/* * random.c -- A strong random number generator * * Version 0.95, last modified 4-Nov-95 * * Copyright Theodore Ts'o, 1994, 1995. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, and the entire permission notice in its entirety, * including the disclaimer of warranties. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. The name of the author may not be used to endorse or promote * products derived from this software without specific prior * written permission. * * ALTERNATIVELY, this product may be distributed under the terms of * the GNU Public License, in which case the provisions of the GPL are * required INSTEAD OF the above restrictions. (This clause is * necessary due to a potential bad interaction between the GPL and * the restrictions contained in a BSD-style copyright.) * * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED * OF THE POSSIBILITY OF SUCH DAMAGE. */ /* * (now, with legal B.S. out of the way.....) * * This routine gathers environmental noise from device drivers, etc., * and returns good random numbers, suitable for cryptographic use. * Besides the obvious cryptographic uses, these numbers are also good * for seeding TCP sequence numbers, and other places where it is * desireable to have numbers which are not only random, but hard to * predict by an attacker. * * Theory of operation * =================== * * Computers are very predictable devices. Hence it is extremely hard * to produce truely random numbers on a computer --- as opposed to * pseudo-random numbers, which can easily generated by using a * algorithm. Unfortunately, it is very easy for attackers to guess * the sequence of pseudo-random number generators, and for some * applications this is not acceptable. So instead, we must try to * gather "environmental noise" from the computer's environment, which * must be hard for outside attackers to observe, and use that to * generate random numbers. In a Unix environment, this is best done * from inside the kernel. * * Sources of randomness from the environment include inter-keyboard * timings, inter-interrupt timings from some interrupts, and other * events which are both (a) non-deterministic and (b) hard for an * outside observer to measure. Randomness from these sources are * added to an "entropy pool", which is mixed using a CRC-like function. * This is not cryptographically strong, but it is adequate assuming * the randomness is not chosen maliciously, and it is fast enough that * the overhead of doing it on every interrupt is very reasonable. * As random bytes are mixed into the entropy pool, the routines keep * an *estimate* of how many bits of randomness have been stored into * the random number generator's internal state. * * When random bytes are desired, they are obtained by taking the MD5 * hash of the contents of the "entropy pool". The MD5 hash avoids * exposing the internal state of the entropy pool. It is believed to * be computationally infeasible to derive any useful information * about the input of MD5 from its output. Even if it is possible to * analyze MD5 in some clever way, as long as the amount of data * returned from the generator is less than the inherent entropy in * the pool, the output data is totally unpredictable. For this * reason, the routine decreases its internal estimate of how many * bits of "true randomness" are contained in the entropy pool as it * outputs random numbers. * * If this estimate goes to zero, the routine can still generate * random numbers; however, an attacker may (at least in theory) be * able to infer the future output of the generator from prior * outputs. This requires successful cryptanalysis of MD5, which is * not believed to be feasible, but there is a remote possiblility. * Nonetheless, these numbers should be useful for the vast majority * of purposes. * * Exported interfaces ---- output * =============================== * * There are three exported interfaces; the first is one designed to * be used from within the kernel: * * void get_random_bytes(void *buf, int nbytes); * * This interface will return the requested number of random bytes, * and place it in the requested buffer. * * The two other interfaces are two character devices /dev/random and * /dev/urandom. /dev/random is suitable for use when very high * quality randomness is desired (for example, for key generation or * one-time pads), as it will only return a maximum of the number of * bits of randomness (as estimated by the random number generator) * contained in the entropy pool. * * The /dev/urandom device does not have this limit, and will return * as many bytes as are requested. As more and more random bytes are * requested without giving time for the entropy pool to recharge, * this will result in random numbers that are merely cryptographically * strong. For many applications, however, this is acceptable. * * Exported interfaces ---- input * ============================== * * The current exported interfaces for gathering environmental noise * from the devices are: * * void add_keyboard_randomness(unsigned char scancode); * void add_mouse_randomness(__u32 mouse_data); * void add_interrupt_randomness(int irq); * void add_blkdev_randomness(int irq); * * add_keyboard_randomness() uses the inter-keypress timing, as well as the * scancode as random inputs into the "entropy pool". * * add_mouse_randomness() uses the mouse interrupt timing, as well as * the reported position of the mouse from the hardware. * * add_interrupt_randomness() uses the inter-interrupt timing as random * inputs to the entropy pool. Note that not all interrupts are good * sources of randomness! For example, the timer interrupts is not a * good choice, because the periodicity of the interrupts is to * regular, and hence predictable to an attacker. Disk interrupts are * a better measure, since the timing of the disk interrupts are more * unpredictable. * * add_blkdev_randomness() times the finishing time of block requests. * * All of these routines try to estimate how many bits of randomness a * particular randomness source. They do this by keeping track of the * first and second order deltas of the event timings. * * Acknowledgements: * ================= * * Ideas for constructing this random number generator were derived * from the Pretty Good Privacy's random number generator, and from * private discussions with Phil Karn. Colin Plumb provided a faster * random number generator, which speed up the mixing function of the * entropy pool, taken from PGP 3.0 (under development). It has since * been modified by myself to provide better mixing in the case where * the input values to add_entropy_word() are mostly small numbers. * * Any flaws in the design are solely my responsibility, and should * not be attributed to the Phil, Colin, or any of authors of PGP. * * The code for MD5 transform was taken from Colin Plumb's * implementation, which has been placed in the public domain. The * MD5 cryptographic checksum was devised by Ronald Rivest, and is * documented in RFC 1321, "The MD5 Message Digest Algorithm". * * Further background information on this topic may be obtained from * RFC 1750, "Randomness Recommendations for Security", by Donald * Eastlake, Steve Crocker, and Jeff Schiller. */ #include #include #include #include #include #include #include #include #include #include /* * The pool is stirred with a primitive polynomial of degree 128 * over GF(2), namely x^128 + x^99 + x^59 + x^31 + x^9 + x^7 + 1. * For a pool of size 64, try x^64+x^62+x^38+x^10+x^6+x+1. */ #define POOLWORDS 128 /* Power of 2 - note that this is 32-bit words */ #define POOLBITS (POOLWORDS*32) #if POOLWORDS == 128 #define TAP1 99 /* The polynomial taps */ #define TAP2 59 #define TAP3 31 #define TAP4 9 #define TAP5 7 #elif POOLWORDS == 64 #define TAP1 62 /* The polynomial taps */ #define TAP2 38 #define TAP3 10 #define TAP4 6 #define TAP5 1 #else #error No primitive polynomial available for chosen POOLWORDS #endif /* There is actually only one of these, globally. */ struct random_bucket { unsigned add_ptr; unsigned entropy_count; int input_rotate; __u32 *pool; }; /* There is one of these per entropy source */ struct timer_rand_state { unsigned long last_time; int last_delta; int dont_count_entropy:1; }; static struct random_bucket random_state; static __u32 random_pool[POOLWORDS]; static struct timer_rand_state keyboard_timer_state; static struct timer_rand_state mouse_timer_state; static struct timer_rand_state extract_timer_state; static struct timer_rand_state *irq_timer_state[NR_IRQS]; static struct timer_rand_state *blkdev_timer_state[MAX_BLKDEV]; static struct wait_queue *random_wait; static int random_read(struct inode * inode, struct file * file, char * buf, int nbytes); static int random_read_unlimited(struct inode * inode, struct file * file, char * buf, int nbytes); static int random_select(struct inode *inode, struct file *file, int sel_type, select_table * wait); static int random_write(struct inode * inode, struct file * file, const char * buffer, int count); static int random_ioctl(struct inode * inode, struct file * file, unsigned int cmd, unsigned long arg); #ifndef MIN #define MIN(a,b) (((a) < (b)) ? (a) : (b)) #endif void rand_initialize(void) { random_state.add_ptr = 0; random_state.entropy_count = 0; random_state.pool = random_pool; memset(irq_timer_state, 0, sizeof(irq_timer_state)); memset(blkdev_timer_state, 0, sizeof(blkdev_timer_state)); extract_timer_state.dont_count_entropy = 1; random_wait = NULL; } void rand_initialize_irq(int irq) { struct timer_rand_state *state; if (irq >= NR_IRQS || irq_timer_state[irq]) return; /* * If kamlloc returns null, we just won't use that entropy * source. */ state = kmalloc(sizeof(struct timer_rand_state), GFP_KERNEL); if (state) { irq_timer_state[irq] = state; memset(state, 0, sizeof(struct timer_rand_state)); } } void rand_initialize_blkdev(int major) { struct timer_rand_state *state; if (major >= MAX_BLKDEV || blkdev_timer_state[major]) return; /* * If kamlloc returns null, we just won't use that entropy * source. */ state = kmalloc(sizeof(struct timer_rand_state), GFP_KERNEL); if (state) { blkdev_timer_state[major] = state; memset(state, 0, sizeof(struct timer_rand_state)); } } /* * This function adds a byte into the entropy "pool". It does not * update the entropy estimate. The caller must do this if appropriate. * * The pool is stirred with a primitive polynomial of degree 128 * over GF(2), namely x^128 + x^99 + x^59 + x^31 + x^9 + x^7 + 1. * For a pool of size 64, try x^64+x^62+x^38+x^10+x^6+x+1. * * We rotate the input word by a changing number of bits, to help * assure that all bits in the entropy get toggled. Otherwise, if we * consistently feed the entropy pool small numbers (like jiffies and * scancodes, for example), the upper bits of the entropy pool don't * get affected. --- TYT, 10/11/95 */ static inline void add_entropy_word(struct random_bucket *r, const __u32 input) { unsigned i; __u32 w; w = (input << r->input_rotate) | (input >> (32 - r->input_rotate)); i = r->add_ptr = (r->add_ptr - 1) & (POOLWORDS-1); if (i) r->input_rotate = (r->input_rotate + 7) & 31; else /* * At the beginning of the pool, add an extra 7 bits * rotation, so that successive passes spread the * input bits across the pool evenly. */ r->input_rotate = (r->input_rotate + 14) & 31; /* XOR in the various taps */ w ^= r->pool[(i+TAP1)&(POOLWORDS-1)]; w ^= r->pool[(i+TAP2)&(POOLWORDS-1)]; w ^= r->pool[(i+TAP3)&(POOLWORDS-1)]; w ^= r->pool[(i+TAP4)&(POOLWORDS-1)]; w ^= r->pool[(i+TAP5)&(POOLWORDS-1)]; w ^= r->pool[i]; /* Rotate w left 1 bit (stolen from SHA) and store */ r->pool[i] = (w << 1) | (w >> 31); } /* * This function adds entropy to the entropy "pool" by using timing * delays. It uses the timer_rand_state structure to make an estimate * of how many bits of entropy this call has added to the pool. * * The number "num" is also added to the pool - it should somehow describe * the type of event which just happened. This is currently 0-255 for * keyboard scan codes, and 256 upwards for interrupts. * On the i386, this is assumed to be at most 16 bits, and the high bits * are used for a high-resolution timer. * * TODO: Read the time stamp register on the Pentium. */ static void add_timer_randomness(struct random_bucket *r, struct timer_rand_state *state, unsigned num) { int delta, delta2; unsigned nbits; __u32 time; #if defined (__i386__) if (x86_capability & 16) { unsigned long low, high; __asm__(".byte 0x0f,0x31" :"=a" (low), "=d" (high)); time = (__u32) low; num ^= (__u32) high; } else { #if 0 /* * On a 386, read the high resolution timer. We assume that * this gives us 2 bits of randomness. * * This is turned off for now because of the speed hit * it entails. */ outb_p(0x00, 0x43); /* latch the count ASAP */ num |= inb_p(0x40) << 16; num |= inb(0x40) << 24; if (!state->dont_count_entropy) r->entropy_count += 2; #endif time = jiffies; } #else time = jiffies; #endif add_entropy_word(r, (__u32) num); add_entropy_word(r, time); /* * Calculate number of bits of randomness we probably * added. We take into account the first and second order * deltas in order to make our estimate. */ if (!state->dont_count_entropy) { delta = time - state->last_time; state->last_time = time; delta2 = delta - state->last_delta; state->last_delta = delta; if (delta < 0) delta = -delta; if (delta2 < 0) delta2 = -delta2; delta = MIN(delta, delta2) >> 1; for (nbits = 0; delta; nbits++) delta >>= 1; r->entropy_count += nbits; /* Prevent overflow */ if (r->entropy_count > POOLBITS) r->entropy_count = POOLBITS; } wake_up_interruptible(&random_wait); } void add_keyboard_randomness(unsigned char scancode) { add_timer_randomness(&random_state, &keyboard_timer_state, scancode); } void add_mouse_randomness(__u32 mouse_data) { add_timer_randomness(&random_state, &mouse_timer_state, mouse_data); } void add_interrupt_randomness(int irq) { if (irq >= NR_IRQS || irq_timer_state[irq] == 0) return; add_timer_randomness(&random_state, irq_timer_state[irq], 0x100+irq); } void add_blkdev_randomness(int major) { if (major >= MAX_BLKDEV || blkdev_timer_state[major] == 0) return; add_timer_randomness(&random_state, blkdev_timer_state[major], 0x200+major); } /* * MD5 transform algorithm, taken from code written by Colin Plumb, * and put into the public domain * * QUESTION: Replace this with SHA, which as generally received better * reviews from the cryptographic community? */ /* The four core functions - F1 is optimized somewhat */ /* #define F1(x, y, z) (x & y | ~x & z) */ #define F1(x, y, z) (z ^ (x & (y ^ z))) #define F2(x, y, z) F1(z, x, y) #define F3(x, y, z) (x ^ y ^ z) #define F4(x, y, z) (y ^ (x | ~z)) /* This is the central step in the MD5 algorithm. */ #define MD5STEP(f, w, x, y, z, data, s) \ ( w += f(x, y, z) + data, w = w<>(32-s), w += x ) /* * The core of the MD5 algorithm, this alters an existing MD5 hash to * reflect the addition of 16 longwords of new data. MD5Update blocks * the data and converts bytes into longwords for this routine. */ static void MD5Transform(__u32 buf[4], __u32 const in[16]) { __u32 a, b, c, d; a = buf[0]; b = buf[1]; c = buf[2]; d = buf[3]; MD5STEP(F1, a, b, c, d, in[ 0]+0xd76aa478, 7); MD5STEP(F1, d, a, b, c, in[ 1]+0xe8c7b756, 12); MD5STEP(F1, c, d, a, b, in[ 2]+0x242070db, 17); MD5STEP(F1, b, c, d, a, in[ 3]+0xc1bdceee, 22); MD5STEP(F1, a, b, c, d, in[ 4]+0xf57c0faf, 7); MD5STEP(F1, d, a, b, c, in[ 5]+0x4787c62a, 12); MD5STEP(F1, c, d, a, b, in[ 6]+0xa8304613, 17); MD5STEP(F1, b, c, d, a, in[ 7]+0xfd469501, 22); MD5STEP(F1, a, b, c, d, in[ 8]+0x698098d8, 7); MD5STEP(F1, d, a, b, c, in[ 9]+0x8b44f7af, 12); MD5STEP(F1, c, d, a, b, in[10]+0xffff5bb1, 17); MD5STEP(F1, b, c, d, a, in[11]+0x895cd7be, 22); MD5STEP(F1, a, b, c, d, in[12]+0x6b901122, 7); MD5STEP(F1, d, a, b, c, in[13]+0xfd987193, 12); MD5STEP(F1, c, d, a, b, in[14]+0xa679438e, 17); MD5STEP(F1, b, c, d, a, in[15]+0x49b40821, 22); MD5STEP(F2, a, b, c, d, in[ 1]+0xf61e2562, 5); MD5STEP(F2, d, a, b, c, in[ 6]+0xc040b340, 9); MD5STEP(F2, c, d, a, b, in[11]+0x265e5a51, 14); MD5STEP(F2, b, c, d, a, in[ 0]+0xe9b6c7aa, 20); MD5STEP(F2, a, b, c, d, in[ 5]+0xd62f105d, 5); MD5STEP(F2, d, a, b, c, in[10]+0x02441453, 9); MD5STEP(F2, c, d, a, b, in[15]+0xd8a1e681, 14); MD5STEP(F2, b, c, d, a, in[ 4]+0xe7d3fbc8, 20); MD5STEP(F2, a, b, c, d, in[ 9]+0x21e1cde6, 5); MD5STEP(F2, d, a, b, c, in[14]+0xc33707d6, 9); MD5STEP(F2, c, d, a, b, in[ 3]+0xf4d50d87, 14); MD5STEP(F2, b, c, d, a, in[ 8]+0x455a14ed, 20); MD5STEP(F2, a, b, c, d, in[13]+0xa9e3e905, 5); MD5STEP(F2, d, a, b, c, in[ 2]+0xfcefa3f8, 9); MD5STEP(F2, c, d, a, b, in[ 7]+0x676f02d9, 14); MD5STEP(F2, b, c, d, a, in[12]+0x8d2a4c8a, 20); MD5STEP(F3, a, b, c, d, in[ 5]+0xfffa3942, 4); MD5STEP(F3, d, a, b, c, in[ 8]+0x8771f681, 11); MD5STEP(F3, c, d, a, b, in[11]+0x6d9d6122, 16); MD5STEP(F3, b, c, d, a, in[14]+0xfde5380c, 23); MD5STEP(F3, a, b, c, d, in[ 1]+0xa4beea44, 4); MD5STEP(F3, d, a, b, c, in[ 4]+0x4bdecfa9, 11); MD5STEP(F3, c, d, a, b, in[ 7]+0xf6bb4b60, 16); MD5STEP(F3, b, c, d, a, in[10]+0xbebfbc70, 23); MD5STEP(F3, a, b, c, d, in[13]+0x289b7ec6, 4); MD5STEP(F3, d, a, b, c, in[ 0]+0xeaa127fa, 11); MD5STEP(F3, c, d, a, b, in[ 3]+0xd4ef3085, 16); MD5STEP(F3, b, c, d, a, in[ 6]+0x04881d05, 23); MD5STEP(F3, a, b, c, d, in[ 9]+0xd9d4d039, 4); MD5STEP(F3, d, a, b, c, in[12]+0xe6db99e5, 11); MD5STEP(F3, c, d, a, b, in[15]+0x1fa27cf8, 16); MD5STEP(F3, b, c, d, a, in[ 2]+0xc4ac5665, 23); MD5STEP(F4, a, b, c, d, in[ 0]+0xf4292244, 6); MD5STEP(F4, d, a, b, c, in[ 7]+0x432aff97, 10); MD5STEP(F4, c, d, a, b, in[14]+0xab9423a7, 15); MD5STEP(F4, b, c, d, a, in[ 5]+0xfc93a039, 21); MD5STEP(F4, a, b, c, d, in[12]+0x655b59c3, 6); MD5STEP(F4, d, a, b, c, in[ 3]+0x8f0ccc92, 10); MD5STEP(F4, c, d, a, b, in[10]+0xffeff47d, 15); MD5STEP(F4, b, c, d, a, in[ 1]+0x85845dd1, 21); MD5STEP(F4, a, b, c, d, in[ 8]+0x6fa87e4f, 6); MD5STEP(F4, d, a, b, c, in[15]+0xfe2ce6e0, 10); MD5STEP(F4, c, d, a, b, in[ 6]+0xa3014314, 15); MD5STEP(F4, b, c, d, a, in[13]+0x4e0811a1, 21); MD5STEP(F4, a, b, c, d, in[ 4]+0xf7537e82, 6); MD5STEP(F4, d, a, b, c, in[11]+0xbd3af235, 10); MD5STEP(F4, c, d, a, b, in[ 2]+0x2ad7d2bb, 15); MD5STEP(F4, b, c, d, a, in[ 9]+0xeb86d391, 21); buf[0] += a; buf[1] += b; buf[2] += c; buf[3] += d; } #undef F1 #undef F2 #undef F3 #undef F4 #undef MD5STEP #if POOLWORDS % 16 #error extract_entropy() assumes that POOLWORDS is a multiple of 16 words. #endif /* * This function extracts randomness from the "entropy pool", and * returns it in a buffer. This function computes how many remaining * bits of entropy are left in the pool, but it does not restrict the * number of bytes that are actually obtained. */ static inline int extract_entropy(struct random_bucket *r, char * buf, int nbytes, int to_user) { int ret, i; __u32 tmp[4]; add_timer_randomness(r, &extract_timer_state, nbytes); /* Redundant, but just in case... */ if (r->entropy_count > POOLBITS) r->entropy_count = POOLBITS; /* Why is this here? Left in from Ted Ts'o. Perhaps to limit time. */ if (nbytes > 32768) nbytes = 32768; ret = nbytes; if (r->entropy_count / 8 >= nbytes) r->entropy_count -= nbytes*8; else r->entropy_count = 0; while (nbytes) { /* Hash the pool to get the output */ tmp[0] = 0x67452301; tmp[1] = 0xefcdab89; tmp[2] = 0x98badcfe; tmp[3] = 0x10325476; for (i = 0; i < POOLWORDS; i += 16) MD5Transform(tmp, r->pool+i); /* Modify pool so next hash will produce different results */ add_entropy_word(r, tmp[0]); add_entropy_word(r, tmp[1]); add_entropy_word(r, tmp[2]); add_entropy_word(r, tmp[3]); /* * Run the MD5 Transform one more time, since we want * to add at least minimal obscuring of the inputs to * add_entropy_word(). --- TYT */ MD5Transform(tmp, r->pool); /* Copy data to destination buffer */ i = MIN(nbytes, 16); if (to_user) memcpy_tofs(buf, (__u8 const *)tmp, i); else memcpy(buf, (__u8 const *)tmp, i); nbytes -= i; buf += i; } /* Wipe data from memory */ memset(tmp, 0, sizeof(tmp)); return ret; } /* * This function is the exported kernel interface. It returns some * number of good random numbers, suitable for seeding TCP sequence * numbers, etc. */ void get_random_bytes(void *buf, int nbytes) { extract_entropy(&random_state, (char *) buf, nbytes, 0); } static int random_read(struct inode * inode, struct file * file, char * buf, int nbytes) { struct wait_queue wait = { current, NULL }; int n; int retval = 0; int count = 0; if (nbytes == 0) return 0; add_wait_queue(&random_wait, &wait); while (nbytes > 0) { current->state = TASK_INTERRUPTIBLE; n = nbytes; if (n > random_state.entropy_count / 8) n = random_state.entropy_count / 8; if (n == 0) { if (file->f_flags & O_NONBLOCK) { retval = -EAGAIN; break; } if (current->signal & ~current->blocked) { retval = -ERESTARTSYS; break; } schedule(); continue; } n = extract_entropy(&random_state, buf, n, 1); count += n; buf += n; nbytes -= n; break; /* This break makes the device work */ /* like a named pipe */ } current->state = TASK_RUNNING; remove_wait_queue(&random_wait, &wait); return (count ? count : retval); } static int random_read_unlimited(struct inode * inode, struct file * file, char * buf, int nbytes) { return extract_entropy(&random_state, buf, nbytes, 1); } static int random_select(struct inode *inode, struct file *file, int sel_type, select_table * wait) { if (sel_type == SEL_IN) { if (random_state.entropy_count >= 8) return 1; select_wait(&random_wait, wait); } return 0; } static int random_write(struct inode * inode, struct file * file, const char * buffer, int count) { int i; __u32 word, *p; for (i = count, p = (__u32 *)buffer; i >= sizeof(__u32); i-= sizeof(__u32), p++) { memcpy_fromfs(&word, p, sizeof(__u32)); add_entropy_word(&random_state, word); } if (i) { word = 0; memcpy_fromfs(&word, p, i); add_entropy_word(&random_state, word); } if (inode) inode->i_mtime = CURRENT_TIME; return count; } static int random_ioctl(struct inode * inode, struct file * file, unsigned int cmd, unsigned long arg) { int *p, size, ent_count; int retval; switch (cmd) { case RNDGETENTCNT: retval = verify_area(VERIFY_WRITE, (void *) arg, sizeof(int)); if (retval) return(retval); put_user(random_state.entropy_count, (int *) arg); return 0; case RNDADDTOENTCNT: if (!suser()) return -EPERM; retval = verify_area(VERIFY_READ, (void *) arg, sizeof(int)); if (retval) return(retval); random_state.entropy_count += get_user((int *) arg); if (random_state.entropy_count > POOLBITS) random_state.entropy_count = POOLBITS; return 0; case RNDGETPOOL: if (!suser()) return -EPERM; p = (int *) arg; retval = verify_area(VERIFY_WRITE, (void *) p, sizeof(int)); if (retval) return(retval); put_user(random_state.entropy_count, p++); retval = verify_area(VERIFY_READ, (void *) p, sizeof(int)); if (retval) return(retval); size = get_user(p); put_user(POOLWORDS, p); if (size < 0) return -EINVAL; if (size > POOLWORDS) size = POOLWORDS; memcpy_tofs(++p, random_state.pool, size*sizeof(__u32)); return 0; case RNDADDENTROPY: if (!suser()) return -EPERM; p = (int *) arg; retval = verify_area(VERIFY_READ, (void *) p, 2*sizeof(int)); if (retval) return(retval); ent_count = get_user(p++); size = get_user(p++); (void) random_write(0, file, (const char *) p, size); random_state.entropy_count += ent_count; if (random_state.entropy_count > POOLBITS) random_state.entropy_count = POOLBITS; return 0; case RNDZAPENTCNT: if (!suser()) return -EPERM; random_state.entropy_count = 0; return 0; default: return -EINVAL; } } struct file_operations random_fops = { NULL, /* random_lseek */ random_read, random_write, NULL, /* random_readdir */ random_select, /* random_select */ random_ioctl, NULL, /* random_mmap */ NULL, /* no special open code */ NULL /* no special release code */ }; struct file_operations urandom_fops = { NULL, /* unrandom_lseek */ random_read_unlimited, random_write, NULL, /* urandom_readdir */ NULL, /* urandom_select */ random_ioctl, NULL, /* urandom_mmap */ NULL, /* no special open code */ NULL /* no special release code */ };