pkgs/tools/security/gnupg/v3-0001-Disallow-compressed-signatures-and-certificates.patch

   1 From 459b61fa21db755d6c879c3ef9ab85b3d1786c9f Mon Sep 17 00:00:00 2001
   2 From: Demi Marie Obenour <demi () invisiblethingslab com>
   3 Date: Fri, 27 May 2022 19:51:19 -0400
   4 Subject: [PATCH GnuPG v3] Disallow compressed signatures and certificates
   5
   6 Compressed packets have significant attack surface, due to the potential
   7 for both denial of service (zip bombs and the like) and for code
   8 execution via memory corruption vulnerabilities in the decompressor.
   9 Furthermore, I am not aware of any implementation that uses them in keys
  10 or detached signatures.  Therefore, disallow their use in such contexts
  11 entirely.  This includes signatures that are part of a cleartext-signed
  12 message.
  13
  14 When parsing detached signatures, forbid any packet that is not a
  15 signature or marker packet.  When parsing keys, return an error when
  16 encountering a compressed packet, instead of decompressing the packet.
  17
  18 Furthermore, certificates, keys, and signatures are not allowed to
  19 contain partial-length or indeterminate-length packets.  Reject those in
  20 parse_packet, rather than activating the partial-length filter code.
  21 This is not (yet) implemented for cleartext-signed messages, as these
  22 messages are internally represented as inline-signed messages.
  23
  24 GnuPG-bug-id: T5993
  25 Signed-off-by: Demi Marie Obenour <demiobenour () gmail com>
  26 ---
  27  g10/import.c       | 18 ++----------------
  28  g10/mainproc.c     | 24 +++++++++++++++++++++---
  29  g10/packet.h       |  2 ++
  30  g10/parse-packet.c | 44 +++++++++++++++++++++++++++++++++++++++++++-
  31  4 files changed, 68 insertions(+), 20 deletions(-)
  32
  33 diff --git a/g10/import.c b/g10/import.c
  34 index bb0bf67934a8316130cde182cd43d56353e0171d..a8136351f6f7dae8c65634ed8e1c242d323e2009 100644
  35 --- a/g10/import.c
  36 +++ b/g10/import.c
  37 @@ -1042,22 +1042,8 @@ read_block( IOBUF a, unsigned int options,
  38        switch (pkt->pkttype)
  39          {
  40          case PKT_COMPRESSED:
  41 -          if (check_compress_algo (pkt->pkt.compressed->algorithm))
  42 -            {
  43 -              rc = GPG_ERR_COMPR_ALGO;
  44 -              goto ready;
  45 -            }
  46 -          else
  47 -            {
  48 -              compress_filter_context_t *cfx = xmalloc_clear( sizeof *cfx );
  49 -              pkt->pkt.compressed->buf = NULL;
  50 -              if (push_compress_filter2 (a, cfx,
  51 -                                         pkt->pkt.compressed->algorithm, 1))
  52 -                xfree (cfx); /* e.g. in case of compression_algo NONE.  */
  53 -            }
  54 -          free_packet (pkt, &parsectx);
  55 -          init_packet(pkt);
  56 -          break;
  57 +          rc = GPG_ERR_UNEXPECTED;
  58 +          goto ready;
  59
  60          case PKT_RING_TRUST:
  61            /* Skip those packets unless we are in restore mode.  */
  62 diff --git a/g10/mainproc.c b/g10/mainproc.c
  63 index af11877aa257e46662c42b6ff573ee01c3ad1547..3629fc921b742afd131e8d8e2664b201095990f0 100644
  64 --- a/g10/mainproc.c
  65 +++ b/g10/mainproc.c
  66 @@ -152,6 +152,7 @@ add_onepass_sig (CTX c, PACKET *pkt)
  67  {
  68    kbnode_t node;
  69
  70 +  log_assert(!(c->sigs_only && c->signed_data.used));
  71    if (c->list) /* Add another packet. */
  72      add_kbnode (c->list, new_kbnode (pkt));
  73    else /* Insert the first one.  */
  74 @@ -1076,8 +1077,16 @@ proc_compressed (CTX c, PACKET *pkt)
  75    int rc;
  76
  77    /*printf("zip: compressed data packet\n");*/
  78 -  if (c->sigs_only)
  79 -    rc = handle_compressed (c->ctrl, c, zd, proc_compressed_cb, c);
  80 +  if ( literals_seen )
  81 +    {
  82 +      log_error ("Compressed packet follows literal data packet\n");
  83 +      rc = GPG_ERR_UNEXPECTED;
  84 +    }
  85 +  else if ( c->sigs_only )
  86 +    {
  87 +      log_assert(!c->signed_data.used);
  88 +      rc = handle_compressed (c->ctrl, c, zd, proc_compressed_cb, c);
  89 +    }
  90    else if( c->encrypt_only )
  91      rc = handle_compressed (c->ctrl, c, zd, proc_encrypt_cb, c);
  92    else
  93 @@ -1596,6 +1605,7 @@ do_proc_packets (CTX c, iobuf_t a)
  94    c->iobuf = a;
  95    init_packet(pkt);
  96    init_parse_packet (&parsectx, a);
  97 +  parsectx.sigs_only = c->sigs_only && c->signed_data.used;
  98    while ((rc=parse_packet (&parsectx, pkt)) != -1)
  99      {
 100        any_data = 1;
 101 @@ -1607,6 +1617,12 @@ do_proc_packets (CTX c, iobuf_t a)
 102            if (gpg_err_code (rc) == GPG_ERR_INV_PACKET
 103                && opt.list_packets == 0)
 104              break;
 105 +
 106 +          if (gpg_err_code (rc) == GPG_ERR_UNEXPECTED)
 107 +            {
 108 +              write_status_text( STATUS_UNEXPECTED, "0" );
 109 +              goto leave;
 110 +            }
 111            continue;
 112         }
 113        newpkt = -1;
 114 @@ -1644,7 +1660,9 @@ do_proc_packets (CTX c, iobuf_t a)
 115              case PKT_COMPRESSED:  rc = proc_compressed (c, pkt); break;
 116              case PKT_ONEPASS_SIG: newpkt = add_onepass_sig (c, pkt); break;
 117              case PKT_GPG_CONTROL: newpkt = add_gpg_control (c, pkt); break;
 118 -            default: newpkt = 0; break;
 119 +            default:
 120 +             log_assert(!c->signed_data.used);
 121 +             newpkt = 0; break;
 122             }
 123         }
 124        else if (c->encrypt_only)
 125 diff --git a/g10/packet.h b/g10/packet.h
 126 index 5a14015a16c872fe7b0b15468598daf7a05ffc02..82dfe786b46051491e7015e64441678140defa9e 100644
 127 --- a/g10/packet.h
 128 +++ b/g10/packet.h
 129 @@ -657,6 +657,7 @@ struct parse_packet_ctx_s
 130    int free_last_pkt; /* Indicates that LAST_PKT must be freed.  */
 131    int skip_meta;     /* Skip ring trust packets.  */
 132    unsigned int n_parsed_packets;       /* Number of parsed packets.  */
 133 +  int sigs_only;     /* Only accept detached signature packets */
 134  };
 135  typedef struct parse_packet_ctx_s *parse_packet_ctx_t;
 136
 137 @@ -667,6 +668,7 @@ typedef struct parse_packet_ctx_s *parse_packet_ctx_t;
 138      (a)->free_last_pkt = 0;         \
 139      (a)->skip_meta = 0;             \
 140      (a)->n_parsed_packets = 0;      \
 141 +    (a)->sigs_only = 0;             \
 142    } while (0)
 143
 144  #define deinit_parse_packet(a) do { \
 145 diff --git a/g10/parse-packet.c b/g10/parse-packet.c
 146 index cea1f7ebc5daec3863ae963c1ab25500f86796fe..dca66ff427ea6778e536782ec6bda83584877342 100644
 147 --- a/g10/parse-packet.c
 148 +++ b/g10/parse-packet.c
 149 @@ -738,6 +738,20 @@ parse (parse_packet_ctx_t ctx, PACKET *pkt, int onlykeypkts, off_t * retpos,
 150              case PKT_ENCRYPTED_MDC:
 151              case PKT_ENCRYPTED_AEAD:
 152              case PKT_COMPRESSED:
 153 +              if (ctx->sigs_only)
 154 +                {
 155 +                  log_error (_("partial length packet of type %d in detached"
 156 +                               " signature\n"), pkttype);
 157 +                  rc = gpg_error (GPG_ERR_UNEXPECTED);
 158 +                  goto leave;
 159 +                }
 160 +              if (onlykeypkts)
 161 +                {
 162 +                  log_error (_("partial length packet of type %d in keyring\n"),
 163 +                             pkttype);
 164 +                  rc = gpg_error (GPG_ERR_UNEXPECTED);
 165 +                  goto leave;
 166 +                }
 167                iobuf_set_partial_body_length_mode (inp, c & 0xff);
 168                pktlen = 0;      /* To indicate partial length.  */
 169                partial = 1;
 170 @@ -775,6 +789,20 @@ parse (parse_packet_ctx_t ctx, PACKET *pkt, int onlykeypkts, off_t * retpos,
 171               rc = gpg_error (GPG_ERR_INV_PACKET);
 172               goto leave;
 173             }
 174 +         else if (ctx->sigs_only)
 175 +           {
 176 +             log_error (_("indeterminate length packet of type %d in detached"
 177 +                           " signature\n"), pkttype);
 178 +             rc = gpg_error (GPG_ERR_UNEXPECTED);
 179 +             goto leave;
 180 +           }
 181 +         else if (onlykeypkts)
 182 +           {
 183 +             log_error (_("indeterminate length packet of type %d in"
 184 +                           " keyring\n"), pkttype);
 185 +             rc = gpg_error (GPG_ERR_UNEXPECTED);
 186 +             goto leave;
 187 +           }
 188         }
 189        else
 190         {
 191 @@ -828,7 +856,21 @@ parse (parse_packet_ctx_t ctx, PACKET *pkt, int onlykeypkts, off_t * retpos,
 192        goto leave;
 193      }
 194
 195 -  if (with_uid && pkttype == PKT_USER_ID)
 196 +  if (ctx->sigs_only)
 197 +    switch (pkttype)
 198 +      {
 199 +      case PKT_SIGNATURE:
 200 +      case PKT_MARKER:
 201 +       break;
 202 +      default:
 203 +        log_error(_("Packet type %d not allowed in detached signature\n"),
 204 +                  pkttype);
 205 +       iobuf_skip_rest (inp, pktlen, partial);
 206 +       *skip = 1;
 207 +       rc = GPG_ERR_UNEXPECTED;
 208 +       goto leave;
 209 +      }
 210 +  else if (with_uid && pkttype == PKT_USER_ID)
 211      /* If ONLYKEYPKTS is set to 2, then we never skip user id packets,
 212         even if DO_SKIP is set.  */
 213      ;
 214 --
 215 2.36.1
 216