#include <asm/uaccess.h>
#include <asm/mmu_context.h>
+#include <asm/tlb.h>
#ifdef CONFIG_KMOD
#include <linux/kmod.h>
goto out;
}
+#ifdef CONFIG_MMU
+
+static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
+ int write)
+{
+ struct page *page;
+ int ret;
+
+#ifdef CONFIG_STACK_GROWSUP
+ if (write) {
+ ret = expand_stack_downwards(bprm->vma, pos);
+ if (ret < 0)
+ return NULL;
+ }
+#endif
+ ret = get_user_pages(current, bprm->mm, pos,
+ 1, write, 1, &page, NULL);
+ if (ret <= 0)
+ return NULL;
+
+ if (write) {
+ struct rlimit *rlim = current->signal->rlim;
+ unsigned long size = bprm->vma->vm_end - bprm->vma->vm_start;
+
+ /*
+ * Limit to 1/4-th the stack size for the argv+env strings.
+ * This ensures that:
+ * - the remaining binfmt code will not run out of stack space,
+ * - the program will have a reasonable amount of stack left
+ * to work from.
+ */
+ if (size > rlim[RLIMIT_STACK].rlim_cur / 4) {
+ put_page(page);
+ return NULL;
+ }
+ }
+
+ return page;
+}
+
+static void put_arg_page(struct page *page)
+{
+ put_page(page);
+}
+
+static void free_arg_page(struct linux_binprm *bprm, int i)
+{
+}
+
+static void free_arg_pages(struct linux_binprm *bprm)
+{
+}
+
+static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
+ struct page *page)
+{
+ flush_cache_page(bprm->vma, pos, page_to_pfn(page));
+}
+
+static int __bprm_mm_init(struct linux_binprm *bprm)
+{
+ int err = -ENOMEM;
+ struct vm_area_struct *vma = NULL;
+ struct mm_struct *mm = bprm->mm;
+
+ bprm->vma = vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
+ if (!vma)
+ goto err;
+
+ down_write(&mm->mmap_sem);
+ vma->vm_mm = mm;
+
+ /*
+ * Place the stack at the largest stack address the architecture
+ * supports. Later, we'll move this to an appropriate place. We don't
+ * use STACK_TOP because that can depend on attributes which aren't
+ * configured yet.
+ */
+ vma->vm_end = STACK_TOP_MAX;
+ vma->vm_start = vma->vm_end - PAGE_SIZE;
+
+ vma->vm_flags = VM_STACK_FLAGS;
+ vma->vm_page_prot = protection_map[vma->vm_flags & 0x7];
+ err = insert_vm_struct(mm, vma);
+ if (err) {
+ up_write(&mm->mmap_sem);
+ goto err;
+ }
+
+ mm->stack_vm = mm->total_vm = 1;
+ up_write(&mm->mmap_sem);
+
+ bprm->p = vma->vm_end - sizeof(void *);
+
+ return 0;
+
+err:
+ if (vma) {
+ bprm->vma = NULL;
+ kmem_cache_free(vm_area_cachep, vma);
+ }
+
+ return err;
+}
+
+static bool valid_arg_len(struct linux_binprm *bprm, long len)
+{
+ return len <= MAX_ARG_STRLEN;
+}
+
+#else
+
+static struct page *get_arg_page(struct linux_binprm *bprm, unsigned long pos,
+ int write)
+{
+ struct page *page;
+
+ page = bprm->page[pos / PAGE_SIZE];
+ if (!page && write) {
+ page = alloc_page(GFP_HIGHUSER|__GFP_ZERO);
+ if (!page)
+ return NULL;
+ bprm->page[pos / PAGE_SIZE] = page;
+ }
+
+ return page;
+}
+
+static void put_arg_page(struct page *page)
+{
+}
+
+static void free_arg_page(struct linux_binprm *bprm, int i)
+{
+ if (bprm->page[i]) {
+ __free_page(bprm->page[i]);
+ bprm->page[i] = NULL;
+ }
+}
+
+static void free_arg_pages(struct linux_binprm *bprm)
+{
+ int i;
+
+ for (i = 0; i < MAX_ARG_PAGES; i++)
+ free_arg_page(bprm, i);
+}
+
+static void flush_arg_page(struct linux_binprm *bprm, unsigned long pos,
+ struct page *page)
+{
+}
+
+static int __bprm_mm_init(struct linux_binprm *bprm)
+{
+ bprm->p = PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *);
+ return 0;
+}
+
+static bool valid_arg_len(struct linux_binprm *bprm, long len)
+{
+ return len <= bprm->p;
+}
+
+#endif /* CONFIG_MMU */
+
+/*
+ * Create a new mm_struct and populate it with a temporary stack
+ * vm_area_struct. We don't have enough context at this point to set the stack
+ * flags, permissions, and offset, so we use temporary values. We'll update
+ * them later in setup_arg_pages().
+ */
+int bprm_mm_init(struct linux_binprm *bprm)
+{
+ int err;
+ struct mm_struct *mm = NULL;
+
+ bprm->mm = mm = mm_alloc();
+ err = -ENOMEM;
+ if (!mm)
+ goto err;
+
+ err = init_new_context(current, mm);
+ if (err)
+ goto err;
+
+ err = __bprm_mm_init(bprm);
+ if (err)
+ goto err;
+
+ return 0;
+
+err:
+ if (mm) {
+ bprm->mm = NULL;
+ mmdrop(mm);
+ }
+
+ return err;
+}
+
/*
* count() counts the number of strings in array ARGV.
*/
}
/*
- * 'copy_strings()' copies argument/environment strings from user
- * memory to free pages in kernel mem. These are in a format ready
- * to be put directly into the top of new user memory.
+ * 'copy_strings()' copies argument/environment strings from the old
+ * processes's memory to the new process's stack. The call to get_user_pages()
+ * ensures the destination page is created and not swapped out.
*/
static int copy_strings(int argc, char __user * __user * argv,
struct linux_binprm *bprm)
{
struct page *kmapped_page = NULL;
char *kaddr = NULL;
+ unsigned long kpos = 0;
int ret;
while (argc-- > 0) {
unsigned long pos;
if (get_user(str, argv+argc) ||
- !(len = strnlen_user(str, bprm->p))) {
+ !(len = strnlen_user(str, MAX_ARG_STRLEN))) {
ret = -EFAULT;
goto out;
}
- if (bprm->p < len) {
+ if (!valid_arg_len(bprm, len)) {
ret = -E2BIG;
goto out;
}
- bprm->p -= len;
- /* XXX: add architecture specific overflow check here. */
+ /* We're going to work our way backwords. */
pos = bprm->p;
+ str += len;
+ bprm->p -= len;
while (len > 0) {
- int i, new, err;
int offset, bytes_to_copy;
- struct page *page;
offset = pos % PAGE_SIZE;
- i = pos/PAGE_SIZE;
- page = bprm->page[i];
- new = 0;
- if (!page) {
- page = alloc_page(GFP_HIGHUSER);
- bprm->page[i] = page;
+ if (offset == 0)
+ offset = PAGE_SIZE;
+
+ bytes_to_copy = offset;
+ if (bytes_to_copy > len)
+ bytes_to_copy = len;
+
+ offset -= bytes_to_copy;
+ pos -= bytes_to_copy;
+ str -= bytes_to_copy;
+ len -= bytes_to_copy;
+
+ if (!kmapped_page || kpos != (pos & PAGE_MASK)) {
+ struct page *page;
+
+ page = get_arg_page(bprm, pos, 1);
if (!page) {
- ret = -ENOMEM;
+ ret = -E2BIG;
goto out;
}
- new = 1;
- }
- if (page != kmapped_page) {
- if (kmapped_page)
+ if (kmapped_page) {
+ flush_kernel_dcache_page(kmapped_page);
kunmap(kmapped_page);
+ put_arg_page(kmapped_page);
+ }
kmapped_page = page;
kaddr = kmap(kmapped_page);
+ kpos = pos & PAGE_MASK;
+ flush_arg_page(bprm, kpos, kmapped_page);
}
- if (new && offset)
- memset(kaddr, 0, offset);
- bytes_to_copy = PAGE_SIZE - offset;
- if (bytes_to_copy > len) {
- bytes_to_copy = len;
- if (new)
- memset(kaddr+offset+len, 0,
- PAGE_SIZE-offset-len);
- }
- err = copy_from_user(kaddr+offset, str, bytes_to_copy);
- if (err) {
+ if (copy_from_user(kaddr+offset, str, bytes_to_copy)) {
ret = -EFAULT;
goto out;
}
-
- pos += bytes_to_copy;
- str += bytes_to_copy;
- len -= bytes_to_copy;
}
}
ret = 0;
out:
- if (kmapped_page)
+ if (kmapped_page) {
+ flush_kernel_dcache_page(kmapped_page);
kunmap(kmapped_page);
+ put_arg_page(kmapped_page);
+ }
return ret;
}
set_fs(oldfs);
return r;
}
-
EXPORT_SYMBOL(copy_strings_kernel);
#ifdef CONFIG_MMU
+
/*
- * This routine is used to map in a page into an address space: needed by
- * execve() for the initial stack and environment pages.
+ * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX. Once
+ * the binfmt code determines where the new stack should reside, we shift it to
+ * its final location. The process proceeds as follows:
*
- * vma->vm_mm->mmap_sem is held for writing.
+ * 1) Use shift to calculate the new vma endpoints.
+ * 2) Extend vma to cover both the old and new ranges. This ensures the
+ * arguments passed to subsequent functions are consistent.
+ * 3) Move vma's page tables to the new range.
+ * 4) Free up any cleared pgd range.
+ * 5) Shrink the vma to cover only the new range.
*/
-void install_arg_page(struct vm_area_struct *vma,
- struct page *page, unsigned long address)
+static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
{
struct mm_struct *mm = vma->vm_mm;
- pte_t * pte;
- spinlock_t *ptl;
+ unsigned long old_start = vma->vm_start;
+ unsigned long old_end = vma->vm_end;
+ unsigned long length = old_end - old_start;
+ unsigned long new_start = old_start - shift;
+ unsigned long new_end = old_end - shift;
+ struct mmu_gather *tlb;
- if (unlikely(anon_vma_prepare(vma)))
- goto out;
+ BUG_ON(new_start > new_end);
- flush_dcache_page(page);
- pte = get_locked_pte(mm, address, &ptl);
- if (!pte)
- goto out;
- if (!pte_none(*pte)) {
- pte_unmap_unlock(pte, ptl);
- goto out;
+ /*
+ * ensure there are no vmas between where we want to go
+ * and where we are
+ */
+ if (vma != find_vma(mm, new_start))
+ return -EFAULT;
+
+ /*
+ * cover the whole range: [new_start, old_end)
+ */
+ vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL);
+
+ /*
+ * move the page tables downwards, on failure we rely on
+ * process cleanup to remove whatever mess we made.
+ */
+ if (length != move_page_tables(vma, old_start,
+ vma, new_start, length))
+ return -ENOMEM;
+
+ lru_add_drain();
+ tlb = tlb_gather_mmu(mm, 0);
+ if (new_end > old_start) {
+ /*
+ * when the old and new regions overlap clear from new_end.
+ */
+ free_pgd_range(&tlb, new_end, old_end, new_end,
+ vma->vm_next ? vma->vm_next->vm_start : 0);
+ } else {
+ /*
+ * otherwise, clean from old_start; this is done to not touch
+ * the address space in [new_end, old_start) some architectures
+ * have constraints on va-space that make this illegal (IA64) -
+ * for the others its just a little faster.
+ */
+ free_pgd_range(&tlb, old_start, old_end, new_end,
+ vma->vm_next ? vma->vm_next->vm_start : 0);
}
- inc_mm_counter(mm, anon_rss);
- lru_cache_add_active(page);
- set_pte_at(mm, address, pte, pte_mkdirty(pte_mkwrite(mk_pte(
- page, vma->vm_page_prot))));
- page_add_new_anon_rmap(page, vma, address);
- pte_unmap_unlock(pte, ptl);
-
- /* no need for flush_tlb */
- return;
-out:
- __free_page(page);
- force_sig(SIGKILL, current);
+ tlb_finish_mmu(tlb, new_end, old_end);
+
+ /*
+ * shrink the vma to just the new range.
+ */
+ vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);
+
+ return 0;
}
#define EXTRA_STACK_VM_PAGES 20 /* random */
+/*
+ * Finalizes the stack vm_area_struct. The flags and permissions are updated,
+ * the stack is optionally relocated, and some extra space is added.
+ */
int setup_arg_pages(struct linux_binprm *bprm,
unsigned long stack_top,
int executable_stack)
{
- unsigned long stack_base;
- struct vm_area_struct *mpnt;
+ unsigned long ret;
+ unsigned long stack_shift;
struct mm_struct *mm = current->mm;
- int i, ret;
- long arg_size;
+ struct vm_area_struct *vma = bprm->vma;
+ struct vm_area_struct *prev = NULL;
+ unsigned long vm_flags;
+ unsigned long stack_base;
#ifdef CONFIG_STACK_GROWSUP
- /* Move the argument and environment strings to the bottom of the
- * stack space.
- */
- int offset, j;
- char *to, *from;
-
- /* Start by shifting all the pages down */
- i = 0;
- for (j = 0; j < MAX_ARG_PAGES; j++) {
- struct page *page = bprm->page[j];
- if (!page)
- continue;
- bprm->page[i++] = page;
- }
-
- /* Now move them within their pages */
- offset = bprm->p % PAGE_SIZE;
- to = kmap(bprm->page[0]);
- for (j = 1; j < i; j++) {
- memmove(to, to + offset, PAGE_SIZE - offset);
- from = kmap(bprm->page[j]);
- memcpy(to + PAGE_SIZE - offset, from, offset);
- kunmap(bprm->page[j - 1]);
- to = from;
- }
- memmove(to, to + offset, PAGE_SIZE - offset);
- kunmap(bprm->page[j - 1]);
-
/* Limit stack size to 1GB */
stack_base = current->signal->rlim[RLIMIT_STACK].rlim_max;
if (stack_base > (1 << 30))
stack_base = 1 << 30;
- stack_base = PAGE_ALIGN(stack_top - stack_base);
- /* Adjust bprm->p to point to the end of the strings. */
- bprm->p = stack_base + PAGE_SIZE * i - offset;
+ /* Make sure we didn't let the argument array grow too large. */
+ if (vma->vm_end - vma->vm_start > stack_base)
+ return -ENOMEM;
- mm->arg_start = stack_base;
- arg_size = i << PAGE_SHIFT;
+ stack_base = PAGE_ALIGN(stack_top - stack_base);
- /* zero pages that were copied above */
- while (i < MAX_ARG_PAGES)
- bprm->page[i++] = NULL;
+ stack_shift = vma->vm_start - stack_base;
+ mm->arg_start = bprm->p - stack_shift;
+ bprm->p = vma->vm_end - stack_shift;
#else
- stack_base = arch_align_stack(stack_top - MAX_ARG_PAGES*PAGE_SIZE);
- stack_base = PAGE_ALIGN(stack_base);
- bprm->p += stack_base;
+ stack_top = arch_align_stack(stack_top);
+ stack_top = PAGE_ALIGN(stack_top);
+ stack_shift = vma->vm_end - stack_top;
+
+ bprm->p -= stack_shift;
mm->arg_start = bprm->p;
- arg_size = stack_top - (PAGE_MASK & (unsigned long) mm->arg_start);
#endif
- arg_size += EXTRA_STACK_VM_PAGES * PAGE_SIZE;
-
if (bprm->loader)
- bprm->loader += stack_base;
- bprm->exec += stack_base;
-
- mpnt = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
- if (!mpnt)
- return -ENOMEM;
+ bprm->loader -= stack_shift;
+ bprm->exec -= stack_shift;
down_write(&mm->mmap_sem);
- {
- mpnt->vm_mm = mm;
-#ifdef CONFIG_STACK_GROWSUP
- mpnt->vm_start = stack_base;
- mpnt->vm_end = stack_base + arg_size;
-#else
- mpnt->vm_end = stack_top;
- mpnt->vm_start = mpnt->vm_end - arg_size;
-#endif
- /* Adjust stack execute permissions; explicitly enable
- * for EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X
- * and leave alone (arch default) otherwise. */
- if (unlikely(executable_stack == EXSTACK_ENABLE_X))
- mpnt->vm_flags = VM_STACK_FLAGS | VM_EXEC;
- else if (executable_stack == EXSTACK_DISABLE_X)
- mpnt->vm_flags = VM_STACK_FLAGS & ~VM_EXEC;
- else
- mpnt->vm_flags = VM_STACK_FLAGS;
- mpnt->vm_flags |= mm->def_flags;
- mpnt->vm_page_prot = protection_map[mpnt->vm_flags & 0x7];
- if ((ret = insert_vm_struct(mm, mpnt))) {
+ vm_flags = vma->vm_flags;
+
+ /*
+ * Adjust stack execute permissions; explicitly enable for
+ * EXSTACK_ENABLE_X, disable for EXSTACK_DISABLE_X and leave alone
+ * (arch default) otherwise.
+ */
+ if (unlikely(executable_stack == EXSTACK_ENABLE_X))
+ vm_flags |= VM_EXEC;
+ else if (executable_stack == EXSTACK_DISABLE_X)
+ vm_flags &= ~VM_EXEC;
+ vm_flags |= mm->def_flags;
+
+ ret = mprotect_fixup(vma, &prev, vma->vm_start, vma->vm_end,
+ vm_flags);
+ if (ret)
+ goto out_unlock;
+ BUG_ON(prev != vma);
+
+ /* Move stack pages down in memory. */
+ if (stack_shift) {
+ ret = shift_arg_pages(vma, stack_shift);
+ if (ret) {
up_write(&mm->mmap_sem);
- kmem_cache_free(vm_area_cachep, mpnt);
return ret;
}
- mm->stack_vm = mm->total_vm = vma_pages(mpnt);
}
- for (i = 0 ; i < MAX_ARG_PAGES ; i++) {
- struct page *page = bprm->page[i];
- if (page) {
- bprm->page[i] = NULL;
- install_arg_page(mpnt, page, stack_base);
- }
- stack_base += PAGE_SIZE;
- }
+#ifdef CONFIG_STACK_GROWSUP
+ stack_base = vma->vm_end + EXTRA_STACK_VM_PAGES * PAGE_SIZE;
+#else
+ stack_base = vma->vm_start - EXTRA_STACK_VM_PAGES * PAGE_SIZE;
+#endif
+ ret = expand_stack(vma, stack_base);
+ if (ret)
+ ret = -EFAULT;
+
+out_unlock:
up_write(&mm->mmap_sem);
-
return 0;
}
-
EXPORT_SYMBOL(setup_arg_pages);
-#define free_arg_pages(bprm) do { } while (0)
-
-#else
-
-static inline void free_arg_pages(struct linux_binprm *bprm)
-{
- int i;
-
- for (i = 0; i < MAX_ARG_PAGES; i++) {
- if (bprm->page[i])
- __free_page(bprm->page[i]);
- bprm->page[i] = NULL;
- }
-}
-
#endif /* CONFIG_MMU */
struct file *open_exec(const char *name)
* points to; chop off the first by relocating brpm->p to right after
* the first '\0' encountered.
*/
-void remove_arg_zero(struct linux_binprm *bprm)
+int remove_arg_zero(struct linux_binprm *bprm)
{
- if (bprm->argc) {
- char ch;
+ int ret = 0;
+ unsigned long offset;
+ char *kaddr;
+ struct page *page;
- do {
- unsigned long offset;
- unsigned long index;
- char *kaddr;
- struct page *page;
-
- offset = bprm->p & ~PAGE_MASK;
- index = bprm->p >> PAGE_SHIFT;
+ if (!bprm->argc)
+ return 0;
- page = bprm->page[index];
- kaddr = kmap_atomic(page, KM_USER0);
+ do {
+ offset = bprm->p & ~PAGE_MASK;
+ page = get_arg_page(bprm, bprm->p, 0);
+ if (!page) {
+ ret = -EFAULT;
+ goto out;
+ }
+ kaddr = kmap_atomic(page, KM_USER0);
- /* run through page until we reach end or find NUL */
- do {
- ch = *(kaddr + offset);
+ for (; offset < PAGE_SIZE && kaddr[offset];
+ offset++, bprm->p++)
+ ;
- /* discard that character... */
- bprm->p++;
- offset++;
- } while (offset < PAGE_SIZE && ch != '\0');
+ kunmap_atomic(kaddr, KM_USER0);
+ put_arg_page(page);
- kunmap_atomic(kaddr, KM_USER0);
+ if (offset == PAGE_SIZE)
+ free_arg_page(bprm, (bprm->p >> PAGE_SHIFT) - 1);
+ } while (offset == PAGE_SIZE);
- /* free the old page */
- if (offset == PAGE_SIZE) {
- __free_page(page);
- bprm->page[index] = NULL;
- }
- } while (ch != '\0');
+ bprm->p++;
+ bprm->argc--;
+ ret = 0;
- bprm->argc--;
- }
+out:
+ return ret;
}
EXPORT_SYMBOL(remove_arg_zero);
fput(bprm->file);
bprm->file = NULL;
- loader = PAGE_SIZE*MAX_ARG_PAGES-sizeof(void *);
+ loader = bprm->vma->vm_end - sizeof(void *);
file = open_exec("/sbin/loader");
retval = PTR_ERR(file);
struct file *file;
unsigned long env_p;
int retval;
- int i;
retval = -ENOMEM;
bprm = kzalloc(sizeof(*bprm), GFP_KERNEL);
sched_exec();
- bprm->p = PAGE_SIZE*MAX_ARG_PAGES-sizeof(void *);
-
bprm->file = file;
bprm->filename = filename;
bprm->interp = filename;
- bprm->mm = mm_alloc();
- retval = -ENOMEM;
- if (!bprm->mm)
- goto out_file;
- retval = init_new_context(current, bprm->mm);
- if (retval < 0)
- goto out_mm;
+ retval = bprm_mm_init(bprm);
+ if (retval)
+ goto out_file;
- bprm->argc = count(argv, bprm->p / sizeof(void *));
+ bprm->argc = count(argv, MAX_ARG_STRINGS);
if ((retval = bprm->argc) < 0)
goto out_mm;
- bprm->envc = count(envp, bprm->p / sizeof(void *));
+ bprm->envc = count(envp, MAX_ARG_STRINGS);
if ((retval = bprm->envc) < 0)
goto out_mm;
retval = search_binary_handler(bprm,regs);
if (retval >= 0) {
- free_arg_pages(bprm);
-
/* execve success */
+ free_arg_pages(bprm);
security_bprm_free(bprm);
acct_update_integrals(current);
kfree(bprm);
}
out:
- /* Something went wrong, return the inode and free the argument pages*/
- for (i = 0 ; i < MAX_ARG_PAGES ; i++) {
- struct page * page = bprm->page[i];
- if (page)
- __free_page(page);
- }
-
+ free_arg_pages(bprm);
if (bprm->security)
security_bprm_free(bprm);
out_mm:
if (bprm->mm)
- mmdrop(bprm->mm);
+ mmput (bprm->mm);
out_file:
if (bprm->file) {
allow_write_access(bprm->file);
fput(bprm->file);
}
-
out_kfree:
kfree(bprm);
projects / deliverable / linux.git / commitdiff
