diff options
Diffstat (limited to 'linkers/elftoolchain/libelf/elf_update.c')
| -rw-r--r-- | linkers/elftoolchain/libelf/elf_update.c | 1184 |
1 files changed, 1184 insertions, 0 deletions
diff --git a/linkers/elftoolchain/libelf/elf_update.c b/linkers/elftoolchain/libelf/elf_update.c new file mode 100644 index 0000000..9806131 --- /dev/null +++ b/linkers/elftoolchain/libelf/elf_update.c @@ -0,0 +1,1184 @@ +/*- + * Copyright (c) 2006-2011 Joseph Koshy + * 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 AND CONTRIBUTORS ``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 OR CONTRIBUTORS 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/mman.h> +#include <sys/stat.h> + +#include <assert.h> +#include <errno.h> +#include <gelf.h> +#include <libelf.h> +#include <stdlib.h> +#include <string.h> +#include <unistd.h> + +#include "_libelf.h" + +LIBELF_VCSID("$Id: elf_update.c 1922 2011-09-23 08:04:33Z jkoshy $"); + +/* + * Layout strategy: + * + * - Case 1: ELF_F_LAYOUT is asserted + * In this case the application has full control over where the + * section header table, program header table, and section data + * will reside. The library only perform error checks. + * + * - Case 2: ELF_F_LAYOUT is not asserted + * + * The library will do the object layout using the following + * ordering: + * - The executable header is placed first, are required by the + * ELF specification. + * - The program header table is placed immediately following the + * executable header. + * - Section data, if any, is placed after the program header + * table, aligned appropriately. + * - The section header table, if needed, is placed last. + * + * There are two sub-cases to be taken care of: + * + * - Case 2a: e->e_cmd == ELF_C_READ or ELF_C_RDWR + * + * In this sub-case, the underlying ELF object may already have + * content in it, which the application may have modified. The + * library will retrieve content from the existing object as + * needed. + * + * - Case 2b: e->e_cmd == ELF_C_WRITE + * + * The ELF object is being created afresh in this sub-case; + * there is no pre-existing content in the underlying ELF + * object. + */ + +/* + * The types of extents in an ELF object. + */ +enum elf_extent { + ELF_EXTENT_EHDR, + ELF_EXTENT_PHDR, + ELF_EXTENT_SECTION, + ELF_EXTENT_SHDR +}; + +/* + * A extent descriptor, used when laying out an ELF object. + */ +struct _Elf_Extent { + SLIST_ENTRY(_Elf_Extent) ex_next; + uint64_t ex_start; /* Start of the region. */ + uint64_t ex_size; /* The size of the region. */ + enum elf_extent ex_type; /* Type of region. */ + void *ex_desc; /* Associated descriptor. */ +}; + +SLIST_HEAD(_Elf_Extent_List, _Elf_Extent); + +/* + * Compute the extents of a section, by looking at the data + * descriptors associated with it. The function returns 1 + * if successful, or zero if an error was detected. + */ +static int +_libelf_compute_section_extents(Elf *e, Elf_Scn *s, off_t rc) +{ + int ec; + size_t fsz, msz; + Elf_Data *d; + Elf32_Shdr *shdr32; + Elf64_Shdr *shdr64; + uint32_t sh_type; + uint64_t d_align; + unsigned int elftype; + uint64_t scn_size, scn_alignment; + uint64_t sh_align, sh_entsize, sh_offset, sh_size; + + ec = e->e_class; + + shdr32 = &s->s_shdr.s_shdr32; + shdr64 = &s->s_shdr.s_shdr64; + if (ec == ELFCLASS32) { + sh_type = shdr32->sh_type; + sh_align = (uint64_t) shdr32->sh_addralign; + sh_entsize = (uint64_t) shdr32->sh_entsize; + sh_offset = (uint64_t) shdr32->sh_offset; + sh_size = (uint64_t) shdr32->sh_size; + } else { + sh_type = shdr64->sh_type; + sh_align = shdr64->sh_addralign; + sh_entsize = shdr64->sh_entsize; + sh_offset = shdr64->sh_offset; + sh_size = shdr64->sh_size; + } + + assert(sh_type != SHT_NULL && sh_type != SHT_NOBITS); + + elftype = _libelf_xlate_shtype(sh_type); + if (elftype > ELF_T_LAST) { + LIBELF_SET_ERROR(SECTION, 0); + return (0); + } + + if (sh_align == 0) + sh_align = _libelf_falign(elftype, ec); + + /* + * Compute the section's size and alignment using the data + * descriptors associated with the section. + */ + if (STAILQ_EMPTY(&s->s_data)) { + /* + * The section's content (if any) has not been read in + * yet. If section is not dirty marked dirty, we can + * reuse the values in the 'sh_size' and 'sh_offset' + * fields of the section header. + */ + if ((s->s_flags & ELF_F_DIRTY) == 0) { + /* + * If the library is doing the layout, then we + * compute the new start offset for the + * section based on the current offset and the + * section's alignment needs. + * + * If the application is doing the layout, we + * can use the value in the 'sh_offset' field + * in the section header directly. + */ + if (e->e_flags & ELF_F_LAYOUT) + goto updatedescriptor; + else + goto computeoffset; + } + + /* + * Otherwise, we need to bring in the section's data + * from the underlying ELF object. + */ + if (e->e_cmd != ELF_C_WRITE && elf_getdata(s, NULL) == NULL) + return (0); + } + + /* + * Loop through the section's data descriptors. + */ + scn_size = 0L; + scn_alignment = 0; + STAILQ_FOREACH(d, &s->s_data, d_next) { + + /* + * The data buffer's type is known. + */ + if (d->d_type >= ELF_T_NUM) { + LIBELF_SET_ERROR(DATA, 0); + return (0); + } + + /* + * The data buffer's version is supported. + */ + if (d->d_version != e->e_version) { + LIBELF_SET_ERROR(VERSION, 0); + return (0); + } + + /* + * The buffer's alignment is non-zero and a power of + * two. + */ + if ((d_align = d->d_align) == 0 || + (d_align & (d_align - 1))) { + LIBELF_SET_ERROR(DATA, 0); + return (0); + } + + /* + * The buffer's size should be a multiple of the + * memory size of the underlying type. + */ + msz = _libelf_msize(d->d_type, ec, e->e_version); + if (d->d_size % msz) { + LIBELF_SET_ERROR(DATA, 0); + return (0); + } + + /* + * If the application is controlling layout, then the + * d_offset field should be compatible with the + * buffer's specified alignment. + */ + if ((e->e_flags & ELF_F_LAYOUT) && + (d->d_off & (d_align - 1))) { + LIBELF_SET_ERROR(LAYOUT, 0); + return (0); + } + + /* + * Compute the section's size. + */ + if (e->e_flags & ELF_F_LAYOUT) { + if ((uint64_t) d->d_off + d->d_size > scn_size) + scn_size = d->d_off + d->d_size; + } else { + scn_size = roundup2(scn_size, d->d_align); + d->d_off = scn_size; + fsz = _libelf_fsize(d->d_type, ec, d->d_version, + d->d_size / msz); + scn_size += fsz; + } + + /* + * The section's alignment is the maximum alignment + * needed for its data buffers. + */ + if (d_align > scn_alignment) + scn_alignment = d_align; + } + + + /* + * If the application is requesting full control over the + * layout of the section, check the section's specified size, + * offsets and alignment for sanity. + */ + if (e->e_flags & ELF_F_LAYOUT) { + if (scn_alignment > sh_align || sh_offset % sh_align || + sh_size < scn_size) { + LIBELF_SET_ERROR(LAYOUT, 0); + return (0); + } + goto updatedescriptor; + } + + /* + * Otherwise, compute the values in the section header. + * + * The section alignment is the maximum alignment for any of + * its contained data descriptors. + */ + if (scn_alignment > sh_align) + sh_align = scn_alignment; + + /* + * If the section entry size is zero, try and fill in an + * appropriate entry size. Per the elf(5) manual page + * sections without fixed-size entries should have their + * 'sh_entsize' field set to zero. + */ + if (sh_entsize == 0 && + (sh_entsize = _libelf_fsize(elftype, ec, e->e_version, + (size_t) 1)) == 1) + sh_entsize = 0; + + sh_size = scn_size; + +computeoffset: + /* + * Compute the new offset for the section based on + * the section's alignment needs. + */ + sh_offset = roundup(rc, sh_align); + + /* + * Update the section header. + */ + if (ec == ELFCLASS32) { + shdr32->sh_addralign = (uint32_t) sh_align; + shdr32->sh_entsize = (uint32_t) sh_entsize; + shdr32->sh_offset = (uint32_t) sh_offset; + shdr32->sh_size = (uint32_t) sh_size; + } else { + shdr64->sh_addralign = sh_align; + shdr64->sh_entsize = sh_entsize; + shdr64->sh_offset = sh_offset; + shdr64->sh_size = sh_size; + } + +updatedescriptor: + /* + * Update the section descriptor. + */ + s->s_size = sh_size; + s->s_offset = sh_offset; + + return (1); +} + +/* + * Free a list of extent descriptors. + */ + +static void +_libelf_release_extents(struct _Elf_Extent_List *extents) +{ + struct _Elf_Extent *ex; + + while ((ex = SLIST_FIRST(extents)) != NULL) { + SLIST_REMOVE_HEAD(extents, ex_next); + free(ex); + } +} + +/* + * Check if an extent 's' defined by [start..start+size) is free. + * This routine assumes that the given extent list is sorted in order + * of ascending extent offsets. + */ + +static int +_libelf_extent_is_unused(struct _Elf_Extent_List *extents, + const uint64_t start, const uint64_t size, struct _Elf_Extent **prevt) +{ + uint64_t tmax, tmin; + struct _Elf_Extent *t, *pt; + const uint64_t smax = start + size; + + /* First, look for overlaps with existing extents. */ + pt = NULL; + SLIST_FOREACH(t, extents, ex_next) { + tmin = t->ex_start; + tmax = tmin + t->ex_size; + + if (tmax <= start) { + /* + * 't' lies entirely before 's': ...| t |...| s |... + */ + pt = t; + continue; + } else if (smax <= tmin) { + /* + * 's' lies entirely before 't', and after 'pt': + * ...| pt |...| s |...| t |... + */ + assert(pt == NULL || + pt->ex_start + pt->ex_size <= start); + break; + } else + /* 's' and 't' overlap. */ + return (0); + } + + if (prevt) + *prevt = pt; + return (1); +} + +/* + * Insert an extent into the list of extents. + */ + +static int +_libelf_insert_extent(struct _Elf_Extent_List *extents, int type, + uint64_t start, uint64_t size, void *desc) +{ + struct _Elf_Extent *ex, *prevt; + + assert(type >= ELF_EXTENT_EHDR && type <= ELF_EXTENT_SHDR); + + prevt = NULL; + + /* + * If the requested range overlaps with an existing extent, + * signal an error. + */ + if (!_libelf_extent_is_unused(extents, start, size, &prevt)) { + LIBELF_SET_ERROR(LAYOUT, 0); + return (0); + } + + /* Allocate and fill in a new extent descriptor. */ + if ((ex = malloc(sizeof(struct _Elf_Extent))) == NULL) { + LIBELF_SET_ERROR(RESOURCE, errno); + return (0); + } + ex->ex_start = start; + ex->ex_size = size; + ex->ex_desc = desc; + ex->ex_type = type; + + /* Insert the region descriptor into the list. */ + if (prevt) + SLIST_INSERT_AFTER(prevt, ex, ex_next); + else + SLIST_INSERT_HEAD(extents, ex, ex_next); + return (1); +} + +/* + * Recompute section layout. + */ + +static off_t +_libelf_resync_sections(Elf *e, off_t rc, struct _Elf_Extent_List *extents) +{ + int ec; + Elf_Scn *s; + size_t sh_type; + + ec = e->e_class; + + /* + * Make a pass through sections, computing the extent of each + * section. + */ + STAILQ_FOREACH(s, &e->e_u.e_elf.e_scn, s_next) { + if (ec == ELFCLASS32) + sh_type = s->s_shdr.s_shdr32.sh_type; + else + sh_type = s->s_shdr.s_shdr64.sh_type; + + if (sh_type == SHT_NOBITS || sh_type == SHT_NULL) + continue; + + if (_libelf_compute_section_extents(e, s, rc) == 0) + return ((off_t) -1); + + if (s->s_size == 0) + continue; + + if (!_libelf_insert_extent(extents, ELF_EXTENT_SECTION, + s->s_offset, s->s_size, s)) + return ((off_t) -1); + + if ((size_t) rc < s->s_offset + s->s_size) + rc = s->s_offset + s->s_size; + } + + return (rc); +} + +/* + * Recompute the layout of the ELF object and update the internal data + * structures associated with the ELF descriptor. + * + * Returns the size in bytes the ELF object would occupy in its file + * representation. + * + * After a successful call to this function, the following structures + * are updated: + * + * - The ELF header is updated. + * - All extents in the ELF object are sorted in order of ascending + * addresses. Sections have their section header table entries + * updated. An error is signalled if an overlap was detected among + * extents. + * - Data descriptors associated with sections are checked for valid + * types, offsets and alignment. + * + * After a resync_elf() successfully returns, the ELF descriptor is + * ready for being handed over to _libelf_write_elf(). + */ + +static off_t +_libelf_resync_elf(Elf *e, struct _Elf_Extent_List *extents) +{ + int ec, eh_class, eh_type; + unsigned int eh_byteorder, eh_version; + size_t align, fsz; + size_t phnum, shnum; + off_t rc, phoff, shoff; + void *ehdr, *phdr; + Elf32_Ehdr *eh32; + Elf64_Ehdr *eh64; + + rc = 0; + + ec = e->e_class; + + assert(ec == ELFCLASS32 || ec == ELFCLASS64); + + /* + * Prepare the EHDR. + */ + if ((ehdr = _libelf_ehdr(e, ec, 0)) == NULL) + return ((off_t) -1); + + eh32 = ehdr; + eh64 = ehdr; + + if (ec == ELFCLASS32) { + eh_byteorder = eh32->e_ident[EI_DATA]; + eh_class = eh32->e_ident[EI_CLASS]; + phoff = (uint64_t) eh32->e_phoff; + shoff = (uint64_t) eh32->e_shoff; + eh_type = eh32->e_type; + eh_version = eh32->e_version; + } else { + eh_byteorder = eh64->e_ident[EI_DATA]; + eh_class = eh64->e_ident[EI_CLASS]; + phoff = eh64->e_phoff; + shoff = eh64->e_shoff; + eh_type = eh64->e_type; + eh_version = eh64->e_version; + } + + if (eh_version == EV_NONE) + eh_version = EV_CURRENT; + + if (eh_version != e->e_version) { /* always EV_CURRENT */ + LIBELF_SET_ERROR(VERSION, 0); + return ((off_t) -1); + } + + if (eh_class != e->e_class) { + LIBELF_SET_ERROR(CLASS, 0); + return ((off_t) -1); + } + + if (e->e_cmd != ELF_C_WRITE && eh_byteorder != e->e_byteorder) { + LIBELF_SET_ERROR(HEADER, 0); + return ((off_t) -1); + } + + shnum = e->e_u.e_elf.e_nscn; + phnum = e->e_u.e_elf.e_nphdr; + + e->e_byteorder = eh_byteorder; + +#define INITIALIZE_EHDR(E,EC,V) do { \ + (E)->e_ident[EI_MAG0] = ELFMAG0; \ + (E)->e_ident[EI_MAG1] = ELFMAG1; \ + (E)->e_ident[EI_MAG2] = ELFMAG2; \ + (E)->e_ident[EI_MAG3] = ELFMAG3; \ + (E)->e_ident[EI_CLASS] = (EC); \ + (E)->e_ident[EI_VERSION] = (V); \ + (E)->e_ehsize = _libelf_fsize(ELF_T_EHDR, (EC), (V), \ + (size_t) 1); \ + (E)->e_phentsize = (phnum == 0) ? 0 : _libelf_fsize( \ + ELF_T_PHDR, (EC), (V), (size_t) 1); \ + (E)->e_shentsize = _libelf_fsize(ELF_T_SHDR, (EC), (V), \ + (size_t) 1); \ + } while (0) + + if (ec == ELFCLASS32) + INITIALIZE_EHDR(eh32, ec, eh_version); + else + INITIALIZE_EHDR(eh64, ec, eh_version); + + (void) elf_flagehdr(e, ELF_C_SET, ELF_F_DIRTY); + + rc += _libelf_fsize(ELF_T_EHDR, ec, eh_version, (size_t) 1); + + if (!_libelf_insert_extent(extents, ELF_EXTENT_EHDR, 0, rc, ehdr)) + return ((off_t) -1); + + /* + * Compute the layout the program header table, if one is + * present. The program header table needs to be aligned to a + * `natural' boundary. + */ + if (phnum) { + fsz = _libelf_fsize(ELF_T_PHDR, ec, eh_version, phnum); + align = _libelf_falign(ELF_T_PHDR, ec); + + if (e->e_flags & ELF_F_LAYOUT) { + /* + * Check offsets for sanity. + */ + if (rc > phoff) { + LIBELF_SET_ERROR(LAYOUT, 0); + return ((off_t) -1); + } + + if (phoff % align) { + LIBELF_SET_ERROR(LAYOUT, 0); + return ((off_t) -1); + } + + } else + phoff = roundup(rc, align); + + rc = phoff + fsz; + + phdr = _libelf_getphdr(e, ec); + + if (!_libelf_insert_extent(extents, ELF_EXTENT_PHDR, phoff, + fsz, phdr)) + return ((off_t) -1); + } else + phoff = 0; + + /* + * Compute the layout of the sections associated with the + * file. + */ + + if (e->e_cmd != ELF_C_WRITE && + (e->e_flags & LIBELF_F_SHDRS_LOADED) == 0 && + _libelf_load_section_headers(e, ehdr) == 0) + return ((off_t) -1); + + if ((rc = _libelf_resync_sections(e, rc, extents)) < 0) + return ((off_t) -1); + + /* + * Compute the space taken up by the section header table, if + * one is needed. + * + * If ELF_F_LAYOUT has been asserted, the application may have + * placed the section header table in between existing + * sections, so the net size of the file need not increase due + * to the presence of the section header table. + * + * If the library is responsible for laying out the object, + * the section header table is placed after section data. + */ + if (shnum) { + fsz = _libelf_fsize(ELF_T_SHDR, ec, eh_version, shnum); + align = _libelf_falign(ELF_T_SHDR, ec); + + if (e->e_flags & ELF_F_LAYOUT) { + if (shoff % align) { + LIBELF_SET_ERROR(LAYOUT, 0); + return ((off_t) -1); + } + } else + shoff = roundup(rc, align); + + if (shoff + fsz > (size_t) rc) + rc = shoff + fsz; + + if (!_libelf_insert_extent(extents, ELF_EXTENT_SHDR, shoff, + fsz, NULL)) + return ((off_t) -1); + } else + shoff = 0; + + /* + * Set the fields of the Executable Header that could potentially use + * extended numbering. + */ + _libelf_setphnum(e, ehdr, ec, phnum); + _libelf_setshnum(e, ehdr, ec, shnum); + + /* + * Update the `e_phoff' and `e_shoff' fields if the library is + * doing the layout. + */ + if ((e->e_flags & ELF_F_LAYOUT) == 0) { + if (ec == ELFCLASS32) { + eh32->e_phoff = (uint32_t) phoff; + eh32->e_shoff = (uint32_t) shoff; + } else { + eh64->e_phoff = (uint64_t) phoff; + eh64->e_shoff = (uint64_t) shoff; + } + } + + return (rc); +} + +/* + * Write out the contents of an ELF section. + */ + +static size_t +_libelf_write_scn(Elf *e, char *nf, struct _Elf_Extent *ex) +{ + int ec; + size_t fsz, msz, nobjects, rc; + uint32_t sh_type; + uint64_t sh_off, sh_size; + int elftype; + Elf_Scn *s; + Elf_Data *d, dst; + + assert(ex->ex_type == ELF_EXTENT_SECTION); + + s = ex->ex_desc; + rc = ex->ex_start; + + if ((ec = e->e_class) == ELFCLASS32) { + sh_type = s->s_shdr.s_shdr32.sh_type; + sh_size = (uint64_t) s->s_shdr.s_shdr32.sh_size; + } else { + sh_type = s->s_shdr.s_shdr64.sh_type; + sh_size = s->s_shdr.s_shdr64.sh_size; + } + + /* + * Ignore sections that do not allocate space in the file. + */ + if (sh_type == SHT_NOBITS || sh_type == SHT_NULL || sh_size == 0) + return (rc); + + elftype = _libelf_xlate_shtype(sh_type); + assert(elftype >= ELF_T_FIRST && elftype <= ELF_T_LAST); + + sh_off = s->s_offset; + assert(sh_off % _libelf_falign(elftype, ec) == 0); + + /* + * If the section has a `rawdata' descriptor, and the section + * contents have not been modified, use its contents directly. + * The `s_rawoff' member contains the offset into the original + * file, while `s_offset' contains its new location in the + * destination. + */ + + if (STAILQ_EMPTY(&s->s_data)) { + + if ((d = elf_rawdata(s, NULL)) == NULL) + return ((off_t) -1); + + STAILQ_FOREACH(d, &s->s_rawdata, d_next) { + if ((uint64_t) rc < sh_off + d->d_off) + (void) memset(nf + rc, + LIBELF_PRIVATE(fillchar), sh_off + + d->d_off - rc); + rc = sh_off + d->d_off; + + assert(d->d_buf != NULL); + assert(d->d_type == ELF_T_BYTE); + assert(d->d_version == e->e_version); + + (void) memcpy(nf + rc, + e->e_rawfile + s->s_rawoff + d->d_off, d->d_size); + + rc += d->d_size; + } + + return (rc); + } + + /* + * Iterate over the set of data descriptors for this section. + * The prior call to _libelf_resync_elf() would have setup the + * descriptors for this step. + */ + + dst.d_version = e->e_version; + + STAILQ_FOREACH(d, &s->s_data, d_next) { + + msz = _libelf_msize(d->d_type, ec, e->e_version); + + if ((uint64_t) rc < sh_off + d->d_off) + (void) memset(nf + rc, + LIBELF_PRIVATE(fillchar), sh_off + d->d_off - rc); + + rc = sh_off + d->d_off; + + assert(d->d_buf != NULL); + assert(d->d_version == e->e_version); + assert(d->d_size % msz == 0); + + nobjects = d->d_size / msz; + + fsz = _libelf_fsize(d->d_type, ec, e->e_version, nobjects); + + dst.d_buf = nf + rc; + dst.d_size = fsz; + + if (_libelf_xlate(&dst, d, e->e_byteorder, ec, ELF_TOFILE) == + NULL) + return ((off_t) -1); + + rc += fsz; + } + + return ((off_t) rc); +} + +/* + * Write out an ELF Executable Header. + */ + +static off_t +_libelf_write_ehdr(Elf *e, char *nf, struct _Elf_Extent *ex) +{ + int ec; + void *ehdr; + size_t fsz, msz; + Elf_Data dst, src; + + assert(ex->ex_type == ELF_EXTENT_EHDR); + assert(ex->ex_start == 0); /* Ehdr always comes first. */ + + ec = e->e_class; + + ehdr = _libelf_ehdr(e, ec, 0); + assert(ehdr != NULL); + + fsz = _libelf_fsize(ELF_T_EHDR, ec, e->e_version, (size_t) 1); + msz = _libelf_msize(ELF_T_EHDR, ec, e->e_version); + + (void) memset(&dst, 0, sizeof(dst)); + (void) memset(&src, 0, sizeof(src)); + + src.d_buf = ehdr; + src.d_size = msz; + src.d_type = ELF_T_EHDR; + src.d_version = dst.d_version = e->e_version; + + dst.d_buf = nf; + dst.d_size = fsz; + + if (_libelf_xlate(&dst, &src, e->e_byteorder, ec, ELF_TOFILE) == + NULL) + return ((off_t) -1); + + return ((off_t) fsz); +} + +/* + * Write out an ELF program header table. + */ + +static off_t +_libelf_write_phdr(Elf *e, char *nf, struct _Elf_Extent *ex) +{ + int ec; + void *ehdr; + Elf32_Ehdr *eh32; + Elf64_Ehdr *eh64; + Elf_Data dst, src; + size_t fsz, phnum; + uint64_t phoff; + + assert(ex->ex_type == ELF_EXTENT_PHDR); + + ec = e->e_class; + ehdr = _libelf_ehdr(e, ec, 0); + phnum = e->e_u.e_elf.e_nphdr; + + assert(phnum > 0); + + if (ec == ELFCLASS32) { + eh32 = (Elf32_Ehdr *) ehdr; + phoff = (uint64_t) eh32->e_phoff; + } else { + eh64 = (Elf64_Ehdr *) ehdr; + phoff = eh64->e_phoff; + } + + assert(phoff > 0); + assert(ex->ex_start == phoff); + assert(phoff % _libelf_falign(ELF_T_PHDR, ec) == 0); + + (void) memset(&dst, 0, sizeof(dst)); + (void) memset(&src, 0, sizeof(src)); + + fsz = _libelf_fsize(ELF_T_PHDR, ec, e->e_version, phnum); + assert(fsz > 0); + + src.d_buf = _libelf_getphdr(e, ec); + src.d_version = dst.d_version = e->e_version; + src.d_type = ELF_T_PHDR; + src.d_size = phnum * _libelf_msize(ELF_T_PHDR, ec, + e->e_version); + + dst.d_size = fsz; + dst.d_buf = nf + ex->ex_start; + + if (_libelf_xlate(&dst, &src, e->e_byteorder, ec, ELF_TOFILE) == + NULL) + return ((off_t) -1); + + return (phoff + fsz); +} + +/* + * Write out an ELF section header table. + */ + +static off_t +_libelf_write_shdr(Elf *e, char *nf, struct _Elf_Extent *ex) +{ + int ec; + void *ehdr; + Elf_Scn *scn; + uint64_t shoff; + Elf32_Ehdr *eh32; + Elf64_Ehdr *eh64; + size_t fsz, nscn; + Elf_Data dst, src; + + assert(ex->ex_type == ELF_EXTENT_SHDR); + + ec = e->e_class; + ehdr = _libelf_ehdr(e, ec, 0); + nscn = e->e_u.e_elf.e_nscn; + + if (ec == ELFCLASS32) { + eh32 = (Elf32_Ehdr *) ehdr; + shoff = (uint64_t) eh32->e_shoff; + } else { + eh64 = (Elf64_Ehdr *) ehdr; + shoff = eh64->e_shoff; + } + + assert(nscn > 0); + assert(shoff % _libelf_falign(ELF_T_SHDR, ec) == 0); + assert(ex->ex_start == shoff); + + (void) memset(&dst, 0, sizeof(dst)); + (void) memset(&src, 0, sizeof(src)); + + src.d_type = ELF_T_SHDR; + src.d_size = _libelf_msize(ELF_T_SHDR, ec, e->e_version); + src.d_version = dst.d_version = e->e_version; + + fsz = _libelf_fsize(ELF_T_SHDR, ec, e->e_version, (size_t) 1); + + STAILQ_FOREACH(scn, &e->e_u.e_elf.e_scn, s_next) { + if (ec == ELFCLASS32) + src.d_buf = &scn->s_shdr.s_shdr32; + else + src.d_buf = &scn->s_shdr.s_shdr64; + + dst.d_size = fsz; + dst.d_buf = nf + ex->ex_start + scn->s_ndx * fsz; + + if (_libelf_xlate(&dst, &src, e->e_byteorder, ec, + ELF_TOFILE) == NULL) + return ((off_t) -1); + } + + return (ex->ex_start + nscn * fsz); +} + +/* + * Write out the file image. + * + * The original file could have been mapped in with an ELF_C_RDWR + * command and the application could have added new content or + * re-arranged its sections before calling elf_update(). Consequently + * its not safe to work `in place' on the original file. So we + * malloc() the required space for the updated ELF object and build + * the object there and write it out to the underlying file at the + * end. Note that the application may have opened the underlying file + * in ELF_C_RDWR and only retrieved/modified a few sections. We take + * care to avoid translating file sections unnecessarily. + * + * Gaps in the coverage of the file by the file's sections will be + * filled with the fill character set by elf_fill(3). + */ + +static off_t +_libelf_write_elf(Elf *e, off_t newsize, struct _Elf_Extent_List *extents) +{ + off_t nrc, rc; + char *newfile; + Elf_Scn *scn, *tscn; + struct _Elf_Extent *ex; + + assert(e->e_kind == ELF_K_ELF); + assert(e->e_cmd == ELF_C_RDWR || e->e_cmd == ELF_C_WRITE); + assert(e->e_fd >= 0); + + if ((newfile = malloc((size_t) newsize)) == NULL) { + LIBELF_SET_ERROR(RESOURCE, errno); + return ((off_t) -1); + } + + nrc = rc = 0; + SLIST_FOREACH(ex, extents, ex_next) { + + /* Fill inter-extent gaps. */ + if (ex->ex_start > (size_t) rc) + (void) memset(newfile + rc, LIBELF_PRIVATE(fillchar), + ex->ex_start - rc); + + switch (ex->ex_type) { + case ELF_EXTENT_EHDR: + if ((nrc = _libelf_write_ehdr(e, newfile, ex)) < 0) + goto error; + break; + + case ELF_EXTENT_PHDR: + if ((nrc = _libelf_write_phdr(e, newfile, ex)) < 0) + goto error; + break; + + case ELF_EXTENT_SECTION: + if ((nrc = _libelf_write_scn(e, newfile, ex)) < 0) + goto error; + break; + + case ELF_EXTENT_SHDR: + if ((nrc = _libelf_write_shdr(e, newfile, ex)) < 0) + goto error; + break; + + default: + assert(0); + break; + } + + assert(ex->ex_start + ex->ex_size == (size_t) nrc); + assert(rc < nrc); + + rc = nrc; + } + + assert(rc == newsize); + + /* + * For regular files, throw away existing file content and + * unmap any existing mappings. + */ + if ((e->e_flags & LIBELF_F_SPECIAL_FILE) == 0) { + if (ftruncate(e->e_fd, (off_t) 0) < 0 || + lseek(e->e_fd, (off_t) 0, SEEK_SET)) { + LIBELF_SET_ERROR(IO, errno); + goto error; + } + if (e->e_flags & LIBELF_F_RAWFILE_MMAP) { + assert(e->e_rawfile != NULL); + assert(e->e_cmd == ELF_C_RDWR); + if (munmap(e->e_rawfile, e->e_rawsize) < 0) { + LIBELF_SET_ERROR(IO, errno); + goto error; + } + } + } + + /* + * Write out the new contents. + */ + if (write(e->e_fd, newfile, (size_t) newsize) != newsize) { + LIBELF_SET_ERROR(IO, errno); + goto error; + } + + /* + * For files opened in ELF_C_RDWR mode, set up the new 'raw' + * contents. + */ + if (e->e_cmd == ELF_C_RDWR) { + assert(e->e_rawfile != NULL); + if (e->e_flags & LIBELF_F_RAWFILE_MMAP) { + if ((e->e_rawfile = mmap(NULL, (size_t) newsize, + PROT_READ, MAP_PRIVATE, e->e_fd, (off_t) 0)) == + MAP_FAILED) { + LIBELF_SET_ERROR(IO, errno); + goto error; + } + } else if (e->e_flags & LIBELF_F_RAWFILE_MALLOC) { + free(e->e_rawfile); + e->e_rawfile = newfile; + newfile = NULL; + } + + /* Record the new size of the file. */ + e->e_rawsize = newsize; + } else { + /* File opened in ELF_C_WRITE mode. */ + assert(e->e_rawfile == NULL); + } + + /* + * Reset flags, remove existing section descriptors and + * {E,P}HDR pointers so that a subsequent elf_get{e,p}hdr() + * and elf_getscn() will function correctly. + */ + + e->e_flags &= ~ELF_F_DIRTY; + + STAILQ_FOREACH_SAFE(scn, &e->e_u.e_elf.e_scn, s_next, tscn) + _libelf_release_scn(scn); + + if (e->e_class == ELFCLASS32) { + free(e->e_u.e_elf.e_ehdr.e_ehdr32); + if (e->e_u.e_elf.e_phdr.e_phdr32) + free(e->e_u.e_elf.e_phdr.e_phdr32); + + e->e_u.e_elf.e_ehdr.e_ehdr32 = NULL; + e->e_u.e_elf.e_phdr.e_phdr32 = NULL; + } else { + free(e->e_u.e_elf.e_ehdr.e_ehdr64); + if (e->e_u.e_elf.e_phdr.e_phdr64) + free(e->e_u.e_elf.e_phdr.e_phdr64); + + e->e_u.e_elf.e_ehdr.e_ehdr64 = NULL; + e->e_u.e_elf.e_phdr.e_phdr64 = NULL; + } + + /* Free the temporary buffer. */ + if (newfile) + free(newfile); + + return (rc); + + error: + free(newfile); + + return ((off_t) -1); +} + +/* + * Update an ELF object. + */ + +off_t +elf_update(Elf *e, Elf_Cmd c) +{ + int ec; + off_t rc; + struct _Elf_Extent_List extents; + + rc = (off_t) -1; + + if (e == NULL || e->e_kind != ELF_K_ELF || + (c != ELF_C_NULL && c != ELF_C_WRITE)) { + LIBELF_SET_ERROR(ARGUMENT, 0); + return (rc); + } + + if ((ec = e->e_class) != ELFCLASS32 && ec != ELFCLASS64) { + LIBELF_SET_ERROR(CLASS, 0); + return (rc); + } + + if (e->e_version == EV_NONE) + e->e_version = EV_CURRENT; + + if (c == ELF_C_WRITE && e->e_cmd == ELF_C_READ) { + LIBELF_SET_ERROR(MODE, 0); + return (rc); + } + + SLIST_INIT(&extents); + + if ((rc = _libelf_resync_elf(e, &extents)) < 0) + goto done; + + if (c == ELF_C_NULL) + goto done; + + if (e->e_fd < 0) { + rc = (off_t) -1; + LIBELF_SET_ERROR(SEQUENCE, 0); + goto done; + } + + return (_libelf_write_elf(e, rc, &extents)); + +done: + _libelf_release_extents(&extents); + return (rc); +} |