linux-user: Add support for setsockopt() option SOL_ALG

Add support for options SOL_ALG of the syscall setsockopt(). This
option is used in relation to Linux kernel Crypto API, and allows
a user to set additional information for the cipher operation via
syscall setsockopt(). The field "optname" must be one of the
following:

  - ALG_SET_KEY – seting the key
  - ALG_SET_AEAD_AUTHSIZE – set the authentication tag size

SOL_ALG is relatively newer setsockopt() option. Therefore, the
code that handles SOL_ALG is enclosed in "ifdef" so that the build
does not fail for older kernels that do not contain support for
SOL_ALG. "ifdef" also contains check if ALG_SET_KEY and
ALG_SET_AEAD_AUTHSIZE are defined.

Signed-off-by: Yunqiang Su <ysu@wavecomp.com>
Signed-off-by: Aleksandar Markovic <amarkovic@wavecomp.com>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Message-Id: <1560953834-29584-3-git-send-email-aleksandar.markovic@rt-rk.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>

linux-user/syscall.c

@@ -102,6 +102,7 @@
 #include <linux/blkpg.h>
 #include <netpacket/packet.h>
 #include <linux/netlink.h>
+#include <linux/if_alg.h>
 #include "linux_loop.h"
 #include "uname.h"
 
@@ -1941,6 +1942,36 @@ static abi_long do_setsockopt(int sockfd, int level, int optname,
             goto unimplemented;
         }
         break;
+#if defined(SOL_ALG) && defined(ALG_SET_KEY) && defined(ALG_SET_AEAD_AUTHSIZE)
+    case SOL_ALG:
+        switch (optname) {
+        case ALG_SET_KEY:
+        {
+            char *alg_key = g_malloc(optlen);
+
+            if (!alg_key) {
+                return -TARGET_ENOMEM;
+            }
+            if (copy_from_user(alg_key, optval_addr, optlen)) {
+                g_free(alg_key);
+                return -TARGET_EFAULT;
+            }
+            ret = get_errno(setsockopt(sockfd, level, optname,
+                                       alg_key, optlen));
+            g_free(alg_key);
+            break;
+        }
+        case ALG_SET_AEAD_AUTHSIZE:
+        {
+            ret = get_errno(setsockopt(sockfd, level, optname,
+                                       NULL, optlen));
+            break;
+        }
+        default:
+            goto unimplemented;
+        }
+        break;
+#endif
     case TARGET_SOL_SOCKET:
         switch (optname) {
         case TARGET_SO_RCVTIMEO: