBG("ptmopen(%d): need to grow\n", (int)ptms_inuse);
/* Allocate new ptms array */
ptms_new = kmem_zalloc(new_size * sizeof (struct pt_ttys *),
KM_NOSLEEP);
if (ptms_new == NULL)
return ((minor_t)0);
/* Increase clone index space */
vaddr = vmem_add(ptms_minor_arena, (void *)(uintptr_t)(old_size + 1),
new_size - old_size, VM_NOSLEEP);
if (vaddr == NULL) {
kmem_free(ptms_new, new_size * sizeof (struct pt_ttys *));
return ((minor_t)0);
}
/* Migrate pt entries to a new location */
ptms_nslots = new_size;
bcopy(ptms_old, ptms_new, old_size * sizeof (struct pt_ttys *));
ptms_slots = ptms_new;
kmem_free(ptms_old, old_size * sizeof (struct pt_ttys *));
/* Allocate minor number and return it */
return ((minor_t)(uintptr_t)
vmem_alloc(ptms_minor_arena, 1, VM_NOSLEEP));
}
/*ARGSUSED*/
static int
ptms_constructor(void *maddr, void *arg, int kmflags)
{
struct pt_ttys *pt = maddr;
pt->pts_rdq = NULL;
pt->ptm_rdq = NULL;
pt->pt_nullmsg = NULL;
pt->pt_pid = NULL;
pt->pt_minor = NULL;
pt->pt_refcnt = 0;
pt->pt_state = 0;
pt->pt_zoneid = GLOBAL_ZONEID;
cv_init(&pt->pt_cv, NULL, CV_DEFAULT, NULL);
mutex_init(&pt->pt_lock, NULL, MUTEX_DEFAULT, NULL);
return (0);
}
/*ARGSUSED*/
static void
ptms_destructor(void *maddr, void *arg)
{
struct pt_ttys *pt = maddr;
ASSERT(pt->pt_refcnt == 0);
ASSERT(pt->pt_state == 0);
ASSERT(pt->ptm_rdq == NULL);
ASSERT(pt->pts_rdq == NULL);
mutex_destroy(&pt->pt_lock);
cv_destroy(&pt->pt_cv);
}
#ifdef DEBUG
void
ptms_log(char *str, uint_t arg)
{
if (ptms_debug) {
if (ptms_debug & 2)
cmn_err(CE_CONT, str, arg);
if (ptms_debug & 4)
(void) strlog(PTMOD_ID, -1, 0, SL_TRACE | SL_ERROR,
str, arg);
else
(void) strlog(PTMOD_ID, -1, 0, SL_TRACE, str, arg);
}
}
void
ptms_logp(char *str, uintptr_t arg)
{
if (ptms_debug) {
if (ptms_debug & 2)
cmn_err(CE_CONT, str, arg);
if (ptms_debug & 4)
(void) strlog(PTMOD_ID, -1, 0, SL_TRACE | SL_ERROR,
str, arg);
else
(void) strlog(PTMOD_ID, -1, 0, SL_TRACE, str, arg);
}
}
#endif