diff options
| -rw-r--r-- | common/ksba-io-support.c | 107 | ||||
| -rw-r--r-- | common/ksba-io-support.h | 1 | ||||
| -rw-r--r-- | common/tlv.c | 3 | ||||
| -rw-r--r-- | doc/gpgsm.texi | 6 | ||||
| -rw-r--r-- | sm/verify.c | 10 |
5 files changed, 120 insertions, 7 deletions
diff --git a/common/ksba-io-support.c b/common/ksba-io-support.c index 2832a4f3d..a279b67ad 100644 --- a/common/ksba-io-support.c +++ b/common/ksba-io-support.c @@ -40,6 +40,7 @@ #include "util.h" #include "i18n.h" +#include "tlv.h" #include "ksba-io-support.h" @@ -65,6 +66,12 @@ struct reader_cb_parm_s int autodetect; /* Try to detect the input encoding. */ int assume_pem; /* Assume input encoding is PEM. */ int assume_base64; /* Assume input is base64 encoded. */ + int strip_zeroes; /* Expect a SEQUENCE followed by zero padding. */ + /* 1 = check state; 2 = reading; 3 = checking */ + /* for zeroes. */ + int use_maxread; /* If true read not more than MAXREAD. */ + unsigned int maxread; /* # of bytes left to read. */ + off_t nzeroes; /* Number of padding zeroes red. */ int identified; int is_pem; @@ -390,6 +397,55 @@ base64_reader_cb (void *cb_value, char *buffer, size_t count, size_t *nread) } +/* Read up to 10 bytes to test whether the data consist of a sequence; + * if that is true, set the limited flag and record the length of the + * entire sequence in PARM. Unget everything then. Return true if we + * have a sequence with a fixed length. */ +static int +starts_with_sequence (struct reader_cb_parm_s *parm) +{ + gpg_error_t err; + unsigned char peekbuf[10]; + int npeeked, c; + int found = 0; + const unsigned char *p; + size_t n, objlen, hdrlen; + int class, tag, constructed, ndef; + + for (npeeked=0; npeeked < sizeof peekbuf; npeeked++) + { + c = es_getc (parm->fp); + if (c == EOF) + goto leave; + peekbuf[npeeked] = c; + } + /* Enough to check for a sequence. */ + + p = peekbuf; + n = npeeked; + err = parse_ber_header (&p, &n, &class, &tag, &constructed, + &ndef, &objlen, &hdrlen); + if (err) + { + log_debug ("%s: error parsing data: %s\n", __func__, gpg_strerror (err)); + goto leave; + } + + if (class == CLASS_UNIVERSAL && constructed && tag == TAG_SEQUENCE && !ndef) + { + /* We need to add 1 due to the way we implement the limit. */ + parm->maxread = objlen + hdrlen + 1; + if (!(parm->maxread < objlen + hdrlen) && parm->maxread) + parm->use_maxread = 1; + found = 1; + } + + leave: + while (npeeked) + es_ungetc (peekbuf[--npeeked], parm->fp); + return found; +} + static int simple_reader_cb (void *cb_value, char *buffer, size_t count, size_t *nread) @@ -402,9 +458,55 @@ simple_reader_cb (void *cb_value, char *buffer, size_t count, size_t *nread) if (!buffer) return -1; /* not supported */ + restart: + if (parm->strip_zeroes) + { + if (parm->strip_zeroes == 1) + { + if (starts_with_sequence (parm)) + parm->strip_zeroes = 2; /* Found fixed length sequence. */ + else + parm->strip_zeroes = 0; /* Disable zero padding check. */ + } + else if (parm->strip_zeroes == 3) + { + /* Limit reached - check that only zeroes follow. */ + while (!(c = es_getc (parm->fp))) + parm->nzeroes++; + if (c == EOF) + { /* only zeroes found. Reset zero padding engine and + * return EOF. */ + parm->strip_zeroes = 0; + parm->eof_seen = 1; + return -1; + } + /* Not only zeroes. Reset engine and continue. */ + parm->strip_zeroes = 0; + } + } + for (n=0; n < count; n++) { - c = es_getc (parm->fp); + if (parm->use_maxread && !--parm->maxread) + { + parm->use_maxread = 0; + if (parm->strip_zeroes) + { + parm->strip_zeroes = 3; + parm->nzeroes = 0; + if (n) + goto leave; /* Return what we already got. */ + goto restart; /* Immediately check for trailing zeroes. */ + } + } + + if (parm->nzeroes) + { + parm->nzeroes--; + c = 0; + } + else + c = es_getc (parm->fp); if (c == EOF) { parm->eof_seen = 1; @@ -417,6 +519,7 @@ simple_reader_cb (void *cb_value, char *buffer, size_t count, size_t *nread) *(byte *)buffer++ = c; } + leave: *nread = n; return 0; } @@ -575,6 +678,7 @@ base64_finish_write (struct writer_cb_parm_s *parm) * GNUPG_KSBA_IO_MULTIPEM - The reader expects that the caller uses * ksba_reader_clear after EOF until no more * objects were found. + * GNUPG_KSBA_IO_STRIP - Strip zero padding from some CMS objects. * * Note that the PEM flag has a higher priority than the BASE64 flag * which in turn has a gight priority than the AUTODETECT flag. @@ -592,6 +696,7 @@ gnupg_ksba_create_reader (gnupg_ksba_io_t *ctx, if (!*ctx) return out_of_core (); (*ctx)->u.rparm.allow_multi_pem = !!(flags & GNUPG_KSBA_IO_MULTIPEM); + (*ctx)->u.rparm.strip_zeroes = !!(flags & GNUPG_KSBA_IO_STRIP); rc = ksba_reader_new (&r); if (rc) diff --git a/common/ksba-io-support.h b/common/ksba-io-support.h index e33e0ed74..02e541b16 100644 --- a/common/ksba-io-support.h +++ b/common/ksba-io-support.h @@ -36,6 +36,7 @@ #define GNUPG_KSBA_IO_BASE64 2 /* Plain Base64 format. */ #define GNUPG_KSBA_IO_AUTODETECT 4 /* Try to autodetect the format. */ #define GNUPG_KSBA_IO_MULTIPEM 8 /* Allow more than one PEM chunk. */ +#define GNUPG_KSBA_IO_STRIP 16 /* Strip off zero padding. */ /* Context object. */ diff --git a/common/tlv.c b/common/tlv.c index 9618d04cb..4cc1dc7cf 100644 --- a/common/tlv.c +++ b/common/tlv.c @@ -156,8 +156,7 @@ gpg_error_t parse_ber_header (unsigned char const **buffer, size_t *size, int *r_class, int *r_tag, int *r_constructed, int *r_ndef, - size_t *r_length, size_t *r_nhdr) -{ + size_t *r_length, size_t *r_nhdr){ int c; unsigned long tag; const unsigned char *buf = *buffer; diff --git a/doc/gpgsm.texi b/doc/gpgsm.texi index a328ea5f0..42090a93f 100644 --- a/doc/gpgsm.texi +++ b/doc/gpgsm.texi @@ -492,8 +492,10 @@ This usually means that Dirmngr is employed to search for the certificate. Note that this option makes a "web bug" like behavior possible. LDAP server operators can see which keys you request, so by sending you a message signed by a brand new key (which you naturally -will not have on your local keybox), the operator can tell both your IP -address and the time when you verified the signature. +will not have on your local keybox), the operator can tell both your +IP address and the time when you verified the signature. Note that if +CRL checking is not disabled issuer certificates are retrieved in any +case using the caIssuers authorityInfoAccess method. @anchor{gpgsm-option --validation-model} diff --git a/sm/verify.c b/sm/verify.c index 9f1216f83..a07d1c9c7 100644 --- a/sm/verify.c +++ b/sm/verify.c @@ -105,12 +105,17 @@ gpgsm_verify (ctrl_t ctrl, int in_fd, int data_fd, estream_t out_fp) int signer; const char *algoid; int algo; - int is_detached; + int is_detached, maybe_detached; estream_t in_fp = NULL; char *p; audit_set_type (ctrl->audit, AUDIT_TYPE_VERIFY); + /* Although we detect detached signatures during the parsing phase, + * we need to know it earlier and thus accept the caller idea of + * what to verify. */ + maybe_detached = (data_fd != -1); + kh = keydb_new (ctrl); if (!kh) { @@ -131,7 +136,8 @@ gpgsm_verify (ctrl_t ctrl, int in_fd, int data_fd, estream_t out_fp) rc = gnupg_ksba_create_reader (&b64reader, ((ctrl->is_pem? GNUPG_KSBA_IO_PEM : 0) | (ctrl->is_base64? GNUPG_KSBA_IO_BASE64 : 0) - | (ctrl->autodetect_encoding? GNUPG_KSBA_IO_AUTODETECT : 0)), + | (ctrl->autodetect_encoding? GNUPG_KSBA_IO_AUTODETECT : 0) + | (maybe_detached? GNUPG_KSBA_IO_STRIP : 0)), in_fp, &reader); if (rc) { |