Mercurial > hg > nginx
view src/core/ngx_crypt.c @ 6351:497d0cff8ace
Resolver: fixed use-after-free memory accesses with CNAME.
When several requests were waiting for a response, then after getting
a CNAME response only the last request's context had the name updated.
Contexts of other requests had the wrong name. This name was used by
ngx_resolve_name_done() to find the node to remove the request context
from. When the name was wrong, the request could not be properly
cancelled, its context was freed but stayed linked to the node's waiting
list. This happened e.g. when the first request was aborted or timed
out before the resolving completed. When it completed, this triggered
a use-after-free memory access by calling ctx->handler of already freed
request context. The bug manifests itself by
"could not cancel <name> resolving" alerts in error_log.
When a request was responded with a CNAME, the request context kept
the pointer to the original node's rn->u.cname. If the original node
expired before the resolving timed out or completed with an error,
this would trigger a use-after-free memory access via ctx->name in
ctx->handler().
The fix is to keep ctx->name unmodified. The name from context
is no longer used by ngx_resolve_name_done(). Instead, we now keep
the pointer to resolver node to which this request is linked.
Keeping the original name intact also improves logging.
author | Roman Arutyunyan <arut@nginx.com> |
---|---|
date | Tue, 26 Jan 2016 16:46:59 +0300 |
parents | 58956c644ad0 |
children | 2cd019520210 |
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/* * Copyright (C) Maxim Dounin */ #include <ngx_config.h> #include <ngx_core.h> #include <ngx_crypt.h> #include <ngx_md5.h> #if (NGX_HAVE_SHA1) #include <ngx_sha1.h> #endif #if (NGX_CRYPT) static ngx_int_t ngx_crypt_apr1(ngx_pool_t *pool, u_char *key, u_char *salt, u_char **encrypted); static ngx_int_t ngx_crypt_plain(ngx_pool_t *pool, u_char *key, u_char *salt, u_char **encrypted); #if (NGX_HAVE_SHA1) static ngx_int_t ngx_crypt_ssha(ngx_pool_t *pool, u_char *key, u_char *salt, u_char **encrypted); static ngx_int_t ngx_crypt_sha(ngx_pool_t *pool, u_char *key, u_char *salt, u_char **encrypted); #endif static u_char *ngx_crypt_to64(u_char *p, uint32_t v, size_t n); ngx_int_t ngx_crypt(ngx_pool_t *pool, u_char *key, u_char *salt, u_char **encrypted) { if (ngx_strncmp(salt, "$apr1$", sizeof("$apr1$") - 1) == 0) { return ngx_crypt_apr1(pool, key, salt, encrypted); } else if (ngx_strncmp(salt, "{PLAIN}", sizeof("{PLAIN}") - 1) == 0) { return ngx_crypt_plain(pool, key, salt, encrypted); #if (NGX_HAVE_SHA1) } else if (ngx_strncmp(salt, "{SSHA}", sizeof("{SSHA}") - 1) == 0) { return ngx_crypt_ssha(pool, key, salt, encrypted); } else if (ngx_strncmp(salt, "{SHA}", sizeof("{SHA}") - 1) == 0) { return ngx_crypt_sha(pool, key, salt, encrypted); #endif } /* fallback to libc crypt() */ return ngx_libc_crypt(pool, key, salt, encrypted); } static ngx_int_t ngx_crypt_apr1(ngx_pool_t *pool, u_char *key, u_char *salt, u_char **encrypted) { ngx_int_t n; ngx_uint_t i; u_char *p, *last, final[16]; size_t saltlen, keylen; ngx_md5_t md5, ctx1; /* Apache's apr1 crypt is Poul-Henning Kamp's md5 crypt with $apr1$ magic */ keylen = ngx_strlen(key); /* true salt: no magic, max 8 chars, stop at first $ */ salt += sizeof("$apr1$") - 1; last = salt + 8; for (p = salt; *p && *p != '$' && p < last; p++) { /* void */ } saltlen = p - salt; /* hash key and salt */ ngx_md5_init(&md5); ngx_md5_update(&md5, key, keylen); ngx_md5_update(&md5, (u_char *) "$apr1$", sizeof("$apr1$") - 1); ngx_md5_update(&md5, salt, saltlen); ngx_md5_init(&ctx1); ngx_md5_update(&ctx1, key, keylen); ngx_md5_update(&ctx1, salt, saltlen); ngx_md5_update(&ctx1, key, keylen); ngx_md5_final(final, &ctx1); for (n = keylen; n > 0; n -= 16) { ngx_md5_update(&md5, final, n > 16 ? 16 : n); } ngx_memzero(final, sizeof(final)); for (i = keylen; i; i >>= 1) { if (i & 1) { ngx_md5_update(&md5, final, 1); } else { ngx_md5_update(&md5, key, 1); } } ngx_md5_final(final, &md5); for (i = 0; i < 1000; i++) { ngx_md5_init(&ctx1); if (i & 1) { ngx_md5_update(&ctx1, key, keylen); } else { ngx_md5_update(&ctx1, final, 16); } if (i % 3) { ngx_md5_update(&ctx1, salt, saltlen); } if (i % 7) { ngx_md5_update(&ctx1, key, keylen); } if (i & 1) { ngx_md5_update(&ctx1, final, 16); } else { ngx_md5_update(&ctx1, key, keylen); } ngx_md5_final(final, &ctx1); } /* output */ *encrypted = ngx_pnalloc(pool, sizeof("$apr1$") - 1 + saltlen + 1 + 22 + 1); if (*encrypted == NULL) { return NGX_ERROR; } p = ngx_cpymem(*encrypted, "$apr1$", sizeof("$apr1$") - 1); p = ngx_copy(p, salt, saltlen); *p++ = '$'; p = ngx_crypt_to64(p, (final[ 0]<<16) | (final[ 6]<<8) | final[12], 4); p = ngx_crypt_to64(p, (final[ 1]<<16) | (final[ 7]<<8) | final[13], 4); p = ngx_crypt_to64(p, (final[ 2]<<16) | (final[ 8]<<8) | final[14], 4); p = ngx_crypt_to64(p, (final[ 3]<<16) | (final[ 9]<<8) | final[15], 4); p = ngx_crypt_to64(p, (final[ 4]<<16) | (final[10]<<8) | final[ 5], 4); p = ngx_crypt_to64(p, final[11], 2); *p = '\0'; return NGX_OK; } static u_char * ngx_crypt_to64(u_char *p, uint32_t v, size_t n) { static u_char itoa64[] = "./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"; while (n--) { *p++ = itoa64[v & 0x3f]; v >>= 6; } return p; } static ngx_int_t ngx_crypt_plain(ngx_pool_t *pool, u_char *key, u_char *salt, u_char **encrypted) { size_t len; u_char *p; len = ngx_strlen(key); *encrypted = ngx_pnalloc(pool, sizeof("{PLAIN}") - 1 + len + 1); if (*encrypted == NULL) { return NGX_ERROR; } p = ngx_cpymem(*encrypted, "{PLAIN}", sizeof("{PLAIN}") - 1); ngx_memcpy(p, key, len + 1); return NGX_OK; } #if (NGX_HAVE_SHA1) static ngx_int_t ngx_crypt_ssha(ngx_pool_t *pool, u_char *key, u_char *salt, u_char **encrypted) { size_t len; ngx_int_t rc; ngx_str_t encoded, decoded; ngx_sha1_t sha1; /* "{SSHA}" base64(SHA1(key salt) salt) */ /* decode base64 salt to find out true salt */ encoded.data = salt + sizeof("{SSHA}") - 1; encoded.len = ngx_strlen(encoded.data); len = ngx_max(ngx_base64_decoded_length(encoded.len), 20); decoded.data = ngx_pnalloc(pool, len); if (decoded.data == NULL) { return NGX_ERROR; } rc = ngx_decode_base64(&decoded, &encoded); if (rc != NGX_OK || decoded.len < 20) { decoded.len = 20; } /* update SHA1 from key and salt */ ngx_sha1_init(&sha1); ngx_sha1_update(&sha1, key, ngx_strlen(key)); ngx_sha1_update(&sha1, decoded.data + 20, decoded.len - 20); ngx_sha1_final(decoded.data, &sha1); /* encode it back to base64 */ len = sizeof("{SSHA}") - 1 + ngx_base64_encoded_length(decoded.len) + 1; *encrypted = ngx_pnalloc(pool, len); if (*encrypted == NULL) { return NGX_ERROR; } encoded.data = ngx_cpymem(*encrypted, "{SSHA}", sizeof("{SSHA}") - 1); ngx_encode_base64(&encoded, &decoded); encoded.data[encoded.len] = '\0'; return NGX_OK; } static ngx_int_t ngx_crypt_sha(ngx_pool_t *pool, u_char *key, u_char *salt, u_char **encrypted) { size_t len; ngx_str_t encoded, decoded; ngx_sha1_t sha1; u_char digest[20]; /* "{SHA}" base64(SHA1(key)) */ decoded.len = sizeof(digest); decoded.data = digest; ngx_sha1_init(&sha1); ngx_sha1_update(&sha1, key, ngx_strlen(key)); ngx_sha1_final(digest, &sha1); len = sizeof("{SHA}") - 1 + ngx_base64_encoded_length(decoded.len) + 1; *encrypted = ngx_pnalloc(pool, len); if (*encrypted == NULL) { return NGX_ERROR; } encoded.data = ngx_cpymem(*encrypted, "{SHA}", sizeof("{SHA}") - 1); ngx_encode_base64(&encoded, &decoded); encoded.data[encoded.len] = '\0'; return NGX_OK; } #endif /* NGX_HAVE_SHA1 */ #endif /* NGX_CRYPT */