crypto: api - Fix module load deadlock with fallback algorithms

With the mandatory algorithm testing at registration, we have
now created a deadlock with algorithms requiring fallbacks.
This can happen if the module containing the algorithm requiring
fallback is loaded first, without the fallback module being loaded
first.  The system will then try to test the new algorithm, find
that it needs to load a fallback, and then try to load that.

As both algorithms share the same module alias, it can attempt
to load the original algorithm again and block indefinitely.

As algorithms requiring fallbacks are a special case, we can fix
this by giving them a different module alias than the rest.  Then
it's just a matter of using the right aliases according to what
algorithms we're trying to find.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/arch/s390/crypto/aes_s390.c b/arch/s390/crypto/aes_s390.c
index c42cd898f68bfdece3e98706e44ab048abe61038..6118890c946d89244e587cdc880726a1d7893073 100644 (file)
--- a/arch/s390/crypto/aes_s390.c
+++ b/arch/s390/crypto/aes_s390.c
@@ -556,7 +556,7 @@ static void __exit aes_s390_fini(void)
 module_init(aes_s390_init);
 module_exit(aes_s390_fini);
 
-MODULE_ALIAS("aes");
+MODULE_ALIAS("aes-all");
 
 MODULE_DESCRIPTION("Rijndael (AES) Cipher Algorithm");
 MODULE_LICENSE("GPL");

diff --git a/crypto/api.c b/crypto/api.c
index efe77df6863f4378f4f0da414591f940870b76ea..38a2bc02a98c7f6648f7a7a3388c6182b88c07f9 100644 (file)
--- a/crypto/api.c
+++ b/crypto/api.c
@@ -215,8 +215,19 @@ struct crypto_alg *crypto_larval_lookup(const char *name, u32 type, u32 mask)
        mask &= ~(CRYPTO_ALG_LARVAL | CRYPTO_ALG_DEAD);
        type &= mask;
 
-       alg = try_then_request_module(crypto_alg_lookup(name, type, mask),
-                                     name);
+       alg = crypto_alg_lookup(name, type, mask);
+       if (!alg) {
+               char tmp[CRYPTO_MAX_ALG_NAME];
+
+               request_module(name);
+
+               if (!((type ^ CRYPTO_ALG_NEED_FALLBACK) & mask) &&
+                   snprintf(tmp, sizeof(tmp), "%s-all", name) < sizeof(tmp))
+                       request_module(tmp);
+
+               alg = crypto_alg_lookup(name, type, mask);
+       }
+
        if (alg)
                return crypto_is_larval(alg) ? crypto_larval_wait(alg) : alg;
 

diff --git a/drivers/crypto/padlock-aes.c b/drivers/crypto/padlock-aes.c
index 856b3cc2558387b7b239923c37c54f9d47b250ff..3f0fdd18255db9febb61836d44b3d7382385140d 100644 (file)
--- a/drivers/crypto/padlock-aes.c
+++ b/drivers/crypto/padlock-aes.c
@@ -489,4 +489,4 @@ MODULE_DESCRIPTION("VIA PadLock AES algorithm support");
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Michal Ludvig");
 
-MODULE_ALIAS("aes");
+MODULE_ALIAS("aes-all");

diff --git a/drivers/crypto/padlock-sha.c b/drivers/crypto/padlock-sha.c
index a7fbadebf62330864734e5302be660d2f39ab51a..a2c8e8514b6340ac85915f158d7780491ce8b4a8 100644 (file)
--- a/drivers/crypto/padlock-sha.c
+++ b/drivers/crypto/padlock-sha.c
@@ -304,7 +304,7 @@ MODULE_DESCRIPTION("VIA PadLock SHA1/SHA256 algorithms support.");
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Michal Ludvig");
 
-MODULE_ALIAS("sha1");
-MODULE_ALIAS("sha256");
+MODULE_ALIAS("sha1-all");
+MODULE_ALIAS("sha256-all");
 MODULE_ALIAS("sha1-padlock");
 MODULE_ALIAS("sha256-padlock");