kern_ctf.c

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/*-
 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
 *
 * Copyright (c) 2008 John Birrell <jb@freebsd.org>
 * 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.
 *
 * $FreeBSD$
 */
 
#include <sys/ctf.h>
 
/*
 * Note this file is included by both link_elf.c and link_elf_obj.c.
 */
 
#ifdef DDB_CTF
#include <contrib/zlib/zlib.h>
#endif
 
static int
link_elf_ctf_get(linker_file_t lf, linker_ctf_t *lc)
{
#ifdef DDB_CTF
        Elf_Ehdr *hdr = NULL;
        Elf_Shdr *shdr = NULL;
        caddr_t ctftab = NULL;
        caddr_t raw = NULL;
        caddr_t shstrtab = NULL;
        elf_file_t ef = (elf_file_t) lf;
        int flags;
        int i;
        int nbytes;
        size_t sz;
        struct nameidata nd;
        struct thread *td = curthread;
        struct ctf_header cth;
#endif
        int error = 0;
 
        if (lf == NULL || lc == NULL)
                return (EINVAL);
 
        /* Set the defaults for no CTF present. That's not a crime! */
        bzero(lc, sizeof(*lc));
 
#ifdef DDB_CTF
        /*
         * First check if we've tried to load CTF data previously and the
         * CTF ELF section wasn't found. We flag that condition by setting
         * ctfcnt to -1. See below.
         */
        if (ef->ctfcnt < 0)
                return (EFTYPE);
 
        /* Now check if we've already loaded the CTF data.. */
        if (ef->ctfcnt > 0) {
                /* We only need to load once. */
                lc->ctftab = ef->ctftab;
                lc->ctfcnt = ef->ctfcnt;
                lc->symtab = ef->ddbsymtab;
                lc->strtab = ef->ddbstrtab;
                lc->strcnt = ef->ddbstrcnt;
                lc->nsym   = ef->ddbsymcnt;
                lc->ctfoffp = (uint32_t **) &ef->ctfoff;
                lc->typoffp = (uint32_t **) &ef->typoff;
                lc->typlenp = &ef->typlen;
                return (0);
        }
 
        /*
         * We need to try reading the CTF data. Flag no CTF data present
         * by default and if we actually succeed in reading it, we'll
         * update ctfcnt to the number of bytes read.
         */
        ef->ctfcnt = -1;
 
        NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, lf->pathname);
        flags = FREAD;
        error = vn_open(&nd, &flags, 0, NULL);
        if (error)
                return (error);
        NDFREE(&nd, NDF_ONLY_PNBUF);
 
        /* Allocate memory for the FLF header. */
        hdr = malloc(sizeof(*hdr), M_LINKER, M_WAITOK);
 
        /* Read the ELF header. */
        if ((error = vn_rdwr(UIO_READ, nd.ni_vp, hdr, sizeof(*hdr),
            0, UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED, NULL,
            td)) != 0)
                goto out;
 
        /* Sanity check. */
        if (!IS_ELF(*hdr)) {
                error = ENOEXEC;
                goto out;
        }
 
        nbytes = hdr->e_shnum * hdr->e_shentsize;
        if (nbytes == 0 || hdr->e_shoff == 0 ||
            hdr->e_shentsize != sizeof(Elf_Shdr)) {
                error = ENOEXEC;
                goto out;
        }
 
        /* Allocate memory for all the section headers */
        shdr = malloc(nbytes, M_LINKER, M_WAITOK);
 
        /* Read all the section headers */
        if ((error = vn_rdwr(UIO_READ, nd.ni_vp, (caddr_t)shdr, nbytes,
            hdr->e_shoff, UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED,
            NULL, td)) != 0)
                goto out;
 
        /*
         * We need to search for the CTF section by name, so if the
         * section names aren't present, then we can't locate the
         * .SUNW_ctf section containing the CTF data.
         */
        if (hdr->e_shstrndx == 0 || shdr[hdr->e_shstrndx].sh_type != SHT_STRTAB) {
                printf("%s(%d): module %s e_shstrndx is %d, sh_type is %d\n",
                    __func__, __LINE__, lf->pathname, hdr->e_shstrndx,
                    shdr[hdr->e_shstrndx].sh_type);
                error = EFTYPE;
                goto out;
        }
 
        /* Allocate memory to buffer the section header strings. */
        shstrtab = malloc(shdr[hdr->e_shstrndx].sh_size, M_LINKER, M_WAITOK);
 
        /* Read the section header strings. */
        if ((error = vn_rdwr(UIO_READ, nd.ni_vp, shstrtab,
            shdr[hdr->e_shstrndx].sh_size, shdr[hdr->e_shstrndx].sh_offset,
            UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred, NOCRED, NULL, td)) != 0)
                goto out;
 
        /* Search for the section containing the CTF data. */
        for (i = 0; i < hdr->e_shnum; i++)
                if (strcmp(".SUNW_ctf", shstrtab + shdr[i].sh_name) == 0)
                        break;
 
        /* Check if the CTF section wasn't found. */
        if (i >= hdr->e_shnum) {
                printf("%s(%d): module %s has no .SUNW_ctf section\n",
                    __func__, __LINE__, lf->pathname);
                error = EFTYPE;
                goto out;
        }
 
        /* Read the CTF header. */
        if ((error = vn_rdwr(UIO_READ, nd.ni_vp, &cth, sizeof(cth),
            shdr[i].sh_offset, UIO_SYSSPACE, IO_NODELOCKED, td->td_ucred,
            NOCRED, NULL, td)) != 0)
                goto out;
 
        /* Check the CTF magic number. */
        if (cth.cth_magic != CTF_MAGIC) {
                printf("%s(%d): module %s has invalid format\n",
                    __func__, __LINE__, lf->pathname);
                error = EFTYPE;
                goto out;
        }
 
        if (cth.cth_version != CTF_VERSION_2 &&
            cth.cth_version != CTF_VERSION_3) {
                printf(
                    "%s(%d): module %s CTF format has unsupported version %d\n",
                    __func__, __LINE__, lf->pathname, cth.cth_version);
                error = EFTYPE;
                goto out;
        }
 
        /* Check if the data is compressed. */
        if ((cth.cth_flags & CTF_F_COMPRESS) != 0) {
                /*
                 * The last two fields in the CTF header are the offset
                 * from the end of the header to the start of the string
                 * data and the length of that string data. Use this
                 * information to determine the decompressed CTF data
                 * buffer required.
                 */
                sz = cth.cth_stroff + cth.cth_strlen + sizeof(cth);
 
                /*
                 * Allocate memory for the compressed CTF data, including
                 * the header (which isn't compressed).
                 */
                raw = malloc(shdr[i].sh_size, M_LINKER, M_WAITOK);
        } else {
                /*
                 * The CTF data is not compressed, so the ELF section
                 * size is the same as the buffer size required.
                 */
                sz = shdr[i].sh_size;
        }
 
        /*
         * Allocate memory to buffer the CTF data in its decompressed
         * form.
         */
        ctftab = malloc(sz, M_LINKER, M_WAITOK);
 
        /*
         * Read the CTF data into the raw buffer if compressed, or
         * directly into the CTF buffer otherwise.
         */
        if ((error = vn_rdwr(UIO_READ, nd.ni_vp, raw == NULL ? ctftab : raw,
            shdr[i].sh_size, shdr[i].sh_offset, UIO_SYSSPACE, IO_NODELOCKED,
            td->td_ucred, NOCRED, NULL, td)) != 0)
                goto out;
 
        /* Check if decompression is required. */
        if (raw != NULL) {
                uLongf destlen;
                int ret;
 
                /*
                 * The header isn't compressed, so copy that into the
                 * CTF buffer first.
                 */
                bcopy(&cth, ctftab, sizeof(cth));
 
                destlen = sz - sizeof(cth);
                ret = uncompress(ctftab + sizeof(cth), &destlen,
                    raw + sizeof(cth), shdr[i].sh_size - sizeof(cth));
                if (ret != Z_OK) {
                        printf("%s(%d): zlib uncompress returned %d\n",
                            __func__, __LINE__, ret);
                        error = EIO;
                        goto out;
                }
        }
 
        /* Got the CTF data! */
        ef->ctftab = ctftab;
        ef->ctfcnt = shdr[i].sh_size;
 
        /* We'll retain the memory allocated for the CTF data. */
        ctftab = NULL;
 
        /* Let the caller use the CTF data read. */
        lc->ctftab = ef->ctftab;
        lc->ctfcnt = ef->ctfcnt;
        lc->symtab = ef->ddbsymtab;
        lc->strtab = ef->ddbstrtab;
        lc->strcnt = ef->ddbstrcnt;
        lc->nsym   = ef->ddbsymcnt;
        lc->ctfoffp = (uint32_t **) &ef->ctfoff;
        lc->typoffp = (uint32_t **) &ef->typoff;
        lc->typlenp = &ef->typlen;
 
out:
        VOP_UNLOCK(nd.ni_vp);
        vn_close(nd.ni_vp, FREAD, td->td_ucred, td);
 
        if (hdr != NULL)
                free(hdr, M_LINKER);
        if (shdr != NULL)
                free(shdr, M_LINKER);
        if (shstrtab != NULL)
                free(shstrtab, M_LINKER);
        if (ctftab != NULL)
                free(ctftab, M_LINKER);
        if (raw != NULL)
                free(raw, M_LINKER);
#else
        error = EOPNOTSUPP;
#endif
 
        return (error);
}