xnu-7195.101.1.tar.gz

[apple/xnu.git] / bsd / vfs / vfs_cprotect.c

diff --git a/bsd/vfs/vfs_cprotect.c b/bsd/vfs/vfs_cprotect.c
index edb00a315a3c5971d26cec2c7586761122b2d963..8355c01273a12660926044b2d620838b7b4843d7 100644 (file)
--- a/bsd/vfs/vfs_cprotect.c
+++ b/bsd/vfs/vfs_cprotect.c
@@ -47,8 +47,7 @@
  * to read/write it.
  */
 
-// cpx_flags
-typedef uint32_t cpx_flags_t;
+// cpx_flags defined in cprotect.h
 enum {
        CPX_SEP_WRAPPEDKEY                      = 0x01,
        CPX_IV_AES_CTX_INITIALIZED      = 0x02,
@@ -63,27 +62,41 @@ enum {
        CPX_WRITE_PROTECTABLE           = 0x40
 };
 
+/*
+ * variable-length CPX structure. See fixed-length variant in cprotect.h
+ */
 struct cpx {
 #if DEBUG
        uint32_t                cpx_magic1;
 #endif
-       aes_encrypt_ctx cpx_iv_aes_ctx;         // Context used for generating the IV
+       aes_encrypt_ctx         *cpx_iv_aes_ctx_ptr;// Pointer to context used for generating the IV
        cpx_flags_t             cpx_flags;
        uint16_t                cpx_max_key_len;
        uint16_t                cpx_key_len;
+       //fixed length up to here.  cpx_cached_key is variable-length
        uint8_t                 cpx_cached_key[];
 };
 
+/* Allows us to switch between CPX types */
+typedef union cpxunion {
+       struct cpx cpx_var;
+       fcpx_t cpx_fixed;
+} cpxunion_t;
+
+ZONE_DECLARE(cpx_zone, "cpx",
+    sizeof(struct fcpx), ZC_ZFREE_CLEARMEM);
+ZONE_DECLARE(aes_ctz_zone, "AES ctx",
+    sizeof(aes_encrypt_ctx), ZC_ZFREE_CLEARMEM | ZC_NOENCRYPT);
+
+// Note: see struct fcpx defined in sys/cprotect.h
+
 // -- cpx_t accessors --
 
 size_t
-cpx_size(size_t key_size)
+cpx_size(size_t key_len)
 {
-       size_t size = sizeof(struct cpx) + key_size;
-
-#if DEBUG
-       size += 4; // Extra for magic
-#endif
+       // This should pick up the 'magic' word in DEBUG for free.
+       size_t size = sizeof(struct cpx) + key_len;
 
        return size;
 }
@@ -95,7 +108,7 @@ cpx_sizex(const struct cpx *cpx)
 }
 
 cpx_t
-cpx_alloc(size_t key_len)
+cpx_alloc(size_t key_len, bool needs_ctx)
 {
        cpx_t cpx = NULL;
 
@@ -105,6 +118,10 @@ cpx_alloc(size_t key_len)
         * This way, we can write-protect as needed.
         */
        size_t cpsize = cpx_size(key_len);
+
+       // silence warning for needs_ctx
+       (void) needs_ctx;
+
        if (cpsize < PAGE_SIZE) {
                /*
                 * Don't use MALLOC to allocate the page-sized structure.  Instead,
@@ -127,15 +144,56 @@ cpx_alloc(size_t key_len)
                panic("cpx_size too large ! (%lu)", cpsize);
        }
 #else
-       /* If key page write protection disabled, just switch to kernel MALLOC */
-       MALLOC(cpx, cpx_t, cpx_size(key_len), M_TEMP, M_WAITOK);
+       /* If key page write protection disabled, just switch to zalloc */
+
+       // error out if you try to request a key that's too big
+       if (key_len > VFS_CP_MAX_CACHEBUFLEN) {
+               return NULL;
+       }
+
+       // the actual key array is fixed-length, but the amount of usable content can vary, via 'key_len'
+       cpx = zalloc_flags(cpx_zone, Z_WAITOK | Z_ZERO);
+
+       // if our encryption type needs it, alloc the context
+       if (needs_ctx) {
+               cpx_alloc_ctx(cpx);
+       }
+
 #endif
        cpx_init(cpx, key_len);
 
        return cpx;
 }
 
-/* this is really a void function */
+int
+cpx_alloc_ctx(cpx_t cpx)
+{
+#if CONFIG_KEYPAGE_WP
+       (void) cpx;
+#else
+       if (cpx->cpx_iv_aes_ctx_ptr) {
+               // already allocated?
+               return 0;
+       }
+
+       cpx->cpx_iv_aes_ctx_ptr = zalloc_flags(aes_ctz_zone, Z_WAITOK | Z_ZERO);
+#endif // CONFIG_KEYPAGE_WP
+
+       return 0;
+}
+
+void
+cpx_free_ctx(cpx_t cpx)
+{
+#if CONFIG_KEYPAGE_WP
+       (void) cpx;
+# else
+       if (cpx->cpx_iv_aes_ctx_ptr) {
+               zfree(aes_ctz_zone, cpx->cpx_iv_aes_ctx_ptr);
+       }
+#endif // CONFIG_KEYPAGE_WP
+}
+
 void
 cpx_writeprotect(cpx_t cpx)
 {
@@ -179,8 +237,9 @@ cpx_free(cpx_t cpx)
                return;
        }
 #else
-       bzero(cpx->cpx_cached_key, cpx->cpx_max_key_len);
-       FREE(cpx, M_TEMP);
+       // free the context if it wasn't already freed
+       cpx_free_ctx(cpx);
+       zfree(cpx_zone, cpx);
        return;
 #endif
 }
@@ -194,7 +253,8 @@ cpx_init(cpx_t cpx, size_t key_len)
 #endif
        cpx->cpx_flags = 0;
        cpx->cpx_key_len = 0;
-       cpx->cpx_max_key_len = key_len;
+       assert(key_len <= UINT16_MAX);
+       cpx->cpx_max_key_len = (uint16_t)key_len;
 }
 
 bool
@@ -307,16 +367,18 @@ cpx_key(const struct cpx *cpx)
 void
 cpx_set_aes_iv_key(struct cpx *cpx, void *iv_key)
 {
-       aes_encrypt_key128(iv_key, &cpx->cpx_iv_aes_ctx);
-       SET(cpx->cpx_flags, CPX_IV_AES_CTX_INITIALIZED | CPX_USE_OFFSET_FOR_IV);
-       CLR(cpx->cpx_flags, CPX_IV_AES_CTX_VFS);
+       if (cpx->cpx_iv_aes_ctx_ptr) {
+               aes_encrypt_key128(iv_key, cpx->cpx_iv_aes_ctx_ptr);
+               SET(cpx->cpx_flags, CPX_IV_AES_CTX_INITIALIZED | CPX_USE_OFFSET_FOR_IV);
+               CLR(cpx->cpx_flags, CPX_IV_AES_CTX_VFS);
+       }
 }
 
 aes_encrypt_ctx *
 cpx_iv_aes_ctx(struct cpx *cpx)
 {
        if (ISSET(cpx->cpx_flags, CPX_IV_AES_CTX_INITIALIZED)) {
-               return &cpx->cpx_iv_aes_ctx;
+               return cpx->cpx_iv_aes_ctx_ptr;
        }
 
        SHA1_CTX sha1ctxt;
@@ -335,14 +397,16 @@ cpx_iv_aes_ctx(struct cpx *cpx)
        cpx_set_aes_iv_key(cpx, digest);
        SET(cpx->cpx_flags, CPX_IV_AES_CTX_VFS);
 
-       return &cpx->cpx_iv_aes_ctx;
+       return cpx->cpx_iv_aes_ctx_ptr;
 }
 
 void
 cpx_flush(cpx_t cpx)
 {
        bzero(cpx->cpx_cached_key, cpx->cpx_max_key_len);
-       bzero(&cpx->cpx_iv_aes_ctx, sizeof(cpx->cpx_iv_aes_ctx));
+       if (cpx->cpx_iv_aes_ctx_ptr) {
+               bzero(cpx->cpx_iv_aes_ctx_ptr, sizeof(aes_encrypt_ctx));
+       }
        cpx->cpx_flags = 0;
        cpx->cpx_key_len = 0;
 }
@@ -361,7 +425,7 @@ cpx_copy(const struct cpx *src, cpx_t dst)
        memcpy(cpx_key(dst), cpx_key(src), key_len);
        dst->cpx_flags = src->cpx_flags;
        if (ISSET(dst->cpx_flags, CPX_IV_AES_CTX_INITIALIZED)) {
-               dst->cpx_iv_aes_ctx = src->cpx_iv_aes_ctx;
+               *(dst->cpx_iv_aes_ctx_ptr) = *(src->cpx_iv_aes_ctx_ptr); // deep copy
        }
 }