patch-2.4.8 linux/arch/ia64/ia32/ia32_ldt.c
Next file: linux/arch/ia64/ia32/ia32_support.c
Previous file: linux/arch/ia64/ia32/ia32_entry.S
Back to the patch index
Back to the overall index
- Lines: 121
- Date:
Tue Jul 31 10:30:08 2001
- Orig file:
v2.4.7/linux/arch/ia64/ia32/ia32_ldt.c
- Orig date:
Wed Dec 31 16:00:00 1969
diff -u --recursive --new-file v2.4.7/linux/arch/ia64/ia32/ia32_ldt.c linux/arch/ia64/ia32/ia32_ldt.c
@@ -0,0 +1,120 @@
+/*
+ * Copyright (C) 2001 Hewlett-Packard Co
+ * Copyright (C) 2001 David Mosberger-Tang <davidm@hpl.hp.com>
+ *
+ * Adapted from arch/i386/kernel/ldt.c
+ */
+
+#include <linux/errno.h>
+#include <linux/sched.h>
+#include <linux/string.h>
+#include <linux/mm.h>
+#include <linux/smp.h>
+#include <linux/smp_lock.h>
+#include <linux/vmalloc.h>
+
+#include <asm/uaccess.h>
+#include <asm/ia32.h>
+
+/*
+ * read_ldt() is not really atomic - this is not a problem since synchronization of reads
+ * and writes done to the LDT has to be assured by user-space anyway. Writes are atomic,
+ * to protect the security checks done on new descriptors.
+ */
+static int
+read_ldt (void *ptr, unsigned long bytecount)
+{
+ char *src, *dst, buf[256]; /* temporary buffer (don't overflow kernel stack!) */
+ unsigned long bytes_left, n;
+
+ if (bytecount > IA32_LDT_ENTRIES*IA32_LDT_ENTRY_SIZE)
+ bytecount = IA32_LDT_ENTRIES*IA32_LDT_ENTRY_SIZE;
+
+ bytes_left = bytecount;
+
+ src = (void *) IA32_LDT_OFFSET;
+ dst = ptr;
+
+ while (bytes_left) {
+ n = sizeof(buf);
+ if (n > bytes_left)
+ n = bytes_left;
+
+ /*
+ * We know we're reading valid memory, but we still must guard against
+ * running out of memory.
+ */
+ if (__copy_from_user(buf, src, n))
+ return -EFAULT;
+
+ if (copy_to_user(dst, buf, n))
+ return -EFAULT;
+
+ src += n;
+ dst += n;
+ bytes_left -= n;
+ }
+ return bytecount;
+}
+
+static int
+write_ldt (void * ptr, unsigned long bytecount, int oldmode)
+{
+ struct ia32_modify_ldt_ldt_s ldt_info;
+ __u64 entry;
+
+ if (bytecount != sizeof(ldt_info))
+ return -EINVAL;
+ if (copy_from_user(&ldt_info, ptr, sizeof(ldt_info)))
+ return -EFAULT;
+
+ if (ldt_info.entry_number >= IA32_LDT_ENTRIES)
+ return -EINVAL;
+ if (ldt_info.contents == 3) {
+ if (oldmode)
+ return -EINVAL;
+ if (ldt_info.seg_not_present == 0)
+ return -EINVAL;
+ }
+
+ if (ldt_info.base_addr == 0 && ldt_info.limit == 0
+ && (oldmode || (ldt_info.contents == 0 && ldt_info.read_exec_only == 1
+ && ldt_info.seg_32bit == 0 && ldt_info.limit_in_pages == 0
+ && ldt_info.seg_not_present == 1 && ldt_info.useable == 0)))
+ /* allow LDTs to be cleared by the user */
+ entry = 0;
+ else
+ /* we must set the "Accessed" bit as IVE doesn't emulate it */
+ entry = IA32_SEG_DESCRIPTOR(ldt_info.base_addr, ldt_info.limit,
+ (((ldt_info.read_exec_only ^ 1) << 1)
+ | (ldt_info.contents << 2)) | 1,
+ 1, 3, ldt_info.seg_not_present ^ 1,
+ (oldmode ? 0 : ldt_info.useable),
+ ldt_info.seg_32bit,
+ ldt_info.limit_in_pages);
+ /*
+ * Install the new entry. We know we're accessing valid (mapped) user-level
+ * memory, but we still need to guard against out-of-memory, hence we must use
+ * put_user().
+ */
+ return __put_user(entry, (__u64 *) IA32_LDT_OFFSET + ldt_info.entry_number);
+}
+
+asmlinkage int
+sys32_modify_ldt (int func, void *ptr, unsigned int bytecount)
+{
+ int ret = -ENOSYS;
+
+ switch (func) {
+ case 0:
+ ret = read_ldt(ptr, bytecount);
+ break;
+ case 1:
+ ret = write_ldt(ptr, bytecount, 1);
+ break;
+ case 0x11:
+ ret = write_ldt(ptr, bytecount, 0);
+ break;
+ }
+ return ret;
+}
FUNET's LINUX-ADM group, linux-adm@nic.funet.fi
TCL-scripts by Sam Shen (who was at: slshen@lbl.gov)