selection.c

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * This module exports the functions:
  4 *
  5 *     'int set_selection_user(struct tiocl_selection __user *,
  6 *			       struct tty_struct *)'
  7 *     'int set_selection_kernel(struct tiocl_selection *, struct tty_struct *)'
  8 *     'void clear_selection(void)'
  9 *     'int paste_selection(struct tty_struct *)'
 10 *     'int sel_loadlut(u32 __user *)'
 11 *
 12 * Now that /dev/vcs exists, most of this can disappear again.
 13 */
 14
 15#include <linux/module.h>
 16#include <linux/tty.h>
 17#include <linux/sched.h>
 18#include <linux/mm.h>
 19#include <linux/mutex.h>
 20#include <linux/slab.h>
 21#include <linux/types.h>
 22
 23#include <linux/uaccess.h>
 24
 25#include <linux/kbd_kern.h>
 26#include <linux/vt_kern.h>
 27#include <linux/consolemap.h>
 28#include <linux/selection.h>
 29#include <linux/tiocl.h>
 30#include <linux/console.h>
 31#include <linux/tty_flip.h>
 32
 33#include <linux/sched/signal.h>
 34
 35/* Don't take this from <ctype.h>: 011-015 on the screen aren't spaces */
 36#define is_space_on_vt(c)	((c) == ' ')
 37
 38/* FIXME: all this needs locking */
 39static struct vc_selection {
 40	struct mutex lock;
 41	struct vc_data *cons;			/* must not be deallocated */
 42	char *buffer;
 43	unsigned int buf_len;
 44	volatile int start;			/* cleared by clear_selection */
 45	int end;
 46} vc_sel = {
 47	.lock = __MUTEX_INITIALIZER(vc_sel.lock),
 48	.start = -1,
 49};
 50
 51/* clear_selection, highlight and highlight_pointer can be called
 52   from interrupt (via scrollback/front) */
 53
 54/* set reverse video on characters s-e of console with selection. */
 55static inline void highlight(const int s, const int e)
 56{
 57	invert_screen(vc_sel.cons, s, e-s+2, true);
 58}
 59
 60/* use complementary color to show the pointer */
 61static inline void highlight_pointer(const int where)
 62{
 63	complement_pos(vc_sel.cons, where);
 64}
 65
 66static u32
 67sel_pos(int n, bool unicode)
 68{
 69	if (unicode)
 70		return screen_glyph_unicode(vc_sel.cons, n / 2);
 71	return inverse_translate(vc_sel.cons, screen_glyph(vc_sel.cons, n),
 72			false);
 73}
 74
 75/**
 76 * clear_selection - remove current selection
 77 *
 78 * Remove the current selection highlight, if any from the console holding the
 79 * selection.
 80 *
 81 * Locking: The caller must hold the console lock.
 82 */
 83void clear_selection(void)
 84{
 85	highlight_pointer(-1); /* hide the pointer */
 86	if (vc_sel.start != -1) {
 87		highlight(vc_sel.start, vc_sel.end);
 88		vc_sel.start = -1;
 89	}
 90}
 91EXPORT_SYMBOL_GPL(clear_selection);
 92
 93bool vc_is_sel(const struct vc_data *vc)
 94{
 95	return vc == vc_sel.cons;
 96}
 97
 98/*
 99 * User settable table: what characters are to be considered alphabetic?
100 * 128 bits. Locked by the console lock.
101 */
102static u32 inwordLut[]={
103  0x00000000, /* control chars     */
104  0x03FFE000, /* digits and "-./"  */
105  0x87FFFFFE, /* uppercase and '_' */
106  0x07FFFFFE, /* lowercase         */
107};
108
109static inline int inword(const u32 c)
110{
111	return c > 0x7f || (( inwordLut[c>>5] >> (c & 0x1F) ) & 1);
112}
113
114/**
115 * sel_loadlut() - load the LUT table
116 * @lut: user table
117 *
118 * Load the LUT table from user space. Make a temporary copy so a partial
119 * update doesn't make a mess.
120 *
121 * Locking: The console lock is acquired.
122 */
123int sel_loadlut(u32 __user *lut)
124{
125	u32 tmplut[ARRAY_SIZE(inwordLut)];
126
127	if (copy_from_user(tmplut, lut, sizeof(inwordLut)))
128		return -EFAULT;
129
130	guard(console_lock)();
131	memcpy(inwordLut, tmplut, sizeof(inwordLut));
132
133	return 0;
134}
135
136/* does screen address p correspond to character at LH/RH edge of screen? */
137static inline int atedge(const int p, int size_row)
138{
139	return (!(p % size_row)	|| !((p + 2) % size_row));
140}
141
142/* stores the char in UTF8 and returns the number of bytes used (1-4) */
143static int store_utf8(u32 c, char *p)
144{
145	if (c < 0x80) {
146		/*  0******* */
147		p[0] = c;
148		return 1;
149	} else if (c < 0x800) {
150		/* 110***** 10****** */
151		p[0] = 0xc0 | (c >> 6);
152		p[1] = 0x80 | (c & 0x3f);
153		return 2;
154	} else if (c < 0x10000) {
155		/* 1110**** 10****** 10****** */
156		p[0] = 0xe0 | (c >> 12);
157		p[1] = 0x80 | ((c >> 6) & 0x3f);
158		p[2] = 0x80 | (c & 0x3f);
159		return 3;
160	} else if (c < 0x110000) {
161		/* 11110*** 10****** 10****** 10****** */
162		p[0] = 0xf0 | (c >> 18);
163		p[1] = 0x80 | ((c >> 12) & 0x3f);
164		p[2] = 0x80 | ((c >> 6) & 0x3f);
165		p[3] = 0x80 | (c & 0x3f);
166		return 4;
167	} else {
168		/* outside Unicode, replace with U+FFFD */
169		p[0] = 0xef;
170		p[1] = 0xbf;
171		p[2] = 0xbd;
172		return 3;
173	}
174}
175
176/**
177 * set_selection_user - set the current selection.
178 * @sel: user selection info
179 * @tty: the console tty
180 *
181 * Invoked by the ioctl handle for the vt layer.
182 *
183 * Locking: The entire selection process is managed under the console_lock.
184 * It's a lot under the lock but its hardly a performance path.
185 */
186int set_selection_user(const struct tiocl_selection __user *sel,
187		       struct tty_struct *tty)
188{
189	struct tiocl_selection v;
190
191	if (copy_from_user(&v, sel, sizeof(*sel)))
192		return -EFAULT;
193
194	/*
195	 * TIOCL_SELCLEAR and TIOCL_SELPOINTER are OK to use without
196	 * CAP_SYS_ADMIN as they do not modify the selection.
197	 */
198	switch (v.sel_mode) {
199	case TIOCL_SELCLEAR:
200	case TIOCL_SELPOINTER:
201		break;
202	default:
203		if (!capable(CAP_SYS_ADMIN))
204			return -EPERM;
205	}
206
207	return set_selection_kernel(&v, tty);
208}
209
210static int vc_selection_store_chars(struct vc_data *vc, bool unicode)
211{
212	char *bp, *obp;
213	unsigned int i;
214
215	/* Allocate a new buffer before freeing the old one ... */
216	/* chars can take up to 4 bytes with unicode */
217	bp = kmalloc_array((vc_sel.end - vc_sel.start) / 2 + 1, unicode ? 4 : 1,
218			   GFP_KERNEL | __GFP_NOWARN);
219	if (!bp) {
220		printk(KERN_WARNING "selection: kmalloc() failed\n");
221		clear_selection();
222		return -ENOMEM;
223	}
224	kfree(vc_sel.buffer);
225	vc_sel.buffer = bp;
226
227	obp = bp;
228	for (i = vc_sel.start; i <= vc_sel.end; i += 2) {
229		u32 c = sel_pos(i, unicode);
230		if (unicode)
231			bp += store_utf8(c, bp);
232		else
233			*bp++ = c;
234		if (!is_space_on_vt(c))
235			obp = bp;
236		if (!((i + 2) % vc->vc_size_row)) {
237			/* strip trailing blanks from line and add newline,
238			   unless non-space at end of line. */
239			if (obp != bp) {
240				bp = obp;
241				*bp++ = '\r';
242			}
243			obp = bp;
244		}
245	}
246	vc_sel.buf_len = bp - vc_sel.buffer;
247
248	return 0;
249}
250
251static int vc_do_selection(struct vc_data *vc, unsigned short mode, int ps,
252		int pe)
253{
254	int new_sel_start, new_sel_end, spc;
255	bool unicode = vt_do_kdgkbmode(fg_console) == K_UNICODE;
256
257	switch (mode) {
258	case TIOCL_SELCHAR:	/* character-by-character selection */
259		new_sel_start = ps;
260		new_sel_end = pe;
261		break;
262	case TIOCL_SELWORD:	/* word-by-word selection */
263		spc = is_space_on_vt(sel_pos(ps, unicode));
264		for (new_sel_start = ps; ; ps -= 2) {
265			if ((spc && !is_space_on_vt(sel_pos(ps, unicode))) ||
266			    (!spc && !inword(sel_pos(ps, unicode))))
267				break;
268			new_sel_start = ps;
269			if (!(ps % vc->vc_size_row))
270				break;
271		}
272
273		spc = is_space_on_vt(sel_pos(pe, unicode));
274		for (new_sel_end = pe; ; pe += 2) {
275			if ((spc && !is_space_on_vt(sel_pos(pe, unicode))) ||
276			    (!spc && !inword(sel_pos(pe, unicode))))
277				break;
278			new_sel_end = pe;
279			if (!((pe + 2) % vc->vc_size_row))
280				break;
281		}
282		break;
283	case TIOCL_SELLINE:	/* line-by-line selection */
284		new_sel_start = rounddown(ps, vc->vc_size_row);
285		new_sel_end = rounddown(pe, vc->vc_size_row) +
286			vc->vc_size_row - 2;
287		break;
288	case TIOCL_SELPOINTER:
289		highlight_pointer(pe);
290		return 0;
291	default:
292		return -EINVAL;
293	}
294
295	/* remove the pointer */
296	highlight_pointer(-1);
297
298	/* select to end of line if on trailing space */
299	if (new_sel_end > new_sel_start &&
300		!atedge(new_sel_end, vc->vc_size_row) &&
301		is_space_on_vt(sel_pos(new_sel_end, unicode))) {
302		for (pe = new_sel_end + 2; ; pe += 2)
303			if (!is_space_on_vt(sel_pos(pe, unicode)) ||
304			    atedge(pe, vc->vc_size_row))
305				break;
306		if (is_space_on_vt(sel_pos(pe, unicode)))
307			new_sel_end = pe;
308	}
309	if (vc_sel.start == -1)	/* no current selection */
310		highlight(new_sel_start, new_sel_end);
311	else if (new_sel_start == vc_sel.start)
312	{
313		if (new_sel_end == vc_sel.end)	/* no action required */
314			return 0;
315		else if (new_sel_end > vc_sel.end)	/* extend to right */
316			highlight(vc_sel.end + 2, new_sel_end);
317		else				/* contract from right */
318			highlight(new_sel_end + 2, vc_sel.end);
319	}
320	else if (new_sel_end == vc_sel.end)
321	{
322		if (new_sel_start < vc_sel.start) /* extend to left */
323			highlight(new_sel_start, vc_sel.start - 2);
324		else				/* contract from left */
325			highlight(vc_sel.start, new_sel_start - 2);
326	}
327	else	/* some other case; start selection from scratch */
328	{
329		clear_selection();
330		highlight(new_sel_start, new_sel_end);
331	}
332	vc_sel.start = new_sel_start;
333	vc_sel.end = new_sel_end;
334
335	return vc_selection_store_chars(vc, unicode);
336}
337
338static int vc_selection(struct vc_data *vc, struct tiocl_selection *v,
339		struct tty_struct *tty)
340{
341	int ps, pe;
342
343	poke_blanked_console();
344
345	if (v->sel_mode == TIOCL_SELCLEAR) {
346		/* useful for screendump without selection highlights */
347		clear_selection();
348		return 0;
349	}
350
351	/* Historically 0 => max value */
352	v->xs = umin(v->xs - 1, vc->vc_cols - 1);
353	v->ys = umin(v->ys - 1, vc->vc_rows - 1);
354	v->xe = umin(v->xe - 1, vc->vc_cols - 1);
355	v->ye = umin(v->ye - 1, vc->vc_rows - 1);
356
357	if (mouse_reporting() && (v->sel_mode & TIOCL_SELMOUSEREPORT)) {
358		mouse_report(tty, v->sel_mode & TIOCL_SELBUTTONMASK, v->xs,
359			     v->ys);
360		return 0;
361	}
362
363	ps = v->ys * vc->vc_size_row + (v->xs << 1);
364	pe = v->ye * vc->vc_size_row + (v->xe << 1);
365	if (ps > pe)	/* make vc_sel.start <= vc_sel.end */
366		swap(ps, pe);
367
368	if (vc_sel.cons != vc) {
369		clear_selection();
370		vc_sel.cons = vc;
371	}
372
373	return vc_do_selection(vc, v->sel_mode, ps, pe);
374}
375
376int set_selection_kernel(struct tiocl_selection *v, struct tty_struct *tty)
377{
378	guard(mutex)(&vc_sel.lock);
379	guard(console_lock)();
380	return vc_selection(vc_cons[fg_console].d, v, tty);
381}
382EXPORT_SYMBOL_GPL(set_selection_kernel);
383
384/* Insert the contents of the selection buffer into the
385 * queue of the tty associated with the current console.
386 * Invoked by ioctl().
387 *
388 * Locking: called without locks. Calls the ldisc wrongly with
389 * unsafe methods,
390 */
391int paste_selection(struct tty_struct *tty)
392{
393	struct vc_data *vc = tty->driver_data;
394	int	pasted = 0;
395	size_t count;
396	struct  tty_ldisc *ld;
397	DECLARE_WAITQUEUE(wait, current);
398	int ret = 0;
399
400	bool bp = vc->vc_bracketed_paste;
401	static const char bracketed_paste_start[] = "\033[200~";
402	static const char bracketed_paste_end[]   = "\033[201~";
403	const char *bps = bp ? bracketed_paste_start : NULL;
404	const char *bpe = bp ? bracketed_paste_end : NULL;
405
406	scoped_guard(console_lock)
407		poke_blanked_console();
408
409	ld = tty_ldisc_ref_wait(tty);
410	if (!ld)
411		return -EIO;	/* ldisc was hung up */
412	tty_buffer_lock_exclusive(&vc->port);
413
414	add_wait_queue(&vc->paste_wait, &wait);
415	mutex_lock(&vc_sel.lock);
416	while (vc_sel.buffer && (vc_sel.buf_len > pasted || bpe)) {
417		set_current_state(TASK_INTERRUPTIBLE);
418		if (signal_pending(current)) {
419			ret = -EINTR;
420			break;
421		}
422		if (tty_throttled(tty)) {
423			mutex_unlock(&vc_sel.lock);
424			schedule();
425			mutex_lock(&vc_sel.lock);
426			continue;
427		}
428		__set_current_state(TASK_RUNNING);
429
430		if (bps) {
431			bps += tty_ldisc_receive_buf(ld, bps, NULL, strlen(bps));
432			if (*bps != '\0')
433				continue;
434			bps = NULL;
435		}
436
437		count = vc_sel.buf_len - pasted;
438		if (count) {
439			pasted += tty_ldisc_receive_buf(ld, vc_sel.buffer + pasted,
440							NULL, count);
441			if (vc_sel.buf_len > pasted)
442				continue;
443		}
444
445		if (bpe) {
446			bpe += tty_ldisc_receive_buf(ld, bpe, NULL, strlen(bpe));
447			if (*bpe == '\0')
448				bpe = NULL;
449		}
450	}
451	mutex_unlock(&vc_sel.lock);
452	remove_wait_queue(&vc->paste_wait, &wait);
453	__set_current_state(TASK_RUNNING);
454
455	tty_buffer_unlock_exclusive(&vc->port);
456	tty_ldisc_deref(ld);
457	return ret;
458}
459EXPORT_SYMBOL_GPL(paste_selection);