FreeBSD-5.3/usr.bin/gcore/elfcore.c
/*-
* 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: src/usr.bin/gcore/elfcore.c,v 1.17 2004/07/12 20:19:40 rwatson Exp $");
#include <sys/param.h>
#include <sys/procfs.h>
#include <sys/queue.h>
#include <sys/linker_set.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 "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_corehdr(int fd, pid_t, vm_map_entry_t, int numsegs,
void *hdr, size_t hdrsize);
static void elf_puthdr(vm_map_entry_t, void *, size_t *,
const prstatus_t *, const prfpregset_t *, const prpsinfo_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 void readhdrinfo(pid_t, prstatus_t *, prfpregset_t *, prpsinfo_t *);
static vm_map_entry_t readmap(pid_t);
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);
}
/*
* 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;
char memname[64];
int memfd;
Elf_Phdr *php;
int i;
/* 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(map, (void *)NULL, &hdrsize,
(const prstatus_t *)NULL, (const prfpregset_t *)NULL,
(const prpsinfo_t *)NULL, seginfo.count);
/*
* Allocate memory for building the header, fill it up,
* and write it out.
*/
hdr = malloc(hdrsize);
if ((hdr = malloc(hdrsize)) == NULL)
errx(1, "out of memory");
elf_corehdr(fd, pid, map, seginfo.count, hdr, hdrsize);
/* Write the contents of all of the writable segments. */
snprintf(memname, sizeof memname, "/proc/%d/mem", pid);
if ((memfd = open(memname, O_RDONLY)) == -1)
err(1, "cannot open %s", memname);
php = (Elf_Phdr *)((char *)hdr + sizeof(Elf_Ehdr)) + 1;
for (i = 0; i < seginfo.count; i++) {
uintmax_t nleft = php->p_filesz;
lseek(memfd, (off_t)php->p_vaddr, SEEK_SET);
while (nleft > 0) {
char buf[8*1024];
size_t nwant;
ssize_t ngot;
if (nleft > sizeof(buf))
nwant = sizeof buf;
else
nwant = nleft;
ngot = read(memfd, buf, nwant);
if (ngot == -1)
err(1, "read from %s", memname);
if ((size_t)ngot < nwant)
errx(1, "short read from %s:"
" wanted %d, got %d", memname,
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;
}
php++;
}
close(memfd);
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);
}
/*
* Write the core file header to the file, including padding up to
* the page boundary.
*/
static void
elf_corehdr(int fd, pid_t pid, vm_map_entry_t map, int numsegs, void *hdr,
size_t hdrsize)
{
size_t off;
prstatus_t status;
prfpregset_t fpregset;
prpsinfo_t psinfo;
/* Gather the information for the header. */
readhdrinfo(pid, &status, &fpregset, &psinfo);
/* Fill in the header. */
memset(hdr, 0, hdrsize);
off = 0;
elf_puthdr(map, hdr, &off, &status, &fpregset, &psinfo, numsegs);
/* Write it to the core file. */
if (write(fd, hdr, hdrsize) == -1)
err(1, "write");
}
/*
* 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(vm_map_entry_t map, void *dst, size_t *off, const prstatus_t *status,
const prfpregset_t *fpregset, const prpsinfo_t *psinfo, int numsegs)
{
size_t ehoff;
size_t phoff;
size_t noteoff;
size_t notesz;
ehoff = *off;
*off += sizeof(Elf_Ehdr);
phoff = *off;
*off += (numsegs + 1) * sizeof(Elf_Phdr);
noteoff = *off;
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_PRPSINFO, psinfo,
sizeof *psinfo);
notesz = *off - noteoff;
/* 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(¬e, (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 information necessary to fill in the core file's header.
*/
static void
readhdrinfo(pid_t pid, prstatus_t *status, prfpregset_t *fpregset,
prpsinfo_t *psinfo)
{
char name[64];
char line[256];
int fd;
int i;
int n;
memset(status, 0, sizeof *status);
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 = pid;
memset(fpregset, 0, sizeof *fpregset);
memset(psinfo, 0, sizeof *psinfo);
psinfo->pr_version = PRPSINFO_VERSION;
psinfo->pr_psinfosz = sizeof(prpsinfo_t);
/* Read the general registers. */
snprintf(name, sizeof name, "/proc/%d/regs", pid);
if ((fd = open(name, O_RDONLY)) == -1)
err(1, "cannot open %s", name);
if ((n = read(fd, &status->pr_reg, sizeof status->pr_reg)) == -1)
err(1, "read error from %s", name);
if ((size_t)n < sizeof(status->pr_reg))
errx(1, "short read from %s: wanted %u, got %d", name,
sizeof status->pr_reg, n);
close(fd);
/* Read the floating point registers. */
snprintf(name, sizeof name, "/proc/%d/fpregs", pid);
if ((fd = open(name, O_RDONLY)) == -1)
err(1, "cannot open %s", name);
if ((n = read(fd, fpregset, sizeof *fpregset)) == -1)
err(1, "read error from %s", name);
if ((size_t)n < sizeof(*fpregset))
errx(1, "short read from %s: wanted %u, got %d", name,
sizeof *fpregset, n);
close(fd);
/* Read and parse the process status. */
snprintf(name, sizeof name, "/proc/%d/status", pid);
if ((fd = open(name, O_RDONLY)) == -1)
err(1, "cannot open %s", name);
if ((n = read(fd, line, sizeof line - 1)) == -1)
err(1, "read error from %s", name);
if (n > MAXCOMLEN)
n = MAXCOMLEN;
for (i = 0; i < n && line[i] != ' '; i++)
psinfo->pr_fname[i] = line[i];
strncpy(psinfo->pr_psargs, psinfo->pr_fname, PRARGSZ);
close(fd);
}
/*
* Read the process's memory map using procfs, 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)
{
char mapname[64];
int mapfd;
ssize_t mapsize;
size_t bufsize;
char *mapbuf;
int pos;
vm_map_entry_t map;
vm_map_entry_t *linkp;
snprintf(mapname, sizeof mapname, "/proc/%d/map", pid);
if ((mapfd = open(mapname, O_RDONLY)) == -1)
err(1, "cannot open %s", mapname);
/*
* Procfs requires (for consistency) that the entire memory map
* be read with a single read() call. Start with a reasonably sized
* buffer, and double it until it is big enough.
*/
bufsize = 8 * 1024;
mapbuf = NULL;
for ( ; ; ) {
if ((mapbuf = realloc(mapbuf, bufsize + 1)) == NULL)
errx(1, "out of memory");
mapsize = read(mapfd, mapbuf, bufsize);
if (mapsize != -1 || errno != EFBIG)
break;
bufsize *= 2;
/* This lseek shouldn't be necessary, but it is. */
lseek(mapfd, (off_t)0, SEEK_SET);
}
if (mapsize == -1)
err(1, "read error from %s", mapname);
if (mapsize == 0)
errx(1, "empty map file %s", mapname);
mapbuf[mapsize] = 0;
close(mapfd);
pos = 0;
map = NULL;
linkp = ↦
while (pos < mapsize) {
vm_map_entry_t ent;
vm_offset_t start;
vm_offset_t end;
char prot[4];
char type[16];
int n;
int len;
len = 0;
n = sscanf(mapbuf + pos, "%x %x %*d %*d %*x %3[-rwx]"
" %*d %*d %*x %*s %*s %16s %*s%*[\n]%n",
&start, &end, prot, type, &len);
if (n != 4 || len == 0)
errx(1, "ill-formed line in %s starting at character %d", mapname, pos + 1);
pos += len;
/* Ignore segments of the wrong kind, and unwritable ones */
if (strncmp(prot, "rw", 2) != 0 ||
(strcmp(type, "default") != 0 &&
strcmp(type, "vnode") != 0 &&
strcmp(type, "swap") != 0))
continue;
if ((ent = (vm_map_entry_t)calloc(1, sizeof *ent)) == NULL)
errx(1, "out of memory");
ent->start = start;
ent->end = end;
ent->protection = VM_PROT_READ | VM_PROT_WRITE;
if (prot[2] == 'x')
ent->protection |= VM_PROT_EXECUTE;
*linkp = ent;
linkp = &ent->next;
}
free(mapbuf);
return map;
}
struct dumpers elfdump = { elf_ident, elf_coredump };
TEXT_SET(dumpset, elfdump);