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view src/core/ngx_sha1.c @ 7629:f47f7d3d1bfa

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Mp4: fixed possible chunk offset overflow. In "co64" atom chunk start offset is a 64-bit unsigned integer. When trimming the "mdat" atom, chunk offsets are casted to off_t values which are typically 64-bit signed integers. A specially crafted mp4 file with huge chunk offsets may lead to off_t overflow and result in negative trim boundaries. The consequences of the overflow are: - Incorrect Content-Length header value in the response. - Negative left boundary of the response file buffer holding the trimmed "mdat". This leads to pread()/sendfile() errors followed by closing the client connection. On rare systems where off_t is a 32-bit integer, this scenario is also feasible with the "stco" atom. The fix is to add checks which make sure data chunks referenced by each track are within the mp4 file boundaries. Additionally a few more checks are added to ensure mp4 file consistency and log errors.
author Roman Arutyunyan <arut@nginx.com>
date Wed, 26 Feb 2020 15:10:46 +0300
parents 9eefb38f0005
children
line wrap: on
line source


/*
 * Copyright (C) Maxim Dounin
 * Copyright (C) Nginx, Inc.
 *
 * An internal SHA1 implementation.
 */


#include <ngx_config.h>
#include <ngx_core.h>
#include <ngx_sha1.h>


static const u_char *ngx_sha1_body(ngx_sha1_t *ctx, const u_char *data,
    size_t size);


void
ngx_sha1_init(ngx_sha1_t *ctx)
{
    ctx->a = 0x67452301;
    ctx->b = 0xefcdab89;
    ctx->c = 0x98badcfe;
    ctx->d = 0x10325476;
    ctx->e = 0xc3d2e1f0;

    ctx->bytes = 0;
}


void
ngx_sha1_update(ngx_sha1_t *ctx, const void *data, size_t size)
{
    size_t  used, free;

    used = (size_t) (ctx->bytes & 0x3f);
    ctx->bytes += size;

    if (used) {
        free = 64 - used;

        if (size < free) {
            ngx_memcpy(&ctx->buffer[used], data, size);
            return;
        }

        ngx_memcpy(&ctx->buffer[used], data, free);
        data = (u_char *) data + free;
        size -= free;
        (void) ngx_sha1_body(ctx, ctx->buffer, 64);
    }

    if (size >= 64) {
        data = ngx_sha1_body(ctx, data, size & ~(size_t) 0x3f);
        size &= 0x3f;
    }

    ngx_memcpy(ctx->buffer, data, size);
}


void
ngx_sha1_final(u_char result[20], ngx_sha1_t *ctx)
{
    size_t  used, free;

    used = (size_t) (ctx->bytes & 0x3f);

    ctx->buffer[used++] = 0x80;

    free = 64 - used;

    if (free < 8) {
        ngx_memzero(&ctx->buffer[used], free);
        (void) ngx_sha1_body(ctx, ctx->buffer, 64);
        used = 0;
        free = 64;
    }

    ngx_memzero(&ctx->buffer[used], free - 8);

    ctx->bytes <<= 3;
    ctx->buffer[56] = (u_char) (ctx->bytes >> 56);
    ctx->buffer[57] = (u_char) (ctx->bytes >> 48);
    ctx->buffer[58] = (u_char) (ctx->bytes >> 40);
    ctx->buffer[59] = (u_char) (ctx->bytes >> 32);
    ctx->buffer[60] = (u_char) (ctx->bytes >> 24);
    ctx->buffer[61] = (u_char) (ctx->bytes >> 16);
    ctx->buffer[62] = (u_char) (ctx->bytes >> 8);
    ctx->buffer[63] = (u_char) ctx->bytes;

    (void) ngx_sha1_body(ctx, ctx->buffer, 64);

    result[0] = (u_char) (ctx->a >> 24);
    result[1] = (u_char) (ctx->a >> 16);
    result[2] = (u_char) (ctx->a >> 8);
    result[3] = (u_char) ctx->a;
    result[4] = (u_char) (ctx->b >> 24);
    result[5] = (u_char) (ctx->b >> 16);
    result[6] = (u_char) (ctx->b >> 8);
    result[7] = (u_char) ctx->b;
    result[8] = (u_char) (ctx->c >> 24);
    result[9] = (u_char) (ctx->c >> 16);
    result[10] = (u_char) (ctx->c >> 8);
    result[11] = (u_char) ctx->c;
    result[12] = (u_char) (ctx->d >> 24);
    result[13] = (u_char) (ctx->d >> 16);
    result[14] = (u_char) (ctx->d >> 8);
    result[15] = (u_char) ctx->d;
    result[16] = (u_char) (ctx->e >> 24);
    result[17] = (u_char) (ctx->e >> 16);
    result[18] = (u_char) (ctx->e >> 8);
    result[19] = (u_char) ctx->e;

    ngx_memzero(ctx, sizeof(*ctx));
}


/*
 * Helper functions.
 */

#define ROTATE(bits, word)  (((word) << (bits)) | ((word) >> (32 - (bits))))

#define F1(b, c, d)  (((b) & (c)) | ((~(b)) & (d)))
#define F2(b, c, d)  ((b) ^ (c) ^ (d))
#define F3(b, c, d)  (((b) & (c)) | ((b) & (d)) | ((c) & (d)))

#define STEP(f, a, b, c, d, e, w, t)                                          \
    temp = ROTATE(5, (a)) + f((b), (c), (d)) + (e) + (w) + (t);               \
    (e) = (d);                                                                \
    (d) = (c);                                                                \
    (c) = ROTATE(30, (b));                                                    \
    (b) = (a);                                                                \
    (a) = temp;


/*
 * GET() reads 4 input bytes in big-endian byte order and returns
 * them as uint32_t.
 */

#define GET(n)                                                                \
    ((uint32_t) p[n * 4 + 3] |                                                \
    ((uint32_t) p[n * 4 + 2] << 8) |                                          \
    ((uint32_t) p[n * 4 + 1] << 16) |                                         \
    ((uint32_t) p[n * 4] << 24))


/*
 * This processes one or more 64-byte data blocks, but does not update
 * the bit counters.  There are no alignment requirements.
 */

static const u_char *
ngx_sha1_body(ngx_sha1_t *ctx, const u_char *data, size_t size)
{
    uint32_t       a, b, c, d, e, temp;
    uint32_t       saved_a, saved_b, saved_c, saved_d, saved_e;
    uint32_t       words[80];
    ngx_uint_t     i;
    const u_char  *p;

    p = data;

    a = ctx->a;
    b = ctx->b;
    c = ctx->c;
    d = ctx->d;
    e = ctx->e;

    do {
        saved_a = a;
        saved_b = b;
        saved_c = c;
        saved_d = d;
        saved_e = e;

        /* Load data block into the words array */

        for (i = 0; i < 16; i++) {
            words[i] = GET(i);
        }

        for (i = 16; i < 80; i++) {
            words[i] = ROTATE(1, words[i - 3] ^ words[i - 8] ^ words[i - 14]
                                 ^ words[i - 16]);
        }

        /* Transformations */

        STEP(F1, a, b, c, d, e, words[0],  0x5a827999);
        STEP(F1, a, b, c, d, e, words[1],  0x5a827999);
        STEP(F1, a, b, c, d, e, words[2],  0x5a827999);
        STEP(F1, a, b, c, d, e, words[3],  0x5a827999);
        STEP(F1, a, b, c, d, e, words[4],  0x5a827999);
        STEP(F1, a, b, c, d, e, words[5],  0x5a827999);
        STEP(F1, a, b, c, d, e, words[6],  0x5a827999);
        STEP(F1, a, b, c, d, e, words[7],  0x5a827999);
        STEP(F1, a, b, c, d, e, words[8],  0x5a827999);
        STEP(F1, a, b, c, d, e, words[9],  0x5a827999);
        STEP(F1, a, b, c, d, e, words[10], 0x5a827999);
        STEP(F1, a, b, c, d, e, words[11], 0x5a827999);
        STEP(F1, a, b, c, d, e, words[12], 0x5a827999);
        STEP(F1, a, b, c, d, e, words[13], 0x5a827999);
        STEP(F1, a, b, c, d, e, words[14], 0x5a827999);
        STEP(F1, a, b, c, d, e, words[15], 0x5a827999);
        STEP(F1, a, b, c, d, e, words[16], 0x5a827999);
        STEP(F1, a, b, c, d, e, words[17], 0x5a827999);
        STEP(F1, a, b, c, d, e, words[18], 0x5a827999);
        STEP(F1, a, b, c, d, e, words[19], 0x5a827999);

        STEP(F2, a, b, c, d, e, words[20], 0x6ed9eba1);
        STEP(F2, a, b, c, d, e, words[21], 0x6ed9eba1);
        STEP(F2, a, b, c, d, e, words[22], 0x6ed9eba1);
        STEP(F2, a, b, c, d, e, words[23], 0x6ed9eba1);
        STEP(F2, a, b, c, d, e, words[24], 0x6ed9eba1);
        STEP(F2, a, b, c, d, e, words[25], 0x6ed9eba1);
        STEP(F2, a, b, c, d, e, words[26], 0x6ed9eba1);
        STEP(F2, a, b, c, d, e, words[27], 0x6ed9eba1);
        STEP(F2, a, b, c, d, e, words[28], 0x6ed9eba1);
        STEP(F2, a, b, c, d, e, words[29], 0x6ed9eba1);
        STEP(F2, a, b, c, d, e, words[30], 0x6ed9eba1);
        STEP(F2, a, b, c, d, e, words[31], 0x6ed9eba1);
        STEP(F2, a, b, c, d, e, words[32], 0x6ed9eba1);
        STEP(F2, a, b, c, d, e, words[33], 0x6ed9eba1);
        STEP(F2, a, b, c, d, e, words[34], 0x6ed9eba1);
        STEP(F2, a, b, c, d, e, words[35], 0x6ed9eba1);
        STEP(F2, a, b, c, d, e, words[36], 0x6ed9eba1);
        STEP(F2, a, b, c, d, e, words[37], 0x6ed9eba1);
        STEP(F2, a, b, c, d, e, words[38], 0x6ed9eba1);
        STEP(F2, a, b, c, d, e, words[39], 0x6ed9eba1);

        STEP(F3, a, b, c, d, e, words[40], 0x8f1bbcdc);
        STEP(F3, a, b, c, d, e, words[41], 0x8f1bbcdc);
        STEP(F3, a, b, c, d, e, words[42], 0x8f1bbcdc);
        STEP(F3, a, b, c, d, e, words[43], 0x8f1bbcdc);
        STEP(F3, a, b, c, d, e, words[44], 0x8f1bbcdc);
        STEP(F3, a, b, c, d, e, words[45], 0x8f1bbcdc);
        STEP(F3, a, b, c, d, e, words[46], 0x8f1bbcdc);
        STEP(F3, a, b, c, d, e, words[47], 0x8f1bbcdc);
        STEP(F3, a, b, c, d, e, words[48], 0x8f1bbcdc);
        STEP(F3, a, b, c, d, e, words[49], 0x8f1bbcdc);
        STEP(F3, a, b, c, d, e, words[50], 0x8f1bbcdc);
        STEP(F3, a, b, c, d, e, words[51], 0x8f1bbcdc);
        STEP(F3, a, b, c, d, e, words[52], 0x8f1bbcdc);
        STEP(F3, a, b, c, d, e, words[53], 0x8f1bbcdc);
        STEP(F3, a, b, c, d, e, words[54], 0x8f1bbcdc);
        STEP(F3, a, b, c, d, e, words[55], 0x8f1bbcdc);
        STEP(F3, a, b, c, d, e, words[56], 0x8f1bbcdc);
        STEP(F3, a, b, c, d, e, words[57], 0x8f1bbcdc);
        STEP(F3, a, b, c, d, e, words[58], 0x8f1bbcdc);
        STEP(F3, a, b, c, d, e, words[59], 0x8f1bbcdc);

        STEP(F2, a, b, c, d, e, words[60], 0xca62c1d6);
        STEP(F2, a, b, c, d, e, words[61], 0xca62c1d6);
        STEP(F2, a, b, c, d, e, words[62], 0xca62c1d6);
        STEP(F2, a, b, c, d, e, words[63], 0xca62c1d6);
        STEP(F2, a, b, c, d, e, words[64], 0xca62c1d6);
        STEP(F2, a, b, c, d, e, words[65], 0xca62c1d6);
        STEP(F2, a, b, c, d, e, words[66], 0xca62c1d6);
        STEP(F2, a, b, c, d, e, words[67], 0xca62c1d6);
        STEP(F2, a, b, c, d, e, words[68], 0xca62c1d6);
        STEP(F2, a, b, c, d, e, words[69], 0xca62c1d6);
        STEP(F2, a, b, c, d, e, words[70], 0xca62c1d6);
        STEP(F2, a, b, c, d, e, words[71], 0xca62c1d6);
        STEP(F2, a, b, c, d, e, words[72], 0xca62c1d6);
        STEP(F2, a, b, c, d, e, words[73], 0xca62c1d6);
        STEP(F2, a, b, c, d, e, words[74], 0xca62c1d6);
        STEP(F2, a, b, c, d, e, words[75], 0xca62c1d6);
        STEP(F2, a, b, c, d, e, words[76], 0xca62c1d6);
        STEP(F2, a, b, c, d, e, words[77], 0xca62c1d6);
        STEP(F2, a, b, c, d, e, words[78], 0xca62c1d6);
        STEP(F2, a, b, c, d, e, words[79], 0xca62c1d6);

        a += saved_a;
        b += saved_b;
        c += saved_c;
        d += saved_d;
        e += saved_e;

        p += 64;

    } while (size -= 64);

    ctx->a = a;
    ctx->b = b;
    ctx->c = c;
    ctx->d = d;
    ctx->e = e;

    return p;
}