diff options
Diffstat (limited to 'usr/src/uts/common/io/ptms_conf.c')
| -rw-r--r-- | usr/src/uts/common/io/ptms_conf.c | 148 |
1 files changed, 77 insertions, 71 deletions
diff --git a/usr/src/uts/common/io/ptms_conf.c b/usr/src/uts/common/io/ptms_conf.c index f593f5313f..b032b093ed 100644 --- a/usr/src/uts/common/io/ptms_conf.c +++ b/usr/src/uts/common/io/ptms_conf.c @@ -21,79 +21,86 @@ /* * Copyright 2008 Sun Microsystems, Inc. All rights reserved. * Use is subject to license terms. + * Copyright 2021 Oxide Computer Company */ /* - * This file contains global data and code shared between master and slave parts - * of the pseudo-terminal driver. + * PSEUDO-TERMINAL COMMON DATA AND ROUTINES (PTM, PTS) * - * Pseudo terminals (or pt's for short) are allocated dynamically. - * pt's are put in the global ptms_slots array indexed by minor numbers. + * This file contains global data and code shared between manager and + * subsidiary parts of the pseudo-terminal driver. * - * The slots array is initially small (of the size NPTY_MIN). When more pt's are + * Pseudo-terminals (or ptys for short) are allocated dynamically. + * ptys 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 ptys are * needed than the slot array size, the larger slot array is allocated and all - * opened pt's move to the new one. + * opened ptys 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(). * - * Resource allocation: + * Minors start from 1 instead of 0, because vmem_alloc() returns 0 in case of + * failure. Also, in anticipation of removing the clone device interface to + * pseudo-terminal subsystem, minor 0 should not be used. (Potential future + * development). * - * 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(). + * After the table slot size reaches pt_maxdelta, we stop 2^N extension + * algorithm and start extending the slot table size by pt_maxdelta. * - * 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). + * Device entries /dev/pts directory are created dynamically by the /dev + * filesystem. We no longer call ddi_create_minor_node() on behalf of the + * subsidiary driver. The /dev filesystem creates /dev/pts nodes based on the + * pt_ttys array. * - * 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 * - * Synchronization: + * All global data synchronization between ptm/pts is done via global ptms_lock + * mutex which is implicitly initialized by declaring it global. * - * 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. * - * 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_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 manager/subsidiary + * 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. * - * 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. * - * 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: + * 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. + * 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: + * + * 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 + * 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); @@ -117,6 +124,7 @@ * 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 @@ -129,32 +137,33 @@ * 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. + * set) free pt entry and corresponding slot. * - * Tuneables and configuration: + * + * 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 + * 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" + * 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. + * 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 + * 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. @@ -193,7 +202,7 @@ * Tuneable variables. */ uint_t pt_cnt = 0; /* Minimum number of ptys */ -size_t pt_max_pty = 0; /* Maximum 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 */ @@ -210,7 +219,7 @@ 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 */ +dev_info_t *pts_dip = NULL; /* Set if subsidiary is attached */ static struct kmem_cache *ptms_cache = NULL; /* pty cache */ @@ -222,9 +231,9 @@ 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. + * Total size occupied by one pty. Each pty manager/subsidiary 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) + \ @@ -239,7 +248,7 @@ int ptms_debug = 0; /* * Clear all bits of x except the highest bit */ -#define truncate(x) ((x) <= 2 ? (x) : (1 << (highbit(x) - 1))) +#define truncate(x) ((x) <= 2 ? (x) : (1 << (highbit(x) - 1))) /* * Roundup the number to the nearest power of 2 @@ -295,7 +304,7 @@ ptms_init(void) * This routine attaches the pts dip. */ int -ptms_attach_slave(void) +ptms_attach_subsidiary(void) { if (pts_dip == NULL && i_ddi_attach_pseudo_node("pts") == NULL) return (-1); @@ -309,7 +318,7 @@ ptms_attach_slave(void) * and if it is, returns its major number. */ major_t -ptms_slave_attached(void) +ptms_subsidiary_attached(void) { major_t maj = DDI_MAJOR_T_NONE; @@ -422,10 +431,7 @@ 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) + if (ruid > MAXUID || rgid > MAXUID) return; /* @@ -478,8 +484,8 @@ ptms_minor_valid(minor_t dminor, uid_t *ruid, gid_t *rgid) mutex_enter(&ptms_lock); pt = ptms_minor2ptty(dminor); if (pt != NULL) { - ASSERT(pt->pt_ruid >= 0); - ASSERT(pt->pt_rgid >= 0); + ASSERT(pt->pt_ruid <= MAXUID); + ASSERT(pt->pt_rgid <= MAXUID); if (pt->pt_zoneid == getzoneid()) { ret = 1; *ruid = pt->pt_ruid; |