From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from forward103b.mail.yandex.net (forward103b.mail.yandex.net [IPv6:2a02:6b8:c02:900:1:45:d181:d103]) by sourceware.org (Postfix) with ESMTPS id D607B3850212 for ; Sat, 18 Mar 2023 16:51:47 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org D607B3850212 Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=yandex.ru Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=yandex.ru Received: from myt6-1289f562e823.qloud-c.yandex.net (myt6-1289f562e823.qloud-c.yandex.net [IPv6:2a02:6b8:c12:259d:0:640:1289:f562]) by forward103b.mail.yandex.net (Yandex) with ESMTP id 3C65D600DF for ; Sat, 18 Mar 2023 19:51:44 +0300 (MSK) Received: by myt6-1289f562e823.qloud-c.yandex.net (smtp/Yandex) with ESMTPSA id cpp3fcrbC8c1-jYeVob8h; Sat, 18 Mar 2023 19:51:43 +0300 X-Yandex-Fwd: 1 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yandex.ru; s=mail; t=1679158303; bh=fvQJURVpiWWMCSblVq0F39gbSCkCzn/8jtllNEoA78c=; h=Message-Id:Date:In-Reply-To:Cc:Subject:References:To:From; b=IHHVSaJymo8Z0hPG2L5SC79ugH18ZBJvTXSTOb/LU7iU6TvFEkV5KCweS9LzNfNWT HK0l16wTu+RGtL6sBBUq/1DHIL/KJSd097h+LzdohJgo4yxTCYFPANYHWBIY5RgmW8 EM9zfgurfqe8RF2tbuJxPQBTYoVIVNE0oyZMu6zo= Authentication-Results: myt6-1289f562e823.qloud-c.yandex.net; dkim=pass header.i=@yandex.ru From: Stas Sergeev To: libc-alpha@sourceware.org Cc: Stas Sergeev Subject: [PATCH 02/13] elf: switch _dl_map_segment() to anonymous mapping Date: Sat, 18 Mar 2023 21:50:59 +0500 Message-Id: <20230318165110.3672749-3-stsp2@yandex.ru> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20230318165110.3672749-1-stsp2@yandex.ru> References: <20230318165110.3672749-1-stsp2@yandex.ru> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Spam-Status: No, score=-11.5 required=5.0 tests=BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_ENVFROM_END_DIGIT,FREEMAIL_FROM,GIT_PATCH_0,SPF_HELO_NONE,SPF_PASS,TXREP autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: _dl_map_segment() was mapping entire file image and then was skipping the load of the first segment. Switch _dl_map_segment() to anonymous mapping and do not skip the map of the first segment. Use PROT_READ|PROT_WRITE as a protection. _dl_map_segments() later sets the proper protection for both file-mapped and anonymous parts. The test-suite was run on x86_64/64 and showed no regressions. Signed-off-by: Stas Sergeev --- elf/dl-map-segments.h | 73 +++++++++++++++++++++++-------------------- 1 file changed, 39 insertions(+), 34 deletions(-) diff --git a/elf/dl-map-segments.h b/elf/dl-map-segments.h index 504cfc0a41..9af8cae188 100644 --- a/elf/dl-map-segments.h +++ b/elf/dl-map-segments.h @@ -22,18 +22,26 @@ /* Map a segment and align it properly. */ static __always_inline ElfW(Addr) -_dl_map_segment (const struct loadcmd *c, ElfW(Addr) mappref, - const size_t maplength, int fd) +_dl_map_segment (ElfW(Addr) mappref, size_t maplength, size_t mapalign) { - if (__glibc_likely (c->mapalign <= GLRO(dl_pagesize))) - return (ElfW(Addr)) __mmap ((void *) mappref, maplength, c->prot, - MAP_COPY|MAP_FILE, fd, c->mapoff); + int err; + unsigned map_flags = MAP_ANONYMOUS | MAP_PRIVATE; + unsigned prot = PROT_READ | PROT_WRITE; + +#ifdef MAP_DENYWRITE + /* Tell mmap() that we are mapping solib. This flag enables things + like LD_PREFER_MAP_32BIT_EXEC. */ + map_flags |= MAP_DENYWRITE; +#endif + if (__glibc_likely (mapalign <= GLRO(dl_pagesize))) + return (ElfW(Addr)) __mmap ((void *) mappref, maplength, prot, + map_flags, -1, 0); /* If the segment alignment > the page size, allocate enough space to ensure that the segment can be properly aligned. */ - ElfW(Addr) maplen = (maplength >= c->mapalign - ? (maplength + c->mapalign) - : (2 * c->mapalign)); + ElfW(Addr) maplen = (maplength >= mapalign + ? (maplength + mapalign) + : (2 * mapalign)); ElfW(Addr) map_start = (ElfW(Addr)) __mmap ((void *) mappref, maplen, PROT_NONE, MAP_ANONYMOUS|MAP_PRIVATE, @@ -41,26 +49,24 @@ _dl_map_segment (const struct loadcmd *c, ElfW(Addr) mappref, if (__glibc_unlikely ((void *) map_start == MAP_FAILED)) return map_start; - ElfW(Addr) map_start_aligned = ALIGN_UP (map_start, c->mapalign); - map_start_aligned = (ElfW(Addr)) __mmap ((void *) map_start_aligned, - maplength, c->prot, - MAP_COPY|MAP_FILE|MAP_FIXED, - fd, c->mapoff); - if (__glibc_unlikely ((void *) map_start_aligned == MAP_FAILED)) - __munmap ((void *) map_start, maplen); - else + ElfW(Addr) map_start_aligned = ALIGN_UP (map_start, mapalign); + err = __mprotect ((void *) map_start_aligned, maplength, prot); + if (__glibc_unlikely (err)) { - /* Unmap the unused regions. */ - ElfW(Addr) delta = map_start_aligned - map_start; - if (delta) - __munmap ((void *) map_start, delta); - ElfW(Addr) map_end = map_start_aligned + maplength; - map_end = ALIGN_UP (map_end, GLRO(dl_pagesize)); - delta = map_start + maplen - map_end; - if (delta) - __munmap ((void *) map_end, delta); + __munmap ((void *) map_start, maplen); + return (ElfW(Addr)) MAP_FAILED; } + /* Unmap the unused regions. */ + ElfW(Addr) delta = map_start_aligned - map_start; + if (delta) + __munmap ((void *) map_start, delta); + ElfW(Addr) map_end = map_start_aligned + maplength; + map_end = ALIGN_UP (map_end, GLRO(dl_pagesize)); + delta = map_start + maplen - map_end; + if (delta) + __munmap ((void *) map_end, delta); + return map_start_aligned; } @@ -98,7 +104,7 @@ _dl_map_segments (struct link_map *l, int fd, - MAP_BASE_ADDR (l)); /* Remember which part of the address space this object uses. */ - l->l_map_start = _dl_map_segment (c, mappref, maplength, fd); + l->l_map_start = _dl_map_segment (mappref, maplength, c->mapalign); if (__glibc_unlikely ((void *) l->l_map_start == MAP_FAILED)) return DL_MAP_SEGMENTS_ERROR_MAP_SEGMENT; @@ -123,14 +129,14 @@ _dl_map_segments (struct link_map *l, int fd, } l->l_contiguous = 1; - - goto postmap; } - - /* Remember which part of the address space this object uses. */ - l->l_map_start = c->mapstart + l->l_addr; - l->l_map_end = l->l_map_start + maplength; - l->l_contiguous = !has_holes; + else + { + /* Remember which part of the address space this object uses. */ + l->l_map_start = c->mapstart + l->l_addr; + l->l_map_end = l->l_map_start + maplength; + l->l_contiguous = !has_holes; + } while (c < &loadcmds[nloadcmds]) { @@ -143,7 +149,6 @@ _dl_map_segments (struct link_map *l, int fd, == MAP_FAILED)) return DL_MAP_SEGMENTS_ERROR_MAP_SEGMENT; - postmap: _dl_postprocess_loadcmd (l, header, c); if (c->allocend > c->dataend) -- 2.37.2