This patch enables to omit anonymous shared memory from a core file
when it is generated.
If you don't want to dump shared memory segments of <pid> process,
set the bit 0 of the /proc/<pid>/core_flags to 1.
$ echo 1 > /proc/<pid>/core_flags
The debug messages from maydump() in fs/binfmt_elf_fdpic.c are changed
appropriately so that we can know what kind of memory segments are
dumped or not.
Signed-off-by: Hidehiro Kawai <[EMAIL PROTECTED]>
---
fs/binfmt_elf.c | 20 ++++++++++++++------
fs/binfmt_elf_fdpic.c | 37 +++++++++++++++++++++++++------------
include/linux/binfmts.h | 3 +++
3 files changed, 42 insertions(+), 18 deletions(-)
Index: linux-2.6.20-rc4-mm1/fs/binfmt_elf.c
===================================================================
--- linux-2.6.20-rc4-mm1.orig/fs/binfmt_elf.c
+++ linux-2.6.20-rc4-mm1/fs/binfmt_elf.c
@@ -1176,15 +1176,21 @@ static int dump_seek(struct file *file,
*
* I think we should skip something. But I am not sure how. H.J.
*/
-static int maydump(struct vm_area_struct *vma)
+static int maydump(struct vm_area_struct *vma, unsigned int core_flags)
{
/* Do not dump I/O mapped devices or special mappings */
if (vma->vm_flags & (VM_IO | VM_RESERVED))
return 0;
- /* Dump shared memory only if mapped from an anonymous file. */
- if (vma->vm_flags & VM_SHARED)
- return vma->vm_file->f_path.dentry->d_inode->i_nlink == 0;
+ /*
+ * Dump shared memory only if mapped from an anonymous file and not
+ * masked by /proc/<pid>/core_flags.
+ */
+ if (vma->vm_flags & VM_SHARED) {
+ if (vma->vm_file->f_path.dentry->d_inode->i_nlink)
+ return 0;
+ return (core_flags & CORE_OMIT_ANON_SHARED) == 0;
+ }
/* If it hasn't been written to, don't write it out */
if (!vma->anon_vma)
@@ -1456,6 +1462,7 @@ static int elf_core_dump(long signr, str
#endif
int thread_status_size = 0;
elf_addr_t *auxv;
+ unsigned int core_flags;
/*
* We no longer stop all VM operations.
@@ -1590,6 +1597,7 @@ static int elf_core_dump(long signr, str
}
dataoff = offset = roundup(offset, ELF_EXEC_PAGESIZE);
+ __set_dump_bits(core_flags, current->mm->core_flags);
/* Write program headers for segments dump */
for (vma = current->mm->mmap; vma != NULL; vma = vma->vm_next) {
@@ -1602,7 +1610,7 @@ static int elf_core_dump(long signr, str
phdr.p_offset = offset;
phdr.p_vaddr = vma->vm_start;
phdr.p_paddr = 0;
- phdr.p_filesz = maydump(vma) ? sz : 0;
+ phdr.p_filesz = maydump(vma, core_flags) ? sz : 0;
phdr.p_memsz = sz;
offset += phdr.p_filesz;
phdr.p_flags = vma->vm_flags & VM_READ ? PF_R : 0;
@@ -1644,7 +1652,7 @@ static int elf_core_dump(long signr, str
for (vma = current->mm->mmap; vma != NULL; vma = vma->vm_next) {
unsigned long addr;
- if (!maydump(vma))
+ if (!maydump(vma, core_flags))
continue;
for (addr = vma->vm_start;
Index: linux-2.6.20-rc4-mm1/fs/binfmt_elf_fdpic.c
===================================================================
--- linux-2.6.20-rc4-mm1.orig/fs/binfmt_elf_fdpic.c
+++ linux-2.6.20-rc4-mm1/fs/binfmt_elf_fdpic.c
@@ -1167,7 +1167,7 @@ static int dump_seek(struct file *file,
*
* I think we should skip something. But I am not sure how. H.J.
*/
-static int maydump(struct vm_area_struct *vma)
+static int maydump(struct vm_area_struct *vma, unsigned int core_flags)
{
/* Do not dump I/O mapped devices or special mappings */
if (vma->vm_flags & (VM_IO | VM_RESERVED)) {
@@ -1183,15 +1183,22 @@ static int maydump(struct vm_area_struct
return 0;
}
- /* Dump shared memory only if mapped from an anonymous file. */
+ /*
+ * Dump shared memory only if mapped from an anonymous file and not
+ * masked by /proc/<pid>/core_flags.
+ */
if (vma->vm_flags & VM_SHARED) {
- if (vma->vm_file->f_path.dentry->d_inode->i_nlink == 0) {
+ if (vma->vm_file->f_path.dentry->d_inode->i_nlink) {
kdcore("%08lx: %08lx: no (share)", vma->vm_start,
vma->vm_flags);
+ return 0;
+ }
+ if (core_flags & CORE_OMIT_ANON_SHARED) {
+ kdcore("%08lx: %08lx: no (anon-share)", vma->vm_start,
vma->vm_flags);
+ return 0;
+ } else {
+ kdcore("%08lx: %08lx: yes (anon-share)", vma->vm_start,
vma->vm_flags);
return 1;
}
-
- kdcore("%08lx: %08lx: no (share)", vma->vm_start,
vma->vm_flags);
- return 0;
}
#ifdef CONFIG_MMU
@@ -1443,14 +1450,15 @@ static int elf_dump_thread_status(long s
*/
#ifdef CONFIG_MMU
static int elf_fdpic_dump_segments(struct file *file, struct mm_struct *mm,
- size_t *size, unsigned long *limit)
+ size_t *size, unsigned long *limit,
+ unsigned int core_flags)
{
struct vm_area_struct *vma;
for (vma = current->mm->mmap; vma; vma = vma->vm_next) {
unsigned long addr;
- if (!maydump(vma))
+ if (!maydump(vma, core_flags))
continue;
for (addr = vma->vm_start;
@@ -1498,14 +1506,15 @@ end_coredump:
*/
#ifndef CONFIG_MMU
static int elf_fdpic_dump_segments(struct file *file, struct mm_struct *mm,
- size_t *size, unsigned long *limit)
+ size_t *size, unsigned long *limit,
+ unsigned int core_flags)
{
struct vm_list_struct *vml;
for (vml = current->mm->context.vmlist; vml; vml = vml->next) {
struct vm_area_struct *vma = vml->vma;
- if (!maydump(vma))
+ if (!maydump(vma, core_flags))
continue;
if ((*size += PAGE_SIZE) > *limit)
@@ -1556,6 +1565,7 @@ static int elf_fdpic_core_dump(long sign
struct vm_list_struct *vml;
#endif
elf_addr_t *auxv;
+ unsigned int core_flags;
/*
* We no longer stop all VM operations.
@@ -1693,6 +1703,8 @@ static int elf_fdpic_core_dump(long sign
/* Page-align dumped data */
dataoff = offset = roundup(offset, ELF_EXEC_PAGESIZE);
+ __set_dump_bits(core_flags, current->mm->core_flags);
+
/* write program headers for segments dump */
for (
#ifdef CONFIG_MMU
@@ -1714,7 +1726,7 @@ static int elf_fdpic_core_dump(long sign
phdr.p_offset = offset;
phdr.p_vaddr = vma->vm_start;
phdr.p_paddr = 0;
- phdr.p_filesz = maydump(vma) ? sz : 0;
+ phdr.p_filesz = maydump(vma, core_flags) ? sz : 0;
phdr.p_memsz = sz;
offset += phdr.p_filesz;
phdr.p_flags = vma->vm_flags & VM_READ ? PF_R : 0;
@@ -1748,7 +1760,8 @@ static int elf_fdpic_core_dump(long sign
DUMP_SEEK(dataoff);
- if (elf_fdpic_dump_segments(file, current->mm, &size, &limit) < 0)
+ if (elf_fdpic_dump_segments(file, current->mm, &size, &limit,
+ core_flags) < 0)
goto end_coredump;
#ifdef ELF_CORE_WRITE_EXTRA_DATA
Index: linux-2.6.20-rc4-mm1/include/linux/binfmts.h
===================================================================
--- linux-2.6.20-rc4-mm1.orig/include/linux/binfmts.h
+++ linux-2.6.20-rc4-mm1/include/linux/binfmts.h
@@ -79,6 +79,9 @@ extern int suid_dumpable;
#define EXSTACK_DISABLE_X 1 /* Disable executable stacks */
#define EXSTACK_ENABLE_X 2 /* Enable executable stacks */
+/* Core dump control flags */
+#define CORE_OMIT_ANON_SHARED 0x1 /* don't dump anonymous shared memory */
+
extern int setup_arg_pages(struct linux_binprm * bprm,
unsigned long stack_top,
int executable_stack);
-
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