6 files changed, 54 insertions, 4 deletions

diff --git a/arch/x86/syscalls/syscall_32.tbl b/arch/x86/syscalls/syscall_32.tbl
index d6b867921612..5b46a618aeb1 100644
--- a/arch/x86/syscalls/syscall_32.tbl
+++ b/arch/x86/syscalls/syscall_32.tbl
@@ -360,3 +360,4 @@
 351     i386    sched_setattr           sys_sched_setattr
 352     i386    sched_getattr           sys_sched_getattr
 353     i386    renameat2               sys_renameat2
+355     i386    getrandom               sys_getrandom
diff --git a/arch/x86/syscalls/syscall_64.tbl b/arch/x86/syscalls/syscall_64.tbl
index ec255a1646d2..0dc4bf891460 100644
--- a/arch/x86/syscalls/syscall_64.tbl
+++ b/arch/x86/syscalls/syscall_64.tbl
@@ -323,6 +323,7 @@
 314     common  sched_setattr           sys_sched_setattr
 315     common  sched_getattr           sys_sched_getattr
 316     common  renameat2               sys_renameat2
+318     common  getrandom               sys_getrandom
 
 #
 # x32-specific system call numbers start at 512 to avoid cache impact
diff --git a/drivers/char/random.c b/drivers/char/random.c
index aa22fe551c2a..7d1682ea1e86 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -258,6 +258,8 @@
 #include <linux/kmemcheck.h>
 #include <linux/workqueue.h>
 #include <linux/irq.h>
+#include <linux/syscalls.h>
+#include <linux/completion.h>
 
 #include <asm/processor.h>
 #include <asm/uaccess.h>
@@ -404,6 +406,7 @@ static struct poolinfo {
  */
 static DECLARE_WAIT_QUEUE_HEAD(random_read_wait);
 static DECLARE_WAIT_QUEUE_HEAD(random_write_wait);
+static DECLARE_WAIT_QUEUE_HEAD(urandom_init_wait);
 static struct fasync_struct *fasync;
 
 /**********************************************************************
@@ -657,6 +660,7 @@ retry:
                 r->entropy_total = 0;
                 if (r == &nonblocking_pool) {
                         prandom_reseed_late();
+                        wake_up_interruptible(&urandom_init_wait);
                         pr_notice("random: %s pool is initialized\n", r->name);
                 }
         }
@@ -1174,13 +1178,14 @@ static ssize_t extract_entropy_user(struct entropy_store *r, void __user *buf,
 {
         ssize_t ret = 0, i;
         __u8 tmp[EXTRACT_SIZE];
+        int large_request = (nbytes > 256);
 
         trace_extract_entropy_user(r->name, nbytes, ENTROPY_BITS(r), _RET_IP_);
         xfer_secondary_pool(r, nbytes);
         nbytes = account(r, nbytes, 0, 0);
 
         while (nbytes) {
-                if (need_resched()) {
+                if (large_request && need_resched()) {
                         if (signal_pending(current)) {
                                 if (ret == 0)
                                         ret = -ERESTARTSYS;
@@ -1355,7 +1360,7 @@ static int arch_random_refill(void)
 }
 
 static ssize_t
-random_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
+_random_read(int nonblock, char __user *buf, size_t nbytes)
 {
         ssize_t n;
 
@@ -1379,7 +1384,7 @@ random_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
                 if (arch_random_refill())
                         continue;
 
-                if (file->f_flags & O_NONBLOCK)
+                if (nonblock)
                         return -EAGAIN;
 
                 wait_event_interruptible(random_read_wait,
@@ -1391,6 +1396,12 @@ random_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
 }
 
 static ssize_t
+random_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
+{
+        return _random_read(file->f_flags & O_NONBLOCK, buf, nbytes);
+}
+
+static ssize_t
 urandom_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
 {
         int ret;
@@ -1533,6 +1544,29 @@ const struct file_operations urandom_fops = {
         .llseek = noop_llseek,
 };
 
+SYSCALL_DEFINE3(getrandom, char __user *, buf, size_t, count,
+                unsigned int, flags)
+{
+        if (flags & ~(GRND_NONBLOCK|GRND_RANDOM))
+                return -EINVAL;
+
+        if (count > INT_MAX)
+                count = INT_MAX;
+
+        if (flags & GRND_RANDOM)
+                return _random_read(flags & GRND_NONBLOCK, buf, count);
+
+        if (unlikely(nonblocking_pool.initialized == 0)) {
+                if (flags & GRND_NONBLOCK)
+                        return -EAGAIN;
+                wait_event_interruptible(urandom_init_wait,
+                                         nonblocking_pool.initialized);
+                if (signal_pending(current))
+                        return -ERESTARTSYS;
+        }
+        return urandom_read(NULL, buf, count, NULL);
+}
+
 /***************************************************************
  * Random UUID interface
  *
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index b0881a0ed322..43324a897cf2 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -866,4 +866,7 @@ asmlinkage long sys_process_vm_writev(pid_t pid,
 asmlinkage long sys_kcmp(pid_t pid1, pid_t pid2, int type,
                          unsigned long idx1, unsigned long idx2);
 asmlinkage long sys_finit_module(int fd, const char __user *uargs, int flags);
+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 333640608087..1d104a2ca643 100644
--- a/include/uapi/asm-generic/unistd.h
+++ b/include/uapi/asm-generic/unistd.h
@@ -699,9 +699,11 @@ __SYSCALL(__NR_sched_setattr, sys_sched_setattr)
 __SYSCALL(__NR_sched_getattr, sys_sched_getattr)
 #define __NR_renameat2 276
 __SYSCALL(__NR_renameat2, sys_renameat2)
+#define __NR_getrandom 278
+__SYSCALL(__NR_getrandom, sys_getrandom)
 
 #undef __NR_syscalls
-#define __NR_syscalls 277
+#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 */