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crypto: user - fix info leaks in report API
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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]>
Signed-off-by: Herbert Xu <[email protected]>
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@minipli @herbertx
minipli authored and herbertx committed Feb 19, 2013
1 parent 7eb9c5d commit 9a5467b
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Showing 8 changed files with 29 additions and 30 deletions.
12 changes: 6 additions & 6 deletions crypto/ablkcipher.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand Down Expand Up @@ -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;
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9 changes: 4 additions & 5 deletions crypto/aead.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand Down Expand Up @@ -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;
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2 changes: 1 addition & 1 deletion crypto/ahash.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand Down
6 changes: 3 additions & 3 deletions crypto/blkcipher.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand Down
22 changes: 11 additions & 11 deletions crypto/crypto_user.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand All @@ -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;
Expand All @@ -108,12 +107,14 @@ static int crypto_report_comp(struct sk_buff *skb, struct crypto_alg *alg)
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);

Expand All @@ -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;
Expand Down
3 changes: 1 addition & 2 deletions crypto/pcompress.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand Down
2 changes: 1 addition & 1 deletion crypto/rng.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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;

Expand Down
3 changes: 2 additions & 1 deletion crypto/shash.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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;

Expand Down

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