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coredump: extend core dump note section to contain file names of mapp…
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…ed files

This note has the following format:

long count     -- how many files are mapped
long page_size -- units for file_ofs
array of [COUNT] elements of
   long start
   long end
   long file_ofs
followed by COUNT filenames in ASCII: "FILE1" NUL "FILE2" NUL...

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Amerigo Wang <amwang@redhat.com>
Cc: "Jonathan M. Foote" <jmfoote@cert.org>
Cc: Roland McGrath <roland@hack.frob.com>
Cc: Pedro Alves <palves@redhat.com>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Denys Vlasenko authored and torvalds committed Oct 5, 2012
1 parent 49ae4d4 commit 2aa362c
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Showing 3 changed files with 108 additions and 4 deletions.
110 changes: 106 additions & 4 deletions fs/binfmt_elf.c
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Original file line number Diff line number Diff line change
Expand Up @@ -27,6 +27,7 @@
#include <linux/compiler.h>
#include <linux/highmem.h>
#include <linux/pagemap.h>
#include <linux/vmalloc.h>
#include <linux/security.h>
#include <linux/random.h>
#include <linux/elf.h>
Expand All @@ -37,6 +38,9 @@
#include <asm/page.h>
#include <asm/exec.h>

#ifndef user_long_t
#define user_long_t long
#endif
#ifndef user_siginfo_t
#define user_siginfo_t siginfo_t
#endif
Expand Down Expand Up @@ -1386,6 +1390,93 @@ static void fill_siginfo_note(struct memelfnote *note, user_siginfo_t *csigdata,
fill_note(note, "CORE", NT_SIGINFO, sizeof(*csigdata), csigdata);
}

#define MAX_FILE_NOTE_SIZE (4*1024*1024)
/*
* Format of NT_FILE note:
*
* long count -- how many files are mapped
* long page_size -- units for file_ofs
* array of [COUNT] elements of
* long start
* long end
* long file_ofs
* followed by COUNT filenames in ASCII: "FILE1" NUL "FILE2" NUL...
*/
static void fill_files_note(struct memelfnote *note)
{
struct vm_area_struct *vma;
unsigned count, size, names_ofs, remaining, n;
user_long_t *data;
user_long_t *start_end_ofs;
char *name_base, *name_curpos;

/* *Estimated* file count and total data size needed */
count = current->mm->map_count;
size = count * 64;

names_ofs = (2 + 3 * count) * sizeof(data[0]);
alloc:
if (size >= MAX_FILE_NOTE_SIZE) /* paranoia check */
goto err;
size = round_up(size, PAGE_SIZE);
data = vmalloc(size);
if (!data)
goto err;

start_end_ofs = data + 2;
name_base = name_curpos = ((char *)data) + names_ofs;
remaining = size - names_ofs;
count = 0;
for (vma = current->mm->mmap; vma != NULL; vma = vma->vm_next) {
struct file *file;
const char *filename;

file = vma->vm_file;
if (!file)
continue;
filename = d_path(&file->f_path, name_curpos, remaining);
if (IS_ERR(filename)) {
if (PTR_ERR(filename) == -ENAMETOOLONG) {
vfree(data);
size = size * 5 / 4;
goto alloc;
}
continue;
}

/* d_path() fills at the end, move name down */
/* n = strlen(filename) + 1: */
n = (name_curpos + remaining) - filename;
remaining = filename - name_curpos;
memmove(name_curpos, filename, n);
name_curpos += n;

*start_end_ofs++ = vma->vm_start;
*start_end_ofs++ = vma->vm_end;
*start_end_ofs++ = vma->vm_pgoff;
count++;
}

/* Now we know exact count of files, can store it */
data[0] = count;
data[1] = PAGE_SIZE;
/*
* Count usually is less than current->mm->map_count,
* we need to move filenames down.
*/
n = current->mm->map_count - count;
if (n != 0) {
unsigned shift_bytes = n * 3 * sizeof(data[0]);
memmove(name_base - shift_bytes, name_base,
name_curpos - name_base);
name_curpos -= shift_bytes;
}

size = name_curpos - (char *)data;
fill_note(note, "CORE", NT_FILE, size, data);
err: ;
}

#ifdef CORE_DUMP_USE_REGSET
#include <linux/regset.h>

Expand All @@ -1401,6 +1492,7 @@ struct elf_note_info {
struct memelfnote psinfo;
struct memelfnote signote;
struct memelfnote auxv;
struct memelfnote files;
user_siginfo_t csigdata;
size_t size;
int thread_notes;
Expand Down Expand Up @@ -1581,6 +1673,9 @@ static int fill_note_info(struct elfhdr *elf, int phdrs,
fill_auxv_note(&info->auxv, current->mm);
info->size += notesize(&info->auxv);

fill_files_note(&info->files);
info->size += notesize(&info->files);

return 1;
}

Expand Down Expand Up @@ -1611,6 +1706,8 @@ static int write_note_info(struct elf_note_info *info,
return 0;
if (first && !writenote(&info->auxv, file, foffset))
return 0;
if (first && !writenote(&info->files, file, foffset))
return 0;

for (i = 1; i < info->thread_notes; ++i)
if (t->notes[i].data &&
Expand All @@ -1637,6 +1734,7 @@ static void free_note_info(struct elf_note_info *info)
kfree(t);
}
kfree(info->psinfo.data);
vfree(info->files.data);
}

#else
Expand Down Expand Up @@ -1713,7 +1811,7 @@ static int elf_note_info_init(struct elf_note_info *info)
INIT_LIST_HEAD(&info->thread_list);

/* Allocate space for ELF notes */
info->notes = kmalloc(7 * sizeof(struct memelfnote), GFP_KERNEL);
info->notes = kmalloc(8 * sizeof(struct memelfnote), GFP_KERNEL);
if (!info->notes)
return 0;
info->psinfo = kmalloc(sizeof(*info->psinfo), GFP_KERNEL);
Expand Down Expand Up @@ -1783,10 +1881,11 @@ static int fill_note_info(struct elfhdr *elf, int phdrs,
fill_note(info->notes + 1, "CORE", NT_PRPSINFO,
sizeof(*info->psinfo), info->psinfo);

info->numnote = 2;
fill_siginfo_note(info->notes + 2, &info->csigdata, siginfo);
fill_auxv_note(info->notes + 3, current->mm);
fill_files_note(info->notes + 4);

fill_siginfo_note(&info->notes[info->numnote++], &info->csigdata, siginfo);
fill_auxv_note(&info->notes[info->numnote++], current->mm);
info->numnote = 5;

/* Try to dump the FPU. */
info->prstatus->pr_fpvalid = elf_core_copy_task_fpregs(current, regs,
Expand Down Expand Up @@ -1848,6 +1947,9 @@ static void free_note_info(struct elf_note_info *info)
kfree(list_entry(tmp, struct elf_thread_status, list));
}

/* Free data allocated by fill_files_note(): */
vfree(info->notes[4].data);

kfree(info->prstatus);
kfree(info->psinfo);
kfree(info->notes);
Expand Down
1 change: 1 addition & 0 deletions fs/compat_binfmt_elf.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -40,6 +40,7 @@
/*
* Some data types as stored in coredump.
*/
#define user_long_t compat_long_t
#define user_siginfo_t compat_siginfo_t
#define copy_siginfo_to_user copy_siginfo_to_user32

Expand Down
1 change: 1 addition & 0 deletions include/linux/elf.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -377,6 +377,7 @@ typedef struct elf64_shdr {
* in the future to accomodate more fields, don't assume it is fixed!
*/
#define NT_SIGINFO 0x53494749
#define NT_FILE 0x46494c45
#define NT_PRXFPREG 0x46e62b7f /* copied from gdb5.1/include/elf/common.h */
#define NT_PPC_VMX 0x100 /* PowerPC Altivec/VMX registers */
#define NT_PPC_SPE 0x101 /* PowerPC SPE/EVR registers */
Expand Down

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