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Diffstat (limited to 'src/or/parsecommon.c')
| -rw-r--r-- | src/or/parsecommon.c | 451 |
1 files changed, 451 insertions, 0 deletions
diff --git a/src/or/parsecommon.c b/src/or/parsecommon.c new file mode 100644 index 0000000000..6c3dd3100e --- /dev/null +++ b/src/or/parsecommon.c @@ -0,0 +1,451 @@ +/* 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(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; +} + |