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| author | Matthew Garrett <mjg59@google.com> | 2018-06-08 14:57:42 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-09-26 08:36:37 +0200 |
| commit | eddbab1384841db30b270bc791ad623ad0cd5a38 (patch) | |
| tree | 45316853ff7c76f3cc9958dc9c865f566e3a9515 | |
| parent | 23bd97eaebc55d5eef9d3cd41e3bd6189a0e9dd6 (diff) | |
| download | linux-stable-eddbab1384841db30b270bc791ad623ad0cd5a38.tar.gz linux-stable-eddbab1384841db30b270bc791ad623ad0cd5a38.tar.bz2 linux-stable-eddbab1384841db30b270bc791ad623ad0cd5a38.zip | |
evm: Don't deadlock if a crypto algorithm is unavailable
[ Upstream commit e2861fa71641c6414831d628a1f4f793b6562580 ]
When EVM attempts to appraise a file signed with a crypto algorithm the
kernel doesn't have support for, it will cause the kernel to trigger a
module load. If the EVM policy includes appraisal of kernel modules this
will in turn call back into EVM - since EVM is holding a lock until the
crypto initialisation is complete, this triggers a deadlock. Add a
CRYPTO_NOLOAD flag and skip module loading if it's set, and add that flag
in the EVM case in order to fail gracefully with an error message
instead of deadlocking.
Signed-off-by: Matthew Garrett <mjg59@google.com>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | crypto/api.c | 2 | ||||
| -rw-r--r-- | include/linux/crypto.h | 5 | ||||
| -rw-r--r-- | security/integrity/evm/evm_crypto.c | 3 |
3 files changed, 8 insertions, 2 deletions
diff --git a/crypto/api.c b/crypto/api.c index bbc147cb5dec..abf53e67e3d8 100644 --- a/crypto/api.c +++ b/crypto/api.c @@ -215,7 +215,7 @@ struct crypto_alg *crypto_larval_lookup(const char *name, u32 type, u32 mask) type &= mask; alg = crypto_alg_lookup(name, type, mask); - if (!alg) { + if (!alg && !(mask & CRYPTO_NOLOAD)) { request_module("crypto-%s", name); if (!((type ^ CRYPTO_ALG_NEED_FALLBACK) & mask & diff --git a/include/linux/crypto.h b/include/linux/crypto.h index 8edb3ba6f640..9de26962338e 100644 --- a/include/linux/crypto.h +++ b/include/linux/crypto.h @@ -109,6 +109,11 @@ #define CRYPTO_ALG_OPTIONAL_KEY 0x00004000 /* + * Don't trigger module loading + */ +#define CRYPTO_NOLOAD 0x00008000 + +/* * Transform masks and values (for crt_flags). */ #define CRYPTO_TFM_NEED_KEY 0x00000001 diff --git a/security/integrity/evm/evm_crypto.c b/security/integrity/evm/evm_crypto.c index bf663915412e..6fcbd8e99baf 100644 --- a/security/integrity/evm/evm_crypto.c +++ b/security/integrity/evm/evm_crypto.c @@ -94,7 +94,8 @@ static struct shash_desc *init_desc(char type) mutex_lock(&mutex); if (*tfm) goto out; - *tfm = crypto_alloc_shash(algo, 0, CRYPTO_ALG_ASYNC); + *tfm = crypto_alloc_shash(algo, 0, + CRYPTO_ALG_ASYNC | CRYPTO_NOLOAD); if (IS_ERR(*tfm)) { rc = PTR_ERR(*tfm); pr_err("Can not allocate %s (reason: %ld)\n", algo, rc); |