queue-4.19/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  crypto/gcm.c |   34 +++++++++++-----------------------
  40  1 file changed, 11 insertions(+), 23 deletions(-)
  41
  42 --- a/crypto/gcm.c
  43 +++ b/crypto/gcm.c
  44 @@ -597,7 +597,6 @@ static void crypto_gcm_free(struct aead_
  45
  46  static int crypto_gcm_create_common(struct crypto_template *tmpl,
  47                                     struct rtattr **tb,
  48 -                                   const char *full_name,
  49                                     const char *ctr_name,
  50                                     const char *ghash_name)
  51  {
  52 @@ -638,7 +637,8 @@ static int crypto_gcm_create_common(stru
  53                 goto err_free_inst;
  54
  55         err = -EINVAL;
  56 -       if (ghash->digestsize != 16)
  57 +       if (strcmp(ghash->base.cra_name, "ghash") != 0 ||
  58 +           ghash->digestsize != 16)
  59                 goto err_drop_ghash;
  60
  61         crypto_set_skcipher_spawn(&ctx->ctr, aead_crypto_instance(inst));
  62 @@ -650,24 +650,24 @@ static int crypto_gcm_create_common(stru
  63
  64         ctr = crypto_spawn_skcipher_alg(&ctx->ctr);
  65
  66 -       /* We only support 16-byte blocks. */
  67 +       /* The skcipher algorithm must be CTR mode, using 16-byte blocks. */
  68         err = -EINVAL;
  69 -       if (crypto_skcipher_alg_ivsize(ctr) != 16)
  70 +       if (strncmp(ctr->base.cra_name, "ctr(", 4) != 0 ||
  71 +           crypto_skcipher_alg_ivsize(ctr) != 16 ||
  72 +           ctr->base.cra_blocksize != 1)
  73                 goto out_put_ctr;
  74
  75 -       /* Not a stream cipher? */
  76 -       if (ctr->base.cra_blocksize != 1)
  77 +       err = -ENAMETOOLONG;
  78 +       if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
  79 +                    "gcm(%s", ctr->base.cra_name + 4) >= CRYPTO_MAX_ALG_NAME)
  80                 goto out_put_ctr;
  81
  82 -       err = -ENAMETOOLONG;
  83         if (snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME,
  84                      "gcm_base(%s,%s)", ctr->base.cra_driver_name,
  85                      ghash_alg->cra_driver_name) >=
  86             CRYPTO_MAX_ALG_NAME)
  87                 goto out_put_ctr;
  88
  89 -       memcpy(inst->alg.base.cra_name, full_name, CRYPTO_MAX_ALG_NAME);
  90 -
  91         inst->alg.base.cra_flags = (ghash->base.cra_flags |
  92                                     ctr->base.cra_flags) & CRYPTO_ALG_ASYNC;
  93         inst->alg.base.cra_priority = (ghash->base.cra_priority +
  94 @@ -709,7 +709,6 @@ static int crypto_gcm_create(struct cryp
  95  {
  96         const char *cipher_name;
  97         char ctr_name[CRYPTO_MAX_ALG_NAME];
  98 -       char full_name[CRYPTO_MAX_ALG_NAME];
  99
 100         cipher_name = crypto_attr_alg_name(tb[1]);
 101         if (IS_ERR(cipher_name))
 102 @@ -719,12 +718,7 @@ static int crypto_gcm_create(struct cryp
 103             CRYPTO_MAX_ALG_NAME)
 104                 return -ENAMETOOLONG;
 105
 106 -       if (snprintf(full_name, CRYPTO_MAX_ALG_NAME, "gcm(%s)", cipher_name) >=
 107 -           CRYPTO_MAX_ALG_NAME)
 108 -               return -ENAMETOOLONG;
 109 -
 110 -       return crypto_gcm_create_common(tmpl, tb, full_name,
 111 -                                       ctr_name, "ghash");
 112 +       return crypto_gcm_create_common(tmpl, tb, ctr_name, "ghash");
 113  }
 114
 115  static struct crypto_template crypto_gcm_tmpl = {
 116 @@ -738,7 +732,6 @@ static int crypto_gcm_base_create(struct
 117  {
 118         const char *ctr_name;
 119         const char *ghash_name;
 120 -       char full_name[CRYPTO_MAX_ALG_NAME];
 121
 122         ctr_name = crypto_attr_alg_name(tb[1]);
 123         if (IS_ERR(ctr_name))
 124 @@ -748,12 +741,7 @@ static int crypto_gcm_base_create(struct
 125         if (IS_ERR(ghash_name))
 126                 return PTR_ERR(ghash_name);
 127
 128 -       if (snprintf(full_name, CRYPTO_MAX_ALG_NAME, "gcm_base(%s,%s)",
 129 -                    ctr_name, ghash_name) >= CRYPTO_MAX_ALG_NAME)
 130 -               return -ENAMETOOLONG;
 131 -
 132 -       return crypto_gcm_create_common(tmpl, tb, full_name,
 133 -                                       ctr_name, ghash_name);
 134 +       return crypto_gcm_create_common(tmpl, tb, ctr_name, ghash_name);
 135  }
 136
 137  static struct crypto_template crypto_gcm_base_tmpl = {