This series fixes kernel memory disclosures (aka info leaks) and a bug
in the empty string test. In addition to the first version of this
series it also ensures all user supplied strings are nul-terminated
before using them.
Patch 1 is the same as in the first series, patch 2 was changed as
suggested by Herbert, patch 3 is new.
Please apply!
Mathias Krause (3):
crypto: user - fix info leaks in report API
crypto: user - fix empty string test in report API
crypto: user - ensure user supplied strings are nul-terminated
crypto/ablkcipher.c | 12 ++++++------
crypto/aead.c | 9 ++++-----
crypto/ahash.c | 2 +-
crypto/blkcipher.c | 6 +++---
crypto/crypto_user.c | 38 ++++++++++++++++++++++++++------------
crypto/pcompress.c | 3 +--
crypto/rng.c | 2 +-
crypto/shash.c | 3 ++-
8 files changed, 44 insertions(+), 31 deletions(-)
--
1.7.10.4
The current test for empty strings fails because it is testing the
address of a field, not a pointer. So the test will always be true.
Test the first character in the string to not be null instead.
Signed-off-by: Mathias Krause <[email protected]>
Cc: Steffen Klassert <[email protected]>
---
v2: - switched to simple character test, as suggested by Herbert Xu
crypto/crypto_user.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/crypto/crypto_user.c b/crypto/crypto_user.c
index f6d9baf..423a267 100644
--- a/crypto/crypto_user.c
+++ b/crypto/crypto_user.c
@@ -196,7 +196,7 @@ static int crypto_report(struct sk_buff *in_skb, struct nlmsghdr *in_nlh,
struct crypto_dump_info info;
int err;
- if (!p->cru_driver_name)
+ if (!p->cru_driver_name[0])
return -EINVAL;
alg = crypto_alg_match(p, 1);
--
1.7.10.4
Three errors resulting in kernel memory disclosure:
1/ The structures used for the netlink based crypto algorithm report API
are located on the stack. As snprintf() does not fill the remainder of
the buffer with null bytes, those stack bytes will be disclosed to users
of the API. Switch to strncpy() to fix this.
2/ crypto_report_one() does not initialize all field of struct
crypto_user_alg. Fix this to fix the heap info leak.
3/ For the module name we should copy only as many bytes as
module_name() returns -- not as much as the destination buffer could
hold. But the current code does not and therefore copies random data
from behind the end of the module name, as the module name is always
shorter than CRYPTO_MAX_ALG_NAME.
Also switch to use strncpy() to copy the algorithm's name and
driver_name. They are strings, after all.
Signed-off-by: Mathias Krause <[email protected]>
Cc: Steffen Klassert <[email protected]>
---
crypto/ablkcipher.c | 12 ++++++------
crypto/aead.c | 9 ++++-----
crypto/ahash.c | 2 +-
crypto/blkcipher.c | 6 +++---
crypto/crypto_user.c | 22 +++++++++++-----------
crypto/pcompress.c | 3 +--
crypto/rng.c | 2 +-
crypto/shash.c | 3 ++-
8 files changed, 29 insertions(+), 30 deletions(-)
diff --git a/crypto/ablkcipher.c b/crypto/ablkcipher.c
index 533de95..7d4a8d2 100644
--- a/crypto/ablkcipher.c
+++ b/crypto/ablkcipher.c
@@ -388,9 +388,9 @@ static int crypto_ablkcipher_report(struct sk_buff *skb, struct crypto_alg *alg)
{
struct crypto_report_blkcipher rblkcipher;
- snprintf(rblkcipher.type, CRYPTO_MAX_ALG_NAME, "%s", "ablkcipher");
- snprintf(rblkcipher.geniv, CRYPTO_MAX_ALG_NAME, "%s",
- alg->cra_ablkcipher.geniv ?: "<default>");
+ strncpy(rblkcipher.type, "ablkcipher", sizeof(rblkcipher.type));
+ strncpy(rblkcipher.geniv, alg->cra_ablkcipher.geniv ?: "<default>",
+ sizeof(rblkcipher.geniv));
rblkcipher.blocksize = alg->cra_blocksize;
rblkcipher.min_keysize = alg->cra_ablkcipher.min_keysize;
@@ -469,9 +469,9 @@ static int crypto_givcipher_report(struct sk_buff *skb, struct crypto_alg *alg)
{
struct crypto_report_blkcipher rblkcipher;
- snprintf(rblkcipher.type, CRYPTO_MAX_ALG_NAME, "%s", "givcipher");
- snprintf(rblkcipher.geniv, CRYPTO_MAX_ALG_NAME, "%s",
- alg->cra_ablkcipher.geniv ?: "<built-in>");
+ strncpy(rblkcipher.type, "givcipher", sizeof(rblkcipher.type));
+ strncpy(rblkcipher.geniv, alg->cra_ablkcipher.geniv ?: "<built-in>",
+ sizeof(rblkcipher.geniv));
rblkcipher.blocksize = alg->cra_blocksize;
rblkcipher.min_keysize = alg->cra_ablkcipher.min_keysize;
diff --git a/crypto/aead.c b/crypto/aead.c
index 0b8121e..27bc487 100644
--- a/crypto/aead.c
+++ b/crypto/aead.c
@@ -117,9 +117,8 @@ static int crypto_aead_report(struct sk_buff *skb, struct crypto_alg *alg)
struct crypto_report_aead raead;
struct aead_alg *aead = &alg->cra_aead;
- snprintf(raead.type, CRYPTO_MAX_ALG_NAME, "%s", "aead");
- snprintf(raead.geniv, CRYPTO_MAX_ALG_NAME, "%s",
- aead->geniv ?: "<built-in>");
+ strncpy(raead.type, "aead", sizeof(raead.type));
+ strncpy(raead.geniv, aead->geniv ?: "<built-in>", sizeof(raead.geniv));
raead.blocksize = alg->cra_blocksize;
raead.maxauthsize = aead->maxauthsize;
@@ -203,8 +202,8 @@ static int crypto_nivaead_report(struct sk_buff *skb, struct crypto_alg *alg)
struct crypto_report_aead raead;
struct aead_alg *aead = &alg->cra_aead;
- snprintf(raead.type, CRYPTO_MAX_ALG_NAME, "%s", "nivaead");
- snprintf(raead.geniv, CRYPTO_MAX_ALG_NAME, "%s", aead->geniv);
+ strncpy(raead.type, "nivaead", sizeof(raead.type));
+ strncpy(raead.geniv, aead->geniv, sizeof(raead.geniv));
raead.blocksize = alg->cra_blocksize;
raead.maxauthsize = aead->maxauthsize;
diff --git a/crypto/ahash.c b/crypto/ahash.c
index 3887856..793a27f 100644
--- a/crypto/ahash.c
+++ b/crypto/ahash.c
@@ -404,7 +404,7 @@ static int crypto_ahash_report(struct sk_buff *skb, struct crypto_alg *alg)
{
struct crypto_report_hash rhash;
- snprintf(rhash.type, CRYPTO_MAX_ALG_NAME, "%s", "ahash");
+ strncpy(rhash.type, "ahash", sizeof(rhash.type));
rhash.blocksize = alg->cra_blocksize;
rhash.digestsize = __crypto_hash_alg_common(alg)->digestsize;
diff --git a/crypto/blkcipher.c b/crypto/blkcipher.c
index a8d85a1..c44e014 100644
--- a/crypto/blkcipher.c
+++ b/crypto/blkcipher.c
@@ -499,9 +499,9 @@ static int crypto_blkcipher_report(struct sk_buff *skb, struct crypto_alg *alg)
{
struct crypto_report_blkcipher rblkcipher;
- snprintf(rblkcipher.type, CRYPTO_MAX_ALG_NAME, "%s", "blkcipher");
- snprintf(rblkcipher.geniv, CRYPTO_MAX_ALG_NAME, "%s",
- alg->cra_blkcipher.geniv ?: "<default>");
+ strncpy(rblkcipher.type, "blkcipher", sizeof(rblkcipher.type));
+ strncpy(rblkcipher.geniv, alg->cra_blkcipher.geniv ?: "<default>",
+ sizeof(rblkcipher.geniv));
rblkcipher.blocksize = alg->cra_blocksize;
rblkcipher.min_keysize = alg->cra_blkcipher.min_keysize;
diff --git a/crypto/crypto_user.c b/crypto/crypto_user.c
index 35d700a..f6d9baf 100644
--- a/crypto/crypto_user.c
+++ b/crypto/crypto_user.c
@@ -75,7 +75,7 @@ static int crypto_report_cipher(struct sk_buff *skb, struct crypto_alg *alg)
{
struct crypto_report_cipher rcipher;
- snprintf(rcipher.type, CRYPTO_MAX_ALG_NAME, "%s", "cipher");
+ strncpy(rcipher.type, "cipher", sizeof(rcipher.type));
rcipher.blocksize = alg->cra_blocksize;
rcipher.min_keysize = alg->cra_cipher.cia_min_keysize;
@@ -94,8 +94,7 @@ static int crypto_report_comp(struct sk_buff *skb, struct crypto_alg *alg)
{
struct crypto_report_comp rcomp;
- snprintf(rcomp.type, CRYPTO_MAX_ALG_NAME, "%s", "compression");
-
+ strncpy(rcomp.type, "compression", sizeof(rcomp.type));
if (nla_put(skb, CRYPTOCFGA_REPORT_COMPRESS,
sizeof(struct crypto_report_comp), &rcomp))
goto nla_put_failure;
@@ -108,12 +107,14 @@ nla_put_failure:
static int crypto_report_one(struct crypto_alg *alg,
struct crypto_user_alg *ualg, struct sk_buff *skb)
{
- memcpy(&ualg->cru_name, &alg->cra_name, sizeof(ualg->cru_name));
- memcpy(&ualg->cru_driver_name, &alg->cra_driver_name,
- sizeof(ualg->cru_driver_name));
- memcpy(&ualg->cru_module_name, module_name(alg->cra_module),
- CRYPTO_MAX_ALG_NAME);
-
+ strncpy(ualg->cru_name, alg->cra_name, sizeof(ualg->cru_name));
+ strncpy(ualg->cru_driver_name, alg->cra_driver_name,
+ sizeof(ualg->cru_driver_name));
+ strncpy(ualg->cru_module_name, module_name(alg->cra_module),
+ sizeof(ualg->cru_module_name));
+
+ ualg->cru_type = 0;
+ ualg->cru_mask = 0;
ualg->cru_flags = alg->cra_flags;
ualg->cru_refcnt = atomic_read(&alg->cra_refcnt);
@@ -122,8 +123,7 @@ static int crypto_report_one(struct crypto_alg *alg,
if (alg->cra_flags & CRYPTO_ALG_LARVAL) {
struct crypto_report_larval rl;
- snprintf(rl.type, CRYPTO_MAX_ALG_NAME, "%s", "larval");
-
+ strncpy(rl.type, "larval", sizeof(rl.type));
if (nla_put(skb, CRYPTOCFGA_REPORT_LARVAL,
sizeof(struct crypto_report_larval), &rl))
goto nla_put_failure;
diff --git a/crypto/pcompress.c b/crypto/pcompress.c
index 04e083f..7140fe7 100644
--- a/crypto/pcompress.c
+++ b/crypto/pcompress.c
@@ -53,8 +53,7 @@ static int crypto_pcomp_report(struct sk_buff *skb, struct crypto_alg *alg)
{
struct crypto_report_comp rpcomp;
- snprintf(rpcomp.type, CRYPTO_MAX_ALG_NAME, "%s", "pcomp");
-
+ strncpy(rpcomp.type, "pcomp", sizeof(rpcomp.type));
if (nla_put(skb, CRYPTOCFGA_REPORT_COMPRESS,
sizeof(struct crypto_report_comp), &rpcomp))
goto nla_put_failure;
diff --git a/crypto/rng.c b/crypto/rng.c
index f3b7894..e0a25c2 100644
--- a/crypto/rng.c
+++ b/crypto/rng.c
@@ -65,7 +65,7 @@ static int crypto_rng_report(struct sk_buff *skb, struct crypto_alg *alg)
{
struct crypto_report_rng rrng;
- snprintf(rrng.type, CRYPTO_MAX_ALG_NAME, "%s", "rng");
+ strncpy(rrng.type, "rng", sizeof(rrng.type));
rrng.seedsize = alg->cra_rng.seedsize;
diff --git a/crypto/shash.c b/crypto/shash.c
index f426330f..929058a 100644
--- a/crypto/shash.c
+++ b/crypto/shash.c
@@ -530,7 +530,8 @@ static int crypto_shash_report(struct sk_buff *skb, struct crypto_alg *alg)
struct crypto_report_hash rhash;
struct shash_alg *salg = __crypto_shash_alg(alg);
- snprintf(rhash.type, CRYPTO_MAX_ALG_NAME, "%s", "shash");
+ strncpy(rhash.type, "shash", sizeof(rhash.type));
+
rhash.blocksize = alg->cra_blocksize;
rhash.digestsize = salg->digestsize;
--
1.7.10.4
To avoid misuse, ensure cru_name and cru_driver_name are always
nul-terminated strings.
Signed-off-by: Mathias Krause <[email protected]>
---
crypto/crypto_user.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/crypto/crypto_user.c b/crypto/crypto_user.c
index 423a267..dfd511f 100644
--- a/crypto/crypto_user.c
+++ b/crypto/crypto_user.c
@@ -30,6 +30,8 @@
#include "internal.h"
+#define null_terminated(x) (strnlen(x, sizeof(x)) < sizeof(x))
+
static DEFINE_MUTEX(crypto_cfg_mutex);
/* The crypto netlink socket */
@@ -196,6 +198,9 @@ static int crypto_report(struct sk_buff *in_skb, struct nlmsghdr *in_nlh,
struct crypto_dump_info info;
int err;
+ if (!null_terminated(p->cru_name) || !null_terminated(p->cru_driver_name))
+ return -EINVAL;
+
if (!p->cru_driver_name[0])
return -EINVAL;
@@ -260,6 +265,9 @@ static int crypto_update_alg(struct sk_buff *skb, struct nlmsghdr *nlh,
struct nlattr *priority = attrs[CRYPTOCFGA_PRIORITY_VAL];
LIST_HEAD(list);
+ if (!null_terminated(p->cru_name) || !null_terminated(p->cru_driver_name))
+ return -EINVAL;
+
if (priority && !strlen(p->cru_driver_name))
return -EINVAL;
@@ -287,6 +295,9 @@ static int crypto_del_alg(struct sk_buff *skb, struct nlmsghdr *nlh,
struct crypto_alg *alg;
struct crypto_user_alg *p = nlmsg_data(nlh);
+ if (!null_terminated(p->cru_name) || !null_terminated(p->cru_driver_name))
+ return -EINVAL;
+
alg = crypto_alg_match(p, 1);
if (!alg)
return -ENOENT;
@@ -368,6 +379,9 @@ static int crypto_add_alg(struct sk_buff *skb, struct nlmsghdr *nlh,
struct crypto_user_alg *p = nlmsg_data(nlh);
struct nlattr *priority = attrs[CRYPTOCFGA_PRIORITY_VAL];
+ if (!null_terminated(p->cru_name) || !null_terminated(p->cru_driver_name))
+ return -EINVAL;
+
if (strlen(p->cru_driver_name))
exact = 1;
--
1.7.10.4
On Tue, Feb 05, 2013 at 06:19:12PM +0100, Mathias Krause wrote:
> This series fixes kernel memory disclosures (aka info leaks) and a bug
> in the empty string test. In addition to the first version of this
> series it also ensures all user supplied strings are nul-terminated
> before using them.
>
> Patch 1 is the same as in the first series, patch 2 was changed as
> suggested by Herbert, patch 3 is new.
>
> Please apply!
All applied to crypto. Thanks!
--
Email: Herbert Xu <[email protected]>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt