1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1990, 1993
5 * The Regents of the University of California. All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the University nor the names of its contributors
16 * may be used to endorse or promote products derived from this software
17 * without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 *
31 * @(#)filedesc.h 8.1 (Berkeley) 6/2/93
32 */
33
34 #ifndef _SYS_FILEDESC_H_
35 #define _SYS_FILEDESC_H_
36
37 #include <sys/types.h>
38 #include <sys/caprights.h>
39 #include <sys/queue.h>
40 #include <sys/event.h>
41 #include <sys/lock.h>
42 #include <sys/mutex.h>
43 #include <sys/priority.h>
44 #include <sys/seqc.h>
45 #include <sys/sx.h>
46 #include <sys/_smr.h>
47 #include <sys/smr_types.h>
48
49 #include <machine/_limits.h>
50
51 struct filecaps {
52 cap_rights_t fc_rights; /* per-descriptor capability rights */
53 u_long *fc_ioctls; /* per-descriptor allowed ioctls */
54 int16_t fc_nioctls; /* fc_ioctls array size */
55 uint32_t fc_fcntls; /* per-descriptor allowed fcntls */
56 };
57
58 struct filedescent {
59 struct file *fde_file; /* file structure for open file */
60 struct filecaps fde_caps; /* per-descriptor rights */
61 uint8_t fde_flags; /* per-process open file flags */
62 seqc_t fde_seqc; /* keep file and caps in sync */
63 };
64 #define fde_rights fde_caps.fc_rights
65 #define fde_fcntls fde_caps.fc_fcntls
66 #define fde_ioctls fde_caps.fc_ioctls
67 #define fde_nioctls fde_caps.fc_nioctls
68
69 #ifdef _KERNEL
70 static inline void
fde_copy(struct filedescent * from,struct filedescent * to)71 fde_copy(struct filedescent *from, struct filedescent *to)
72 {
73
74 to->fde_file = from->fde_file;
75 to->fde_caps = from->fde_caps;
76 to->fde_flags = from->fde_flags;
77 }
78 #endif
79
80 struct fdescenttbl {
81 int fdt_nfiles; /* number of open files allocated */
82 struct filedescent fdt_ofiles[0]; /* open files */
83 };
84 #define fd_seqc(fdt, fd) (&(fdt)->fdt_ofiles[(fd)].fde_seqc)
85
86 #define NDSLOTTYPE u_long
87
88 /*
89 * This struct is copy-on-write and allocated from an SMR zone.
90 * All fields are constant after initialization apart from the reference count.
91 * The ABI root directory is initialized as the root directory and changed
92 * during process transiting to or from non-native ABI.
93 *
94 * Check pwd_* routines for usage.
95 */
96 struct pwd {
97 u_int pwd_refcount;
98 struct vnode *pwd_cdir; /* current directory */
99 struct vnode *pwd_rdir; /* root directory */
100 struct vnode *pwd_jdir; /* jail root directory */
101 struct vnode *pwd_adir; /* abi root directory */
102 };
103 typedef SMR_POINTER(struct pwd *) smrpwd_t;
104
105 struct pwddesc {
106 struct mtx pd_lock; /* protects members of this struct */
107 smrpwd_t pd_pwd; /* directories */
108 u_int pd_refcount;
109 u_short pd_cmask; /* mask for file creation */
110 };
111
112 /*
113 * This structure is used for the management of descriptors. It may be
114 * shared by multiple processes.
115 */
116 struct filedesc {
117 struct fdescenttbl *fd_files; /* open files table */
118 NDSLOTTYPE *fd_map; /* bitmap of free fds */
119 int fd_freefile; /* approx. next free file */
120 int fd_refcnt; /* thread reference count */
121 int fd_holdcnt; /* hold count on structure + mutex */
122 struct sx fd_sx; /* protects members of this struct */
123 struct kqlist fd_kqlist; /* list of kqueues on this filedesc */
124 int fd_holdleaderscount; /* block fdfree() for shared close() */
125 int fd_holdleaderswakeup; /* fdfree() needs wakeup */
126 };
127
128 /*
129 * Structure to keep track of (process leader, struct fildedesc) tuples.
130 * Each process has a pointer to such a structure when detailed tracking
131 * is needed, e.g., when rfork(RFPROC | RFMEM) causes a file descriptor
132 * table to be shared by processes having different "p_leader" pointers
133 * and thus distinct POSIX style locks.
134 *
135 * fdl_refcount and fdl_holdcount are protected by struct filedesc mtx.
136 */
137 struct filedesc_to_leader {
138 int fdl_refcount; /* references from struct proc */
139 int fdl_holdcount; /* temporary hold during closef */
140 int fdl_wakeup; /* fdfree() waits on closef() */
141 struct proc *fdl_leader; /* owner of POSIX locks */
142 /* Circular list: */
143 struct filedesc_to_leader *fdl_prev;
144 struct filedesc_to_leader *fdl_next;
145 };
146 #define fd_nfiles fd_files->fdt_nfiles
147 #define fd_ofiles fd_files->fdt_ofiles
148
149 /*
150 * Per-process open flags.
151 */
152 #define UF_EXCLOSE 0x01 /* auto-close on exec */
153
154 #ifdef _KERNEL
155
156 /* Lock a paths descriptor table. */
157 #define PWDDESC_LOCK(pdp) (&(pdp)->pd_lock)
158 #define PWDDESC_LOCK_INIT(pdp) \
159 mtx_init(PWDDESC_LOCK(pdp), "pwddesc", NULL, MTX_DEF)
160 #define PWDDESC_LOCK_DESTROY(pdp) mtx_destroy(PWDDESC_LOCK(pdp))
161 #define PWDDESC_XLOCK(pdp) mtx_lock(PWDDESC_LOCK(pdp))
162 #define PWDDESC_XUNLOCK(pdp) mtx_unlock(PWDDESC_LOCK(pdp))
163 #define PWDDESC_LOCK_ASSERT(pdp, what) \
164 mtx_assert(PWDDESC_LOCK(pdp), (what))
165 #define PWDDESC_ASSERT_XLOCKED(pdp) \
166 PWDDESC_LOCK_ASSERT((pdp), MA_OWNED)
167 #define PWDDESC_ASSERT_UNLOCKED(pdp) \
168 PWDDESC_LOCK_ASSERT((pdp), MA_NOTOWNED)
169
170 #define PWDDESC_XLOCKED_LOAD_PWD(pdp) ({ \
171 struct pwddesc *_pdp = (pdp); \
172 struct pwd *_pwd; \
173 _pwd = smr_serialized_load(&(_pdp)->pd_pwd, \
174 (PWDDESC_ASSERT_XLOCKED(_pdp), true)); \
175 _pwd; \
176 })
177
178 /* Lock a file descriptor table. */
179 #define FILEDESC_LOCK_INIT(fdp) sx_init(&(fdp)->fd_sx, "filedesc structure")
180 #define FILEDESC_LOCK_DESTROY(fdp) sx_destroy(&(fdp)->fd_sx)
181 #define FILEDESC_LOCK(fdp) (&(fdp)->fd_sx)
182 #define FILEDESC_XLOCK(fdp) sx_xlock(&(fdp)->fd_sx)
183 #define FILEDESC_XUNLOCK(fdp) sx_xunlock(&(fdp)->fd_sx)
184 #define FILEDESC_SLOCK(fdp) sx_slock(&(fdp)->fd_sx)
185 #define FILEDESC_SUNLOCK(fdp) sx_sunlock(&(fdp)->fd_sx)
186
187 #define FILEDESC_LOCK_ASSERT(fdp) sx_assert(&(fdp)->fd_sx, SX_LOCKED | \
188 SX_NOTRECURSED)
189 #define FILEDESC_XLOCK_ASSERT(fdp) sx_assert(&(fdp)->fd_sx, SX_XLOCKED | \
190 SX_NOTRECURSED)
191 #define FILEDESC_UNLOCK_ASSERT(fdp) sx_assert(&(fdp)->fd_sx, SX_UNLOCKED)
192
193 #define FILEDESC_IS_ONLY_USER(fdp) ({ \
194 struct filedesc *_fdp = (fdp); \
195 MPASS(curproc->p_fd == _fdp); \
196 (curproc->p_numthreads == 1 && refcount_load(&_fdp->fd_refcnt) == 1); \
197 })
198
199 #else
200
201 /*
202 * Accessor for libkvm et al.
203 */
204 #define PWDDESC_KVM_LOAD_PWD(pdp) ({ \
205 struct pwddesc *_pdp = (pdp); \
206 struct pwd *_pwd; \
207 _pwd = smr_kvm_load(&(_pdp)->pd_pwd); \
208 _pwd; \
209 })
210
211 #endif
212
213 #ifdef _KERNEL
214
215 /* Operation types for kern_dup(). */
216 enum {
217 FDDUP_NORMAL, /* dup() behavior. */
218 FDDUP_FCNTL, /* fcntl()-style errors. */
219 FDDUP_FIXED, /* Force fixed allocation. */
220 FDDUP_LASTMODE,
221 };
222
223 /* Flags for kern_dup(). */
224 #define FDDUP_FLAG_CLOEXEC 0x1 /* Atomically set UF_EXCLOSE. */
225
226 /* For backward compatibility. */
227 #define falloc(td, resultfp, resultfd, flags) \
228 falloc_caps(td, resultfp, resultfd, flags, NULL)
229
230 struct mount;
231 struct thread;
232
233 static __inline void
filecaps_init(struct filecaps * fcaps)234 filecaps_init(struct filecaps *fcaps)
235 {
236
237 bzero(fcaps, sizeof(*fcaps));
238 fcaps->fc_nioctls = -1;
239 }
240 bool filecaps_copy(const struct filecaps *src, struct filecaps *dst,
241 bool locked);
242 void filecaps_move(struct filecaps *src, struct filecaps *dst);
243 void filecaps_free(struct filecaps *fcaps);
244
245 int closef(struct file *fp, struct thread *td);
246 void closef_nothread(struct file *fp);
247 int descrip_check_write_mp(struct filedesc *fdp, struct mount *mp);
248 int dupfdopen(struct thread *td, struct filedesc *fdp, int dfd, int mode,
249 int openerror, int *indxp);
250 int falloc_caps(struct thread *td, struct file **resultfp, int *resultfd,
251 int flags, struct filecaps *fcaps);
252 void falloc_abort(struct thread *td, struct file *fp);
253 int _falloc_noinstall(struct thread *td, struct file **resultfp, u_int n);
254 #define falloc_noinstall(td, resultfp) _falloc_noinstall(td, resultfp, 1)
255 void _finstall(struct filedesc *fdp, struct file *fp, int fd, int flags,
256 struct filecaps *fcaps);
257 int finstall(struct thread *td, struct file *fp, int *resultfd, int flags,
258 struct filecaps *fcaps);
259 int finstall_refed(struct thread *td, struct file *fp, int *resultfd, int flags,
260 struct filecaps *fcaps);
261 int fdalloc(struct thread *td, int minfd, int *result);
262 int fdallocn(struct thread *td, int minfd, int *fds, int n);
263 int fdcheckstd(struct thread *td);
264 void fdclose(struct thread *td, struct file *fp, int idx);
265 void fdcloseexec(struct thread *td);
266 void fdsetugidsafety(struct thread *td);
267 struct filedesc *fdcopy(struct filedesc *fdp);
268 void fdunshare(struct thread *td);
269 void fdescfree(struct thread *td);
270 int fdlastfile(struct filedesc *fdp);
271 int fdlastfile_single(struct filedesc *fdp);
272 struct filedesc *fdinit(void);
273 struct filedesc *fdshare(struct filedesc *fdp);
274 struct filedesc_to_leader *
275 filedesc_to_leader_alloc(struct filedesc_to_leader *old,
276 struct filedesc *fdp, struct proc *leader);
277 struct filedesc_to_leader *
278 filedesc_to_leader_share(struct filedesc_to_leader *fdtol,
279 struct filedesc *fdp);
280 int getvnode(struct thread *td, int fd, cap_rights_t *rightsp,
281 struct file **fpp);
282 int getvnode_path(struct thread *td, int fd, cap_rights_t *rightsp,
283 struct file **fpp);
284 void mountcheckdirs(struct vnode *olddp, struct vnode *newdp);
285
286 int fget_cap_noref(struct filedesc *fdp, int fd, cap_rights_t *needrightsp,
287 struct file **fpp, struct filecaps *havecapsp);
288 int fget_cap(struct thread *td, int fd, cap_rights_t *needrightsp,
289 struct file **fpp, struct filecaps *havecapsp);
290 /* Return a referenced file from an unlocked descriptor. */
291 int fget_unlocked(struct thread *td, int fd, cap_rights_t *needrightsp,
292 struct file **fpp);
293 /* Return a file pointer without a ref. FILEDESC_IS_ONLY_USER must be true. */
294 int fget_only_user(struct filedesc *fdp, int fd, cap_rights_t *needrightsp,
295 struct file **fpp);
296 #define fput_only_user(fdp, fp) ({ \
297 MPASS(FILEDESC_IS_ONLY_USER(fdp)); \
298 MPASS(refcount_load(&fp->f_count) > 0); \
299 })
300
301 /* Requires a FILEDESC_{S,X}LOCK held and returns without a ref. */
302 static __inline struct file *
fget_noref(struct filedesc * fdp,int fd)303 fget_noref(struct filedesc *fdp, int fd)
304 {
305
306 FILEDESC_LOCK_ASSERT(fdp);
307
308 if (__predict_false((u_int)fd >= (u_int)fdp->fd_nfiles))
309 return (NULL);
310
311 return (fdp->fd_ofiles[fd].fde_file);
312 }
313
314 static __inline struct filedescent *
fdeget_noref(struct filedesc * fdp,int fd)315 fdeget_noref(struct filedesc *fdp, int fd)
316 {
317 struct filedescent *fde;
318
319 FILEDESC_LOCK_ASSERT(fdp);
320
321 if (__predict_false((u_int)fd >= (u_int)fdp->fd_nfiles))
322 return (NULL);
323
324 fde = &fdp->fd_ofiles[fd];
325 if (__predict_false(fde->fde_file == NULL))
326 return (NULL);
327
328 return (fde);
329 }
330
331 #ifdef CAPABILITIES
332 static __inline bool
fd_modified(struct filedesc * fdp,int fd,seqc_t seqc)333 fd_modified(struct filedesc *fdp, int fd, seqc_t seqc)
334 {
335
336 return (!seqc_consistent(fd_seqc(fdp->fd_files, fd), seqc));
337 }
338 #endif
339
340 int proc_nfiles(struct proc *p);
341
342 /* cdir/rdir/jdir manipulation functions. */
343 struct pwddesc *pdcopy(struct pwddesc *pdp);
344 void pdescfree(struct thread *td);
345 struct pwddesc *pdinit(struct pwddesc *pdp, bool keeplock);
346 struct pwddesc *pdshare(struct pwddesc *pdp);
347 void pdunshare(struct thread *td);
348
349 void pwd_altroot(struct thread *td, struct vnode *altroot_vp);
350 void pwd_chdir(struct thread *td, struct vnode *vp);
351 int pwd_chroot(struct thread *td, struct vnode *vp);
352 int pwd_chroot_chdir(struct thread *td, struct vnode *vp);
353 void pwd_ensure_dirs(void);
354 void pwd_set_rootvnode(void);
355
356 struct pwd *pwd_hold_pwddesc(struct pwddesc *pdp);
357 bool pwd_hold_smr(struct pwd *pwd);
358 struct pwd *pwd_hold_proc(struct proc *p);
359 struct pwd *pwd_hold(struct thread *td);
360 void pwd_drop(struct pwd *pwd);
361 static inline void
pwd_set(struct pwddesc * pdp,struct pwd * newpwd)362 pwd_set(struct pwddesc *pdp, struct pwd *newpwd)
363 {
364 smr_serialized_store(&pdp->pd_pwd, newpwd,
365 (PWDDESC_ASSERT_XLOCKED(pdp), true));
366 }
367 #define pwd_get_smr() vfs_smr_entered_load(&curproc->p_pd->pd_pwd)
368
369 #endif /* _KERNEL */
370
371 #endif /* !_SYS_FILEDESC_H_ */
372