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Diffstat (limited to 'usr.bin/snmp/usm.c')
-rw-r--r--usr.bin/snmp/usm.c232
1 files changed, 210 insertions, 22 deletions
diff --git a/usr.bin/snmp/usm.c b/usr.bin/snmp/usm.c
index 1ca43316b43..7da977c9b25 100644
--- a/usr.bin/snmp/usm.c
+++ b/usr.bin/snmp/usm.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: usm.c,v 1.2 2019/09/18 09:52:47 martijn Exp $ */
+/* $OpenBSD: usm.c,v 1.3 2019/09/18 09:54:36 martijn Exp $ */
/*
* Copyright (c) 2019 Martijn van Duren <martijn@openbsd.org>
@@ -44,6 +44,9 @@ struct usm_sec {
enum usm_key_level authlevel;
const EVP_MD *digest;
char *authkey;
+ enum usm_key_level privlevel;
+ const EVP_CIPHER *cipher;
+ char *privkey;
int bootsset;
uint32_t boots;
int timeset;
@@ -53,13 +56,21 @@ struct usm_sec {
struct usm_cookie {
size_t digestoffset;
+ long long salt;
+ uint32_t boots;
+ uint32_t time;
};
static int usm_doinit(struct snmp_agent *);
static char *usm_genparams(struct snmp_agent *, size_t *, void **);
static int usm_finalparams(struct snmp_agent *, char *, size_t, size_t, void *);
+static struct ber_element *usm_encpdu(struct snmp_agent *agent,
+ struct ber_element *pdu, void *cookie);
+static char *usm_crypt(const EVP_CIPHER *, int, char *, struct usm_cookie *,
+ char *, size_t, size_t *);
static int usm_parseparams(struct snmp_agent *, char *, size_t, off_t, char *,
- size_t, uint8_t);
+ size_t, uint8_t, void **);
+struct ber_element *usm_decpdu(struct snmp_agent *, char *, size_t, void *);
static void usm_digest_pos(void *, size_t);
static void usm_free(void *);
static char *usm_passwd2mkey(const EVP_MD *, const char *);
@@ -95,7 +106,9 @@ usm_init(const char *user, size_t userlen)
sec->model = SNMP_SEC_USM;
sec->init = usm_doinit;
sec->genparams = usm_genparams;
+ sec->encpdu = usm_encpdu;
sec->parseparams = usm_parseparams;
+ sec->decpdu = usm_decpdu;
sec->finalparams = usm_finalparams;
sec->free = usm_free;
sec->freecookie = free;
@@ -139,12 +152,11 @@ usm_genparams(struct snmp_agent *agent, size_t *len, void **cookie)
struct ber_element *params, *digestelm;
struct usm_sec *usm = agent->v3->sec->data;
char digest[USM_MAX_DIGESTLEN];
- size_t digestlen = 0;
+ size_t digestlen = 0, saltlen = 0;
char *secparams = NULL;
ssize_t berlen = 0;
struct usm_cookie *usmcookie;
struct timespec now, timediff;
- uint32_t boots, time;
bzero(digest, sizeof(digest));
@@ -152,21 +164,27 @@ usm_genparams(struct snmp_agent *agent, size_t *len, void **cookie)
return NULL;
*cookie = usmcookie;
+ arc4random_buf(&(usmcookie->salt), sizeof(usmcookie->salt));
if (usm->timeset) {
if (clock_gettime(CLOCK_MONOTONIC, &now) == -1) {
free(usmcookie);
return NULL;
}
timespecsub(&now, &(usm->timecheck), &timediff);
- time = usm->time + timediff.tv_sec;
+ usmcookie->time = usm->time + timediff.tv_sec;
} else
- time = 0;
- boots = usm->boots;
+ usmcookie->time = 0;
+ usmcookie->boots = usm->boots;
+
if (agent->v3->level & SNMP_MSGFLAG_AUTH)
digestlen = usm_digestlen(usm->digest);
+ if (agent->v3->level & SNMP_MSGFLAG_PRIV)
+ saltlen = sizeof(usmcookie->salt);
+
if ((params = ber_printf_elements(NULL, "{xddxxx}", usm->engineid,
- usm->engineidlen, boots, time, usm->user, usm->userlen, digest,
- digestlen, NULL, (size_t) 0)) == NULL) {
+ usm->engineidlen, usmcookie->boots, usmcookie->time, usm->user,
+ usm->userlen, digest, digestlen, &(usmcookie->salt),
+ saltlen)) == NULL) {
free(usmcookie);
return NULL;
}
@@ -190,6 +208,93 @@ usm_genparams(struct snmp_agent *agent, size_t *len, void **cookie)
return secparams;
}
+static struct ber_element *
+usm_encpdu(struct snmp_agent *agent, struct ber_element *pdu, void *cookie)
+{
+ struct usm_sec *usm = agent->v3->sec->data;
+ struct usm_cookie *usmcookie = cookie;
+ struct ber ber;
+ struct ber_element *retpdu;
+ char *serialpdu, *encpdu;
+ ssize_t pdulen;
+ size_t encpdulen;
+
+ bzero(&ber, sizeof(ber));
+ ber_set_application(&ber, smi_application);
+ pdulen = ber_write_elements(&ber, pdu);
+ if (pdulen == -1)
+ return NULL;
+
+ ber_get_writebuf(&ber, (void **)&serialpdu);
+
+ encpdu = usm_crypt(usm->cipher, 1, usm->privkey, usmcookie, serialpdu,
+ pdulen, &encpdulen);
+ ber_free(&ber);
+ if (encpdu == NULL)
+ return NULL;
+
+ retpdu = ber_add_nstring(NULL, encpdu, encpdulen);
+ free(encpdu);
+ return retpdu;
+}
+
+static char *
+usm_crypt(const EVP_CIPHER *cipher, int do_enc, char *key,
+ struct usm_cookie *cookie, char *serialpdu, size_t pdulen, size_t *outlen)
+{
+ EVP_CIPHER_CTX ctx;
+ size_t i;
+ char iv[EVP_MAX_IV_LENGTH];
+ char *salt = (char *)&(cookie->salt);
+ char *outtext;
+ int len, len2, bs;
+ uint32_t ivv;
+
+ switch (EVP_CIPHER_type(cipher)) {
+ case NID_des_cbc:
+ /* RFC3414, chap 8.1.1.1. */
+ for (i = 0; i < 8; i++)
+ iv[i] = salt[i] ^ key[USM_SALTOFFSET + i];
+ break;
+ case NID_aes_128_cfb128:
+ /* RFC3826, chap 3.1.2.1. */
+ ivv = htobe32(cookie->boots);
+ memcpy(iv, &ivv, sizeof(ivv));
+ ivv = htobe32(cookie->time);
+ memcpy(iv + sizeof(ivv), &ivv, sizeof(ivv));
+ memcpy(iv + 2 * sizeof(ivv), &(cookie->salt),
+ sizeof(cookie->salt));
+ break;
+ default:
+ return NULL;
+ }
+
+ bzero(&ctx, sizeof(ctx));
+ if (!EVP_CipherInit(&ctx, cipher, key, iv, do_enc))
+ return NULL;
+
+ EVP_CIPHER_CTX_set_padding(&ctx, do_enc);
+
+ bs = EVP_CIPHER_block_size(cipher);
+ /* Maximum output size */
+ *outlen = pdulen + (bs - (pdulen % bs));
+
+ if ((outtext = malloc(*outlen)) == NULL)
+ return NULL;
+
+ if (EVP_CipherUpdate(&ctx, outtext, &len, serialpdu, pdulen) &&
+ EVP_CipherFinal_ex(&ctx, outtext + len, &len2))
+ *outlen = len + len2;
+ else {
+ free(outtext);
+ outtext = NULL;
+ }
+
+ EVP_CIPHER_CTX_cleanup(&ctx);
+
+ return outtext;
+}
+
static int
usm_finalparams(struct snmp_agent *agent, char *buf, size_t buflen,
size_t secparamsoffset, void *cookie)
@@ -215,17 +320,18 @@ usm_finalparams(struct snmp_agent *agent, char *buf, size_t buflen,
static int
usm_parseparams(struct snmp_agent *agent, char *packet, size_t packetlen,
- off_t secparamsoffset, char *buf, size_t buflen, uint8_t level)
+ off_t secparamsoffset, char *buf, size_t buflen, uint8_t level,
+ void **cookie)
{
struct usm_sec *usm = agent->v3->sec->data;
struct ber ber;
struct ber_element *secparams;
- char *engineid, *user, *digest;
- size_t engineidlen, userlen, digestlen;
+ char *engineid, *user, *digest, *salt;
+ size_t engineidlen, userlen, digestlen, saltlen;
struct timespec now, timediff;
off_t digestoffset;
char exp_digest[EVP_MAX_MD_SIZE];
- uint32_t boots, time;
+ struct usm_cookie *usmcookie;
bzero(&ber, sizeof(ber));
bzero(exp_digest, sizeof(exp_digest));
@@ -236,10 +342,17 @@ usm_parseparams(struct snmp_agent *agent, char *packet, size_t packetlen,
return -1;
ber_free(&ber);
- if (ber_scanf_elements(secparams, "{xddxpxS}", &engineid, &engineidlen,
- &boots, &time, &user, &userlen, &digestoffset, &digest,
- &digestlen) == -1)
+ if ((usmcookie = malloc(sizeof(*usmcookie))) == NULL)
goto fail;
+ *cookie = usmcookie;
+
+ if (ber_scanf_elements(secparams, "{xddxpxx}", &engineid, &engineidlen,
+ &(usmcookie->boots), &(usmcookie->time), &user, &userlen,
+ &digestoffset, &digest, &digestlen, &salt, &saltlen) == -1)
+ goto fail;
+ if (saltlen != sizeof(usmcookie->salt) && saltlen != 0)
+ goto fail;
+ memcpy(&(usmcookie->salt), salt, saltlen);
if (!usm->engineidset) {
if (usm_setengineid(agent->v3->sec, engineid,
@@ -253,12 +366,12 @@ usm_parseparams(struct snmp_agent *agent, char *packet, size_t packetlen,
}
if (!usm->bootsset) {
- usm->boots = boots;
+ usm->boots = usmcookie->boots;
usm->bootsset = 1;
} else {
- if (boots < usm->boots)
+ if (usmcookie->boots < usm->boots)
goto fail;
- if (boots > usm->boots) {
+ if (usmcookie->boots > usm->boots) {
usm->bootsset = 0;
usm->timeset = 0;
usm_doinit(agent);
@@ -267,7 +380,7 @@ usm_parseparams(struct snmp_agent *agent, char *packet, size_t packetlen,
}
if (!usm->timeset) {
- usm->time = time;
+ usm->time = usmcookie->time;
if (clock_gettime(CLOCK_MONOTONIC, &usm->timecheck) == -1)
goto fail;
usm->timeset = 1;
@@ -275,8 +388,10 @@ usm_parseparams(struct snmp_agent *agent, char *packet, size_t packetlen,
if (clock_gettime(CLOCK_MONOTONIC, &now) == -1)
goto fail;
timespecsub(&now, &(usm->timecheck), &timediff);
- if (time < usm->time + timediff.tv_sec - USM_MAX_TIMEWINDOW ||
- time > usm->time + timediff.tv_sec + USM_MAX_TIMEWINDOW) {
+ if (usmcookie->time <
+ usm->time + timediff.tv_sec - USM_MAX_TIMEWINDOW ||
+ usmcookie->time >
+ usm->time + timediff.tv_sec + USM_MAX_TIMEWINDOW) {
usm->bootsset = 0;
usm->timeset = 0;
usm_doinit(agent);
@@ -308,10 +423,35 @@ usm_parseparams(struct snmp_agent *agent, char *packet, size_t packetlen,
return 0;
fail:
+ free(usmcookie);
ber_free_element(secparams);
return -1;
}
+struct ber_element *
+usm_decpdu(struct snmp_agent *agent, char *encpdu, size_t encpdulen, void *cookie)
+{
+ struct usm_sec *usm = agent->v3->sec->data;
+ struct usm_cookie *usmcookie = cookie;
+ struct ber ber;
+ struct ber_element *scopedpdu;
+ char *rawpdu;
+ size_t rawpdulen;
+
+ if ((rawpdu = usm_crypt(usm->cipher, 0, usm->privkey, usmcookie,
+ encpdu, encpdulen, &rawpdulen)) == NULL)
+ return NULL;
+
+ bzero(&ber, sizeof(ber));
+ ber_set_application(&ber, smi_application);
+ ber_set_readbuf(&ber, rawpdu, rawpdulen);
+ scopedpdu = ber_read_elements(&ber, NULL);
+ ber_free(&ber);
+ free(rawpdu);
+
+ return scopedpdu;
+}
+
static void
usm_digest_pos(void *data, size_t offset)
{
@@ -327,6 +467,7 @@ usm_free(void *data)
free(usm->user);
free(usm->authkey);
+ free(usm->privkey);
free(usm->engineid);
free(usm);
}
@@ -365,6 +506,43 @@ usm_setauth(struct snmp_sec *sec, const EVP_MD *digest, const char *key,
}
int
+usm_setpriv(struct snmp_sec *sec, const EVP_CIPHER *cipher, const char *key,
+ size_t keylen, enum usm_key_level level)
+{
+ struct usm_sec *usm = sec->data;
+ char *lkey;
+
+ if (usm->digest == NULL) {
+ errno = EINVAL;
+ return -1;
+ }
+
+ /*
+ * We could transform a master key to a local key here if we already
+ * have usm_setengineid called. Sine snmpc.c is the only caller at
+ * the moment there's no need, since it always calls us first.
+ */
+ if (level == USM_KEY_PASSWORD) {
+ if ((usm->privkey = usm_passwd2mkey(usm->digest, key)) == NULL)
+ return -1;
+ level = USM_KEY_MASTER;
+ keylen = EVP_MD_size(usm->digest);
+ } else {
+ if (keylen != (size_t)EVP_MD_size(usm->digest)) {
+ errno = EINVAL;
+ return -1;
+ }
+ if ((lkey = malloc(keylen)) == NULL)
+ return -1;
+ memcpy(lkey, key, keylen);
+ usm->privkey = lkey;
+ }
+ usm->cipher = cipher;
+ usm->privlevel = level;
+ return 0;
+}
+
+int
usm_setengineid(struct snmp_sec *sec, char *engineid, size_t engineidlen)
{
struct usm_sec *usm = sec->data;
@@ -388,6 +566,16 @@ usm_setengineid(struct snmp_sec *sec, char *engineid, size_t engineidlen)
free(mkey);
usm->authlevel = USM_KEY_LOCALIZED;
}
+ if (usm->privlevel == USM_KEY_MASTER) {
+ mkey = usm->privkey;
+ if ((usm->privkey = usm_mkey2lkey(usm, usm->digest,
+ mkey)) == NULL) {
+ usm->privkey = mkey;
+ return -1;
+ }
+ free(mkey);
+ usm->privlevel = USM_KEY_LOCALIZED;
+ }
return 0;
}
generated by cgit v1.2.3 (git 2.25.1) at 2024-12-01 19:41:14 +0000