Why does CRYPTO_USER require CAP_NET_ADMIN?

PATCH In review Matthias-Christian Ott 3 participants 7 messages Apr 5, 2014 – May 8, 2014 Crypto API

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Matthias-Christian Ott

author

2014-04-05 15:07 UTC #0 lore raw

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

Matthias-Christian Ott

author

2014-04-24 22:50 UTC #1 lore raw

PATCH 1/1 crypto: user - Allow CRYPTO_MSG_GETALG without CAP_NET_ADMIN

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 <[email protected]>

---
 crypto/crypto_user.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

crypto/crypto_user.c +9 -3

index 1512e41..aa906b8 100644
@@ -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;

Marek Vasut

2014-04-28 21:52 UTC #2 lore raw

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

Quoted 10 lines · Matthias-Christian Ott

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 <[email protected]>
---
 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

Matthias-Christian Ott

author

2014-04-30 19:22 UTC #3 lore raw

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

Quoted 7 lines · Marek Vasut

Quoted 6 lines · Matthias-Christian Ott
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.

Quoted 7 lines

Quoted 4 lines
Signed-off-by Matthias-Christian Ott <[email protected]>
---
 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

Marek Vasut

2014-05-01 14:27 UTC #4 lore raw

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

Quoted 14 lines · Matthias-Christian Ott

Quoted 13 lines · Marek Vasut
Quoted 11 lines · Matthias-Christian Ott
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 <[email protected]>
---
 crypto/crypto_user.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

Quoted 7 lines

Quoted 2 lines
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

Matthias-Christian Ott

author

2014-05-04 01:43 UTC #5 lore raw

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

Quoted 18 lines · Marek Vasut

Quoted 17 lines · Matthias-Christian Ott
Quoted 15 lines · Marek Vasut
Quoted 11 lines · Matthias-Christian Ott
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 <[email protected]>
---
 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?

Quoted 7 lines

Quoted 4 lines
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.

Quoted 1 line

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

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

Herbert Xu

maintainer

2014-05-08 14:01 UTC #6 lore raw

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

In reply to Matthias-Christian Ott

Quoted 8 lines · Matthias-Christian Ott

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 <[email protected]>

Patch applied.

Signature · 3 lines

Email: Herbert Xu <[email protected]>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt