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-rw-r--r--fs/binfmt_elf.c78
-rw-r--r--include/linux/sched.h3
2 files changed, 55 insertions, 26 deletions
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 66cd711a6b1a..4263326ede04 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -1201,35 +1201,68 @@ static int dump_seek(struct file *file, loff_t off)
}
/*
- * Decide whether a segment is worth dumping; default is yes to be
- * sure (missing info is worse than too much; etc).
- * Personally I'd include everything, and use the coredump limit...
- *
- * I think we should skip something. But I am not sure how. H.J.
+ * Decide what to dump of a segment, part, all or none.
*/
-static int maydump(struct vm_area_struct *vma, unsigned long mm_flags)
+static unsigned long vma_dump_size(struct vm_area_struct *vma,
+ unsigned long mm_flags)
{
/* The vma can be set up to tell us the answer directly. */
if (vma->vm_flags & VM_ALWAYSDUMP)
- return 1;
+ goto whole;
/* Do not dump I/O mapped devices or special mappings */
if (vma->vm_flags & (VM_IO | VM_RESERVED))
return 0;
+#define FILTER(type) (mm_flags & (1UL << MMF_DUMP_##type))
+
/* By default, dump shared memory if mapped from an anonymous file. */
if (vma->vm_flags & VM_SHARED) {
- if (vma->vm_file->f_path.dentry->d_inode->i_nlink == 0)
- return test_bit(MMF_DUMP_ANON_SHARED, &mm_flags);
- else
- return test_bit(MMF_DUMP_MAPPED_SHARED, &mm_flags);
+ if (vma->vm_file->f_path.dentry->d_inode->i_nlink == 0 ?
+ FILTER(ANON_SHARED) : FILTER(MAPPED_SHARED))
+ goto whole;
+ return 0;
}
- /* By default, if it hasn't been written to, don't write it out. */
- if (!vma->anon_vma)
- return test_bit(MMF_DUMP_MAPPED_PRIVATE, &mm_flags);
+ /* Dump segments that have been written to. */
+ if (vma->anon_vma && FILTER(ANON_PRIVATE))
+ goto whole;
+ if (vma->vm_file == NULL)
+ return 0;
- return test_bit(MMF_DUMP_ANON_PRIVATE, &mm_flags);
+ if (FILTER(MAPPED_PRIVATE))
+ goto whole;
+
+ /*
+ * If this looks like the beginning of a DSO or executable mapping,
+ * check for an ELF header. If we find one, dump the first page to
+ * aid in determining what was mapped here.
+ */
+ if (FILTER(ELF_HEADERS) && vma->vm_file != NULL && vma->vm_pgoff == 0) {
+ u32 __user *header = (u32 __user *) vma->vm_start;
+ u32 word;
+ /*
+ * Doing it this way gets the constant folded by GCC.
+ */
+ union {
+ u32 cmp;
+ char elfmag[SELFMAG];
+ } magic;
+ BUILD_BUG_ON(SELFMAG != sizeof word);
+ magic.elfmag[EI_MAG0] = ELFMAG0;
+ magic.elfmag[EI_MAG1] = ELFMAG1;
+ magic.elfmag[EI_MAG2] = ELFMAG2;
+ magic.elfmag[EI_MAG3] = ELFMAG3;
+ if (get_user(word, header) == 0 && word == magic.cmp)
+ return PAGE_SIZE;
+ }
+
+#undef FILTER
+
+ return 0;
+
+whole:
+ return vma->vm_end - vma->vm_start;
}
/* An ELF note in memory */
@@ -1669,16 +1702,13 @@ static int elf_core_dump(long signr, struct pt_regs *regs, struct file *file, un
for (vma = first_vma(current, gate_vma); vma != NULL;
vma = next_vma(vma, gate_vma)) {
struct elf_phdr phdr;
- size_t sz;
-
- sz = vma->vm_end - vma->vm_start;
phdr.p_type = PT_LOAD;
phdr.p_offset = offset;
phdr.p_vaddr = vma->vm_start;
phdr.p_paddr = 0;
- phdr.p_filesz = maydump(vma, mm_flags) ? sz : 0;
- phdr.p_memsz = sz;
+ phdr.p_filesz = vma_dump_size(vma, mm_flags);
+ phdr.p_memsz = vma->vm_end - vma->vm_start;
offset += phdr.p_filesz;
phdr.p_flags = vma->vm_flags & VM_READ ? PF_R : 0;
if (vma->vm_flags & VM_WRITE)
@@ -1718,13 +1748,11 @@ static int elf_core_dump(long signr, struct pt_regs *regs, struct file *file, un
for (vma = first_vma(current, gate_vma); vma != NULL;
vma = next_vma(vma, gate_vma)) {
unsigned long addr;
+ unsigned long end;
- if (!maydump(vma, mm_flags))
- continue;
+ end = vma->vm_start + vma_dump_size(vma, mm_flags);
- for (addr = vma->vm_start;
- addr < vma->vm_end;
- addr += PAGE_SIZE) {
+ for (addr = vma->vm_start; addr < end; addr += PAGE_SIZE) {
struct page *page;
struct vm_area_struct *vma;
diff --git a/include/linux/sched.h b/include/linux/sched.h
index e643357eda05..cb952bc225e4 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -359,8 +359,9 @@ extern int get_dumpable(struct mm_struct *mm);
#define MMF_DUMP_ANON_SHARED 3
#define MMF_DUMP_MAPPED_PRIVATE 4
#define MMF_DUMP_MAPPED_SHARED 5
+#define MMF_DUMP_ELF_HEADERS 6
#define MMF_DUMP_FILTER_SHIFT MMF_DUMPABLE_BITS
-#define MMF_DUMP_FILTER_BITS 4
+#define MMF_DUMP_FILTER_BITS 5
#define MMF_DUMP_FILTER_MASK \
(((1 << MMF_DUMP_FILTER_BITS) - 1) << MMF_DUMP_FILTER_SHIFT)
#define MMF_DUMP_FILTER_DEFAULT \