xnu-4570.71.2.tar.gz

[apple/xnu.git] / osfmk / i386 / user_ldt.c

diff --git a/osfmk/i386/user_ldt.c b/osfmk/i386/user_ldt.c
index afb9795a3f4cec50088f57dbed5d96e45c1c63cb..35dd2cef786250a813c63b76ef44612c0a45efd7 100644 (file)
--- a/osfmk/i386/user_ldt.c
+++ b/osfmk/i386/user_ldt.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2000-2004 Apple Computer, Inc. All rights reserved.
+ * Copyright (c) 2000-2009 Apple Inc. All rights reserved.
  *
  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
  * 
@@ -68,14 +68,14 @@
 
 #include <vm/vm_kern.h>
 
-#include <i386/seg.h>
-#include <i386/thread.h>
-#include <i386/user_ldt.h>
-#include <i386/mp_desc.h>
-#include <i386/proc_reg.h>
 #include <i386/machdep_call.h>
+#include <i386/user_ldt.h>
 #include <i386/mp.h>
 #include <i386/machine_routines.h>
+#include <i386/proc_reg.h>
+#include <i386/mp_desc.h>
+#include <i386/seg.h>
+#include <i386/thread.h>
 
 #include <sys/errno.h>
 
@@ -88,7 +88,7 @@ static void user_ldt_set_action(void *);
 
 int
 i386_set_ldt(
-       int                     *retval,
+       uint32_t                *retval,
        uint32_t                start_sel,
        uint32_t                descs,  /* out */
        uint32_t                num_sels)
@@ -106,7 +106,7 @@ i386_set_ldt(
            && (start_sel < min_selector || start_sel >= LDTSZ))
            return EINVAL;
        if (start_sel != LDT_AUTO_ALLOC
-           && start_sel + num_sels > LDTSZ)
+           && (uint64_t)start_sel + (uint64_t)num_sels > LDTSZ) /* cast to uint64_t to detect wrap-around */
            return EINVAL;
 
        task_lock(task);
@@ -152,7 +152,7 @@ i386_set_ldt(
                start_sel = LDTSZ_MIN;
            }
                
-           if (start_sel + num_sels > LDTSZ) {
+           if ((uint64_t)start_sel + (uint64_t)num_sels > LDTSZ) {
                task_unlock(task);
                return ENOMEM;
            }
@@ -176,7 +176,7 @@ i386_set_ldt(
            }
 
            ldt_count = end_sel - begin_sel;
-
+           /* XXX allocation under task lock */
            new_ldt = (user_ldt_t)kalloc(sizeof(struct user_ldt) + (ldt_count * sizeof(struct real_descriptor)));
            if (new_ldt == NULL) {
                task_unlock(task);
@@ -212,6 +212,7 @@ i386_set_ldt(
             * Install new descriptors.
             */
            if (descs != 0) {
+                   /* XXX copyin under task lock */
                err = copyin(descs, (char *)&new_ldt->ldt[start_sel - begin_sel],
                             num_sels * sizeof(struct real_descriptor));
                if (err != 0)
@@ -223,10 +224,9 @@ i386_set_ldt(
            } else {
                bzero(&new_ldt->ldt[start_sel - begin_sel], num_sels * sizeof(struct real_descriptor));
            }
-
            /*
             * Validate descriptors.
-            * Only allow descriptors with user priviledges.
+            * Only allow descriptors with user privileges.
             */
            for (i = 0, dp = (struct real_descriptor *) &new_ldt->ldt[start_sel - begin_sel];
                 i < num_sels;
@@ -235,7 +235,8 @@ i386_set_ldt(
                switch (dp->access & ~ACC_A) {
                    case 0:
                    case ACC_P:
-                       /* valid empty descriptor */
+                       /* valid empty descriptor, clear Present preemptively */
+                       dp->access &= (~ACC_P & 0xff);
                        break;
                    case ACC_P | ACC_PL_U | ACC_DATA:
                    case ACC_P | ACC_PL_U | ACC_DATA_W:
@@ -245,14 +246,18 @@ i386_set_ldt(
                    case ACC_P | ACC_PL_U | ACC_CODE_R:
                    case ACC_P | ACC_PL_U | ACC_CODE_C:
                    case ACC_P | ACC_PL_U | ACC_CODE_CR:
-                   case ACC_P | ACC_PL_U | ACC_CALL_GATE_16:
-                   case ACC_P | ACC_PL_U | ACC_CALL_GATE:
                        break;
                    default:
                        task_unlock(task);
                        user_ldt_free(new_ldt);
                        return EACCES;
                }
+               /* Reject attempts to create segments with 64-bit granules */
+               if (dp->granularity & SZ_64) {
+                       task_unlock(task);
+                       user_ldt_free(new_ldt);
+                       return EACCES;
+               }
            }
        }
 
@@ -264,7 +269,7 @@ i386_set_ldt(
         * and we need to make sure the new LDT is in place
         * throughout the task before returning to the user.
         */
-       mp_rendezvous_no_intrs(user_ldt_set_action, task);
+       mp_broadcast(user_ldt_set_action, task);
 
        task_unlock(task);
 
@@ -282,7 +287,7 @@ i386_set_ldt(
 
 int
 i386_get_ldt(
-       int                     *retval,
+       uint32_t                *retval,
        uint32_t                start_sel,
        uint32_t                descs,  /* out */
        uint32_t                num_sels)
@@ -292,9 +297,9 @@ i386_get_ldt(
        unsigned int    ldt_count;
        kern_return_t   err;
 
-       if (start_sel >= 8192)
+       if (start_sel >= LDTSZ)
            return EINVAL;
-       if (start_sel + num_sels > 8192)
+       if ((uint64_t)start_sel + (uint64_t)num_sels > LDTSZ)
            return EINVAL;
        if (descs == 0)
            return EINVAL;
@@ -389,7 +394,7 @@ user_ldt_set(
            bcopy(user_ldt->ldt, &ldtp[user_ldt->start],
                  sizeof(struct real_descriptor) * (user_ldt->count));
 
-           gdt_desc_p(USER_LDT)->limit_low = (sizeof(struct real_descriptor) * (user_ldt->start + user_ldt->count)) - 1;
+           gdt_desc_p(USER_LDT)->limit_low = (uint16_t)((sizeof(struct real_descriptor) * (user_ldt->start + user_ldt->count)) - 1);
 
            ml_cpu_set_ldt(USER_LDT);
        } else {