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tor/src/or/parsecommon.c

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/* Copyright (c) 2016-2017, The Tor Project, Inc. */
/* See LICENSE for licensing information */
/**
* \file parsecommon.c
* \brief Common code to parse and validate various type of descriptors.
**/
#include "parsecommon.h"
#include "torlog.h"
#include "util_format.h"
#define MIN_ANNOTATION A_PURPOSE
#define MAX_ANNOTATION A_UNKNOWN_
#define ALLOC_ZERO(sz) memarea_alloc_zero(area,sz)
#define ALLOC(sz) memarea_alloc(area,sz)
#define STRDUP(str) memarea_strdup(area,str)
#define STRNDUP(str,n) memarea_strndup(area,(str),(n))
#define RET_ERR(msg) \
STMT_BEGIN \
if (tok) token_clear(tok); \
tok = ALLOC_ZERO(sizeof(directory_token_t)); \
tok->tp = ERR_; \
tok->error = STRDUP(msg); \
goto done_tokenizing; \
STMT_END
/** Free all resources allocated for <b>tok</b> */
void
token_clear(directory_token_t *tok)
{
if (tok->key)
crypto_pk_free(tok->key);
}
/** Read all tokens from a string between <b>start</b> and <b>end</b>, and add
* them to <b>out</b>. Parse according to the token rules in <b>table</b>.
* Caller must free tokens in <b>out</b>. If <b>end</b> is NULL, use the
* entire string.
*/
int
tokenize_string(memarea_t *area,
const char *start, const char *end, smartlist_t *out,
token_rule_t *table, int flags)
{
const char **s;
directory_token_t *tok = NULL;
int counts[NIL_];
int i;
int first_nonannotation;
int prev_len = smartlist_len(out);
tor_assert(area);
s = &start;
if (!end) {
end = start+strlen(start);
} else {
/* it's only meaningful to check for nuls if we got an end-of-string ptr */
if (memchr(start, '\0', end-start)) {
log_warn(LD_DIR, "parse error: internal NUL character.");
return -1;
}
}
for (i = 0; i < NIL_; ++i)
counts[i] = 0;
SMARTLIST_FOREACH(out, const directory_token_t *, t, ++counts[t->tp]);
while (*s < end && (!tok || tok->tp != EOF_)) {
tok = get_next_token(area, s, end, table);
if (tok->tp == ERR_) {
log_warn(LD_DIR, "parse error: %s", tok->error);
token_clear(tok);
return -1;
}
++counts[tok->tp];
smartlist_add(out, tok);
*s = eat_whitespace_eos(*s, end);
}
if (flags & TS_NOCHECK)
return 0;
if ((flags & TS_ANNOTATIONS_OK)) {
first_nonannotation = -1;
for (i = 0; i < smartlist_len(out); ++i) {
tok = smartlist_get(out, i);
if (tok->tp < MIN_ANNOTATION || tok->tp > MAX_ANNOTATION) {
first_nonannotation = i;
break;
}
}
if (first_nonannotation < 0) {
log_warn(LD_DIR, "parse error: item contains only annotations");
return -1;
}
for (i=first_nonannotation; i < smartlist_len(out); ++i) {
tok = smartlist_get(out, i);
if (tok->tp >= MIN_ANNOTATION && tok->tp <= MAX_ANNOTATION) {
log_warn(LD_DIR, "parse error: Annotations mixed with keywords");
return -1;
}
}
if ((flags & TS_NO_NEW_ANNOTATIONS)) {
if (first_nonannotation != prev_len) {
log_warn(LD_DIR, "parse error: Unexpected annotations.");
return -1;
}
}
} else {
for (i=0; i < smartlist_len(out); ++i) {
tok = smartlist_get(out, i);
if (tok->tp >= MIN_ANNOTATION && tok->tp <= MAX_ANNOTATION) {
log_warn(LD_DIR, "parse error: no annotations allowed.");
return -1;
}
}
first_nonannotation = 0;
}
for (i = 0; table[i].t; ++i) {
if (counts[table[i].v] < table[i].min_cnt) {
log_warn(LD_DIR, "Parse error: missing %s element.", table[i].t);
return -1;
}
if (counts[table[i].v] > table[i].max_cnt) {
log_warn(LD_DIR, "Parse error: too many %s elements.", table[i].t);
return -1;
}
if (table[i].pos & AT_START) {
if (smartlist_len(out) < 1 ||
(tok = smartlist_get(out, first_nonannotation))->tp != table[i].v) {
log_warn(LD_DIR, "Parse error: first item is not %s.", table[i].t);
return -1;
}
}
if (table[i].pos & AT_END) {
if (smartlist_len(out) < 1 ||
(tok = smartlist_get(out, smartlist_len(out)-1))->tp != table[i].v) {
log_warn(LD_DIR, "Parse error: last item is not %s.", table[i].t);
return -1;
}
}
}
return 0;
}
/** Helper: parse space-separated arguments from the string <b>s</b> ending at
* <b>eol</b>, and store them in the args field of <b>tok</b>. Store the
* number of parsed elements into the n_args field of <b>tok</b>. Allocate
* all storage in <b>area</b>. Return the number of arguments parsed, or
* return -1 if there was an insanely high number of arguments. */
static inline int
get_token_arguments(memarea_t *area, directory_token_t *tok,
const char *s, const char *eol)
{
/** Largest number of arguments we'll accept to any token, ever. */
#define MAX_ARGS 512
char *mem = memarea_strndup(area, s, eol-s);
char *cp = mem;
int j = 0;
char *args[MAX_ARGS];
memset(args, 0, sizeof(args));
while (*cp) {
if (j == MAX_ARGS)
return -1;
args[j++] = cp;
cp = (char*)find_whitespace(cp);
if (!cp || !*cp)
break; /* End of the line. */
*cp++ = '\0';
cp = (char*)eat_whitespace(cp);
}
tok->n_args = j;
tok->args = memarea_memdup(area, args, j*sizeof(char*));
return j;
#undef MAX_ARGS
}
/** Helper: make sure that the token <b>tok</b> with keyword <b>kwd</b> obeys
* the object syntax of <b>o_syn</b>. Allocate all storage in <b>area</b>.
* Return <b>tok</b> on success, or a new ERR_ token if the token didn't
* conform to the syntax we wanted.
**/
static inline directory_token_t *
token_check_object(memarea_t *area, const char *kwd,
directory_token_t *tok, obj_syntax o_syn)
{
char ebuf[128];
switch (o_syn) {
case NO_OBJ:
/* No object is allowed for this token. */
if (tok->object_body) {
tor_snprintf(ebuf, sizeof(ebuf), "Unexpected object for %s", kwd);
RET_ERR(ebuf);
}
if (tok->key) {
tor_snprintf(ebuf, sizeof(ebuf), "Unexpected public key for %s", kwd);
RET_ERR(ebuf);
}
break;
case NEED_OBJ:
/* There must be a (non-key) object. */
if (!tok->object_body) {
tor_snprintf(ebuf, sizeof(ebuf), "Missing object for %s", kwd);
RET_ERR(ebuf);
}
break;
case NEED_KEY_1024: /* There must be a 1024-bit public key. */
case NEED_SKEY_1024: /* There must be a 1024-bit private key. */
if (tok->key && crypto_pk_num_bits(tok->key) != PK_BYTES*8) {
tor_snprintf(ebuf, sizeof(ebuf), "Wrong size on key for %s: %d bits",
kwd, crypto_pk_num_bits(tok->key));
RET_ERR(ebuf);
}
/* fall through */
case NEED_KEY: /* There must be some kind of key. */
if (!tok->key) {
tor_snprintf(ebuf, sizeof(ebuf), "Missing public key for %s", kwd);
RET_ERR(ebuf);
}
if (o_syn != NEED_SKEY_1024) {
if (crypto_pk_key_is_private(tok->key)) {
tor_snprintf(ebuf, sizeof(ebuf),
"Private key given for %s, which wants a public key", kwd);
RET_ERR(ebuf);
}
} else { /* o_syn == NEED_SKEY_1024 */
if (!crypto_pk_key_is_private(tok->key)) {
tor_snprintf(ebuf, sizeof(ebuf),
"Public key given for %s, which wants a private key", kwd);
RET_ERR(ebuf);
}
}
break;
case OBJ_OK:
/* Anything goes with this token. */
break;
}
done_tokenizing:
return tok;
}
/** Helper function: read the next token from *s, advance *s to the end of the
* token, and return the parsed token. Parse *<b>s</b> according to the list
* of tokens in <b>table</b>.
*/
directory_token_t *
get_next_token(memarea_t *area,
const char **s, const char *eos, token_rule_t *table)
{
/** Reject any object at least this big; it is probably an overflow, an
* attack, a bug, or some other nonsense. */
#define MAX_UNPARSED_OBJECT_SIZE (128*1024)
/** Reject any line at least this big; it is probably an overflow, an
* attack, a bug, or some other nonsense. */
#define MAX_LINE_LENGTH (128*1024)
const char *next, *eol, *obstart;
size_t obname_len;
int i;
directory_token_t *tok;
obj_syntax o_syn = NO_OBJ;
char ebuf[128];
const char *kwd = "";
tor_assert(area);
tok = ALLOC_ZERO(sizeof(directory_token_t));
tok->tp = ERR_;
/* Set *s to first token, eol to end-of-line, next to after first token */
*s = eat_whitespace_eos(*s, eos); /* eat multi-line whitespace */
tor_assert(eos >= *s);
eol = memchr(*s, '\n', eos-*s);
if (!eol)
eol = eos;
if (eol - *s > MAX_LINE_LENGTH) {
RET_ERR("Line far too long");
}
next = find_whitespace_eos(*s, eol);
if (!strcmp_len(*s, "opt", next-*s)) {
/* Skip past an "opt" at the start of the line. */
*s = eat_whitespace_eos_no_nl(next, eol);
next = find_whitespace_eos(*s, eol);
} else if (*s == eos) { /* If no "opt", and end-of-line, line is invalid */
RET_ERR("Unexpected EOF");
}
/* Search the table for the appropriate entry. (I tried a binary search
* instead, but it wasn't any faster.) */
for (i = 0; table[i].t ; ++i) {
if (!strcmp_len(*s, table[i].t, next-*s)) {
/* We've found the keyword. */
kwd = table[i].t;
tok->tp = table[i].v;
o_syn = table[i].os;
*s = eat_whitespace_eos_no_nl(next, eol);
/* We go ahead whether there are arguments or not, so that tok->args is
* always set if we want arguments. */
if (table[i].concat_args) {
/* The keyword takes the line as a single argument */
tok->args = ALLOC(sizeof(char*));
tok->args[0] = STRNDUP(*s,eol-*s); /* Grab everything on line */
tok->n_args = 1;
} else {
/* This keyword takes multiple arguments. */
if (get_token_arguments(area, tok, *s, eol)<0) {
tor_snprintf(ebuf, sizeof(ebuf),"Far too many arguments to %s", kwd);
RET_ERR(ebuf);
}
*s = eol;
}
if (tok->n_args < table[i].min_args) {
tor_snprintf(ebuf, sizeof(ebuf), "Too few arguments to %s", kwd);
RET_ERR(ebuf);
} else if (tok->n_args > table[i].max_args) {
tor_snprintf(ebuf, sizeof(ebuf), "Too many arguments to %s", kwd);
RET_ERR(ebuf);
}
break;
}
}
if (tok->tp == ERR_) {
/* No keyword matched; call it an "K_opt" or "A_unrecognized" */
if (*s < eol && **s == '@')
tok->tp = A_UNKNOWN_;
else
tok->tp = K_OPT;
tok->args = ALLOC(sizeof(char*));
tok->args[0] = STRNDUP(*s, eol-*s);
tok->n_args = 1;
o_syn = OBJ_OK;
}
/* Check whether there's an object present */
*s = eat_whitespace_eos(eol, eos); /* Scan from end of first line */
tor_assert(eos >= *s);
eol = memchr(*s, '\n', eos-*s);
if (!eol || eol-*s<11 || strcmpstart(*s, "-----BEGIN ")) /* No object. */
goto check_object;
obstart = *s; /* Set obstart to start of object spec */
if (*s+16 >= eol || memchr(*s+11,'\0',eol-*s-16) || /* no short lines, */
strcmp_len(eol-5, "-----", 5) || /* nuls or invalid endings */
(eol-*s) > MAX_UNPARSED_OBJECT_SIZE) { /* name too long */
RET_ERR("Malformed object: bad begin line");
}
tok->object_type = STRNDUP(*s+11, eol-*s-16);
obname_len = eol-*s-16; /* store objname length here to avoid a strlen() */
*s = eol+1; /* Set *s to possible start of object data (could be eos) */
/* Go to the end of the object */
next = tor_memstr(*s, eos-*s, "-----END ");
if (!next) {
RET_ERR("Malformed object: missing object end line");
}
tor_assert(eos >= next);
eol = memchr(next, '\n', eos-next);
if (!eol) /* end-of-line marker, or eos if there's no '\n' */
eol = eos;
/* Validate the ending tag, which should be 9 + NAME + 5 + eol */
if ((size_t)(eol-next) != 9+obname_len+5 ||
strcmp_len(next+9, tok->object_type, obname_len) ||
strcmp_len(eol-5, "-----", 5)) {
tor_snprintf(ebuf, sizeof(ebuf), "Malformed object: mismatched end tag %s",
tok->object_type);
ebuf[sizeof(ebuf)-1] = '\0';
RET_ERR(ebuf);
}
if (next - *s > MAX_UNPARSED_OBJECT_SIZE)
RET_ERR("Couldn't parse object: missing footer or object much too big.");
if (!strcmp(tok->object_type, "RSA PUBLIC KEY")) { /* If it's a public key */
tok->key = crypto_pk_new();
if (crypto_pk_read_public_key_from_string(tok->key, obstart, eol-obstart))
RET_ERR("Couldn't parse public key.");
} else if (!strcmp(tok->object_type, "RSA PRIVATE KEY")) { /* private key */
tok->key = crypto_pk_new();
if (crypto_pk_read_private_key_from_string(tok->key, obstart, eol-obstart))
RET_ERR("Couldn't parse private key.");
} else { /* If it's something else, try to base64-decode it */
int r;
tok->object_body = ALLOC(next-*s); /* really, this is too much RAM. */
r = base64_decode(tok->object_body, next-*s, *s, next-*s);
if (r<0)
RET_ERR("Malformed object: bad base64-encoded data");
tok->object_size = r;
}
*s = eol;
check_object:
tok = token_check_object(area, kwd, tok, o_syn);
done_tokenizing:
return tok;
#undef RET_ERR
#undef ALLOC
#undef ALLOC_ZERO
#undef STRDUP
#undef STRNDUP
}
/** Find the first token in <b>s</b> whose keyword is <b>keyword</b>; fail
* with an assert if no such keyword is found.
*/
directory_token_t *
find_by_keyword_(smartlist_t *s, directory_keyword keyword,
const char *keyword_as_string)
{
directory_token_t *tok = find_opt_by_keyword(s, keyword);
if (PREDICT_UNLIKELY(!tok)) {
log_err(LD_BUG, "Missing %s [%d] in directory object that should have "
"been validated. Internal error.", keyword_as_string, (int)keyword);
tor_assert(tok);
}
return tok;
}
/** Find the first token in <b>s</b> whose keyword is <b>keyword</b>; return
* NULL if no such keyword is found.
*/
directory_token_t *
find_opt_by_keyword(const smartlist_t *s, directory_keyword keyword)
{
SMARTLIST_FOREACH(s, directory_token_t *, t, if (t->tp == keyword) return t);
return NULL;
}
/** If there are any directory_token_t entries in <b>s</b> whose keyword is
* <b>k</b>, return a newly allocated smartlist_t containing all such entries,
* in the same order in which they occur in <b>s</b>. Otherwise return
* NULL. */
smartlist_t *
find_all_by_keyword(const smartlist_t *s, directory_keyword k)
{
smartlist_t *out = NULL;
SMARTLIST_FOREACH(s, directory_token_t *, t,
if (t->tp == k) {
if (!out)
out = smartlist_new();
smartlist_add(out, t);
});
return out;
}
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