1 files changed, 525 insertions, 0 deletions

diff --git a/libexec/rtld-elf/map_object.c b/libexec/rtld-elf/map_object.c
new file mode 100644
index 000000000000..5e5774c0b017
--- /dev/null
+++ b/libexec/rtld-elf/map_object.c
@@ -0,0 +1,525 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright 1996-1998 John D. Polstra.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <sys/param.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+
+#include <errno.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "debug.h"
+#include "rtld.h"
+
+static Elf_Ehdr *get_elf_header(int, const char *, const struct stat *,
+    Elf_Phdr **phdr);
+static int convert_flags(int); /* Elf flags -> mmap flags */
+
+static bool
+phdr_in_zero_page(const Elf_Ehdr *hdr)
+{
+	return (hdr->e_phoff + hdr->e_phnum * sizeof(Elf_Phdr) <= page_size);
+}
+
+/*
+ * Map a shared object into memory.  The "fd" argument is a file descriptor,
+ * which must be open on the object and positioned at its beginning.
+ * The "path" argument is a pathname that is used only for error messages.
+ *
+ * The return value is a pointer to a newly-allocated Obj_Entry structure
+ * for the shared object.  Returns NULL on failure.
+ */
+Obj_Entry *
+map_object(int fd, const char *path, const struct stat *sb, bool ismain)
+{
+	Obj_Entry *obj;
+	Elf_Ehdr *hdr;
+	int i;
+	Elf_Phdr *phdr;
+	Elf_Phdr *phlimit;
+	Elf_Phdr **segs;
+	int nsegs;
+	Elf_Phdr *phdyn;
+	Elf_Phdr *phinterp;
+	Elf_Phdr *phtls;
+	caddr_t mapbase;
+	size_t mapsize;
+	Elf_Addr base_vaddr;
+	Elf_Addr base_vlimit;
+	caddr_t base_addr;
+	int base_flags;
+	Elf_Off data_offset;
+	Elf_Addr data_vaddr;
+	Elf_Addr data_vlimit;
+	caddr_t data_addr;
+	int data_prot;
+	int data_flags;
+	Elf_Addr clear_vaddr;
+	caddr_t clear_addr;
+	caddr_t clear_page;
+	Elf_Addr phdr_vaddr;
+	size_t nclear, phsize;
+	Elf_Addr bss_vaddr;
+	Elf_Addr bss_vlimit;
+	caddr_t bss_addr;
+	Elf_Word stack_flags;
+	Elf_Addr note_start;
+	Elf_Addr note_end;
+	char *note_map;
+	size_t note_map_len;
+	Elf_Addr text_end;
+
+	hdr = get_elf_header(fd, path, sb, &phdr);
+	if (hdr == NULL)
+		return (NULL);
+
+	/*
+	 * Scan the program header entries, and save key information.
+	 * We expect that the loadable segments are ordered by load address.
+	 */
+	phsize = hdr->e_phnum * sizeof(phdr[0]);
+	phlimit = phdr + hdr->e_phnum;
+	nsegs = -1;
+	phdyn = phinterp = phtls = NULL;
+	phdr_vaddr = 0;
+	note_start = 0;
+	note_end = 0;
+	note_map = NULL;
+	note_map_len = 0;
+	segs = alloca(sizeof(segs[0]) * hdr->e_phnum);
+	stack_flags = PF_X | PF_R | PF_W;
+	text_end = 0;
+	while (phdr < phlimit) {
+		switch (phdr->p_type) {
+		case PT_INTERP:
+			phinterp = phdr;
+			break;
+
+		case PT_LOAD:
+			segs[++nsegs] = phdr;
+			if ((segs[nsegs]->p_align & (page_size - 1)) != 0) {
+				_rtld_error(
+				    "%s: PT_LOAD segment %d not page-aligned",
+				    path, nsegs);
+				goto error;
+			}
+			if ((segs[nsegs]->p_flags & PF_X) == PF_X) {
+				text_end = MAX(text_end,
+				    rtld_round_page(segs[nsegs]->p_vaddr +
+				    segs[nsegs]->p_memsz));
+			}
+			break;
+
+		case PT_PHDR:
+			phdr_vaddr = phdr->p_vaddr;
+			phsize = phdr->p_memsz;
+			break;
+
+		case PT_DYNAMIC:
+			phdyn = phdr;
+			break;
+
+		case PT_TLS:
+			phtls = phdr;
+			break;
+
+		case PT_GNU_STACK:
+			stack_flags = phdr->p_flags;
+			break;
+
+		case PT_NOTE:
+			if (phdr->p_offset > page_size ||
+			    phdr->p_offset + phdr->p_filesz > page_size) {
+				note_map_len = rtld_round_page(phdr->p_offset +
+				    phdr->p_filesz) -
+				    rtld_trunc_page(phdr->p_offset);
+				note_map = mmap(NULL, note_map_len, PROT_READ,
+				    MAP_PRIVATE, fd,
+				    rtld_trunc_page(phdr->p_offset));
+				if (note_map == MAP_FAILED) {
+					_rtld_error(
+					    "%s: error mapping PT_NOTE (%d)",
+					    path, errno);
+					goto error;
+				}
+				note_start = (Elf_Addr)(note_map +
+				    phdr->p_offset -
+				    rtld_trunc_page(phdr->p_offset));
+			} else {
+				note_start = (Elf_Addr)(char *)hdr +
+				    phdr->p_offset;
+			}
+			note_end = note_start + phdr->p_filesz;
+			break;
+		}
+
+		++phdr;
+	}
+	if (phdyn == NULL) {
+		_rtld_error("%s: object is not dynamically-linked", path);
+		goto error;
+	}
+
+	if (nsegs < 0) {
+		_rtld_error("%s: too few PT_LOAD segments", path);
+		goto error;
+	}
+
+	/*
+	 * Map the entire address space of the object, to stake out our
+	 * contiguous region, and to establish the base address for relocation.
+	 */
+	base_vaddr = rtld_trunc_page(segs[0]->p_vaddr);
+	base_vlimit = rtld_round_page(segs[nsegs]->p_vaddr +
+	    segs[nsegs]->p_memsz);
+	mapsize = base_vlimit - base_vaddr;
+	base_addr = (caddr_t)base_vaddr;
+	base_flags = MAP_GUARD;
+	if (npagesizes > 1 &&  rtld_round_page(segs[0]->p_filesz) >=
+	    pagesizes[1])
+		base_flags |= MAP_ALIGNED_SUPER;
+	if (base_vaddr != 0)
+		base_flags |= MAP_FIXED | MAP_EXCL;
+
+	mapbase = mmap(base_addr, mapsize, PROT_NONE, base_flags, -1, 0);
+	if (mapbase == MAP_FAILED) {
+		_rtld_error("%s: mmap of entire address space failed: %s",
+		    path, rtld_strerror(errno));
+		goto error;
+	}
+	if (base_addr != NULL && mapbase != base_addr) {
+		_rtld_error(
+		    "%s: mmap returned wrong address: wanted %p, got %p",
+		    path, base_addr, mapbase);
+		goto error1;
+	}
+
+	for (i = 0; i <= nsegs; i++) {
+		/* Overlay the segment onto the proper region. */
+		data_offset = rtld_trunc_page(segs[i]->p_offset);
+		data_vaddr = rtld_trunc_page(segs[i]->p_vaddr);
+		data_vlimit = rtld_round_page(segs[i]->p_vaddr +
+		    segs[i]->p_filesz);
+		data_addr = mapbase + (data_vaddr - base_vaddr);
+		data_prot = convert_prot(segs[i]->p_flags);
+		data_flags = convert_flags(segs[i]->p_flags) | MAP_FIXED;
+		if (data_vlimit != data_vaddr && mmap(data_addr,
+		    data_vlimit - data_vaddr, data_prot, data_flags |
+		    MAP_PREFAULT_READ, fd, data_offset) == MAP_FAILED) {
+			_rtld_error("%s: mmap of data failed: %s",
+			    path, rtld_strerror(errno));
+			goto error1;
+		}
+
+		/* Do BSS setup */
+		if (segs[i]->p_filesz != segs[i]->p_memsz) {
+			/* Clear any BSS in the last page of the segment. */
+			clear_vaddr = segs[i]->p_vaddr + segs[i]->p_filesz;
+			clear_addr = mapbase + (clear_vaddr - base_vaddr);
+			clear_page = mapbase + (rtld_trunc_page(clear_vaddr) -
+			    base_vaddr);
+
+			if ((nclear = data_vlimit - clear_vaddr) > 0) {
+				/*
+				 * Make sure the end of the segment is
+				 * writable.
+				 */
+				if ((data_prot & PROT_WRITE) == 0 &&
+				    mprotect(clear_page, page_size,
+				    data_prot | PROT_WRITE) == -1) {
+					_rtld_error("%s: mprotect failed: %s",
+					    path, rtld_strerror(errno));
+					goto error1;
+				}
+
+				memset(clear_addr, 0, nclear);
+
+				/* Reset the data protection back */
+				if ((data_prot & PROT_WRITE) == 0)
+					mprotect(clear_page, page_size,
+					    data_prot);
+			}
+
+			/* Overlay the BSS segment onto the proper region. */
+			bss_vaddr = data_vlimit;
+			bss_vlimit = rtld_round_page(segs[i]->p_vaddr +
+			    segs[i]->p_memsz);
+			bss_addr = mapbase + (bss_vaddr - base_vaddr);
+			if (bss_vlimit > bss_vaddr) {
+				/* There is something to do */
+				if (mmap(bss_addr, bss_vlimit - bss_vaddr,
+				    data_prot, data_flags | MAP_ANON, -1,
+				    0) == MAP_FAILED) {
+					_rtld_error(
+					    "%s: mmap of bss failed: %s",
+					    path, rtld_strerror(errno));
+					goto error1;
+				}
+			}
+		}
+
+		if (phdr_vaddr == 0 && data_offset <= hdr->e_phoff &&
+		    data_vlimit - data_vaddr + data_offset >=
+		    hdr->e_phoff + hdr->e_phnum * sizeof(Elf_Phdr)) {
+			phdr_vaddr = data_vaddr + hdr->e_phoff - data_offset;
+		}
+	}
+
+	obj = obj_new();
+	if (sb != NULL) {
+		obj->dev = sb->st_dev;
+		obj->ino = sb->st_ino;
+	}
+	obj->mapbase = mapbase;
+	obj->mapsize = mapsize;
+	obj->vaddrbase = base_vaddr;
+	obj->relocbase = mapbase - base_vaddr;
+	obj->dynamic = (const Elf_Dyn *)(obj->relocbase + phdyn->p_vaddr);
+	if (hdr->e_entry != 0)
+		obj->entry = (caddr_t)(obj->relocbase + hdr->e_entry);
+	if (phdr_vaddr != 0) {
+		obj->phdr = (const Elf_Phdr *)(obj->relocbase + phdr_vaddr);
+	} else {
+		obj->phdr = malloc(phsize);
+		if (obj->phdr == NULL) {
+			obj_free(obj);
+			_rtld_error("%s: cannot allocate program header",
+			    path);
+			goto error1;
+		}
+		memcpy(__DECONST(char *, obj->phdr), (char *)hdr + hdr->e_phoff,
+		    phsize);
+		obj->phdr_alloc = true;
+	}
+	obj->phsize = phsize;
+	if (phinterp != NULL)
+		obj->interp = (const char *)(obj->relocbase +
+		    phinterp->p_vaddr);
+	if (phtls != NULL) {
+		if (ismain)
+			obj->tlsindex = 1;
+		else {
+			tls_dtv_generation++;
+			obj->tlsindex = ++tls_max_index;
+		}
+		obj->tlssize = phtls->p_memsz;
+		obj->tlsalign = phtls->p_align;
+		obj->tlspoffset = phtls->p_offset;
+		obj->tlsinitsize = phtls->p_filesz;
+		obj->tlsinit = obj->relocbase + phtls->p_vaddr;
+	}
+	obj->stack_flags = stack_flags;
+	if (note_start < note_end)
+		digest_notes(obj, note_start, note_end);
+	if (note_map != NULL)
+		munmap(note_map, note_map_len);
+	munmap(hdr, page_size);
+	return (obj);
+
+error1:
+	munmap(mapbase, mapsize);
+error:
+	if (note_map != NULL && note_map != MAP_FAILED)
+		munmap(note_map, note_map_len);
+	if (!phdr_in_zero_page(hdr))
+		munmap(phdr, hdr->e_phnum * sizeof(phdr[0]));
+	munmap(hdr, page_size);
+	return (NULL);
+}
+
+bool
+check_elf_headers(const Elf_Ehdr *hdr, const char *path)
+{
+	if (!IS_ELF(*hdr)) {
+		_rtld_error("%s: invalid file format", path);
+		return (false);
+	}
+	if (hdr->e_ident[EI_CLASS] != ELF_TARG_CLASS ||
+	    hdr->e_ident[EI_DATA] != ELF_TARG_DATA) {
+		_rtld_error("%s: unsupported file layout", path);
+		return (false);
+	}
+	if (hdr->e_ident[EI_VERSION] != EV_CURRENT ||
+	    hdr->e_version != EV_CURRENT) {
+		_rtld_error("%s: unsupported file version", path);
+		return (false);
+	}
+	if (hdr->e_type != ET_EXEC && hdr->e_type != ET_DYN) {
+		_rtld_error("%s: unsupported file type", path);
+		return (false);
+	}
+	if (hdr->e_machine != ELF_TARG_MACH) {
+		_rtld_error("%s: unsupported machine", path);
+		return (false);
+	}
+	if (hdr->e_phentsize != sizeof(Elf_Phdr)) {
+		_rtld_error(
+	    "%s: invalid shared object: e_phentsize != sizeof(Elf_Phdr)",
+		    path);
+		return (false);
+	}
+	return (true);
+}
+
+static Elf_Ehdr *
+get_elf_header(int fd, const char *path, const struct stat *sbp,
+    Elf_Phdr **phdr_p)
+{
+	Elf_Ehdr *hdr;
+	Elf_Phdr *phdr;
+
+	/* Make sure file has enough data for the ELF header */
+	if (sbp != NULL && sbp->st_size < (off_t)sizeof(Elf_Ehdr)) {
+		_rtld_error("%s: invalid file format", path);
+		return (NULL);
+	}
+
+	hdr = mmap(NULL, page_size, PROT_READ, MAP_PRIVATE | MAP_PREFAULT_READ,
+	    fd, 0);
+	if (hdr == MAP_FAILED) {
+		_rtld_error("%s: read error: %s", path, rtld_strerror(errno));
+		return (NULL);
+	}
+
+	/* Make sure the file is valid */
+	if (!check_elf_headers(hdr, path))
+		goto error;
+
+	/*
+	 * We rely on the program header being in the first page.  This is
+	 * not strictly required by the ABI specification, but it seems to
+	 * always true in practice.  And, it simplifies things considerably.
+	 */
+	if (phdr_in_zero_page(hdr)) {
+		phdr = (Elf_Phdr *)((char *)hdr + hdr->e_phoff);
+	} else {
+		phdr = mmap(NULL, hdr->e_phnum * sizeof(phdr[0]), PROT_READ,
+		    MAP_PRIVATE | MAP_PREFAULT_READ, fd, hdr->e_phoff);
+		if (phdr == MAP_FAILED) {
+			_rtld_error("%s: error mapping phdr: %s", path,
+			    rtld_strerror(errno));
+			goto error;
+		}
+	}
+	*phdr_p = phdr;
+	return (hdr);
+
+error:
+	munmap(hdr, page_size);
+	return (NULL);
+}
+
+void
+obj_free(Obj_Entry *obj)
+{
+	Objlist_Entry *elm;
+
+	if (obj->tls_static)
+		free_tls_offset(obj);
+	while (obj->needed != NULL) {
+		Needed_Entry *needed = obj->needed;
+
+		obj->needed = needed->next;
+		free(needed);
+	}
+	while (!STAILQ_EMPTY(&obj->names)) {
+		Name_Entry *entry = STAILQ_FIRST(&obj->names);
+
+		STAILQ_REMOVE_HEAD(&obj->names, link);
+		free(entry);
+	}
+	while (!STAILQ_EMPTY(&obj->dldags)) {
+		elm = STAILQ_FIRST(&obj->dldags);
+		STAILQ_REMOVE_HEAD(&obj->dldags, link);
+		free(elm);
+	}
+	while (!STAILQ_EMPTY(&obj->dagmembers)) {
+		elm = STAILQ_FIRST(&obj->dagmembers);
+		STAILQ_REMOVE_HEAD(&obj->dagmembers, link);
+		free(elm);
+	}
+	if (obj->vertab)
+		free(obj->vertab);
+	if (obj->origin_path)
+		free(obj->origin_path);
+	if (obj->z_origin)
+		free(__DECONST(void *, obj->rpath));
+	if (obj->priv)
+		free(obj->priv);
+	if (obj->path)
+		free(obj->path);
+	if (obj->phdr_alloc)
+		free(__DECONST(void *, obj->phdr));
+	free(obj);
+}
+
+Obj_Entry *
+obj_new(void)
+{
+	Obj_Entry *obj;
+
+	obj = CNEW(Obj_Entry);
+	STAILQ_INIT(&obj->dldags);
+	STAILQ_INIT(&obj->dagmembers);
+	STAILQ_INIT(&obj->names);
+	return (obj);
+}
+
+/*
+ * Given a set of ELF protection flags, return the corresponding protection
+ * flags for MMAP.
+ */
+int
+convert_prot(int elfflags)
+{
+	int prot = 0;
+
+	if ((elfflags & PF_R) != 0)
+		prot |= PROT_READ;
+	if ((elfflags & PF_W) != 0)
+		prot |= PROT_WRITE;
+	if ((elfflags & PF_X) != 0)
+		prot |= PROT_EXEC;
+	return (prot);
+}
+
+static int
+convert_flags(int elfflags)
+{
+	int flags = MAP_PRIVATE; /* All mappings are private */
+
+	/*
+	 * Readonly mappings are marked "MAP_NOCORE", because they can be
+	 * reconstructed by a debugger.
+	 */
+	if ((elfflags & PF_W) == 0)
+		flags |= MAP_NOCORE;
+	return (flags);
+}