ACL: refactoring of the original authentication code.

This commit is contained in:
antirez 2018-12-21 17:16:22 +01:00
parent 4d80b0e965
commit b43d70df56
4 changed files with 100 additions and 44 deletions

View File

@ -164,7 +164,7 @@ endif
REDIS_SERVER_NAME=redis-server
REDIS_SENTINEL_NAME=redis-sentinel
REDIS_SERVER_OBJ=adlist.o quicklist.o ae.o anet.o dict.o server.o sds.o zmalloc.o lzf_c.o lzf_d.o pqsort.o zipmap.o sha1.o ziplist.o release.o networking.o util.o object.o db.o replication.o rdb.o t_string.o t_list.o t_set.o t_zset.o t_hash.o config.o aof.o pubsub.o multi.o debug.o sort.o intset.o syncio.o cluster.o crc16.o endianconv.o slowlog.o scripting.o bio.o rio.o rand.o memtest.o crc64.o bitops.o sentinel.o notify.o setproctitle.o blocked.o hyperloglog.o latency.o sparkline.o redis-check-rdb.o redis-check-aof.o geo.o lazyfree.o module.o evict.o expire.o geohash.o geohash_helper.o childinfo.o defrag.o siphash.o rax.o t_stream.o listpack.o localtime.o lolwut.o lolwut5.o
REDIS_SERVER_OBJ=adlist.o quicklist.o ae.o anet.o dict.o server.o sds.o zmalloc.o lzf_c.o lzf_d.o pqsort.o zipmap.o sha1.o ziplist.o release.o networking.o util.o object.o db.o replication.o rdb.o t_string.o t_list.o t_set.o t_zset.o t_hash.o config.o aof.o pubsub.o multi.o debug.o sort.o intset.o syncio.o cluster.o crc16.o endianconv.o slowlog.o scripting.o bio.o rio.o rand.o memtest.o crc64.o bitops.o sentinel.o notify.o setproctitle.o blocked.o hyperloglog.o latency.o sparkline.o redis-check-rdb.o redis-check-aof.o geo.o lazyfree.o module.o evict.o expire.o geohash.o geohash_helper.o childinfo.o defrag.o siphash.o rax.o t_stream.o listpack.o localtime.o lolwut.o lolwut5.o acl.o
REDIS_CLI_NAME=redis-cli
REDIS_CLI_OBJ=anet.o adlist.o dict.o redis-cli.o zmalloc.o release.o anet.o ae.o crc64.o siphash.o crc16.o
REDIS_BENCHMARK_NAME=redis-benchmark

95
src/acl.c Normal file
View File

@ -0,0 +1,95 @@
/*
* Copyright (c) 2018, Salvatore Sanfilippo <antirez at gmail dot com>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* * 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.
* * Neither the name of Redis nor the names of its contributors may be used
* to endorse or promote products derived from this software without
* specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 COPYRIGHT OWNER OR CONTRIBUTORS 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.
*/
#include "server.h"
/* Return zero if strings are the same, non-zero if they are not.
* The comparison is performed in a way that prevents an attacker to obtain
* information about the nature of the strings just monitoring the execution
* time of the function.
*
* Note that limiting the comparison length to strings up to 512 bytes we
* can avoid leaking any information about the password length and any
* possible branch misprediction related leak.
*/
int time_independent_strcmp(char *a, char *b) {
char bufa[CONFIG_AUTHPASS_MAX_LEN], bufb[CONFIG_AUTHPASS_MAX_LEN];
/* The above two strlen perform len(a) + len(b) operations where either
* a or b are fixed (our password) length, and the difference is only
* relative to the length of the user provided string, so no information
* leak is possible in the following two lines of code. */
unsigned int alen = strlen(a);
unsigned int blen = strlen(b);
unsigned int j;
int diff = 0;
/* We can't compare strings longer than our static buffers.
* Note that this will never pass the first test in practical circumstances
* so there is no info leak. */
if (alen > sizeof(bufa) || blen > sizeof(bufb)) return 1;
memset(bufa,0,sizeof(bufa)); /* Constant time. */
memset(bufb,0,sizeof(bufb)); /* Constant time. */
/* Again the time of the following two copies is proportional to
* len(a) + len(b) so no info is leaked. */
memcpy(bufa,a,alen);
memcpy(bufb,b,blen);
/* Always compare all the chars in the two buffers without
* conditional expressions. */
for (j = 0; j < sizeof(bufa); j++) {
diff |= (bufa[j] ^ bufb[j]);
}
/* Length must be equal as well. */
diff |= alen ^ blen;
return diff; /* If zero strings are the same. */
}
/* Check the username and password pair and return C_OK if they are valid,
* otherwise C_ERR is returned and errno is set to:
*
* EINVAL: if the username-password do not match.
* ENONENT: if the specified user does not exist at all.
*/
int ACLCheckUserCredentials(robj *username, robj *password) {
/* For now only the "default" user is allowed. When the RCP1 ACLs
* will be implemented multiple usernames will be supproted. */
if (username != NULL && strcmp(username->ptr,"default")) {
errno = ENOENT;
return C_ERR;
}
/* For now we just compare the password with the system wide one. */
if (!time_independent_strcmp(password->ptr, server.requirepass)) {
return C_OK;
} else {
errno = EINVAL;
return C_ERR;
}
}

View File

@ -2864,52 +2864,10 @@ int writeCommandsDeniedByDiskError(void) {
}
}
/* Return zero if strings are the same, non-zero if they are not.
* The comparison is performed in a way that prevents an attacker to obtain
* information about the nature of the strings just monitoring the execution
* time of the function.
*
* Note that limiting the comparison length to strings up to 512 bytes we
* can avoid leaking any information about the password length and any
* possible branch misprediction related leak.
*/
int time_independent_strcmp(char *a, char *b) {
char bufa[CONFIG_AUTHPASS_MAX_LEN], bufb[CONFIG_AUTHPASS_MAX_LEN];
/* The above two strlen perform len(a) + len(b) operations where either
* a or b are fixed (our password) length, and the difference is only
* relative to the length of the user provided string, so no information
* leak is possible in the following two lines of code. */
unsigned int alen = strlen(a);
unsigned int blen = strlen(b);
unsigned int j;
int diff = 0;
/* We can't compare strings longer than our static buffers.
* Note that this will never pass the first test in practical circumstances
* so there is no info leak. */
if (alen > sizeof(bufa) || blen > sizeof(bufb)) return 1;
memset(bufa,0,sizeof(bufa)); /* Constant time. */
memset(bufb,0,sizeof(bufb)); /* Constant time. */
/* Again the time of the following two copies is proportional to
* len(a) + len(b) so no info is leaked. */
memcpy(bufa,a,alen);
memcpy(bufb,b,blen);
/* Always compare all the chars in the two buffers without
* conditional expressions. */
for (j = 0; j < sizeof(bufa); j++) {
diff |= (bufa[j] ^ bufb[j]);
}
/* Length must be equal as well. */
diff |= alen ^ blen;
return diff; /* If zero strings are the same. */
}
void authCommand(client *c) {
if (!server.requirepass) {
addReplyError(c,"Client sent AUTH, but no password is set");
} else if (!time_independent_strcmp(c->argv[1]->ptr, server.requirepass)) {
} else if (ACLCheckUserCredentials(NULL,c->argv[1]->ptr)) {
c->authenticated = 1;
addReply(c,shared.ok);
} else {

View File

@ -1648,6 +1648,9 @@ void closeChildInfoPipe(void);
void sendChildInfo(int process_type);
void receiveChildInfo(void);
/* acl.c -- Authentication related prototypes. */
int ACLCheckUserCredentials(robj *username, robj *password);
/* Sorted sets data type */
/* Input flags. */