queue-4.4/crypto-gcm-fix-incompatibility-between-gcm-and-gcm_base.patch

   1 From f699594d436960160f6d5ba84ed4a222f20d11cd Mon Sep 17 00:00:00 2001
   2 From: Eric Biggers <ebiggers@google.com>
   3 Date: Thu, 18 Apr 2019 14:43:02 -0700
   4 Subject: crypto: gcm - fix incompatibility between "gcm" and "gcm_base"
   5
   6 From: Eric Biggers <ebiggers@google.com>
   7
   8 commit f699594d436960160f6d5ba84ed4a222f20d11cd upstream.
   9
  10 GCM instances can be created by either the "gcm" template, which only
  11 allows choosing the block cipher, e.g. "gcm(aes)"; or by "gcm_base",
  12 which allows choosing the ctr and ghash implementations, e.g.
  13 "gcm_base(ctr(aes-generic),ghash-generic)".
  14
  15 However, a "gcm_base" instance prevents a "gcm" instance from being
  16 registered using the same implementations.  Nor will the instance be
  17 found by lookups of "gcm".  This can be used as a denial of service.
  18 Moreover, "gcm_base" instances are never tested by the crypto
  19 self-tests, even if there are compatible "gcm" tests.
  20
  21 The root cause of these problems is that instances of the two templates
  22 use different cra_names.  Therefore, fix these problems by making
  23 "gcm_base" instances set the same cra_name as "gcm" instances, e.g.
  24 "gcm(aes)" instead of "gcm_base(ctr(aes-generic),ghash-generic)".
  25
  26 This requires extracting the block cipher name from the name of the ctr
  27 algorithm.  It also requires starting to verify that the algorithms are
  28 really ctr and ghash, not something else entirely.  But it would be
  29 bizarre if anyone were actually using non-gcm-compatible algorithms with
  30 gcm_base, so this shouldn't break anyone in practice.
  31
  32 Fixes: d00aa19b507b ("[CRYPTO] gcm: Allow block cipher parameter")
  33 Cc: stable@vger.kernel.org
  34 Signed-off-by: Eric Biggers <ebiggers@google.com>
  35 Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
  36 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  37
  38
  39 ---
  40  crypto/gcm.c |   34 +++++++++++-----------------------
  41  1 file changed, 11 insertions(+), 23 deletions(-)
  42
  43 --- a/crypto/gcm.c
  44 +++ b/crypto/gcm.c
  45 @@ -616,7 +616,6 @@ static void crypto_gcm_free(struct aead_
  46
  47  static int crypto_gcm_create_common(struct crypto_template *tmpl,
  48                                     struct rtattr **tb,
  49 -                                   const char *full_name,
  50                                     const char *ctr_name,
  51                                     const char *ghash_name)
  52  {
  53 @@ -657,7 +656,8 @@ static int crypto_gcm_create_common(stru
  54                 goto err_free_inst;
  55
  56         err = -EINVAL;
  57 -       if (ghash->digestsize != 16)
  58 +       if (strcmp(ghash->base.cra_name, "ghash") != 0 ||
  59 +           ghash->digestsize != 16)
  60                 goto err_drop_ghash;
  61
  62         crypto_set_skcipher_spawn(&ctx->ctr, aead_crypto_instance(inst));
  63 @@ -669,24 +669,24 @@ static int crypto_gcm_create_common(stru
  64
  65         ctr = crypto_skcipher_spawn_alg(&ctx->ctr);
  66
  67 -       /* We only support 16-byte blocks. */
  68 +       /* The skcipher algorithm must be CTR mode, using 16-byte blocks. */
  69         err = -EINVAL;
  70 -       if (ctr->cra_ablkcipher.ivsize != 16)
  71 +       if (strncmp(ctr->cra_name, "ctr(", 4) != 0 ||
  72 +           ctr->cra_ablkcipher.ivsize != 16 ||
  73 +           ctr->cra_blocksize != 1)
  74                 goto out_put_ctr;
  75
  76 -       /* Not a stream cipher? */
  77 -       if (ctr->cra_blocksize != 1)
  78 +       err = -ENAMETOOLONG;
  79 +       if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
  80 +                    "gcm(%s", ctr->cra_name + 4) >= CRYPTO_MAX_ALG_NAME)
  81                 goto out_put_ctr;
  82
  83 -       err = -ENAMETOOLONG;
  84         if (snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME,
  85                      "gcm_base(%s,%s)", ctr->cra_driver_name,
  86                      ghash_alg->cra_driver_name) >=
  87             CRYPTO_MAX_ALG_NAME)
  88                 goto out_put_ctr;
  89
  90 -       memcpy(inst->alg.base.cra_name, full_name, CRYPTO_MAX_ALG_NAME);
  91 -
  92         inst->alg.base.cra_flags = (ghash->base.cra_flags | ctr->cra_flags) &
  93                                    CRYPTO_ALG_ASYNC;
  94         inst->alg.base.cra_priority = (ghash->base.cra_priority +
  95 @@ -727,7 +727,6 @@ static int crypto_gcm_create(struct cryp
  96  {
  97         const char *cipher_name;
  98         char ctr_name[CRYPTO_MAX_ALG_NAME];
  99 -       char full_name[CRYPTO_MAX_ALG_NAME];
 100
 101         cipher_name = crypto_attr_alg_name(tb[1]);
 102         if (IS_ERR(cipher_name))
 103 @@ -737,12 +736,7 @@ static int crypto_gcm_create(struct cryp
 104             CRYPTO_MAX_ALG_NAME)
 105                 return -ENAMETOOLONG;
 106
 107 -       if (snprintf(full_name, CRYPTO_MAX_ALG_NAME, "gcm(%s)", cipher_name) >=
 108 -           CRYPTO_MAX_ALG_NAME)
 109 -               return -ENAMETOOLONG;
 110 -
 111 -       return crypto_gcm_create_common(tmpl, tb, full_name,
 112 -                                       ctr_name, "ghash");
 113 +       return crypto_gcm_create_common(tmpl, tb, ctr_name, "ghash");
 114  }
 115
 116  static struct crypto_template crypto_gcm_tmpl = {
 117 @@ -756,7 +750,6 @@ static int crypto_gcm_base_create(struct
 118  {
 119         const char *ctr_name;
 120         const char *ghash_name;
 121 -       char full_name[CRYPTO_MAX_ALG_NAME];
 122
 123         ctr_name = crypto_attr_alg_name(tb[1]);
 124         if (IS_ERR(ctr_name))
 125 @@ -766,12 +759,7 @@ static int crypto_gcm_base_create(struct
 126         if (IS_ERR(ghash_name))
 127                 return PTR_ERR(ghash_name);
 128
 129 -       if (snprintf(full_name, CRYPTO_MAX_ALG_NAME, "gcm_base(%s,%s)",
 130 -                    ctr_name, ghash_name) >= CRYPTO_MAX_ALG_NAME)
 131 -               return -ENAMETOOLONG;
 132 -
 133 -       return crypto_gcm_create_common(tmpl, tb, full_name,
 134 -                                       ctr_name, ghash_name);
 135 +       return crypto_gcm_create_common(tmpl, tb, ctr_name, ghash_name);
 136  }
 137
 138  static struct crypto_template crypto_gcm_base_tmpl = {