freebsd-dev/sys/dev/ksyms/ksyms.c
Eric van Gyzen f9cc8410e1 vm_ooffset_t is now unsigned
vm_ooffset_t is now unsigned. Remove some tests for negative values,
or make other adjustments accordingly.

Reported by:	Coverity
Reviewed by:	kib markj
Sponsored by:	Dell EMC Isilon
Differential Revision:	https://reviews.freebsd.org/D26214
2020-09-18 16:48:08 +00:00

527 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/rwlock.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 <vm/vm_page.h>
#include <vm/vm_pager.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;
bool fixup;
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);
#ifdef RELOCATABLE_KERNEL
fixup = true;
#else
fixup = lf->id > 1;
#endif
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 (fixup && 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_object_t object;
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;
object = vm_pager_allocate(OBJT_PHYS, NULL, round_page(elfsz),
VM_PROT_ALL, 0, td->td_ucred);
sc->sc_obj = object;
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 >= 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);