freebsd-dev/sys/dev/ksyms/ksyms.c
Pedro F. Giffuni 718cf2ccb9 sys/dev: further adoption of SPDX licensing ID tags.
Mainly focus on files that use BSD 2-Clause license, however the tool I
was using misidentified many licenses so this was mostly a manual - error
prone - task.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.
2017-11-27 14:52:40 +00:00

515 lines
13 KiB
C

/*-
* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
*
* Copyright (c) 2008-2009, Stacey Son <sson@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/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/conf.h>
#include <sys/elf.h>
#include <sys/linker.h>
#include <sys/malloc.h>
#include <sys/mman.h>
#include <sys/module.h>
#include <sys/proc.h>
#include <sys/queue.h>
#include <sys/resourcevar.h>
#include <sys/stat.h>
#include <sys/sx.h>
#include <sys/uio.h>
#include <machine/elf.h>
#include <vm/pmap.h>
#include <vm/vm.h>
#include <vm/vm_extern.h>
#include <vm/vm_object.h>
#include "linker_if.h"
#define SHDR_NULL 0
#define SHDR_SYMTAB 1
#define SHDR_STRTAB 2
#define SHDR_SHSTRTAB 3
#define SHDR_NUM 4
#define STR_SYMTAB ".symtab"
#define STR_STRTAB ".strtab"
#define STR_SHSTRTAB ".shstrtab"
#define KSYMS_DNAME "ksyms"
static d_open_t ksyms_open;
static d_read_t ksyms_read;
static d_mmap_single_t ksyms_mmap_single;
static struct cdevsw ksyms_cdevsw = {
.d_version = D_VERSION,
.d_flags = 0,
.d_open = ksyms_open,
.d_read = ksyms_read,
.d_mmap_single = ksyms_mmap_single,
.d_name = KSYMS_DNAME
};
struct ksyms_softc {
LIST_ENTRY(ksyms_softc) sc_list;
vm_offset_t sc_uaddr;
size_t sc_usize;
vm_object_t sc_obj;
vm_size_t sc_objsz;
struct proc *sc_proc;
};
static struct sx ksyms_mtx;
static struct cdev *ksyms_dev;
static LIST_HEAD(, ksyms_softc) ksyms_list = LIST_HEAD_INITIALIZER(ksyms_list);
static const char ksyms_shstrtab[] =
"\0" STR_SYMTAB "\0" STR_STRTAB "\0" STR_SHSTRTAB "\0";
struct ksyms_hdr {
Elf_Ehdr kh_ehdr;
Elf_Phdr kh_txtphdr;
Elf_Phdr kh_datphdr;
Elf_Shdr kh_shdr[SHDR_NUM];
char kh_shstrtab[sizeof(ksyms_shstrtab)];
};
struct tsizes {
size_t ts_symsz;
size_t ts_strsz;
};
struct toffsets {
struct ksyms_softc *to_sc;
vm_offset_t to_symoff;
vm_offset_t to_stroff;
unsigned to_stridx;
size_t to_resid;
};
static MALLOC_DEFINE(M_KSYMS, "KSYMS", "Kernel Symbol Table");
/*
* Get the symbol and string table sizes for a kernel module. Add it to the
* running total.
*/
static int
ksyms_size_permod(linker_file_t lf, void *arg)
{
struct tsizes *ts;
const Elf_Sym *symtab;
caddr_t strtab;
long syms;
ts = arg;
syms = LINKER_SYMTAB_GET(lf, &symtab);
ts->ts_symsz += syms * sizeof(Elf_Sym);
ts->ts_strsz += LINKER_STRTAB_GET(lf, &strtab);
return (0);
}
/*
* For kernel module get the symbol and string table sizes, returning the
* totals in *ts.
*/
static void
ksyms_size_calc(struct tsizes *ts)
{
ts->ts_symsz = 0;
ts->ts_strsz = 0;
(void)linker_file_foreach(ksyms_size_permod, ts);
}
static int
ksyms_emit(struct ksyms_softc *sc, void *buf, off_t off, size_t sz)
{
struct iovec iov;
struct uio uio;
iov.iov_base = buf;
iov.iov_len = sz;
uio.uio_iov = &iov;
uio.uio_iovcnt = 1;
uio.uio_offset = off;
uio.uio_resid = (ssize_t)sz;
uio.uio_segflg = UIO_SYSSPACE;
uio.uio_rw = UIO_WRITE;
uio.uio_td = curthread;
return (uiomove_object(sc->sc_obj, sc->sc_objsz, &uio));
}
#define SYMBLKSZ (256 * sizeof(Elf_Sym))
/*
* For a kernel module, add the symbol and string tables into the
* snapshot buffer. Fix up the offsets in the tables.
*/
static int
ksyms_add(linker_file_t lf, void *arg)
{
char *buf;
struct ksyms_softc *sc;
struct toffsets *to;
const Elf_Sym *symtab;
Elf_Sym *symp;
caddr_t strtab;
size_t len, numsyms, strsz, symsz;
linker_symval_t symval;
int error, i, nsyms;
buf = malloc(SYMBLKSZ, M_KSYMS, M_WAITOK);
to = arg;
sc = to->to_sc;
MOD_SLOCK;
numsyms = LINKER_SYMTAB_GET(lf, &symtab);
strsz = LINKER_STRTAB_GET(lf, &strtab);
symsz = numsyms * sizeof(Elf_Sym);
while (symsz > 0) {
len = min(SYMBLKSZ, symsz);
bcopy(symtab, buf, len);
/*
* Fix up symbol table for kernel modules:
* string offsets need adjusted
* symbol values made absolute
*/
symp = (Elf_Sym *) buf;
nsyms = len / sizeof(Elf_Sym);
for (i = 0; i < nsyms; i++) {
symp[i].st_name += to->to_stridx;
if (lf->id > 1 && LINKER_SYMBOL_VALUES(lf,
(c_linker_sym_t)&symtab[i], &symval) == 0) {
symp[i].st_value = (uintptr_t)symval.value;
}
}
if (len > to->to_resid) {
MOD_SUNLOCK;
free(buf, M_KSYMS);
return (ENXIO);
}
to->to_resid -= len;
error = ksyms_emit(sc, buf, to->to_symoff, len);
to->to_symoff += len;
if (error != 0) {
MOD_SUNLOCK;
free(buf, M_KSYMS);
return (error);
}
symtab += nsyms;
symsz -= len;
}
free(buf, M_KSYMS);
MOD_SUNLOCK;
if (strsz > to->to_resid)
return (ENXIO);
to->to_resid -= strsz;
error = ksyms_emit(sc, strtab, to->to_stroff, strsz);
to->to_stroff += strsz;
to->to_stridx += strsz;
return (error);
}
/*
* Create a single ELF symbol table for the kernel and kernel modules loaded
* at this time. Write this snapshot out in the process address space. Return
* 0 on success, otherwise error.
*/
static int
ksyms_snapshot(struct ksyms_softc *sc, struct tsizes *ts)
{
struct toffsets to;
struct ksyms_hdr *hdr;
int error;
hdr = malloc(sizeof(*hdr), M_KSYMS, M_WAITOK | M_ZERO);
/*
* Create the ELF header.
*/
hdr->kh_ehdr.e_ident[EI_PAD] = 0;
hdr->kh_ehdr.e_ident[EI_MAG0] = ELFMAG0;
hdr->kh_ehdr.e_ident[EI_MAG1] = ELFMAG1;
hdr->kh_ehdr.e_ident[EI_MAG2] = ELFMAG2;
hdr->kh_ehdr.e_ident[EI_MAG3] = ELFMAG3;
hdr->kh_ehdr.e_ident[EI_DATA] = ELF_DATA;
hdr->kh_ehdr.e_ident[EI_OSABI] = ELFOSABI_FREEBSD;
hdr->kh_ehdr.e_ident[EI_CLASS] = ELF_CLASS;
hdr->kh_ehdr.e_ident[EI_VERSION] = EV_CURRENT;
hdr->kh_ehdr.e_ident[EI_ABIVERSION] = 0;
hdr->kh_ehdr.e_type = ET_EXEC;
hdr->kh_ehdr.e_machine = ELF_ARCH;
hdr->kh_ehdr.e_version = EV_CURRENT;
hdr->kh_ehdr.e_entry = 0;
hdr->kh_ehdr.e_phoff = offsetof(struct ksyms_hdr, kh_txtphdr);
hdr->kh_ehdr.e_shoff = offsetof(struct ksyms_hdr, kh_shdr);
hdr->kh_ehdr.e_flags = 0;
hdr->kh_ehdr.e_ehsize = sizeof(Elf_Ehdr);
hdr->kh_ehdr.e_phentsize = sizeof(Elf_Phdr);
hdr->kh_ehdr.e_phnum = 2; /* Text and Data */
hdr->kh_ehdr.e_shentsize = sizeof(Elf_Shdr);
hdr->kh_ehdr.e_shnum = SHDR_NUM;
hdr->kh_ehdr.e_shstrndx = SHDR_SHSTRTAB;
/*
* Add both the text and data program headers.
*/
hdr->kh_txtphdr.p_type = PT_LOAD;
/* XXX - is there a way to put the actual .text addr/size here? */
hdr->kh_txtphdr.p_vaddr = 0;
hdr->kh_txtphdr.p_memsz = 0;
hdr->kh_txtphdr.p_flags = PF_R | PF_X;
hdr->kh_datphdr.p_type = PT_LOAD;
/* XXX - is there a way to put the actual .data addr/size here? */
hdr->kh_datphdr.p_vaddr = 0;
hdr->kh_datphdr.p_memsz = 0;
hdr->kh_datphdr.p_flags = PF_R | PF_W | PF_X;
/*
* Add the section headers: null, symtab, strtab, shstrtab.
*/
/* First section header - null */
/* Second section header - symtab */
hdr->kh_shdr[SHDR_SYMTAB].sh_name = 1; /* String offset (skip null) */
hdr->kh_shdr[SHDR_SYMTAB].sh_type = SHT_SYMTAB;
hdr->kh_shdr[SHDR_SYMTAB].sh_flags = 0;
hdr->kh_shdr[SHDR_SYMTAB].sh_addr = 0;
hdr->kh_shdr[SHDR_SYMTAB].sh_offset = sizeof(*hdr);
hdr->kh_shdr[SHDR_SYMTAB].sh_size = ts->ts_symsz;
hdr->kh_shdr[SHDR_SYMTAB].sh_link = SHDR_STRTAB;
hdr->kh_shdr[SHDR_SYMTAB].sh_info = ts->ts_symsz / sizeof(Elf_Sym);
hdr->kh_shdr[SHDR_SYMTAB].sh_addralign = sizeof(long);
hdr->kh_shdr[SHDR_SYMTAB].sh_entsize = sizeof(Elf_Sym);
/* Third section header - strtab */
hdr->kh_shdr[SHDR_STRTAB].sh_name = 1 + sizeof(STR_SYMTAB);
hdr->kh_shdr[SHDR_STRTAB].sh_type = SHT_STRTAB;
hdr->kh_shdr[SHDR_STRTAB].sh_flags = 0;
hdr->kh_shdr[SHDR_STRTAB].sh_addr = 0;
hdr->kh_shdr[SHDR_STRTAB].sh_offset =
hdr->kh_shdr[SHDR_SYMTAB].sh_offset + ts->ts_symsz;
hdr->kh_shdr[SHDR_STRTAB].sh_size = ts->ts_strsz;
hdr->kh_shdr[SHDR_STRTAB].sh_link = 0;
hdr->kh_shdr[SHDR_STRTAB].sh_info = 0;
hdr->kh_shdr[SHDR_STRTAB].sh_addralign = sizeof(char);
hdr->kh_shdr[SHDR_STRTAB].sh_entsize = 0;
/* Fourth section - shstrtab */
hdr->kh_shdr[SHDR_SHSTRTAB].sh_name = 1 + sizeof(STR_SYMTAB) +
sizeof(STR_STRTAB);
hdr->kh_shdr[SHDR_SHSTRTAB].sh_type = SHT_STRTAB;
hdr->kh_shdr[SHDR_SHSTRTAB].sh_flags = 0;
hdr->kh_shdr[SHDR_SHSTRTAB].sh_addr = 0;
hdr->kh_shdr[SHDR_SHSTRTAB].sh_offset =
offsetof(struct ksyms_hdr, kh_shstrtab);
hdr->kh_shdr[SHDR_SHSTRTAB].sh_size = sizeof(ksyms_shstrtab);
hdr->kh_shdr[SHDR_SHSTRTAB].sh_link = 0;
hdr->kh_shdr[SHDR_SHSTRTAB].sh_info = 0;
hdr->kh_shdr[SHDR_SHSTRTAB].sh_addralign = 0 /* sizeof(char) */;
hdr->kh_shdr[SHDR_SHSTRTAB].sh_entsize = 0;
/* Copy shstrtab into the header. */
bcopy(ksyms_shstrtab, hdr->kh_shstrtab, sizeof(ksyms_shstrtab));
to.to_sc = sc;
to.to_symoff = hdr->kh_shdr[SHDR_SYMTAB].sh_offset;
to.to_stroff = hdr->kh_shdr[SHDR_STRTAB].sh_offset;
to.to_stridx = 0;
to.to_resid = sc->sc_objsz - sizeof(struct ksyms_hdr);
/* emit header */
error = ksyms_emit(sc, hdr, 0, sizeof(*hdr));
free(hdr, M_KSYMS);
if (error != 0)
return (error);
/* Add symbol and string tables for each kernel module. */
error = linker_file_foreach(ksyms_add, &to);
if (error != 0)
return (error);
if (to.to_resid != 0)
return (ENXIO);
return (0);
}
static void
ksyms_cdevpriv_dtr(void *data)
{
struct ksyms_softc *sc;
vm_object_t obj;
sc = (struct ksyms_softc *)data;
sx_xlock(&ksyms_mtx);
LIST_REMOVE(sc, sc_list);
sx_xunlock(&ksyms_mtx);
obj = sc->sc_obj;
if (obj != NULL)
vm_object_deallocate(obj);
free(sc, M_KSYMS);
}
static int
ksyms_open(struct cdev *dev, int flags, int fmt __unused, struct thread *td)
{
struct tsizes ts;
struct ksyms_softc *sc;
vm_size_t elfsz;
int error, try;
/*
* Limit one open() per process. The process must close()
* before open()'ing again.
*/
sx_xlock(&ksyms_mtx);
LIST_FOREACH(sc, &ksyms_list, sc_list) {
if (sc->sc_proc == td->td_proc) {
sx_xunlock(&ksyms_mtx);
return (EBUSY);
}
}
sc = malloc(sizeof(*sc), M_KSYMS, M_WAITOK | M_ZERO);
sc->sc_proc = td->td_proc;
LIST_INSERT_HEAD(&ksyms_list, sc, sc_list);
sx_xunlock(&ksyms_mtx);
error = devfs_set_cdevpriv(sc, ksyms_cdevpriv_dtr);
if (error != 0) {
ksyms_cdevpriv_dtr(sc);
return (error);
}
/*
* MOD_SLOCK doesn't work here (because of a lock reversal with
* KLD_SLOCK). Therefore, simply try up to 3 times to get a "clean"
* snapshot of the kernel symbol table. This should work fine in the
* rare case of a kernel module being loaded/unloaded at the same
* time.
*/
for (try = 0; try < 3; try++) {
ksyms_size_calc(&ts);
elfsz = sizeof(struct ksyms_hdr) + ts.ts_symsz + ts.ts_strsz;
sc->sc_obj = vm_object_allocate(OBJT_DEFAULT,
OFF_TO_IDX(round_page(elfsz)));
sc->sc_objsz = elfsz;
error = ksyms_snapshot(sc, &ts);
if (error == 0)
break;
vm_object_deallocate(sc->sc_obj);
sc->sc_obj = NULL;
}
return (error);
}
static int
ksyms_read(struct cdev *dev, struct uio *uio, int flags __unused)
{
struct ksyms_softc *sc;
int error;
error = devfs_get_cdevpriv((void **)&sc);
if (error != 0)
return (error);
return (uiomove_object(sc->sc_obj, sc->sc_objsz, uio));
}
static int
ksyms_mmap_single(struct cdev *dev, vm_ooffset_t *offset, vm_size_t size,
vm_object_t *objp, int nprot)
{
struct ksyms_softc *sc;
vm_object_t obj;
int error;
error = devfs_get_cdevpriv((void **)&sc);
if (error != 0)
return (error);
if (*offset < 0 || *offset >= round_page(sc->sc_objsz) ||
size > round_page(sc->sc_objsz) - *offset ||
(nprot & ~PROT_READ) != 0)
return (EINVAL);
obj = sc->sc_obj;
vm_object_reference(obj);
*objp = obj;
return (0);
}
static int
ksyms_modevent(module_t mod __unused, int type, void *data __unused)
{
int error;
error = 0;
switch (type) {
case MOD_LOAD:
sx_init(&ksyms_mtx, "KSyms mtx");
ksyms_dev = make_dev(&ksyms_cdevsw, 0, UID_ROOT, GID_WHEEL,
0400, KSYMS_DNAME);
break;
case MOD_UNLOAD:
if (!LIST_EMPTY(&ksyms_list))
return (EBUSY);
destroy_dev(ksyms_dev);
sx_destroy(&ksyms_mtx);
break;
case MOD_SHUTDOWN:
break;
default:
error = EOPNOTSUPP;
break;
}
return (error);
}
DEV_MODULE(ksyms, ksyms_modevent, NULL);
MODULE_VERSION(ksyms, 1);