Merge tag 'random_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/random

Pull randomness updates from Ted Ts'o:
 "Cleanups and bug fixes to /dev/random, add a new getrandom(2) system
  call, which is a superset of OpenBSD's getentropy(2) call, for use
  with userspace crypto libraries such as LibreSSL.

  Also add the ability to have a kernel thread to pull entropy from
  hardware rng devices into /dev/random"

* tag 'random_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/random:
  hwrng: Pass entropy to add_hwgenerator_randomness() in bits, not bytes
  random: limit the contribution of the hw rng to at most half
  random: introduce getrandom(2) system call
  hw_random: fix sparse warning (NULL vs 0 for pointer)
  random: use registers from interrupted code for CPU's w/o a cycle counter
  hwrng: add per-device entropy derating
  hwrng: create filler thread
  random: add_hwgenerator_randomness() for feeding entropy from devices
  random: use an improved fast_mix() function
  random: clean up interrupt entropy accounting for archs w/o cycle counters
  random: only update the last_pulled time if we actually transferred entropy
  random: remove unneeded hash of a portion of the entropy pool
  random: always update the entropy pool under the spinlock

4 files changed, 20 insertions, 1 deletions

diff --git a/include/linux/hw_random.h b/include/linux/hw_random.h
index b4b0eef5fddf..914bb08cd738 100644
--- a/include/linux/hw_random.h
+++ b/include/linux/hw_random.h
@@ -29,6 +29,8 @@
  * @read:               New API. drivers can fill up to max bytes of data
  *                      into the buffer. The buffer is aligned for any type.
  * @priv:               Private data, for use by the RNG driver.
+ * @quality:            Estimation of true entropy in RNG's bitstream
+ *                      (per mill).
  */
 struct hwrng {
         const char *name;
@@ -38,6 +40,7 @@ struct hwrng {
         int (*data_read)(struct hwrng *rng, u32 *data);
         int (*read)(struct hwrng *rng, void *data, size_t max, bool wait);
         unsigned long priv;
+        unsigned short quality;
 
         /* internal. */
         struct list_head list;
@@ -47,5 +50,7 @@ struct hwrng {
 extern int hwrng_register(struct hwrng *rng);
 /** Unregister a Hardware Random Number Generator driver. */
 extern void hwrng_unregister(struct hwrng *rng);
+/** Feed random bits into the pool. */
+extern void add_hwgenerator_randomness(const char *buffer, size_t count, size_t entropy);
 
 #endif /* LINUX_HWRANDOM_H_ */
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 1713977ee26f..701daff5d899 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -868,4 +868,7 @@ asmlinkage long sys_kcmp(pid_t pid1, pid_t pid2, int type,
 asmlinkage long sys_finit_module(int fd, const char __user *uargs, int flags);
 asmlinkage long sys_seccomp(unsigned int op, unsigned int flags,
                             const char __user *uargs);
+asmlinkage long sys_getrandom(char __user *buf, size_t count,
+                              unsigned int flags);
+
 #endif
diff --git a/include/uapi/asm-generic/unistd.h b/include/uapi/asm-generic/unistd.h
index 65acbf0e2867..f1afd607f043 100644
--- a/include/uapi/asm-generic/unistd.h
+++ b/include/uapi/asm-generic/unistd.h
@@ -701,9 +701,11 @@ __SYSCALL(__NR_sched_getattr, sys_sched_getattr)
 __SYSCALL(__NR_renameat2, sys_renameat2)
 #define __NR_seccomp 277
 __SYSCALL(__NR_seccomp, sys_seccomp)
+#define __NR_getrandom 278
+__SYSCALL(__NR_getrandom, sys_getrandom)
 
 #undef __NR_syscalls
-#define __NR_syscalls 278
+#define __NR_syscalls 279
 
 /*
  * All syscalls below here should go away really,
diff --git a/include/uapi/linux/random.h b/include/uapi/linux/random.h
index fff3528a078f..3f93d1695e7f 100644
--- a/include/uapi/linux/random.h
+++ b/include/uapi/linux/random.h
@@ -40,4 +40,13 @@ struct rand_pool_info {
         __u32   buf[0];
 };
 
+/*
+ * Flags for getrandom(2)
+ *
+ * GRND_NONBLOCK        Don't block and return EAGAIN instead
+ * GRND_RANDOM          Use the /dev/random pool instead of /dev/urandom
+ */
+#define GRND_NONBLOCK   0x0001
+#define GRND_RANDOM     0x0002
+
 #endif /* _UAPI_LINUX_RANDOM_H */