Why does CRYPTO_USER require CAP_NET_ADMIN?

Why does CRYPTO_USER require CAP_NET_ADMIN?

[Matthias-Christian Ott]

If I'm not mistaken, CRYPTO_USER requires CAP_NET_ADMIN for all
requests. Is there any reason for this requirement for read-only requests?

I think read-only requests should not require CAP_NET_ADMIN. An example
where this is important is important is AF_ALG. I'm working on AF_ALG
support for GnuTLS, encryption and decryption via AF_ALG does not
require special capabilities. However, retrieving the cipher priority to
determine whether the cipher is hardware accelerated does require
CAP_NET_ADMIN.

Regards,
Matthias-Christian

[PATCH] crypto: user - Allow CRYPTO_MSG_GETALG without CAP_NET_ADMIN

[Matthias-Christian Ott]

[-- Attachment #1: Type: text/plain, Size: 485 bytes --]


CRYPTO_USER requires CAP_NET_ADMIN for all operations. Most information
provided by CRYPTO_MSG_GETALG is also accessible through /proc/modules
and AF_ALG. CRYPTO_MSG_GETALG should not require CAP_NET_ADMIN so that
processes without CAP_NET_ADMIN can use CRYPTO_MSG_GETALG to get cipher
details, such as cipher priorities, for AF_ALG.

Signed-off-by: Matthias-Christian Ott <ott@mirix.org>
---
 crypto/crypto_user.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)



[-- Attachment #2: 0001-crypto-user-Allow-CRYPTO_MSG_GETALG-without-CAP_NET_.patch --]
[-- Type: text/x-patch, Size: 1456 bytes --]

diff --git a/crypto/crypto_user.c b/crypto/crypto_user.c
index 1512e41..aa906b8 100644
--- a/crypto/crypto_user.c
+++ b/crypto/crypto_user.c
@@ -265,6 +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 (!capable(CAP_NET_ADMIN))
+		return -EPERM;
+
 	if (!null_terminated(p->cru_name) || !null_terminated(p->cru_driver_name))
 		return -EINVAL;
 
@@ -295,6 +298,9 @@ 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 (!capable(CAP_NET_ADMIN))
+		return -EPERM;
+
 	if (!null_terminated(p->cru_name) || !null_terminated(p->cru_driver_name))
 		return -EINVAL;
 
@@ -379,6 +385,9 @@ 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 (!capable(CAP_NET_ADMIN))
+		return -EPERM;
+
 	if (!null_terminated(p->cru_name) || !null_terminated(p->cru_driver_name))
 		return -EINVAL;
 
@@ -466,9 +475,6 @@ static int crypto_user_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
 	type -= CRYPTO_MSG_BASE;
 	link = &crypto_dispatch[type];
 
-	if (!capable(CAP_NET_ADMIN))
-		return -EPERM;
-
 	if ((type == (CRYPTO_MSG_GETALG - CRYPTO_MSG_BASE) &&
 	    (nlh->nlmsg_flags & NLM_F_DUMP))) {
 		struct crypto_alg *alg;

Re: [PATCH] crypto: user - Allow CRYPTO_MSG_GETALG without CAP_NET_ADMIN

[Marek Vasut]

On Friday, April 25, 2014 at 12:51:06 AM, Matthias-Christian Ott wrote:
> CRYPTO_USER requires CAP_NET_ADMIN for all operations. Most information
> provided by CRYPTO_MSG_GETALG is also accessible through /proc/modules
> and AF_ALG. CRYPTO_MSG_GETALG should not require CAP_NET_ADMIN so that
> processes without CAP_NET_ADMIN can use CRYPTO_MSG_GETALG to get cipher
> details, such as cipher priorities, for AF_ALG.
> 
> Signed-off-by: Matthias-Christian Ott <ott@mirix.org>
> ---
>  crypto/crypto_user.c | 12 +++++++++---
>  1 file changed, 9 insertions(+), 3 deletions(-)

Can you please submit the patch using git send-email so we can properly review 
it?

Thank you !

Best regards,
Marek Vasut

Re: [PATCH] crypto: user - Allow CRYPTO_MSG_GETALG without CAP_NET_ADMIN

[Matthias-Christian Ott]

On 04/28/14 23:37, Marek Vasut wrote:
> On Friday, April 25, 2014 at 12:51:06 AM, Matthias-Christian Ott wrote:
>> CRYPTO_USER requires CAP_NET_ADMIN for all operations. Most information
>> provided by CRYPTO_MSG_GETALG is also accessible through /proc/modules
>> and AF_ALG. CRYPTO_MSG_GETALG should not require CAP_NET_ADMIN so that
>> processes without CAP_NET_ADMIN can use CRYPTO_MSG_GETALG to get cipher
>> details, such as cipher priorities, for AF_ALG.
>>
>> Signed-off-by: Matthias-Christian Ott <ott@mirix.org>
>> ---
>>  crypto/crypto_user.c | 12 +++++++++---
>>  1 file changed, 9 insertions(+), 3 deletions(-)
> 
> Can you please submit the patch using git send-email so we can properly review 
> it?

git-send-email or more specifically Net::SMTP only works with IPv4. The
SMTP server I use for submission only listens IPv6 addresses. Moreover,
TLS seems broken. I patched Net::SMTP to use IO::Socket::INET6 but gave
up because of the TLS issues and used git format-patch and git imap-send.

Regards,
Matthias-Christian

Re: [PATCH] crypto: user - Allow CRYPTO_MSG_GETALG without CAP_NET_ADMIN

[Marek Vasut]

On Wednesday, April 30, 2014 at 09:23:40 PM, Matthias-Christian Ott wrote:
> On 04/28/14 23:37, Marek Vasut wrote:
> > On Friday, April 25, 2014 at 12:51:06 AM, Matthias-Christian Ott wrote:
> >> CRYPTO_USER requires CAP_NET_ADMIN for all operations. Most information
> >> provided by CRYPTO_MSG_GETALG is also accessible through /proc/modules
> >> and AF_ALG. CRYPTO_MSG_GETALG should not require CAP_NET_ADMIN so that
> >> processes without CAP_NET_ADMIN can use CRYPTO_MSG_GETALG to get cipher
> >> details, such as cipher priorities, for AF_ALG.
> >> 
> >> Signed-off-by: Matthias-Christian Ott <ott@mirix.org>
> >> ---
> >> 
> >>  crypto/crypto_user.c | 12 +++++++++---
> >>  1 file changed, 9 insertions(+), 3 deletions(-)
> > 
> > Can you please submit the patch using git send-email so we can properly
> > review it?
> 
> git-send-email or more specifically Net::SMTP only works with IPv4. The
> SMTP server I use for submission only listens IPv6 addresses. Moreover,
> TLS seems broken. I patched Net::SMTP to use IO::Socket::INET6 but gave
> up because of the TLS issues and used git format-patch and git imap-send.

You can always set up a separate mailserver or use one of the many free-to-use 
mailservers to follow the agreed-upon submission process, right?

Of course, patches for Net::SMTP are welcome.

Best regards,
Marek Vasut

Re: [PATCH] crypto: user - Allow CRYPTO_MSG_GETALG without CAP_NET_ADMIN

[Matthias-Christian Ott]

On 05/01/14 12:53, Marek Vasut wrote:
> On Wednesday, April 30, 2014 at 09:23:40 PM, Matthias-Christian Ott wrote:
>> On 04/28/14 23:37, Marek Vasut wrote:
>>> On Friday, April 25, 2014 at 12:51:06 AM, Matthias-Christian Ott wrote:
>>>> CRYPTO_USER requires CAP_NET_ADMIN for all operations. Most information
>>>> provided by CRYPTO_MSG_GETALG is also accessible through /proc/modules
>>>> and AF_ALG. CRYPTO_MSG_GETALG should not require CAP_NET_ADMIN so that
>>>> processes without CAP_NET_ADMIN can use CRYPTO_MSG_GETALG to get cipher
>>>> details, such as cipher priorities, for AF_ALG.
>>>>
>>>> Signed-off-by: Matthias-Christian Ott <ott@mirix.org>
>>>> ---
>>>>
>>>>  crypto/crypto_user.c | 12 +++++++++---
>>>>  1 file changed, 9 insertions(+), 3 deletions(-)
>>>
>>> Can you please submit the patch using git send-email so we can properly
>>> review it?
>>
>> git-send-email or more specifically Net::SMTP only works with IPv4. The
>> SMTP server I use for submission only listens IPv6 addresses. Moreover,
>> TLS seems broken. I patched Net::SMTP to use IO::Socket::INET6 but gave
>> up because of the TLS issues and used git format-patch and git imap-send.
> 
> You can always set up a separate mailserver or use one of the many free-to-use 
> mailservers to follow the agreed-upon submission process, right?

I don't comment on this statement to keep this discussion focused (send
me a private email if you want to discuss it).

I did try to submit the email directly (with SPF disabled) from git
send-email to vger.kernel.org but vger.kernel.org uses greylisting, so I
can't help you with that.

Can you simply copy the file that was attached on the first email I
sent, save it to the filesystem and simply commit it in git? You would
have to do this anyway if I filed a bug in the Kernel Bug Tracker. So
there is an “agreed-upon submission process” to commit a file.

> Of course, patches for Net::SMTP are welcome.

I reported the bug and someone who actually knows Perl is working on it.

Re: [PATCH] crypto: user - Allow CRYPTO_MSG_GETALG without CAP_NET_ADMIN

[Herbert Xu]

On Thu, Apr 24, 2014 at 10:51:06PM +0000, Matthias-Christian Ott wrote:
> 
> CRYPTO_USER requires CAP_NET_ADMIN for all operations. Most information
> provided by CRYPTO_MSG_GETALG is also accessible through /proc/modules
> and AF_ALG. CRYPTO_MSG_GETALG should not require CAP_NET_ADMIN so that
> processes without CAP_NET_ADMIN can use CRYPTO_MSG_GETALG to get cipher
> details, such as cipher priorities, for AF_ALG.
> 
> Signed-off-by: Matthias-Christian Ott <ott@mirix.org>

Patch applied.
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt