From 60596973b503637c742b597aeb862eecae9f9c91 Mon Sep 17 00:00:00 2001
From: Jakub Hrozek <jhrozek@redhat.com>
Date: Mon, 8 Aug 2016 14:07:04 +0200
Subject: [PATCH 109/111] UTIL: Use sss_atomic_read_s in generate_csprng_buffer
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There was a bug in generate_csprng_buffer() where if we read the exact
amount of bytes from /dev/urandom, we would always return EIO. Instead,
let's reuse the existing code from sss_atomic_read_s() which fixes this
bug and reduces code duplication.

Reviewed-by: Lukáš Slebodník <lslebodn@redhat.com>
Reviewed-by: Fabiano Fidêncio <fabiano@fidencio.org>
---
 Makefile.am                  |  2 ++
 src/util/crypto/sss_crypto.c | 29 +++++------------------------
 2 files changed, 7 insertions(+), 24 deletions(-)

diff --git a/Makefile.am b/Makefile.am
index 4d90c7a46e2ee0fe652aa392cf647d056e06c7fc..a32a1e37c85e2370fa006ee73b730145f03c3fc1 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -815,6 +815,7 @@ if HAVE_NSS
                         src/util/crypto/nss/nss_nite.c \
                         src/util/crypto/nss/nss_util.c \
 			src/util/crypto/sss_crypto.c \
+			src/util/atomic_io.c \
 			$(NULL)
     SSS_CRYPT_CFLAGS = $(NSS_CFLAGS)
     SSS_CRYPT_LIBS = $(NSS_LIBS)
@@ -836,6 +837,7 @@ else
                         src/util/crypto/libcrypto/crypto_obfuscate.c \
                         src/util/crypto/libcrypto/crypto_nite.c \
 			src/util/crypto/sss_crypto.c \
+			src/util/atomic_io.c \
 			$(NULL)
     SSS_CRYPT_CFLAGS = $(CRYPTO_CFLAGS)
     SSS_CRYPT_LIBS = $(CRYPTO_LIBS)
diff --git a/src/util/crypto/sss_crypto.c b/src/util/crypto/sss_crypto.c
index 4c775f3d926ae32f3cb72b1329c0a025a0550ed5..ac90bac07c7006a2950331b86bcc412207a3e401 100644
--- a/src/util/crypto/sss_crypto.c
+++ b/src/util/crypto/sss_crypto.c
@@ -25,41 +25,22 @@
 int generate_csprng_buffer(uint8_t *buf, size_t size)
 {
     ssize_t rsize;
-    ssize_t pos;
     int ret;
     int fd;
 
     fd = open("/dev/urandom", O_RDONLY);
     if (fd == -1) return errno;
 
-    rsize = 0;
-    pos = 0;
-    while (rsize < size) {
-        rsize = read(fd, buf + pos, size - pos);
-        switch (rsize) {
-        case -1:
-            if (errno == EINTR) continue;
-            ret = EIO;
-            goto done;
-        case 0:
-            ret = EIO;
-            goto done;
-        default:
-            if (rsize + pos < size - pos) {
-                pos += rsize;
-                continue;
-            }
-            ret = EIO;
-            goto done;
-        }
-    }
-    if (rsize != size) {
+    rsize = sss_atomic_read_s(fd, buf, size);
+    if (rsize == -1) {
+        ret = errno;
+        goto done;
+    } else if (rsize != size) {
         ret = EFAULT;
         goto done;
     }
 
     ret = EOK;
-
 done:
     close(fd);
     return ret;
-- 
2.4.11