diff options
| -rw-r--r-- | include/linux/net.h | 1 | ||||
| -rw-r--r-- | net/core/dev.c | 2 | ||||
| -rw-r--r-- | net/core/utils.c | 104 |
3 files changed, 102 insertions, 5 deletions
diff --git a/include/linux/net.h b/include/linux/net.h index cec1482f28e2..80e7fec727e3 100644 --- a/include/linux/net.h +++ b/include/linux/net.h @@ -169,6 +169,7 @@ extern struct socket *sockfd_lookup(int fd, int *err); extern int net_ratelimit(void); extern unsigned long net_random(void); extern void net_srandom(unsigned long); +extern void net_random_init(void); extern int kernel_sendmsg(struct socket *sock, struct msghdr *msg, struct kvec *vec, size_t num, size_t len); diff --git a/net/core/dev.c b/net/core/dev.c index 547469d2ac6f..293123d8fab4 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -3280,6 +3280,8 @@ static int __init net_dev_init(void) BUG_ON(!dev_boot_phase); + net_random_init(); + if (dev_proc_init()) goto out; diff --git a/net/core/utils.c b/net/core/utils.c index 8058d9c5e236..6093174581fd 100644 --- a/net/core/utils.c +++ b/net/core/utils.c @@ -19,22 +19,116 @@ #include <linux/mm.h> #include <linux/string.h> #include <linux/types.h> +#include <linux/random.h> +#include <linux/percpu.h> #include <asm/system.h> #include <asm/uaccess.h> -static unsigned long net_rand_seed = 152L; + +/* + This is a maximally equidistributed combined Tausworthe generator + based on code from GNU Scientific Library 1.5 (30 Jun 2004) + + x_n = (s1_n ^ s2_n ^ s3_n) + + s1_{n+1} = (((s1_n & 4294967294) <<12) ^ (((s1_n <<13) ^ s1_n) >>19)) + s2_{n+1} = (((s2_n & 4294967288) << 4) ^ (((s2_n << 2) ^ s2_n) >>25)) + s3_{n+1} = (((s3_n & 4294967280) <<17) ^ (((s3_n << 3) ^ s3_n) >>11)) + + The period of this generator is about 2^88. + + From: P. L'Ecuyer, "Maximally Equidistributed Combined Tausworthe + Generators", Mathematics of Computation, 65, 213 (1996), 203--213. + + This is available on the net from L'Ecuyer's home page, + + http://www.iro.umontreal.ca/~lecuyer/myftp/papers/tausme.ps + ftp://ftp.iro.umontreal.ca/pub/simulation/lecuyer/papers/tausme.ps + + There is an erratum in the paper "Tables of Maximally + Equidistributed Combined LFSR Generators", Mathematics of + Computation, 68, 225 (1999), 261--269: + http://www.iro.umontreal.ca/~lecuyer/myftp/papers/tausme2.ps + + ... the k_j most significant bits of z_j must be non- + zero, for each j. (Note: this restriction also applies to the + computer code given in [4], but was mistakenly not mentioned in + that paper.) + + This affects the seeding procedure by imposing the requirement + s1 > 1, s2 > 7, s3 > 15. + +*/ +struct nrnd_state { + u32 s1, s2, s3; +}; + +static DEFINE_PER_CPU(struct nrnd_state, net_rand_state); + +static u32 __net_random(struct nrnd_state *state) +{ +#define TAUSWORTHE(s,a,b,c,d) ((s&c)<<d) ^ (((s <<a) ^ s)>>b) + + state->s1 = TAUSWORTHE(state->s1, 13, 19, 4294967294UL, 12); + state->s2 = TAUSWORTHE(state->s2, 2, 25, 4294967288UL, 4); + state->s3 = TAUSWORTHE(state->s3, 3, 11, 4294967280UL, 17); + + return (state->s1 ^ state->s2 ^ state->s3); +} + +static void __net_srandom(struct nrnd_state *state, unsigned long entropy) +{ + u32 s = state->s1 ^ entropy; + + if (s == 0) + s = 1; /* default seed is 1 */ + +#define LCG(n) (69069 * n) + state->s1 = LCG(s); + state->s2 = LCG(state->s1); + state->s3 = LCG(state->s2); + + /* "warm it up" */ + __net_random(state); + __net_random(state); + __net_random(state); + __net_random(state); + __net_random(state); + __net_random(state); +} + unsigned long net_random(void) { - net_rand_seed=net_rand_seed*69069L+1; - return net_rand_seed^jiffies; + unsigned long r; + struct nrnd_state *state = &get_cpu_var(net_rand_state); + r = __net_random(state); + put_cpu_var(state); + return r; } + void net_srandom(unsigned long entropy) { - net_rand_seed ^= entropy; - net_random(); + struct nrnd_state *state = &get_cpu_var(net_rand_state); + __net_srandom(state, entropy); + put_cpu_var(state); +} + +void __init net_random_init(void) +{ + int i; + unsigned long seed[NR_CPUS]; + + get_random_bytes(seed, sizeof(seed)); + + for (i = 0; i < NR_CPUS; i++) { + struct nrnd_state *state = &per_cpu(net_rand_state,i); + + memset(state, 0, sizeof(*state)); + __net_srandom(state, seed[i]); + } } int net_msg_cost = 5*HZ; |