[v7,26/28] NET: Add SO_PEERCONTEXT for multiple LSMs
diff mbox series

Message ID 20190807194410.9762-27-casey@schaufler-ca.com
State Superseded
Headers show
Series
  • LSM: Module stacking for AppArmor
Related show

Commit Message

Casey Schaufler Aug. 7, 2019, 7:44 p.m. UTC
The getsockopt SO_PEERSEC provides the LSM based security
information for a single module, but for reasons of backward
compatibility cannot include the information for multiple
modules. A new option SO_PEERCONTEXT is added to report the
security "context" of multiple modules using a "compound" format

	lsm1\0value\0lsm2\0value\0

This is expected to be used by system services, including dbus-daemon.
The exact format of a compound context has been the subject of
considerable debate. This format was suggested by Simon McVittie,
a dbus maintainer with a significant stake in the format being
uasable.

Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
---
 arch/alpha/include/uapi/asm/socket.h  |  1 +
 arch/mips/include/uapi/asm/socket.h   |  1 +
 arch/parisc/include/uapi/asm/socket.h |  1 +
 arch/sparc/include/uapi/asm/socket.h  |  1 +
 include/linux/lsm_hooks.h             |  9 ++-
 include/linux/security.h              | 10 ++-
 include/uapi/asm-generic/socket.h     |  1 +
 net/core/sock.c                       |  7 +-
 security/apparmor/lsm.c               | 20 ++----
 security/security.c                   | 94 ++++++++++++++++++++++++---
 security/selinux/hooks.c              | 20 ++----
 security/smack/smack_lsm.c            | 31 ++++-----
 12 files changed, 134 insertions(+), 62 deletions(-)

Comments

Kees Cook Aug. 8, 2019, 10:21 p.m. UTC | #1
On Wed, Aug 07, 2019 at 12:44:08PM -0700, Casey Schaufler wrote:
> The getsockopt SO_PEERSEC provides the LSM based security
> information for a single module, but for reasons of backward
> compatibility cannot include the information for multiple
> modules. A new option SO_PEERCONTEXT is added to report the
> security "context" of multiple modules using a "compound" format
> 
> 	lsm1\0value\0lsm2\0value\0
> 
> This is expected to be used by system services, including dbus-daemon.
> The exact format of a compound context has been the subject of
> considerable debate. This format was suggested by Simon McVittie,
> a dbus maintainer with a significant stake in the format being
> uasable.
> 
> Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
> ---
> [...]
> diff --git a/security/security.c b/security/security.c
> index 2f4a430a1126..0ea7ee27e331 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -2117,8 +2117,8 @@ int security_setprocattr(const char *lsm, const char *name, void *value,
>  	hlist_for_each_entry(hp, &security_hook_heads.setprocattr, list) {
>  		if (lsm != NULL && strcmp(lsm, hp->lsmid->lsm))
>  			continue;
> -		if (lsm == NULL && *display != LSMBLOB_INVALID &&
> -		    *display != hp->lsmid->slot)
> +		if (lsm == NULL && display != NULL &&
> +		    *display != LSMBLOB_INVALID && *display != hp->lsmid->slot)
>  			continue;
>  		return hp->hook.setprocattr(name, value, size);
>  	}
> @@ -2342,17 +2342,91 @@ int security_sock_rcv_skb(struct sock *sk, struct sk_buff *skb)
>  EXPORT_SYMBOL(security_sock_rcv_skb);
>  
>  int security_socket_getpeersec_stream(struct socket *sock, char __user *optval,
> -				      int __user *optlen, unsigned len)
> +				      int __user *optlen, unsigned len,
> +				      int display)
>  {
> -	int display = lsm_task_display(current);
>  	struct security_hook_list *hp;
> +	char *final = NULL;
> +	char *cp;
> +	char *tp;
> +	int rc = 0;
> +	unsigned finallen = 0;
> +	unsigned llen;
> +	unsigned clen = 0;
> +	unsigned tlen;

Please move the case-specific variables into the case scope, like (and
expand type names):

	case LSMBLOB_COMPOUND: {
		unsigned int clen ...;

> +
> +	switch (display) {
> +	case LSMBLOB_DISPLAY:
> +		rc = -ENOPROTOOPT;
> +		display = lsm_task_display(current);
> +		hlist_for_each_entry(hp,
> +				&security_hook_heads.socket_getpeersec_stream,
> +				list)
> +			if (display == LSMBLOB_INVALID ||
> +			    display == hp->lsmid->slot) {
> +				rc = hp->hook.socket_getpeersec_stream(sock,
> +							&final, &finallen, len);
> +				break;
> +			}
> +		break;
> +	case LSMBLOB_COMPOUND:
> +		/*
> +		 * A compound context, in the form [lsm\0value\0]...
> +		 */
> +		hlist_for_each_entry(hp,
> +				&security_hook_heads.socket_getpeersec_stream,
> +				list) {
> +			rc = hp->hook.socket_getpeersec_stream(sock, &cp, &clen,
> +							       len);

Is passing "len" here useful at all? It's kind of a lie, but nothing
else wouldn't also be a lie. :)

> +			if (rc == -EINVAL || rc == -ENOPROTOOPT) {
> +				rc = 0;
> +				continue;
> +			}
> +			if (rc) {
> +				kfree(final);
> +				return rc;
> +			}
> +			/*
> +			 * Don't propogate trailing nul bytes.

typo: propagate

> +			 */
> +			clen = strnlen(cp, clen) + 1;
> +			llen = strlen(hp->lsmid->lsm) + 1;
> +			tlen = llen + clen;
> +			if (final)
> +				tlen += finallen;

You can drop the "if (final)" since finallen is initialized to 0.

> +			tp = kzalloc(tlen, GFP_KERNEL);

I'm not a huge fan of "c", "l", and "t" prefixes -- can you just make
these a little more self-documenting? cp and clen could be value and
value_len. llen could be lsm_name_len. tp and tlen could be tuple and
tuple_len. (And maybe final and finallen could be compound and
compound_len?)

> +			if (tp == NULL) {
> +				kfree(cp);
> +				kfree(final);
> +				return -ENOMEM;
> +			}
> +			if (final)
> +				memcpy(tp, final, finallen);
> +			memcpy(tp + finallen, hp->lsmid->lsm, llen);
> +			memcpy(tp + finallen + llen, cp, clen);
> +			kfree(cp);
> +			if (final)
> +				kfree(final);

Just kfree(final) is safe here -- kfree(NULL) is valid.

> +			final = tp;
> +			finallen = tlen;
> +		}
> +		if (final == NULL)
> +			return -EINVAL;
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
>  
> -	hlist_for_each_entry(hp, &security_hook_heads.socket_getpeersec_stream,
> -			     list)
> -		if (display == LSMBLOB_INVALID || display == hp->lsmid->slot)
> -			return hp->hook.socket_getpeersec_stream(sock, optval,
> -								 optlen, len);
> -	return -ENOPROTOOPT;
> +	if (finallen > len)
> +		rc = -ERANGE;
> +	else if (copy_to_user(optval, final, finallen))
> +		rc = -EFAULT;
> +
> +	if (put_user(finallen, optlen))
> +		rc = -EFAULT;
> +
> +	kfree(final);
> +	return rc;
>  }

Otherwise, looks good.

Reviewed-by: Kees Cook <keescook@chromium.org>

-Kees

>  
>  int security_socket_getpeersec_dgram(struct socket *sock, struct sk_buff *skb,
> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
> index fcad2e3432d2..5e7d61754798 100644
> --- a/security/selinux/hooks.c
> +++ b/security/selinux/hooks.c
> @@ -4923,10 +4923,8 @@ static int selinux_socket_sock_rcv_skb(struct sock *sk, struct sk_buff *skb)
>  	return err;
>  }
>  
> -static int selinux_socket_getpeersec_stream(struct socket *sock,
> -					    char __user *optval,
> -					    int __user *optlen,
> -					    unsigned int len)
> +static int selinux_socket_getpeersec_stream(struct socket *sock, char **optval,
> +					    int *optlen, unsigned int len)
>  {
>  	int err = 0;
>  	char *scontext;
> @@ -4946,18 +4944,12 @@ static int selinux_socket_getpeersec_stream(struct socket *sock,
>  	if (err)
>  		return err;
>  
> -	if (scontext_len > len) {
> +	if (scontext_len > len)
>  		err = -ERANGE;
> -		goto out_len;
> -	}
> -
> -	if (copy_to_user(optval, scontext, scontext_len))
> -		err = -EFAULT;
> +	else
> +		*optval = scontext;
>  
> -out_len:
> -	if (put_user(scontext_len, optlen))
> -		err = -EFAULT;
> -	kfree(scontext);
> +	*optlen = scontext_len;
>  	return err;
>  }
>  
> diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
> index 7a30b8692b1e..40c75205a914 100644
> --- a/security/smack/smack_lsm.c
> +++ b/security/smack/smack_lsm.c
> @@ -3919,28 +3919,29 @@ static int smack_socket_sock_rcv_skb(struct sock *sk, struct sk_buff *skb)
>   *
>   * returns zero on success, an error code otherwise
>   */
> -static int smack_socket_getpeersec_stream(struct socket *sock,
> -					  char __user *optval,
> -					  int __user *optlen, unsigned len)
> +static int smack_socket_getpeersec_stream(struct socket *sock, char **optval,
> +					  int *optlen, unsigned len)
>  {
> -	struct socket_smack *ssp;
> -	char *rcp = "";
> -	int slen = 1;
> +	struct socket_smack *ssp = smack_sock(sock->sk);
> +	char *rcp;
> +	int slen;
>  	int rc = 0;
>  
> -	ssp = smack_sock(sock->sk);
> -	if (ssp->smk_packet != NULL) {
> -		rcp = ssp->smk_packet->smk_known;
> -		slen = strlen(rcp) + 1;
> +	if (ssp->smk_packet == NULL) {
> +		*optlen = 0;
> +		return -EINVAL;
>  	}
>  
> +	rcp = ssp->smk_packet->smk_known;
> +	slen = strlen(rcp) + 1;
>  	if (slen > len)
>  		rc = -ERANGE;
> -	else if (copy_to_user(optval, rcp, slen) != 0)
> -		rc = -EFAULT;
> -
> -	if (put_user(slen, optlen) != 0)
> -		rc = -EFAULT;
> +	else {
> +		*optval = kstrdup(rcp, GFP_KERNEL);
> +		if (*optval == NULL)
> +			rc = -ENOMEM;
> +	}
> +	*optlen = slen;
>  
>  	return rc;
>  }
> -- 
> 2.20.1
>
Casey Schaufler Aug. 9, 2019, 12:18 a.m. UTC | #2
On 8/8/2019 3:21 PM, Kees Cook wrote:
> On Wed, Aug 07, 2019 at 12:44:08PM -0700, Casey Schaufler wrote:
>> The getsockopt SO_PEERSEC provides the LSM based security
>> information for a single module, but for reasons of backward
>> compatibility cannot include the information for multiple
>> modules. A new option SO_PEERCONTEXT is added to report the
>> security "context" of multiple modules using a "compound" format
>>
>> 	lsm1\0value\0lsm2\0value\0
>>
>> This is expected to be used by system services, including dbus-daemon.
>> The exact format of a compound context has been the subject of
>> considerable debate. This format was suggested by Simon McVittie,
>> a dbus maintainer with a significant stake in the format being
>> uasable.
>>
>> Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
>> ---
>> [...]
>> diff --git a/security/security.c b/security/security.c
>> index 2f4a430a1126..0ea7ee27e331 100644
>> --- a/security/security.c
>> +++ b/security/security.c
>> @@ -2117,8 +2117,8 @@ int security_setprocattr(const char *lsm, const char *name, void *value,
>>  	hlist_for_each_entry(hp, &security_hook_heads.setprocattr, list) {
>>  		if (lsm != NULL && strcmp(lsm, hp->lsmid->lsm))
>>  			continue;
>> -		if (lsm == NULL && *display != LSMBLOB_INVALID &&
>> -		    *display != hp->lsmid->slot)
>> +		if (lsm == NULL && display != NULL &&
>> +		    *display != LSMBLOB_INVALID && *display != hp->lsmid->slot)
>>  			continue;
>>  		return hp->hook.setprocattr(name, value, size);
>>  	}
>> @@ -2342,17 +2342,91 @@ int security_sock_rcv_skb(struct sock *sk, struct sk_buff *skb)
>>  EXPORT_SYMBOL(security_sock_rcv_skb);
>>  
>>  int security_socket_getpeersec_stream(struct socket *sock, char __user *optval,
>> -				      int __user *optlen, unsigned len)
>> +				      int __user *optlen, unsigned len,
>> +				      int display)
>>  {
>> -	int display = lsm_task_display(current);
>>  	struct security_hook_list *hp;
>> +	char *final = NULL;
>> +	char *cp;
>> +	char *tp;
>> +	int rc = 0;
>> +	unsigned finallen = 0;
>> +	unsigned llen;
>> +	unsigned clen = 0;
>> +	unsigned tlen;
> Please move the case-specific variables into the case scope, like (and
> expand type names):
>
> 	case LSMBLOB_COMPOUND: {
> 		unsigned int clen ...;

I've never been a fan of that style. I'll probably make the
special cases into functions.

>
>> +
>> +	switch (display) {
>> +	case LSMBLOB_DISPLAY:
>> +		rc = -ENOPROTOOPT;
>> +		display = lsm_task_display(current);
>> +		hlist_for_each_entry(hp,
>> +				&security_hook_heads.socket_getpeersec_stream,
>> +				list)
>> +			if (display == LSMBLOB_INVALID ||
>> +			    display == hp->lsmid->slot) {
>> +				rc = hp->hook.socket_getpeersec_stream(sock,
>> +							&final, &finallen, len);
>> +				break;
>> +			}
>> +		break;
>> +	case LSMBLOB_COMPOUND:
>> +		/*
>> +		 * A compound context, in the form [lsm\0value\0]...
>> +		 */
>> +		hlist_for_each_entry(hp,
>> +				&security_hook_heads.socket_getpeersec_stream,
>> +				list) {
>> +			rc = hp->hook.socket_getpeersec_stream(sock, &cp, &clen,
>> +							       len);
> Is passing "len" here useful at all? It's kind of a lie, but nothing
> else wouldn't also be a lie. :)

I could be reducing the value of len for each component gathered.
It requires yet another temporary length variable, and exceeding the
len passed has to get checked in here anyway. I may be able to make
this more sensible.

>
>> +			if (rc == -EINVAL || rc == -ENOPROTOOPT) {
>> +				rc = 0;
>> +				continue;
>> +			}
>> +			if (rc) {
>> +				kfree(final);
>> +				return rc;
>> +			}
>> +			/*
>> +			 * Don't propogate trailing nul bytes.
> typo: propagate

Not a typo, a spelling error. I'm real good at spelling errors.

>
>> +			 */
>> +			clen = strnlen(cp, clen) + 1;
>> +			llen = strlen(hp->lsmid->lsm) + 1;
>> +			tlen = llen + clen;
>> +			if (final)
>> +				tlen += finallen;
> You can drop the "if (final)" since finallen is initialized to 0.

Right you are.

>
>> +			tp = kzalloc(tlen, GFP_KERNEL);
> I'm not a huge fan of "c", "l", and "t" prefixes -- can you just make
> these a little more self-documenting? cp and clen could be value and
> value_len. llen could be lsm_name_len. tp and tlen could be tuple and
> tuple_len. (And maybe final and finallen could be compound and
> compound_len?)

You didn't spend much time using TTY33s, did you? Or 80 column punch cards
where the last 8 are reserved for collation numbers, I'd bet. Kids. OK,
I'll see what I can do since I will be fiddling about anyway.

>
>> +			if (tp == NULL) {
>> +				kfree(cp);
>> +				kfree(final);
>> +				return -ENOMEM;
>> +			}
>> +			if (final)
>> +				memcpy(tp, final, finallen);
>> +			memcpy(tp + finallen, hp->lsmid->lsm, llen);
>> +			memcpy(tp + finallen + llen, cp, clen);
>> +			kfree(cp);
>> +			if (final)
>> +				kfree(final);
> Just kfree(final) is safe here -- kfree(NULL) is valid.

Just so. At some point there was more in the if condition.

>
>> +			final = tp;
>> +			finallen = tlen;
>> +		}
>> +		if (final == NULL)
>> +			return -EINVAL;
>> +		break;
>> +	default:
>> +		return -EINVAL;
>> +	}
>>  
>> -	hlist_for_each_entry(hp, &security_hook_heads.socket_getpeersec_stream,
>> -			     list)
>> -		if (display == LSMBLOB_INVALID || display == hp->lsmid->slot)
>> -			return hp->hook.socket_getpeersec_stream(sock, optval,
>> -								 optlen, len);
>> -	return -ENOPROTOOPT;
>> +	if (finallen > len)
>> +		rc = -ERANGE;
>> +	else if (copy_to_user(optval, final, finallen))
>> +		rc = -EFAULT;
>> +
>> +	if (put_user(finallen, optlen))
>> +		rc = -EFAULT;
>> +
>> +	kfree(final);
>> +	return rc;
>>  }
> Otherwise, looks good.
>
> Reviewed-by: Kees Cook <keescook@chromium.org>
>
> -Kees
>
>>  
>>  int security_socket_getpeersec_dgram(struct socket *sock, struct sk_buff *skb,
>> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
>> index fcad2e3432d2..5e7d61754798 100644
>> --- a/security/selinux/hooks.c
>> +++ b/security/selinux/hooks.c
>> @@ -4923,10 +4923,8 @@ static int selinux_socket_sock_rcv_skb(struct sock *sk, struct sk_buff *skb)
>>  	return err;
>>  }
>>  
>> -static int selinux_socket_getpeersec_stream(struct socket *sock,
>> -					    char __user *optval,
>> -					    int __user *optlen,
>> -					    unsigned int len)
>> +static int selinux_socket_getpeersec_stream(struct socket *sock, char **optval,
>> +					    int *optlen, unsigned int len)
>>  {
>>  	int err = 0;
>>  	char *scontext;
>> @@ -4946,18 +4944,12 @@ static int selinux_socket_getpeersec_stream(struct socket *sock,
>>  	if (err)
>>  		return err;
>>  
>> -	if (scontext_len > len) {
>> +	if (scontext_len > len)
>>  		err = -ERANGE;
>> -		goto out_len;
>> -	}
>> -
>> -	if (copy_to_user(optval, scontext, scontext_len))
>> -		err = -EFAULT;
>> +	else
>> +		*optval = scontext;
>>  
>> -out_len:
>> -	if (put_user(scontext_len, optlen))
>> -		err = -EFAULT;
>> -	kfree(scontext);
>> +	*optlen = scontext_len;
>>  	return err;
>>  }
>>  
>> diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
>> index 7a30b8692b1e..40c75205a914 100644
>> --- a/security/smack/smack_lsm.c
>> +++ b/security/smack/smack_lsm.c
>> @@ -3919,28 +3919,29 @@ static int smack_socket_sock_rcv_skb(struct sock *sk, struct sk_buff *skb)
>>   *
>>   * returns zero on success, an error code otherwise
>>   */
>> -static int smack_socket_getpeersec_stream(struct socket *sock,
>> -					  char __user *optval,
>> -					  int __user *optlen, unsigned len)
>> +static int smack_socket_getpeersec_stream(struct socket *sock, char **optval,
>> +					  int *optlen, unsigned len)
>>  {
>> -	struct socket_smack *ssp;
>> -	char *rcp = "";
>> -	int slen = 1;
>> +	struct socket_smack *ssp = smack_sock(sock->sk);
>> +	char *rcp;
>> +	int slen;
>>  	int rc = 0;
>>  
>> -	ssp = smack_sock(sock->sk);
>> -	if (ssp->smk_packet != NULL) {
>> -		rcp = ssp->smk_packet->smk_known;
>> -		slen = strlen(rcp) + 1;
>> +	if (ssp->smk_packet == NULL) {
>> +		*optlen = 0;
>> +		return -EINVAL;
>>  	}
>>  
>> +	rcp = ssp->smk_packet->smk_known;
>> +	slen = strlen(rcp) + 1;
>>  	if (slen > len)
>>  		rc = -ERANGE;
>> -	else if (copy_to_user(optval, rcp, slen) != 0)
>> -		rc = -EFAULT;
>> -
>> -	if (put_user(slen, optlen) != 0)
>> -		rc = -EFAULT;
>> +	else {
>> +		*optval = kstrdup(rcp, GFP_KERNEL);
>> +		if (*optval == NULL)
>> +			rc = -ENOMEM;
>> +	}
>> +	*optlen = slen;
>>  
>>  	return rc;
>>  }
>> -- 
>> 2.20.1
>>

Patch
diff mbox series

diff --git a/arch/alpha/include/uapi/asm/socket.h b/arch/alpha/include/uapi/asm/socket.h
index 976e89b116e5..019e5fa8bcda 100644
--- a/arch/alpha/include/uapi/asm/socket.h
+++ b/arch/alpha/include/uapi/asm/socket.h
@@ -121,6 +121,7 @@ 
 
 #define SO_RCVTIMEO_NEW         66
 #define SO_SNDTIMEO_NEW         67
+#define SO_PEERCONTEXT          68
 
 #if !defined(__KERNEL__)
 
diff --git a/arch/mips/include/uapi/asm/socket.h b/arch/mips/include/uapi/asm/socket.h
index d41765cfbc6e..df8d984d76ed 100644
--- a/arch/mips/include/uapi/asm/socket.h
+++ b/arch/mips/include/uapi/asm/socket.h
@@ -132,6 +132,7 @@ 
 
 #define SO_RCVTIMEO_NEW         66
 #define SO_SNDTIMEO_NEW         67
+#define SO_PEERCONTEXT          68
 
 #if !defined(__KERNEL__)
 
diff --git a/arch/parisc/include/uapi/asm/socket.h b/arch/parisc/include/uapi/asm/socket.h
index 66c5dd245ac7..9ae358309f46 100644
--- a/arch/parisc/include/uapi/asm/socket.h
+++ b/arch/parisc/include/uapi/asm/socket.h
@@ -113,6 +113,7 @@ 
 
 #define SO_RCVTIMEO_NEW         0x4040
 #define SO_SNDTIMEO_NEW         0x4041
+#define SO_PEERCONTEXT          0x4042
 
 #if !defined(__KERNEL__)
 
diff --git a/arch/sparc/include/uapi/asm/socket.h b/arch/sparc/include/uapi/asm/socket.h
index 9265a9eece15..e8a53ef65210 100644
--- a/arch/sparc/include/uapi/asm/socket.h
+++ b/arch/sparc/include/uapi/asm/socket.h
@@ -114,6 +114,7 @@ 
 
 #define SO_RCVTIMEO_NEW          0x0044
 #define SO_SNDTIMEO_NEW          0x0045
+#define SO_PEERCONTEXT           0x0046
 
 #if !defined(__KERNEL__)
 
diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
index 33e5ab4af9f8..b0f788bf82b6 100644
--- a/include/linux/lsm_hooks.h
+++ b/include/linux/lsm_hooks.h
@@ -864,8 +864,8 @@ 
  *	SO_GETPEERSEC.  For tcp sockets this can be meaningful if the
  *	socket is associated with an ipsec SA.
  *	@sock is the local socket.
- *	@optval userspace memory where the security state is to be copied.
- *	@optlen userspace int where the module should copy the actual length
+ *	@optval memory where the security state is to be copied.
+ *	@optlen int where the module should copy the actual length
  *	of the security state.
  *	@len as input is the maximum length to copy to userspace provided
  *	by the caller.
@@ -1697,9 +1697,8 @@  union security_list_options {
 	int (*socket_setsockopt)(struct socket *sock, int level, int optname);
 	int (*socket_shutdown)(struct socket *sock, int how);
 	int (*socket_sock_rcv_skb)(struct sock *sk, struct sk_buff *skb);
-	int (*socket_getpeersec_stream)(struct socket *sock,
-					char __user *optval,
-					int __user *optlen, unsigned len);
+	int (*socket_getpeersec_stream)(struct socket *sock, char **optval,
+					int *optlen, unsigned len);
 	int (*socket_getpeersec_dgram)(struct socket *sock,
 					struct sk_buff *skb, u32 *secid);
 	int (*sk_alloc_security)(struct sock *sk, int family, gfp_t priority);
diff --git a/include/linux/security.h b/include/linux/security.h
index 12f6d5fcbf6a..0665a27a2891 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -130,6 +130,7 @@  struct lsmblob {
 #define LSMBLOB_NOT_NEEDED	-3	/* Slot not requested */
 #define LSMBLOB_DISPLAY		-4	/* Use the "display" slot */
 #define LSMBLOB_FIRST		-5	/* Use the default "display" slot */
+#define LSMBLOB_COMPOUND	-6	/* A compound "display" */
 
 /**
  * lsmblob_init - initialize an lsmblob structure.
@@ -1324,7 +1325,8 @@  int security_socket_setsockopt(struct socket *sock, int level, int optname);
 int security_socket_shutdown(struct socket *sock, int how);
 int security_sock_rcv_skb(struct sock *sk, struct sk_buff *skb);
 int security_socket_getpeersec_stream(struct socket *sock, char __user *optval,
-				      int __user *optlen, unsigned len);
+				      int __user *optlen, unsigned len,
+				      int display);
 int security_socket_getpeersec_dgram(struct socket *sock, struct sk_buff *skb,
 				     struct lsmblob *blob);
 int security_sk_alloc(struct sock *sk, int family, gfp_t priority);
@@ -1458,8 +1460,10 @@  static inline int security_sock_rcv_skb(struct sock *sk,
 	return 0;
 }
 
-static inline int security_socket_getpeersec_stream(struct socket *sock, char __user *optval,
-						    int __user *optlen, unsigned len)
+static inline int security_socket_getpeersec_stream(struct socket *sock,
+						    char __user *optval,
+						    int __user *optlen,
+						    unsigned len, int display)
 {
 	return -ENOPROTOOPT;
 }
diff --git a/include/uapi/asm-generic/socket.h b/include/uapi/asm-generic/socket.h
index 8c1391c89171..b38d080c2802 100644
--- a/include/uapi/asm-generic/socket.h
+++ b/include/uapi/asm-generic/socket.h
@@ -116,6 +116,7 @@ 
 
 #define SO_RCVTIMEO_NEW         66
 #define SO_SNDTIMEO_NEW         67
+#define SO_PEERCONTEXT          68
 
 #if !defined(__KERNEL__)
 
diff --git a/net/core/sock.c b/net/core/sock.c
index 782343bb925b..b0955a34167c 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -1412,7 +1412,12 @@  int sock_getsockopt(struct socket *sock, int level, int optname,
 		break;
 
 	case SO_PEERSEC:
-		return security_socket_getpeersec_stream(sock, optval, optlen, len);
+		return security_socket_getpeersec_stream(sock, optval, optlen,
+							 len, LSMBLOB_DISPLAY);
+
+	case SO_PEERCONTEXT:
+		return security_socket_getpeersec_stream(sock, optval, optlen,
+							 len, LSMBLOB_COMPOUND);
 
 	case SO_MARK:
 		v.val = sk->sk_mark;
diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c
index ec2e39aa9a84..5d25959610f9 100644
--- a/security/apparmor/lsm.c
+++ b/security/apparmor/lsm.c
@@ -1037,10 +1037,8 @@  static struct aa_label *sk_peer_label(struct sock *sk)
  *
  * Note: for tcp only valid if using ipsec or cipso on lan
  */
-static int apparmor_socket_getpeersec_stream(struct socket *sock,
-					     char __user *optval,
-					     int __user *optlen,
-					     unsigned int len)
+static int apparmor_socket_getpeersec_stream(struct socket *sock, char **optval,
+					     int *optlen, unsigned int len)
 {
 	char *name;
 	int slen, error = 0;
@@ -1060,17 +1058,11 @@  static int apparmor_socket_getpeersec_stream(struct socket *sock,
 	if (slen < 0) {
 		error = -ENOMEM;
 	} else {
-		if (slen > len) {
+		if (slen > len)
 			error = -ERANGE;
-		} else if (copy_to_user(optval, name, slen)) {
-			error = -EFAULT;
-			goto out;
-		}
-		if (put_user(slen, optlen))
-			error = -EFAULT;
-out:
-		kfree(name);
-
+		else
+			*optval = name;
+		*optlen = slen;
 	}
 
 done:
diff --git a/security/security.c b/security/security.c
index 2f4a430a1126..0ea7ee27e331 100644
--- a/security/security.c
+++ b/security/security.c
@@ -2117,8 +2117,8 @@  int security_setprocattr(const char *lsm, const char *name, void *value,
 	hlist_for_each_entry(hp, &security_hook_heads.setprocattr, list) {
 		if (lsm != NULL && strcmp(lsm, hp->lsmid->lsm))
 			continue;
-		if (lsm == NULL && *display != LSMBLOB_INVALID &&
-		    *display != hp->lsmid->slot)
+		if (lsm == NULL && display != NULL &&
+		    *display != LSMBLOB_INVALID && *display != hp->lsmid->slot)
 			continue;
 		return hp->hook.setprocattr(name, value, size);
 	}
@@ -2342,17 +2342,91 @@  int security_sock_rcv_skb(struct sock *sk, struct sk_buff *skb)
 EXPORT_SYMBOL(security_sock_rcv_skb);
 
 int security_socket_getpeersec_stream(struct socket *sock, char __user *optval,
-				      int __user *optlen, unsigned len)
+				      int __user *optlen, unsigned len,
+				      int display)
 {
-	int display = lsm_task_display(current);
 	struct security_hook_list *hp;
+	char *final = NULL;
+	char *cp;
+	char *tp;
+	int rc = 0;
+	unsigned finallen = 0;
+	unsigned llen;
+	unsigned clen = 0;
+	unsigned tlen;
+
+	switch (display) {
+	case LSMBLOB_DISPLAY:
+		rc = -ENOPROTOOPT;
+		display = lsm_task_display(current);
+		hlist_for_each_entry(hp,
+				&security_hook_heads.socket_getpeersec_stream,
+				list)
+			if (display == LSMBLOB_INVALID ||
+			    display == hp->lsmid->slot) {
+				rc = hp->hook.socket_getpeersec_stream(sock,
+							&final, &finallen, len);
+				break;
+			}
+		break;
+	case LSMBLOB_COMPOUND:
+		/*
+		 * A compound context, in the form [lsm\0value\0]...
+		 */
+		hlist_for_each_entry(hp,
+				&security_hook_heads.socket_getpeersec_stream,
+				list) {
+			rc = hp->hook.socket_getpeersec_stream(sock, &cp, &clen,
+							       len);
+			if (rc == -EINVAL || rc == -ENOPROTOOPT) {
+				rc = 0;
+				continue;
+			}
+			if (rc) {
+				kfree(final);
+				return rc;
+			}
+			/*
+			 * Don't propogate trailing nul bytes.
+			 */
+			clen = strnlen(cp, clen) + 1;
+			llen = strlen(hp->lsmid->lsm) + 1;
+			tlen = llen + clen;
+			if (final)
+				tlen += finallen;
+			tp = kzalloc(tlen, GFP_KERNEL);
+			if (tp == NULL) {
+				kfree(cp);
+				kfree(final);
+				return -ENOMEM;
+			}
+			if (final)
+				memcpy(tp, final, finallen);
+			memcpy(tp + finallen, hp->lsmid->lsm, llen);
+			memcpy(tp + finallen + llen, cp, clen);
+			kfree(cp);
+			if (final)
+				kfree(final);
+			final = tp;
+			finallen = tlen;
+		}
+		if (final == NULL)
+			return -EINVAL;
+		break;
+	default:
+		return -EINVAL;
+	}
 
-	hlist_for_each_entry(hp, &security_hook_heads.socket_getpeersec_stream,
-			     list)
-		if (display == LSMBLOB_INVALID || display == hp->lsmid->slot)
-			return hp->hook.socket_getpeersec_stream(sock, optval,
-								 optlen, len);
-	return -ENOPROTOOPT;
+	if (finallen > len)
+		rc = -ERANGE;
+	else if (copy_to_user(optval, final, finallen))
+		rc = -EFAULT;
+
+	if (put_user(finallen, optlen))
+		rc = -EFAULT;
+
+	kfree(final);
+	return rc;
 }
 
 int security_socket_getpeersec_dgram(struct socket *sock, struct sk_buff *skb,
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index fcad2e3432d2..5e7d61754798 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -4923,10 +4923,8 @@  static int selinux_socket_sock_rcv_skb(struct sock *sk, struct sk_buff *skb)
 	return err;
 }
 
-static int selinux_socket_getpeersec_stream(struct socket *sock,
-					    char __user *optval,
-					    int __user *optlen,
-					    unsigned int len)
+static int selinux_socket_getpeersec_stream(struct socket *sock, char **optval,
+					    int *optlen, unsigned int len)
 {
 	int err = 0;
 	char *scontext;
@@ -4946,18 +4944,12 @@  static int selinux_socket_getpeersec_stream(struct socket *sock,
 	if (err)
 		return err;
 
-	if (scontext_len > len) {
+	if (scontext_len > len)
 		err = -ERANGE;
-		goto out_len;
-	}
-
-	if (copy_to_user(optval, scontext, scontext_len))
-		err = -EFAULT;
+	else
+		*optval = scontext;
 
-out_len:
-	if (put_user(scontext_len, optlen))
-		err = -EFAULT;
-	kfree(scontext);
+	*optlen = scontext_len;
 	return err;
 }
 
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 7a30b8692b1e..40c75205a914 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -3919,28 +3919,29 @@  static int smack_socket_sock_rcv_skb(struct sock *sk, struct sk_buff *skb)
  *
  * returns zero on success, an error code otherwise
  */
-static int smack_socket_getpeersec_stream(struct socket *sock,
-					  char __user *optval,
-					  int __user *optlen, unsigned len)
+static int smack_socket_getpeersec_stream(struct socket *sock, char **optval,
+					  int *optlen, unsigned len)
 {
-	struct socket_smack *ssp;
-	char *rcp = "";
-	int slen = 1;
+	struct socket_smack *ssp = smack_sock(sock->sk);
+	char *rcp;
+	int slen;
 	int rc = 0;
 
-	ssp = smack_sock(sock->sk);
-	if (ssp->smk_packet != NULL) {
-		rcp = ssp->smk_packet->smk_known;
-		slen = strlen(rcp) + 1;
+	if (ssp->smk_packet == NULL) {
+		*optlen = 0;
+		return -EINVAL;
 	}
 
+	rcp = ssp->smk_packet->smk_known;
+	slen = strlen(rcp) + 1;
 	if (slen > len)
 		rc = -ERANGE;
-	else if (copy_to_user(optval, rcp, slen) != 0)
-		rc = -EFAULT;
-
-	if (put_user(slen, optlen) != 0)
-		rc = -EFAULT;
+	else {
+		*optval = kstrdup(rcp, GFP_KERNEL);
+		if (*optval == NULL)
+			rc = -ENOMEM;
+	}
+	*optlen = slen;
 
 	return rc;
 }