[PATCH] Add support for /dev/[u]random ioctls

[Rasmus Villemoes]

* random_ioctl.c: New file.
* Makefile.am (strace_SOURCES): Add it.
* defs.h (DECL_IOCTL): Add random.
* ioctl.c (ioctl_decode): Add 'R' case.

Signed-off-by: Rasmus Villemoes <rasmus.villemoes at prevas.dk>
---
 Makefile.am    |  1 +
 defs.h         |  1 +
 ioctl.c        |  2 ++
 random_ioctl.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 58 insertions(+)
 create mode 100644 random_ioctl.c

diff --git a/Makefile.am b/Makefile.am
index 913d26a9..0680763e 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -267,6 +267,7 @@ strace_SOURCES =	\
 	ptp.c		\
 	ptrace.h	\
 	quota.c		\
+	random_ioctl.c	\
 	readahead.c	\
 	readlink.c	\
 	reboot.c	\
diff --git a/defs.h b/defs.h
index 5ba95f53..b8d561aa 100644
--- a/defs.h
+++ b/defs.h
@@ -973,6 +973,7 @@ DECL_IOCTL(kvm);
 DECL_IOCTL(nbd);
 DECL_IOCTL(nsfs);
 DECL_IOCTL(ptp);
+DECL_IOCTL(random);
 DECL_IOCTL(scsi);
 DECL_IOCTL(term);
 DECL_IOCTL(ubi);
diff --git a/ioctl.c b/ioctl.c
index 4c9e7db3..e7dd4c4e 100644
--- a/ioctl.c
+++ b/ioctl.c
@@ -329,6 +329,8 @@ ioctl_decode(struct tcb *tcp)
 		return inotify_ioctl(tcp, code, arg);
 	case 0xab:
 		return nbd_ioctl(tcp, code, arg);
+	case 'R':
+		return random_ioctl(tcp, code, arg);
 	default:
 		break;
 	}
diff --git a/random_ioctl.c b/random_ioctl.c
new file mode 100644
index 00000000..8acbc34b
--- /dev/null
+++ b/random_ioctl.c
@@ -0,0 +1,54 @@
+
+#include "defs.h"
+
+#include <linux/random.h>
+
+/*
+ * RNDGETPOOL was removed in 2.6.9, so non-ancient kernels always
+ * return -EINVAL for that.
+ */
+
+int
+random_ioctl(struct tcb *const tcp, const unsigned int code,
+	   const kernel_ulong_t arg)
+{
+	struct rand_pool_info info;
+	int count;
+	
+	switch (code) {
+	case RNDGETENTCNT:
+		if (entering(tcp))
+			return 0;
+		ATTRIBUTE_FALLTHROUGH;
+	case RNDADDTOENTCNT:
+		tprints(", ");
+		if (umove_or_printaddr(tcp, arg, &count))
+			return RVAL_IOCTL_DECODED;
+		tprintf("entropy_count=%d", count);
+		break;
+		
+	case RNDADDENTROPY:
+		tprints(", ");
+		if (umove_or_printaddr(tcp, arg, &info))
+			return RVAL_IOCTL_DECODED;
+		/* 
+		 * It might be nice to print a few bytes from the
+		 * ->buf, but we don't that we can even fetch one byte
+		 * beyond until we know buf_size. So keep it simple.
+		 */
+		tprintf("{entropy_count=%d, buf_size=%d}",
+			info.entropy_count, info.buf_size);
+		break;
+		
+	/* ioctls with no parameters */
+	case RNDZAPENTCNT:
+	case RNDCLEARPOOL:
+#ifdef RNDRESEEDCRNG /* only linux 4.17+ */
+	case RNDRESEEDCRNG:
+#endif
+		break;
+	default:
+		return RVAL_DECODED;
+	}
+	return RVAL_IOCTL_DECODED;
+}
-- 
2.19.1.6.gbde171bbf5