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Diffstat (limited to 'gfx/thebes/gfxGraphiteShaper.cpp')
| -rw-r--r-- | gfx/thebes/gfxGraphiteShaper.cpp | 513 |
1 files changed, 513 insertions, 0 deletions
diff --git a/gfx/thebes/gfxGraphiteShaper.cpp b/gfx/thebes/gfxGraphiteShaper.cpp new file mode 100644 index 0000000000..7021ffb362 --- /dev/null +++ b/gfx/thebes/gfxGraphiteShaper.cpp @@ -0,0 +1,513 @@ +/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- + * This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ + +#include "gfxGraphiteShaper.h" +#include "nsString.h" +#include "gfxContext.h" +#include "gfxFontConstants.h" +#include "gfxTextRun.h" + +#include "graphite2/Font.h" +#include "graphite2/GraphiteExtra.h" +#include "graphite2/Segment.h" + +#include "harfbuzz/hb.h" + +#include "mozilla/ScopeExit.h" + +#include "ThebesRLBox.h" + +#define FloatToFixed(f) (65536 * (f)) +#define FixedToFloat(f) ((f) * (1.0 / 65536.0)) +// Right shifts of negative (signed) integers are undefined, as are overflows +// when converting unsigned to negative signed integers. +// (If speed were an issue we could make some 2's complement assumptions.) +#define FixedToIntRound(f) \ + ((f) > 0 ? ((32768 + (f)) >> 16) : -((32767 - (f)) >> 16)) + +#define CopyAndVerifyOrFail(t, cond, failed) \ + (t).copy_and_verify([&](auto val) { \ + if (!(cond)) { \ + *(failed) = true; \ + } \ + return val; \ + }) + +using namespace mozilla; // for AutoSwap_* types + +/* + * Creation and destruction; on deletion, release any font tables we're holding + */ + +gfxGraphiteShaper::gfxGraphiteShaper(gfxFont* aFont) + : gfxFontShaper(aFont), + mGrFace(mFont->GetFontEntry()->GetGrFace()), + mSandbox(mFont->GetFontEntry()->GetGrSandbox()), + mCallback(mFont->GetFontEntry()->GetGrSandboxAdvanceCallbackHandle()), + mFallbackToSmallCaps(false) { + mCallbackData.mFont = aFont; +} + +gfxGraphiteShaper::~gfxGraphiteShaper() { + auto t_mGrFont = rlbox::from_opaque(mGrFont); + if (t_mGrFont) { + sandbox_invoke(*mSandbox, gr_font_destroy, t_mGrFont); + } + mFont->GetFontEntry()->ReleaseGrFace(mGrFace); +} + +/*static*/ +thread_local gfxGraphiteShaper::CallbackData* + gfxGraphiteShaper::tl_GrGetAdvanceData = nullptr; + +/*static*/ +tainted_opaque_gr<float> gfxGraphiteShaper::GrGetAdvance( + rlbox_sandbox_gr& sandbox, + tainted_opaque_gr<const void*> /* appFontHandle */, + tainted_opaque_gr<uint16_t> t_glyphid) { + CallbackData* cb = tl_GrGetAdvanceData; + if (!cb) { + // GrGetAdvance callback called unexpectedly. Just return safe value. + tainted_gr<float> ret = 0; + return ret.to_opaque(); + } + auto glyphid = rlbox::from_opaque(t_glyphid).unverified_safe_because( + "Here the only use of a glyphid is for lookup to get a width. " + "Implementations of GetGlyphWidth in this code base use a hashtable " + "which is robust to unknown keys. So no validation is required."); + tainted_gr<float> ret = FixedToFloat(cb->mFont->GetGlyphWidth(glyphid)); + return ret.to_opaque(); +} + +static inline uint32_t MakeGraphiteLangTag(uint32_t aTag) { + uint32_t grLangTag = aTag; + // replace trailing space-padding with NULs for graphite + uint32_t mask = 0x000000FF; + while ((grLangTag & mask) == ' ') { + grLangTag &= ~mask; + mask <<= 8; + } + return grLangTag; +} + +struct GrFontFeatures { + tainted_gr<gr_face*> mFace; + tainted_gr<gr_feature_val*> mFeatures; + rlbox_sandbox_gr* mSandbox; +}; + +static void AddFeature(uint32_t aTag, uint32_t aValue, void* aUserArg) { + GrFontFeatures* f = static_cast<GrFontFeatures*>(aUserArg); + + tainted_gr<const gr_feature_ref*> fref = + sandbox_invoke(*(f->mSandbox), gr_face_find_fref, f->mFace, aTag); + if (fref) { + sandbox_invoke(*(f->mSandbox), gr_fref_set_feature_value, fref, aValue, + f->mFeatures); + } +} + +// Count the number of Unicode characters in a UTF-16 string (i.e. surrogate +// pairs are counted as 1, although they are 2 code units). +// (Any isolated surrogates will count 1 each, because in decoding they would +// be replaced by individual U+FFFD REPLACEMENT CHARACTERs.) +static inline size_t CountUnicodes(const char16_t* aText, uint32_t aLength) { + size_t total = 0; + const char16_t* end = aText + aLength; + while (aText < end) { + if (NS_IS_HIGH_SURROGATE(*aText) && aText + 1 < end && + NS_IS_LOW_SURROGATE(*(aText + 1))) { + aText += 2; + } else { + aText++; + } + total++; + } + return total; +} + +bool gfxGraphiteShaper::ShapeText(DrawTarget* aDrawTarget, + const char16_t* aText, uint32_t aOffset, + uint32_t aLength, Script aScript, + nsAtom* aLanguage, bool aVertical, + RoundingFlags aRounding, + gfxShapedText* aShapedText) { + const gfxFontStyle* style = mFont->GetStyle(); + auto t_mGrFace = rlbox::from_opaque(mGrFace); + auto t_mGrFont = rlbox::from_opaque(mGrFont); + + if (!t_mGrFont) { + if (!t_mGrFace) { + return false; + } + + if (mFont->ProvidesGlyphWidths()) { + auto p_ops = mSandbox->malloc_in_sandbox<gr_font_ops>(); + if (!p_ops) { + return false; + } + auto clean_ops = MakeScopeExit([&] { mSandbox->free_in_sandbox(p_ops); }); + p_ops->size = sizeof(*p_ops); + p_ops->glyph_advance_x = *mCallback; + p_ops->glyph_advance_y = nullptr; // vertical text not yet implemented + t_mGrFont = sandbox_invoke( + *mSandbox, gr_make_font_with_ops, mFont->GetAdjustedSize(), + // For security, we do not pass the callback data to this arg, and use + // a TLS var instead. However, gr_make_font_with_ops expects this to + // be a non null ptr, and changes its behavior if it isn't. Therefore, + // we should pass some dummy non null pointer which will be passed to + // the GrGetAdvance callback, but never used. Let's just pass p_ops + // again, as this is a non-null tainted pointer. + p_ops /* mCallbackData */, p_ops, t_mGrFace); + } else { + t_mGrFont = sandbox_invoke(*mSandbox, gr_make_font, + mFont->GetAdjustedSize(), t_mGrFace); + } + mGrFont = t_mGrFont.to_opaque(); + + if (!t_mGrFont) { + return false; + } + + // determine whether petite-caps falls back to small-caps + if (style->variantCaps != NS_FONT_VARIANT_CAPS_NORMAL) { + switch (style->variantCaps) { + case NS_FONT_VARIANT_CAPS_ALLPETITE: + case NS_FONT_VARIANT_CAPS_PETITECAPS: + bool synLower, synUpper; + mFont->SupportsVariantCaps(aScript, style->variantCaps, + mFallbackToSmallCaps, synLower, synUpper); + break; + default: + break; + } + } + } + + gfxFontEntry* entry = mFont->GetFontEntry(); + uint32_t grLang = 0; + if (style->languageOverride) { + grLang = MakeGraphiteLangTag(style->languageOverride); + } else if (entry->mLanguageOverride) { + grLang = MakeGraphiteLangTag(entry->mLanguageOverride); + } else if (aLanguage) { + nsAutoCString langString; + aLanguage->ToUTF8String(langString); + grLang = GetGraphiteTagForLang(langString); + } + tainted_gr<gr_feature_val*> grFeatures = + sandbox_invoke(*mSandbox, gr_face_featureval_for_lang, t_mGrFace, grLang); + + // insert any merged features into Graphite feature list + GrFontFeatures f = {t_mGrFace, grFeatures, mSandbox}; + MergeFontFeatures(style, mFont->GetFontEntry()->mFeatureSettings, + aShapedText->DisableLigatures(), + mFont->GetFontEntry()->FamilyName(), mFallbackToSmallCaps, + AddFeature, &f); + + // Graphite shaping doesn't map U+00a0 (nbsp) to space if it is missing + // from the font, so check for that possibility. (Most fonts double-map + // the space glyph to both 0x20 and 0xA0, so this won't often be needed; + // so we don't copy the text until we know it's required.) + nsAutoString transformed; + const char16_t NO_BREAK_SPACE = 0x00a0; + if (!entry->HasCharacter(NO_BREAK_SPACE)) { + nsDependentSubstring src(aText, aLength); + if (src.FindChar(NO_BREAK_SPACE) != kNotFound) { + transformed = src; + transformed.ReplaceChar(NO_BREAK_SPACE, ' '); + aText = transformed.BeginReading(); + } + } + + size_t numChars = CountUnicodes(aText, aLength); + gr_bidirtl grBidi = gr_bidirtl( + aShapedText->IsRightToLeft() ? (gr_rtl | gr_nobidi) : gr_nobidi); + + tainted_gr<char16_t*> t_aText = + mSandbox->malloc_in_sandbox<char16_t>(aLength); + if (!t_aText) { + return false; + } + auto clean_txt = MakeScopeExit([&] { mSandbox->free_in_sandbox(t_aText); }); + + rlbox::memcpy(*mSandbox, t_aText, aText, aLength * sizeof(char16_t)); + + tl_GrGetAdvanceData = &mCallbackData; + auto clean_adv_data = MakeScopeExit([&] { tl_GrGetAdvanceData = nullptr; }); + + tainted_gr<gr_segment*> seg = + sandbox_invoke(*mSandbox, gr_make_seg, mGrFont, t_mGrFace, 0, grFeatures, + gr_utf16, t_aText, numChars, grBidi); + + sandbox_invoke(*mSandbox, gr_featureval_destroy, grFeatures); + + if (!seg) { + return false; + } + + nsresult rv = + SetGlyphsFromSegment(aShapedText, aOffset, aLength, aText, + t_aText.to_opaque(), seg.to_opaque(), aRounding); + + sandbox_invoke(*mSandbox, gr_seg_destroy, seg); + + return NS_SUCCEEDED(rv); +} + +nsresult gfxGraphiteShaper::SetGlyphsFromSegment( + gfxShapedText* aShapedText, uint32_t aOffset, uint32_t aLength, + const char16_t* aText, tainted_opaque_gr<char16_t*> t_aText, + tainted_opaque_gr<gr_segment*> aSegment, RoundingFlags aRounding) { + typedef gfxShapedText::CompressedGlyph CompressedGlyph; + + int32_t dev2appUnits = aShapedText->GetAppUnitsPerDevUnit(); + bool rtl = aShapedText->IsRightToLeft(); + + // identify clusters; graphite may have reordered/expanded/ligated glyphs. + tainted_gr<gr_glyph_to_char_association*> data = + sandbox_invoke(*mSandbox, gr_get_glyph_to_char_association, aSegment, + aLength, rlbox::from_opaque(t_aText)); + + if (!data) { + return NS_ERROR_FAILURE; + } + + tainted_gr<gr_glyph_to_char_cluster*> clusters = data->clusters; + tainted_gr<uint16_t*> gids = data->gids; + tainted_gr<float*> xLocs = data->xLocs; + tainted_gr<float*> yLocs = data->yLocs; + + CompressedGlyph* charGlyphs = aShapedText->GetCharacterGlyphs() + aOffset; + + bool roundX = bool(aRounding & RoundingFlags::kRoundX); + bool roundY = bool(aRounding & RoundingFlags::kRoundY); + + bool failedVerify = false; + + // cIndex is primarily used to index into the clusters array which has size + // aLength below. As cIndex is not changing anymore, let's just verify it + // and remove the tainted wrapper. + uint32_t cIndex = + CopyAndVerifyOrFail(data->cIndex, val < aLength, &failedVerify); + if (failedVerify) { + return NS_ERROR_ILLEGAL_VALUE; + } + // now put glyphs into the textrun, one cluster at a time + for (uint32_t i = 0; i <= cIndex; ++i) { + // We makes a local copy of "clusters[i]" which is of type + // tainted_gr<gr_glyph_to_char_cluster> below. We do this intentionally + // rather than taking a reference. Taking a reference with the code + // + // tainted_volatile_gr<gr_glyph_to_char_cluster>& c = clusters[i]; + // + // produces a tainted_volatile which means the value can change at any + // moment allowing for possible time-of-check-time-of-use vuln. We thus + // make a local copy to simplify the verification. + tainted_gr<gr_glyph_to_char_cluster> c = clusters[i]; + + tainted_gr<float> t_adv; // total advance of the cluster + if (rtl) { + if (i == 0) { + t_adv = sandbox_invoke(*mSandbox, gr_seg_advance_X, aSegment) - + xLocs[c.baseGlyph]; + } else { + t_adv = xLocs[clusters[i - 1].baseGlyph] - xLocs[c.baseGlyph]; + } + } else { + if (i == cIndex) { + t_adv = sandbox_invoke(*mSandbox, gr_seg_advance_X, aSegment) - + xLocs[c.baseGlyph]; + } else { + t_adv = xLocs[clusters[i + 1].baseGlyph] - xLocs[c.baseGlyph]; + } + } + + float adv = t_adv.unverified_safe_because( + "Per Bug 1569464 - this is the advance width of a glyph or cluster of " + "glyphs. There are no a-priori limits on what that might be. Incorrect " + "values will tend to result in bad layout or missing text, or bad " + "nscoord values. But, these will not result in safety issues."); + + // check unexpected offset - offs used to index into aText + uint32_t offs = + CopyAndVerifyOrFail(c.baseChar, val < aLength, &failedVerify); + if (failedVerify) { + return NS_ERROR_ILLEGAL_VALUE; + } + + // Check for default-ignorable char that didn't get filtered, combined, + // etc by the shaping process, and skip it. + auto one_glyph = c.nGlyphs == static_cast<uint32_t>(1); + auto one_char = c.nChars == static_cast<uint32_t>(1); + + if ((one_glyph && one_char) + .unverified_safe_because( + "using this boolean check to decide whether to ignore a " + "character or not. The worst that can happen is a bad " + "rendering.")) { + if (aShapedText->FilterIfIgnorable(aOffset + offs, aText[offs])) { + continue; + } + } + + uint32_t appAdvance = roundX ? NSToIntRound(adv) * dev2appUnits + : NSToIntRound(adv * dev2appUnits); + + const char gid_simple_value[] = + "Per Bug 1569464 - these are glyph IDs that can range from 0 to the " + "maximum glyph ID supported by the font. However, out-of-range values " + "here should not lead to safety issues; they would simply result in " + "blank rendering, although this depends on the platform back-end."; + + // gids[c.baseGlyph] is checked and used below. Since this is a + // tainted_volatile, which can change at any moment, we make a local copy + // first to prevent a time-of-check-time-of-use vuln. + uint16_t gid_of_base_glyph = + gids[c.baseGlyph].unverified_safe_because(gid_simple_value); + + const char fast_path[] = + "Even if the number of glyphs set is an incorrect value, the else " + "branch is a more general purpose algorithm which can handle other " + "values of nGlyphs"; + + if (one_glyph.unverified_safe_because(fast_path) && + CompressedGlyph::IsSimpleGlyphID(gid_of_base_glyph) && + CompressedGlyph::IsSimpleAdvance(appAdvance) && + charGlyphs[offs].IsClusterStart() && + (yLocs[c.baseGlyph] == 0).unverified_safe_because(fast_path)) { + charGlyphs[offs].SetSimpleGlyph(appAdvance, gid_of_base_glyph); + + } else { + // not a one-to-one mapping with simple metrics: use DetailedGlyph + AutoTArray<gfxShapedText::DetailedGlyph, 8> details; + float clusterLoc; + + uint32_t glyph_end = + (c.baseGlyph + c.nGlyphs) + .unverified_safe_because( + "This only controls the total number of glyphs set for this " + "particular text. Worst that can happen is a bad rendering"); + + // check overflow - ensure loop start is before the end + uint32_t glyph_start = + CopyAndVerifyOrFail(c.baseGlyph, val <= glyph_end, &failedVerify); + if (failedVerify) { + return NS_ERROR_ILLEGAL_VALUE; + } + + for (uint32_t j = glyph_start; j < glyph_end; ++j) { + gfxShapedText::DetailedGlyph* d = details.AppendElement(); + d->mGlyphID = gids[j].unverified_safe_because(gid_simple_value); + + const char safe_coordinates[] = + "There are no limits on coordinates. Worst case, bad values would " + "force rendering off-screen, but there are no memory safety " + "issues."; + + float yLocs_j = yLocs[j].unverified_safe_because(safe_coordinates); + float xLocs_j = xLocs[j].unverified_safe_because(safe_coordinates); + + d->mOffset.y = roundY ? NSToIntRound(-yLocs_j) * dev2appUnits + : -yLocs_j * dev2appUnits; + if (j == glyph_start) { + d->mAdvance = appAdvance; + clusterLoc = xLocs_j; + } else { + float dx = + rtl ? (xLocs_j - clusterLoc) : (xLocs_j - clusterLoc - adv); + d->mOffset.x = + roundX ? NSToIntRound(dx) * dev2appUnits : dx * dev2appUnits; + d->mAdvance = 0; + } + } + aShapedText->SetDetailedGlyphs(aOffset + offs, details.Length(), + details.Elements()); + } + + // check unexpected offset + uint32_t char_end = CopyAndVerifyOrFail(c.baseChar + c.nChars, + val <= aLength, &failedVerify); + // check overflow - ensure loop start is before the end + uint32_t char_start = + CopyAndVerifyOrFail(c.baseChar + 1, val <= char_end, &failedVerify); + if (failedVerify) { + return NS_ERROR_ILLEGAL_VALUE; + } + + for (uint32_t j = char_start; j < char_end; ++j) { + CompressedGlyph& g = charGlyphs[j]; + NS_ASSERTION(!g.IsSimpleGlyph(), "overwriting a simple glyph"); + g.SetComplex(g.IsClusterStart(), false); + } + } + + sandbox_invoke(*mSandbox, gr_free_char_association, data); + return NS_OK; +} + +// for language tag validation - include list of tags from the IANA registry +#include "gfxLanguageTagList.cpp" + +nsTHashSet<uint32_t>* gfxGraphiteShaper::sLanguageTags; + +/*static*/ +uint32_t gfxGraphiteShaper::GetGraphiteTagForLang(const nsCString& aLang) { + int len = aLang.Length(); + if (len < 2) { + return 0; + } + + // convert primary language subtag to a left-packed, NUL-padded integer + // for the Graphite API + uint32_t grLang = 0; + for (int i = 0; i < 4; ++i) { + grLang <<= 8; + if (i < len) { + uint8_t ch = aLang[i]; + if (ch == '-') { + // found end of primary language subtag, truncate here + len = i; + continue; + } + if (ch < 'a' || ch > 'z') { + // invalid character in tag, so ignore it completely + return 0; + } + grLang += ch; + } + } + + // valid tags must have length = 2 or 3 + if (len < 2 || len > 3) { + return 0; + } + + if (!sLanguageTags) { + // store the registered IANA tags in a hash for convenient validation + sLanguageTags = new nsTHashSet<uint32_t>(ArrayLength(sLanguageTagList)); + for (const uint32_t* tag = sLanguageTagList; *tag != 0; ++tag) { + sLanguageTags->Insert(*tag); + } + } + + // only accept tags known in the IANA registry + if (sLanguageTags->Contains(grLang)) { + return grLang; + } + + return 0; +} + +/*static*/ +void gfxGraphiteShaper::Shutdown() { +#ifdef NS_FREE_PERMANENT_DATA + if (sLanguageTags) { + sLanguageTags->Clear(); + delete sLanguageTags; + sLanguageTags = nullptr; + } +#endif +} |