102 lines
2.4 KiB
C
102 lines
2.4 KiB
C
/*
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* linux/kernel/ldt.c
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*
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* Copyright (C) 1992 Krishna Balasubramanian and Linus Torvalds
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*/
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#include <linux/config.h>
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#include <linux/errno.h>
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#include <linux/sched.h>
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#include <linux/string.h>
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#include <asm/segment.h>
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#include <asm/system.h>
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#include <linux/ldt.h>
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static int read_ldt(void * ptr, unsigned long bytecount)
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{
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int error;
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void * address = current->ldt;
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unsigned long size;
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if (!ptr)
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return -EINVAL;
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size = LDT_ENTRIES*LDT_ENTRY_SIZE;
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if (!address) {
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address = &default_ldt;
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size = sizeof(default_ldt);
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}
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if (size > bytecount)
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size = bytecount;
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error = verify_area(VERIFY_WRITE, ptr, size);
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if (error)
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return error;
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memcpy_tofs(ptr, address, size);
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return size;
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}
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static int write_ldt(void * ptr, unsigned long bytecount)
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{
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struct modify_ldt_ldt_s ldt_info;
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unsigned long *lp;
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unsigned long base, limit;
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int error, i;
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if (bytecount != sizeof(ldt_info))
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return -EINVAL;
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error = verify_area(VERIFY_READ, ptr, sizeof(ldt_info));
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if (error)
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return error;
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memcpy_fromfs(&ldt_info, ptr, sizeof(ldt_info));
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if (ldt_info.contents == 3 || ldt_info.entry_number >= LDT_ENTRIES)
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return -EINVAL;
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limit = ldt_info.limit;
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base = ldt_info.base_addr;
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if (ldt_info.limit_in_pages)
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limit *= PAGE_SIZE;
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limit += base;
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if (limit < base || limit >= 0xC0000000)
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return -EINVAL;
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if (!current->ldt) {
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for (i=1 ; i<NR_TASKS ; i++) {
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if (task[i] == current) {
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if (!(current->ldt = (struct desc_struct*) vmalloc(LDT_ENTRIES*LDT_ENTRY_SIZE)))
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return -ENOMEM;
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set_ldt_desc(gdt+(i<<1)+FIRST_LDT_ENTRY, current->ldt, LDT_ENTRIES);
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load_ldt(i);
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}
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}
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}
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lp = (unsigned long *) ¤t->ldt[ldt_info.entry_number];
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/* Allow LDTs to be cleared by the user. */
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if (ldt_info.base_addr == 0 && ldt_info.limit == 0) {
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*lp = 0;
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*(lp+1) = 0;
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return 0;
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}
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*lp = ((ldt_info.base_addr & 0x0000ffff) << 16) |
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(ldt_info.limit & 0x0ffff);
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*(lp+1) = (ldt_info.base_addr & 0xff000000) |
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((ldt_info.base_addr & 0x00ff0000)>>16) |
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(ldt_info.limit & 0xf0000) |
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(ldt_info.contents << 10) |
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((ldt_info.read_exec_only ^ 1) << 9) |
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(ldt_info.seg_32bit << 22) |
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(ldt_info.limit_in_pages << 23) |
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0xf000;
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return 0;
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}
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asmlinkage int sys_modify_ldt(int func, void *ptr, unsigned long bytecount)
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{
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if (func == 0)
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return read_ldt(ptr, bytecount);
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if (func == 1)
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return write_ldt(ptr, bytecount);
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return -ENOSYS;
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}
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