diff mbox series

[1/2] linux-user: Split out do_mmap

Message ID 20230808025542.50392-2-richard.henderson@linaro.org
State Superseded
Headers show
Series linux-user: Fix MAP_SHARED_VALIDATE, MAP_FIXED_NOREPLACE | expand

Commit Message

Richard Henderson Aug. 8, 2023, 2:55 a.m. UTC 
New function that rejects unsupported map types and flags.
In 4b840f96 we should not have accepted MAP_SHARED_VALIDATE
without actually validating the rest of the flags.

Fixes: 4b840f96 ("linux-user: Populate more bits in mmap_flags_tbl")
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 linux-user/syscall.c | 90 +++++++++++++++++++++++++++++++++++---------
 1 file changed, 73 insertions(+), 17 deletions(-)

Comments

Alex Bennée Aug. 9, 2023, 9:15 a.m. UTC | #1 
Richard Henderson <richard.henderson@linaro.org> writes:

> New function that rejects unsupported map types and flags.
> In 4b840f96 we should not have accepted MAP_SHARED_VALIDATE
> without actually validating the rest of the flags.
>
> Fixes: 4b840f96 ("linux-user: Populate more bits in mmap_flags_tbl")
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
diff mbox series

Patch

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index a15bce2be2..34deff0723 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -5985,10 +5985,6 @@  static const StructEntry struct_termios_def = {
 #endif
 
 static const bitmask_transtbl mmap_flags_tbl[] = {
-    { TARGET_MAP_TYPE, TARGET_MAP_SHARED, MAP_TYPE, MAP_SHARED },
-    { TARGET_MAP_TYPE, TARGET_MAP_PRIVATE, MAP_TYPE, MAP_PRIVATE },
-    { TARGET_MAP_TYPE, TARGET_MAP_SHARED_VALIDATE,
-      MAP_TYPE, MAP_SHARED_VALIDATE },
     { TARGET_MAP_FIXED, TARGET_MAP_FIXED, MAP_FIXED, MAP_FIXED },
     { TARGET_MAP_ANONYMOUS, TARGET_MAP_ANONYMOUS,
       MAP_ANONYMOUS, MAP_ANONYMOUS },
@@ -6006,7 +6002,6 @@  static const bitmask_transtbl mmap_flags_tbl[] = {
        Recognize it for the target insofar as we do not want to pass
        it through to the host.  */
     { TARGET_MAP_STACK, TARGET_MAP_STACK, 0, 0 },
-    { TARGET_MAP_SYNC, TARGET_MAP_SYNC, MAP_SYNC, MAP_SYNC },
     { TARGET_MAP_NONBLOCK, TARGET_MAP_NONBLOCK, MAP_NONBLOCK, MAP_NONBLOCK },
     { TARGET_MAP_POPULATE, TARGET_MAP_POPULATE, MAP_POPULATE, MAP_POPULATE },
     { TARGET_MAP_FIXED_NOREPLACE, TARGET_MAP_FIXED_NOREPLACE,
@@ -6016,6 +6011,75 @@  static const bitmask_transtbl mmap_flags_tbl[] = {
     { 0, 0, 0, 0 }
 };
 
+/*
+ * Arrange for legacy / undefined architecture specific flags to be
+ * ignored by mmap handling code.
+ */
+#ifndef TARGET_MAP_32BIT
+#define TARGET_MAP_32BIT 0
+#endif
+#ifndef TARGET_MAP_HUGE_2MB
+#define TARGET_MAP_HUGE_2MB 0
+#endif
+#ifndef TARGET_MAP_HUGE_1GB
+#define TARGET_MAP_HUGE_1GB 0
+#endif
+
+static abi_long do_mmap(abi_ulong addr, abi_ulong len, int prot,
+                        int target_flags, int fd, off_t offset)
+{
+    /*
+     * The historical set of flags that all mmap types implicitly support.
+     */
+    enum {
+        TARGET_LEGACY_MAP_MASK = TARGET_MAP_SHARED
+                               | TARGET_MAP_PRIVATE
+                               | TARGET_MAP_FIXED
+                               | TARGET_MAP_ANONYMOUS
+                               | TARGET_MAP_DENYWRITE
+                               | TARGET_MAP_EXECUTABLE
+                               | TARGET_MAP_UNINITIALIZED
+                               | TARGET_MAP_GROWSDOWN
+                               | TARGET_MAP_LOCKED
+                               | TARGET_MAP_NORESERVE
+                               | TARGET_MAP_POPULATE
+                               | TARGET_MAP_NONBLOCK
+                               | TARGET_MAP_STACK
+                               | TARGET_MAP_HUGETLB
+                               | TARGET_MAP_32BIT
+                               | TARGET_MAP_HUGE_2MB
+                               | TARGET_MAP_HUGE_1GB
+    };
+    int host_flags;
+
+    switch (target_flags & TARGET_MAP_TYPE) {
+    case TARGET_MAP_PRIVATE:
+        host_flags = MAP_PRIVATE;
+        break;
+    case TARGET_MAP_SHARED:
+        host_flags = MAP_SHARED;
+        break;
+    case TARGET_MAP_SHARED_VALIDATE:
+        /*
+         * MAP_SYNC is only supported for MAP_SHARED_VALIDATE, and is
+         * therefore omitted from mmap_flags_tbl and TARGET_LEGACY_MAP_MASK.
+         */
+        if (target_flags & ~(TARGET_LEGACY_MAP_MASK | TARGET_MAP_SYNC)) {
+            return -TARGET_EOPNOTSUPP;
+        }
+        host_flags = MAP_SHARED_VALIDATE;
+        if (target_flags & TARGET_MAP_SYNC) {
+            host_flags |= MAP_SYNC;
+        }
+        break;
+    default:
+        return -TARGET_EINVAL;
+    }
+    host_flags |= target_to_host_bitmask(target_flags, mmap_flags_tbl);
+
+    return get_errno(target_mmap(addr, len, prot, host_flags, fd, offset));
+}
+
 /*
  * NOTE: TARGET_ABI32 is defined for TARGET_I386 (but not for TARGET_X86_64)
  *       TARGET_I386 is defined if TARGET_X86_64 is defined
@@ -10536,28 +10600,20 @@  static abi_long do_syscall1(CPUArchState *cpu_env, int num, abi_long arg1,
             v5 = tswapal(v[4]);
             v6 = tswapal(v[5]);
             unlock_user(v, arg1, 0);
-            ret = get_errno(target_mmap(v1, v2, v3,
-                                        target_to_host_bitmask(v4, mmap_flags_tbl),
-                                        v5, v6));
+            return do_mmap(v1, v2, v3, v4, v5, v6);
         }
 #else
         /* mmap pointers are always untagged */
-        ret = get_errno(target_mmap(arg1, arg2, arg3,
-                                    target_to_host_bitmask(arg4, mmap_flags_tbl),
-                                    arg5,
-                                    arg6));
+        return do_mmap(arg1, arg2, arg3, arg4, arg5, arg6);
 #endif
-        return ret;
 #endif
 #ifdef TARGET_NR_mmap2
     case TARGET_NR_mmap2:
 #ifndef MMAP_SHIFT
 #define MMAP_SHIFT 12
 #endif
-        ret = target_mmap(arg1, arg2, arg3,
-                          target_to_host_bitmask(arg4, mmap_flags_tbl),
-                          arg5, (off_t)(abi_ulong)arg6 << MMAP_SHIFT);
-        return get_errno(ret);
+        return do_mmap(arg1, arg2, arg3, arg4, arg5,
+                       (off_t)(abi_ulong)arg6 << MMAP_SHIFT);
 #endif
     case TARGET_NR_munmap:
         arg1 = cpu_untagged_addr(cpu, arg1);