diff options
Diffstat (limited to 'mm/mprotect.c')
| -rw-r--r-- | mm/mprotect.c | 251 |
1 files changed, 251 insertions, 0 deletions
diff --git a/mm/mprotect.c b/mm/mprotect.c new file mode 100644 index 000000000..ecf73730c --- /dev/null +++ b/mm/mprotect.c @@ -0,0 +1,251 @@ +/* + * linux/mm/mprotect.c + * + * (C) Copyright 1994 Linus Torvalds + */ +#include <linux/stat.h> +#include <linux/sched.h> +#include <linux/kernel.h> +#include <linux/mm.h> +#include <linux/shm.h> +#include <linux/errno.h> +#include <linux/mman.h> +#include <linux/string.h> +#include <linux/malloc.h> + +#include <asm/segment.h> +#include <asm/system.h> +#include <asm/pgtable.h> + +static inline void change_pte_range(pmd_t * pmd, unsigned long address, + unsigned long size, pgprot_t newprot) +{ + pte_t * pte; + unsigned long end; + + if (pmd_none(*pmd)) + return; + if (pmd_bad(*pmd)) { + printk("change_pte_range: bad pmd (%08lx)\n", pmd_val(*pmd)); + pmd_clear(pmd); + return; + } + pte = pte_offset(pmd, address); + address &= ~PMD_MASK; + end = address + size; + if (end > PMD_SIZE) + end = PMD_SIZE; + do { + pte_t entry = *pte; + if (pte_present(entry)) + *pte = pte_modify(entry, newprot); + address += PAGE_SIZE; + pte++; + } while (address < end); +} + +static inline void change_pmd_range(pgd_t * pgd, unsigned long address, + unsigned long size, pgprot_t newprot) +{ + pmd_t * pmd; + unsigned long end; + + if (pgd_none(*pgd)) + return; + if (pgd_bad(*pgd)) { + printk("change_pmd_range: bad pgd (%08lx)\n", pgd_val(*pgd)); + pgd_clear(pgd); + return; + } + pmd = pmd_offset(pgd, address); + address &= ~PGDIR_MASK; + end = address + size; + if (end > PGDIR_SIZE) + end = PGDIR_SIZE; + do { + change_pte_range(pmd, address, end - address, newprot); + address = (address + PMD_SIZE) & PMD_MASK; + pmd++; + } while (address < end); +} + +static void change_protection(unsigned long start, unsigned long end, pgprot_t newprot) +{ + pgd_t *dir; + + dir = pgd_offset(current, start); + while (start < end) { + change_pmd_range(dir, start, end - start, newprot); + start = (start + PGDIR_SIZE) & PGDIR_MASK; + dir++; + } + invalidate(); + return; +} + +static inline int mprotect_fixup_all(struct vm_area_struct * vma, + int newflags, pgprot_t prot) +{ + vma->vm_flags = newflags; + vma->vm_page_prot = prot; + return 0; +} + +static inline int mprotect_fixup_start(struct vm_area_struct * vma, + unsigned long end, + int newflags, pgprot_t prot) +{ + struct vm_area_struct * n; + + n = (struct vm_area_struct *) kmalloc(sizeof(struct vm_area_struct), GFP_KERNEL); + if (!n) + return -ENOMEM; + *n = *vma; + vma->vm_start = end; + n->vm_end = end; + vma->vm_offset += vma->vm_start - n->vm_start; + n->vm_flags = newflags; + n->vm_page_prot = prot; + if (n->vm_inode) + n->vm_inode->i_count++; + if (n->vm_ops && n->vm_ops->open) + n->vm_ops->open(n); + insert_vm_struct(current, n); + return 0; +} + +static inline int mprotect_fixup_end(struct vm_area_struct * vma, + unsigned long start, + int newflags, pgprot_t prot) +{ + struct vm_area_struct * n; + + n = (struct vm_area_struct *) kmalloc(sizeof(struct vm_area_struct), GFP_KERNEL); + if (!n) + return -ENOMEM; + *n = *vma; + vma->vm_end = start; + n->vm_start = start; + n->vm_offset += n->vm_start - vma->vm_start; + n->vm_flags = newflags; + n->vm_page_prot = prot; + if (n->vm_inode) + n->vm_inode->i_count++; + if (n->vm_ops && n->vm_ops->open) + n->vm_ops->open(n); + insert_vm_struct(current, n); + return 0; +} + +static inline int mprotect_fixup_middle(struct vm_area_struct * vma, + unsigned long start, unsigned long end, + int newflags, pgprot_t prot) +{ + struct vm_area_struct * left, * right; + + left = (struct vm_area_struct *) kmalloc(sizeof(struct vm_area_struct), GFP_KERNEL); + if (!left) + return -ENOMEM; + right = (struct vm_area_struct *) kmalloc(sizeof(struct vm_area_struct), GFP_KERNEL); + if (!right) { + kfree(left); + return -ENOMEM; + } + *left = *vma; + *right = *vma; + left->vm_end = start; + vma->vm_start = start; + vma->vm_end = end; + right->vm_start = end; + vma->vm_offset += vma->vm_start - left->vm_start; + right->vm_offset += right->vm_start - left->vm_start; + vma->vm_flags = newflags; + vma->vm_page_prot = prot; + if (vma->vm_inode) + vma->vm_inode->i_count += 2; + if (vma->vm_ops && vma->vm_ops->open) { + vma->vm_ops->open(left); + vma->vm_ops->open(right); + } + insert_vm_struct(current, left); + insert_vm_struct(current, right); + return 0; +} + +static int mprotect_fixup(struct vm_area_struct * vma, + unsigned long start, unsigned long end, unsigned int newflags) +{ + pgprot_t newprot; + int error; + + if (newflags == vma->vm_flags) + return 0; + newprot = protection_map[newflags & 0xf]; + if (start == vma->vm_start) + if (end == vma->vm_end) + error = mprotect_fixup_all(vma, newflags, newprot); + else + error = mprotect_fixup_start(vma, end, newflags, newprot); + else if (end == vma->vm_end) + error = mprotect_fixup_end(vma, start, newflags, newprot); + else + error = mprotect_fixup_middle(vma, start, end, newflags, newprot); + + if (error) + return error; + + change_protection(start, end, newprot); + return 0; +} + +asmlinkage int sys_mprotect(unsigned long start, size_t len, unsigned long prot) +{ + unsigned long nstart, end, tmp; + struct vm_area_struct * vma, * next; + int error; + + if (start & ~PAGE_MASK) + return -EINVAL; + len = (len + ~PAGE_MASK) & PAGE_MASK; + end = start + len; + if (end < start) + return -EINVAL; + if (prot & ~(PROT_READ | PROT_WRITE | PROT_EXEC)) + return -EINVAL; + if (end == start) + return 0; + vma = find_vma(current, start); + if (!vma || vma->vm_start > start) + return -EFAULT; + + for (nstart = start ; ; ) { + unsigned int newflags; + + /* Here we know that vma->vm_start <= nstart < vma->vm_end. */ + + newflags = prot | (vma->vm_flags & ~(PROT_READ | PROT_WRITE | PROT_EXEC)); + if ((newflags & ~(newflags >> 4)) & 0xf) { + error = -EACCES; + break; + } + + if (vma->vm_end >= end) { + error = mprotect_fixup(vma, nstart, end, newflags); + break; + } + + tmp = vma->vm_end; + next = vma->vm_next; + error = mprotect_fixup(vma, nstart, tmp, newflags); + if (error) + break; + nstart = tmp; + vma = next; + if (!vma || vma->vm_start != nstart) { + error = -EFAULT; + break; + } + } + merge_segments(current, start, end); + return error; +} |