Backport getrandom syscall

Signed-off-by: Christophe Chapuis <[email protected]>

Author: Tofee

arch/arm/include/asm/unistd.h

@@ -405,6 +405,7 @@
 #define __NR_process_vm_readv		(__NR_SYSCALL_BASE+376)
 #define __NR_process_vm_writev		(__NR_SYSCALL_BASE+377)
 #define __NR_seccomp			(__NR_SYSCALL_BASE+383)
+#define __NR_getrandom			(__NR_SYSCALL_BASE+384)
 
 /*
  * The following SWIs are ARM private.
@@ -416,6 +417,14 @@
 #define __ARM_NR_usr32			(__ARM_NR_BASE+4)
 #define __ARM_NR_set_tls		(__ARM_NR_BASE+5)
 
+/*
+ * This may need to be greater than __NR_last_syscall+1 in order to
+ * account for the padding in the syscall table
+ */
+#ifdef __KERNEL__
+#define __NR_syscalls  (388)
+#endif
+
 /*
  * *NOTE*: This is a ghost syscall private to the kernel.  Only the
  * __kuser_cmpxchg code in entry-armv.S should be aware of its

arch/arm/kernel/calls.S

@@ -393,6 +393,7 @@
 		CALL(sys_ni_syscall)
 		CALL(sys_ni_syscall)
 		CALL(sys_seccomp)
+		CALL(sys_getrandom)
 #ifndef syscalls_counted
 .equ syscalls_padding, ((NR_syscalls + 3) & ~3) - NR_syscalls
 #define syscalls_counted

arch/x86/syscalls/syscall_32.tbl

@@ -356,3 +356,4 @@
 347	i386	process_vm_readv	sys_process_vm_readv		compat_sys_process_vm_readv
 348	i386	process_vm_writev	sys_process_vm_writev		compat_sys_process_vm_writev
 354	i386	seccomp			sys_seccomp
+355	i386	getrandom		sys_getrandom

arch/x86/syscalls/syscall_64.tbl

@@ -319,6 +319,7 @@
 310	64	process_vm_readv	sys_process_vm_readv
 311	64	process_vm_writev	sys_process_vm_writev
 317	common	seccomp			sys_seccomp
+318	common	getrandom		sys_getrandom
 
 #
 # x32-specific system call numbers start at 512 to avoid cache impact

drivers/char/random.c

@@ -255,6 +255,8 @@
 #include <linux/fips.h>
 #include <linux/ptrace.h>
 #include <linux/kmemcheck.h>
+#include <linux/syscalls.h>
+#include <linux/completion.h>
 
 #ifdef CONFIG_GENERIC_HARDIRQS
 # include <linux/irq.h>
@@ -397,6 +399,7 @@ 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;
 
 #if 0
@@ -607,10 +610,15 @@ static void credit_entropy_bits(struct entropy_store *r, int nbits)
 	if (cmpxchg(&r->entropy_count, orig, entropy_count) != orig)
 		goto retry;
 
-	if (!r->initialized && nbits > 0) {
-		r->entropy_total += nbits;
-		if (r->entropy_total > 128)
-			r->initialized = 1;
+	r->entropy_total += nbits;
+	if (!r->initialized && r->entropy_total > 128) {
+		r->initialized = 1;
+		r->entropy_total = 0;
+		if (r == &nonblocking_pool) {
+			prandom_reseed_late();
+			wake_up_all(&urandom_init_wait);
+			pr_notice("random: %s pool is initialized\n", r->name);
+		}
 	}
 
 	trace_credit_entropy_bits(r->name, nbits, entropy_count,
@@ -999,13 +1007,14 @@ 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, r->entropy_count, _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;
@@ -1138,7 +1147,7 @@ void rand_initialize_disk(struct gendisk *disk)
 #endif
 
 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, retval = 0, count = 0;
 
@@ -1158,7 +1167,7 @@ random_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
 			  n*8, (nbytes-n)*8);
 
 		if (n == 0) {
-			if (file->f_flags & O_NONBLOCK) {
+			if (nonblock) {
 				retval = -EAGAIN;
 				break;
 			}
@@ -1193,6 +1202,12 @@ random_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
 	return (count ? count : retval);
 }
 
+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)
 {
@@ -1319,6 +1334,29 @@ 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
  *

drivers/scsi/fcoe/fcoe_ctlr.c

@@ -2048,7 +2048,7 @@ static void fcoe_ctlr_vn_restart(struct fcoe_ctlr *fip)
 	 */
 	port_id = fip->port_id;
 	if (fip->probe_tries)
-		port_id = prandom32(&fip->rnd_state) & 0xffff;
+		port_id = prandom_u32_state(&fip->rnd_state) & 0xffff;
 	else if (!port_id)
 		port_id = fip->lp->wwpn & 0xffff;
 	if (!port_id || port_id == 0xffff)
@@ -2073,7 +2073,7 @@ static void fcoe_ctlr_vn_restart(struct fcoe_ctlr *fip)
 static void fcoe_ctlr_vn_start(struct fcoe_ctlr *fip)
 {
 	fip->probe_tries = 0;
-	prandom32_seed(&fip->rnd_state, fip->lp->wwpn);
+	prandom_seed_state(&fip->rnd_state, fip->lp->wwpn);
 	fcoe_ctlr_vn_restart(fip);
 }
 

include/asm-generic/unistd.h

@@ -693,9 +693,11 @@ __SC_COMP(__NR_process_vm_writev, sys_process_vm_writev, \
           compat_sys_process_vm_writev)
 #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,

include/linux/random.h

@@ -46,6 +46,15 @@ struct rnd_state {
 
 /* Exported functions */
 
+/*
+ * 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
+
 #ifdef __KERNEL__
 
 extern void add_device_randomness(const void *, unsigned int);
@@ -66,10 +75,20 @@ unsigned int get_random_int(void);
 unsigned long get_random_long(void);
 unsigned long randomize_range(unsigned long start, unsigned long end, unsigned long len);
 
-u32 random32(void);
-void srandom32(u32 seed);
+u32 prandom_u32(void);
+void prandom_bytes(void *buf, int nbytes);
+void prandom_seed(u32 seed);
+void prandom_reseed_late(void);
+
+/*
+ * These macros are preserved for backward compatibility and should be
+ * removed as soon as a transition is finished.
+ */
+#define random32() prandom_u32()
+#define srandom32(seed) prandom_seed(seed)
 
-u32 prandom32(struct rnd_state *);
+u32 prandom_u32_state(struct rnd_state *);
+void prandom_bytes_state(struct rnd_state *state, void *buf, int nbytes);
 
 /*
  * Handle minimum values for seeds
@@ -80,11 +99,11 @@ static inline u32 __seed(u32 x, u32 m)
 }
 
 /**
- * prandom32_seed - set seed for prandom32().
+ * prandom_seed_state - set seed for prandom_u32_state().
  * @state: pointer to state structure to receive the seed.
  * @seed: arbitrary 64-bit value to use as a seed.
  */
-static inline void prandom32_seed(struct rnd_state *state, u64 seed)
+static inline void prandom_seed_state(struct rnd_state *state, u64 seed)
 {
 	u32 i = (seed >> 32) ^ (seed << 10) ^ seed;
 

include/linux/syscalls.h

@@ -860,4 +860,6 @@ asmlinkage long sys_process_vm_writev(pid_t pid,
 
 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