freebsd-dev/usr.bin/gcore/elfcore.c
2011-07-11 05:46:15 +00:00

535 lines
14 KiB
C

/*-
* Copyright (c) 2007 Sandvine Incorporated
* Copyright (c) 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 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/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/procfs.h>
#include <sys/ptrace.h>
#include <sys/queue.h>
#include <sys/linker_set.h>
#include <sys/sysctl.h>
#include <sys/user.h>
#include <sys/wait.h>
#include <machine/elf.h>
#include <vm/vm_param.h>
#include <vm/vm.h>
#include <vm/pmap.h>
#include <vm/vm_map.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <libutil.h>
#include "extern.h"
/*
* Code for generating ELF core dumps.
*/
typedef void (*segment_callback)(vm_map_entry_t, void *);
/* Closure for cb_put_phdr(). */
struct phdr_closure {
Elf_Phdr *phdr; /* Program header to fill in */
Elf_Off offset; /* Offset of segment in core file */
};
/* Closure for cb_size_segment(). */
struct sseg_closure {
int count; /* Count of writable segments. */
size_t size; /* Total size of all writable segments. */
};
static void cb_put_phdr(vm_map_entry_t, void *);
static void cb_size_segment(vm_map_entry_t, void *);
static void each_writable_segment(vm_map_entry_t, segment_callback,
void *closure);
static void elf_detach(void); /* atexit() handler. */
static void elf_puthdr(pid_t, vm_map_entry_t, void *, size_t *, int numsegs);
static void elf_putnote(void *dst, size_t *off, const char *name, int type,
const void *desc, size_t descsz);
static void freemap(vm_map_entry_t);
static vm_map_entry_t readmap(pid_t);
static pid_t g_pid; /* Pid being dumped, global for elf_detach */
static int
elf_ident(int efd, pid_t pid __unused, char *binfile __unused)
{
Elf_Ehdr hdr;
int cnt;
cnt = read(efd, &hdr, sizeof(hdr));
if (cnt != sizeof(hdr))
return (0);
if (IS_ELF(hdr))
return (1);
return (0);
}
static void
elf_detach(void)
{
if (g_pid != 0)
ptrace(PT_DETACH, g_pid, (caddr_t)1, 0);
}
/*
* Write an ELF coredump for the given pid to the given fd.
*/
static void
elf_coredump(int efd __unused, int fd, pid_t pid)
{
vm_map_entry_t map;
struct sseg_closure seginfo;
void *hdr;
size_t hdrsize;
Elf_Phdr *php;
int i;
/* Attach to process to dump. */
g_pid = pid;
if (atexit(elf_detach) != 0)
err(1, "atexit");
errno = 0;
ptrace(PT_ATTACH, pid, NULL, 0);
if (errno)
err(1, "PT_ATTACH");
if (waitpid(pid, NULL, 0) == -1)
err(1, "waitpid");
/* Get the program's memory map. */
map = readmap(pid);
/* Size the program segments. */
seginfo.count = 0;
seginfo.size = 0;
each_writable_segment(map, cb_size_segment, &seginfo);
/*
* Calculate the size of the core file header area by making
* a dry run of generating it. Nothing is written, but the
* size is calculated.
*/
hdrsize = 0;
elf_puthdr(pid, map, NULL, &hdrsize, seginfo.count);
/*
* Allocate memory for building the header, fill it up,
* and write it out.
*/
if ((hdr = calloc(1, hdrsize)) == NULL)
errx(1, "out of memory");
/* Fill in the header. */
hdrsize = 0;
elf_puthdr(pid, map, hdr, &hdrsize, seginfo.count);
/* Write it to the core file. */
if (write(fd, hdr, hdrsize) == -1)
err(1, "write");
/* Write the contents of all of the writable segments. */
php = (Elf_Phdr *)((char *)hdr + sizeof(Elf_Ehdr)) + 1;
for (i = 0; i < seginfo.count; i++) {
struct ptrace_io_desc iorequest;
uintmax_t nleft = php->p_filesz;
iorequest.piod_op = PIOD_READ_D;
iorequest.piod_offs = (caddr_t)php->p_vaddr;
while (nleft > 0) {
char buf[8*1024];
size_t nwant;
ssize_t ngot;
if (nleft > sizeof(buf))
nwant = sizeof buf;
else
nwant = nleft;
iorequest.piod_addr = buf;
iorequest.piod_len = nwant;
ptrace(PT_IO, pid, (caddr_t)&iorequest, 0);
ngot = iorequest.piod_len;
if ((size_t)ngot < nwant)
errx(1, "short read wanted %zu, got %zd",
nwant, ngot);
ngot = write(fd, buf, nwant);
if (ngot == -1)
err(1, "write of segment %d failed", i);
if ((size_t)ngot != nwant)
errx(1, "short write");
nleft -= nwant;
iorequest.piod_offs += ngot;
}
php++;
}
free(hdr);
freemap(map);
}
/*
* A callback for each_writable_segment() to write out the segment's
* program header entry.
*/
static void
cb_put_phdr(vm_map_entry_t entry, void *closure)
{
struct phdr_closure *phc = (struct phdr_closure *)closure;
Elf_Phdr *phdr = phc->phdr;
phc->offset = round_page(phc->offset);
phdr->p_type = PT_LOAD;
phdr->p_offset = phc->offset;
phdr->p_vaddr = entry->start;
phdr->p_paddr = 0;
phdr->p_filesz = phdr->p_memsz = entry->end - entry->start;
phdr->p_align = PAGE_SIZE;
phdr->p_flags = 0;
if (entry->protection & VM_PROT_READ)
phdr->p_flags |= PF_R;
if (entry->protection & VM_PROT_WRITE)
phdr->p_flags |= PF_W;
if (entry->protection & VM_PROT_EXECUTE)
phdr->p_flags |= PF_X;
phc->offset += phdr->p_filesz;
phc->phdr++;
}
/*
* A callback for each_writable_segment() to gather information about
* the number of segments and their total size.
*/
static void
cb_size_segment(vm_map_entry_t entry, void *closure)
{
struct sseg_closure *ssc = (struct sseg_closure *)closure;
ssc->count++;
ssc->size += entry->end - entry->start;
}
/*
* For each segment in the given memory map, call the given function
* with a pointer to the map entry and some arbitrary caller-supplied
* data.
*/
static void
each_writable_segment(vm_map_entry_t map, segment_callback func, void *closure)
{
vm_map_entry_t entry;
for (entry = map; entry != NULL; entry = entry->next)
(*func)(entry, closure);
}
static void
elf_getstatus(pid_t pid, prpsinfo_t *psinfo)
{
struct kinfo_proc kobj;
int name[4];
size_t len;
name[0] = CTL_KERN;
name[1] = KERN_PROC;
name[2] = KERN_PROC_PID;
name[3] = pid;
len = sizeof(kobj);
if (sysctl(name, 4, &kobj, &len, NULL, 0) == -1)
err(1, "error accessing kern.proc.pid.%u sysctl", pid);
if (kobj.ki_pid != pid)
err(1, "error accessing kern.proc.pid.%u sysctl datas", pid);
strncpy(psinfo->pr_fname, kobj.ki_comm, MAXCOMLEN);
strncpy(psinfo->pr_psargs, psinfo->pr_fname, PRARGSZ);
}
/*
* Generate the ELF coredump header into the buffer at "dst". "dst" may
* be NULL, in which case the header is sized but not actually generated.
*/
static void
elf_puthdr(pid_t pid, vm_map_entry_t map, void *dst, size_t *off, int numsegs)
{
struct ptrace_lwpinfo lwpinfo;
struct {
prstatus_t status;
prfpregset_t fpregset;
prpsinfo_t psinfo;
thrmisc_t thrmisc;
} *tempdata;
size_t ehoff;
size_t phoff;
size_t noteoff;
size_t notesz;
size_t threads;
lwpid_t *tids;
int i;
prstatus_t *status;
prfpregset_t *fpregset;
prpsinfo_t *psinfo;
thrmisc_t *thrmisc;
ehoff = *off;
*off += sizeof(Elf_Ehdr);
phoff = *off;
*off += (numsegs + 1) * sizeof(Elf_Phdr);
noteoff = *off;
if (dst != NULL) {
if ((tempdata = calloc(1, sizeof(*tempdata))) == NULL)
errx(1, "out of memory");
status = &tempdata->status;
fpregset = &tempdata->fpregset;
psinfo = &tempdata->psinfo;
thrmisc = &tempdata->thrmisc;
} else {
tempdata = NULL;
status = NULL;
fpregset = NULL;
psinfo = NULL;
thrmisc = NULL;
}
errno = 0;
threads = ptrace(PT_GETNUMLWPS, pid, NULL, 0);
if (errno)
err(1, "PT_GETNUMLWPS");
if (dst != NULL) {
psinfo->pr_version = PRPSINFO_VERSION;
psinfo->pr_psinfosz = sizeof(prpsinfo_t);
elf_getstatus(pid, psinfo);
}
elf_putnote(dst, off, "FreeBSD", NT_PRPSINFO, psinfo,
sizeof *psinfo);
if (dst != NULL) {
tids = malloc(threads * sizeof(*tids));
if (tids == NULL)
errx(1, "out of memory");
errno = 0;
ptrace(PT_GETLWPLIST, pid, (void *)tids, threads);
if (errno)
err(1, "PT_GETLWPLIST");
}
for (i = 0; i < threads; ++i) {
if (dst != NULL) {
status->pr_version = PRSTATUS_VERSION;
status->pr_statussz = sizeof(prstatus_t);
status->pr_gregsetsz = sizeof(gregset_t);
status->pr_fpregsetsz = sizeof(fpregset_t);
status->pr_osreldate = __FreeBSD_version;
status->pr_pid = tids[i];
ptrace(PT_GETREGS, tids[i], (void *)&status->pr_reg, 0);
ptrace(PT_GETFPREGS, tids[i], (void *)fpregset, 0);
ptrace(PT_LWPINFO, tids[i], (void *)&lwpinfo,
sizeof(lwpinfo));
memset(&thrmisc->_pad, 0, sizeof(thrmisc->_pad));
strcpy(thrmisc->pr_tname, lwpinfo.pl_tdname);
}
elf_putnote(dst, off, "FreeBSD", NT_PRSTATUS, status,
sizeof *status);
elf_putnote(dst, off, "FreeBSD", NT_FPREGSET, fpregset,
sizeof *fpregset);
elf_putnote(dst, off, "FreeBSD", NT_THRMISC, thrmisc,
sizeof *thrmisc);
}
notesz = *off - noteoff;
if (dst != NULL) {
free(tids);
free(tempdata);
}
/* Align up to a page boundary for the program segments. */
*off = round_page(*off);
if (dst != NULL) {
Elf_Ehdr *ehdr;
Elf_Phdr *phdr;
struct phdr_closure phc;
/*
* Fill in the ELF header.
*/
ehdr = (Elf_Ehdr *)((char *)dst + ehoff);
ehdr->e_ident[EI_MAG0] = ELFMAG0;
ehdr->e_ident[EI_MAG1] = ELFMAG1;
ehdr->e_ident[EI_MAG2] = ELFMAG2;
ehdr->e_ident[EI_MAG3] = ELFMAG3;
ehdr->e_ident[EI_CLASS] = ELF_CLASS;
ehdr->e_ident[EI_DATA] = ELF_DATA;
ehdr->e_ident[EI_VERSION] = EV_CURRENT;
ehdr->e_ident[EI_OSABI] = ELFOSABI_FREEBSD;
ehdr->e_ident[EI_ABIVERSION] = 0;
ehdr->e_ident[EI_PAD] = 0;
ehdr->e_type = ET_CORE;
ehdr->e_machine = ELF_ARCH;
ehdr->e_version = EV_CURRENT;
ehdr->e_entry = 0;
ehdr->e_phoff = phoff;
ehdr->e_flags = 0;
ehdr->e_ehsize = sizeof(Elf_Ehdr);
ehdr->e_phentsize = sizeof(Elf_Phdr);
ehdr->e_phnum = numsegs + 1;
ehdr->e_shentsize = sizeof(Elf_Shdr);
ehdr->e_shnum = 0;
ehdr->e_shstrndx = SHN_UNDEF;
/*
* Fill in the program header entries.
*/
phdr = (Elf_Phdr *)((char *)dst + phoff);
/* The note segment. */
phdr->p_type = PT_NOTE;
phdr->p_offset = noteoff;
phdr->p_vaddr = 0;
phdr->p_paddr = 0;
phdr->p_filesz = notesz;
phdr->p_memsz = 0;
phdr->p_flags = 0;
phdr->p_align = 0;
phdr++;
/* All the writable segments from the program. */
phc.phdr = phdr;
phc.offset = *off;
each_writable_segment(map, cb_put_phdr, &phc);
}
}
/*
* Emit one note section to "dst", or just size it if "dst" is NULL.
*/
static void
elf_putnote(void *dst, size_t *off, const char *name, int type,
const void *desc, size_t descsz)
{
Elf_Note note;
note.n_namesz = strlen(name) + 1;
note.n_descsz = descsz;
note.n_type = type;
if (dst != NULL)
bcopy(&note, (char *)dst + *off, sizeof note);
*off += sizeof note;
if (dst != NULL)
bcopy(name, (char *)dst + *off, note.n_namesz);
*off += roundup2(note.n_namesz, sizeof(Elf_Size));
if (dst != NULL)
bcopy(desc, (char *)dst + *off, note.n_descsz);
*off += roundup2(note.n_descsz, sizeof(Elf_Size));
}
/*
* Free the memory map.
*/
static void
freemap(vm_map_entry_t map)
{
while (map != NULL) {
vm_map_entry_t next = map->next;
free(map);
map = next;
}
}
/*
* Read the process's memory map using kinfo_getvmmap(), and return a list of
* VM map entries. Only the non-device read/writable segments are
* returned. The map entries in the list aren't fully filled in; only
* the items we need are present.
*/
static vm_map_entry_t
readmap(pid_t pid)
{
vm_map_entry_t ent, *linkp, map;
struct kinfo_vmentry *vmentl, *kve;
int i, nitems;
vmentl = kinfo_getvmmap(pid, &nitems);
if (vmentl == NULL)
err(1, "cannot retrieve mappings for %u process", pid);
map = NULL;
linkp = &map;
for (i = 0; i < nitems; i++) {
kve = &vmentl[i];
/*
* Ignore 'malformed' segments or ones representing memory
* mapping with MAP_NOCORE on.
* If the 'full' support is disabled, just dump the most
* meaningful data segments.
*/
if ((kve->kve_protection & KVME_PROT_READ) == 0 ||
(kve->kve_flags & KVME_FLAG_NOCOREDUMP) != 0 ||
kve->kve_type == KVME_TYPE_DEAD ||
kve->kve_type == KVME_TYPE_UNKNOWN ||
((pflags & PFLAGS_FULL) == 0 &&
kve->kve_type != KVME_TYPE_DEFAULT &&
kve->kve_type != KVME_TYPE_VNODE &&
kve->kve_type != KVME_TYPE_SWAP))
continue;
ent = calloc(1, sizeof(*ent));
if (ent == NULL)
errx(1, "out of memory");
ent->start = (vm_offset_t)kve->kve_start;
ent->end = (vm_offset_t)kve->kve_end;
ent->protection = VM_PROT_READ | VM_PROT_WRITE;
if ((kve->kve_protection & KVME_PROT_EXEC) != 0)
ent->protection |= VM_PROT_EXECUTE;
*linkp = ent;
linkp = &ent->next;
}
free(vmentl);
return (map);
}
struct dumpers elfdump = { elf_ident, elf_coredump };
TEXT_SET(dumpset, elfdump);