[v7,27/28] LSM: Add /proc attr entry for full LSM context
diff mbox series

Message ID 20190807194410.9762-28-casey@schaufler-ca.com
State New
Headers show
Series
  • LSM: Module stacking for AppArmor
Related show

Commit Message

Casey Schaufler Aug. 7, 2019, 7:44 p.m. UTC
Add an entry /proc/.../attr/context which displays the full
process security "context" in compound format:'
	lsm1\0value\0lsm2\0value\0...
This entry is not writable.

Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
---
 fs/proc/base.c      |  1 +
 security/security.c | 45 +++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 46 insertions(+)

Comments

Kees Cook Aug. 8, 2019, 10:22 p.m. UTC | #1
On Wed, Aug 07, 2019 at 12:44:09PM -0700, Casey Schaufler wrote:
> Add an entry /proc/.../attr/context which displays the full
> process security "context" in compound format:'
> 	lsm1\0value\0lsm2\0value\0...
> This entry is not writable.
> 
> Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
> ---
>  fs/proc/base.c      |  1 +
>  security/security.c | 45 +++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 46 insertions(+)
> 
> diff --git a/fs/proc/base.c b/fs/proc/base.c
> index 7bf70e041315..79600df5f7a2 100644
> --- a/fs/proc/base.c
> +++ b/fs/proc/base.c
> @@ -2619,6 +2619,7 @@ static const struct pid_entry attr_dir_stuff[] = {
>  	ATTR(NULL, "keycreate",		0666),
>  	ATTR(NULL, "sockcreate",	0666),
>  	ATTR(NULL, "display",		0666),
> +	ATTR(NULL, "context",		0666),
>  #ifdef CONFIG_SECURITY_SMACK
>  	DIR("smack",			0555,
>  	    proc_smack_attr_dir_inode_ops, proc_smack_attr_dir_ops),
> diff --git a/security/security.c b/security/security.c
> index 0ea7ee27e331..e9f579483d12 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -2046,6 +2046,14 @@ int security_getprocattr(struct task_struct *p, const char *lsm, char *name,
>  				char **value)
>  {
>  	struct security_hook_list *hp;
> +	char *final = NULL;
> +	char *cp;
> +	char *tp;
> +	int rc = 0;
> +	int finallen = 0;
> +	int llen;
> +	int clen;
> +	int tlen;
>  	int display = lsm_task_display(current);
>  	int slot = 0;
>  
> @@ -2063,6 +2071,43 @@ int security_getprocattr(struct task_struct *p, const char *lsm, char *name,
>  		return -ENOMEM;
>  	}
>  
> +	if (!strcmp(name, "context")) {
> +		hlist_for_each_entry(hp, &security_hook_heads.getprocattr,
> +				     list) {
> +			rc = hp->hook.getprocattr(p, "current", &cp);
> +			if (rc == -EINVAL || rc == -ENOPROTOOPT)
> +				continue;
> +			if (rc < 0) {
> +				kfree(final);
> +				return rc;
> +			}
> +			llen = strlen(hp->lsmid->lsm) + 1;
> +			clen = strlen(cp) + 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;
> +		*value = final;
> +		return finallen;
> +	}

Instead of a copy-paste here, please add a helper for use in both
places...

> +
>  	hlist_for_each_entry(hp, &security_hook_heads.getprocattr, list) {
>  		if (lsm != NULL && strcmp(lsm, hp->lsmid->lsm))
>  			continue;
> -- 
> 2.20.1
>
Casey Schaufler Aug. 9, 2019, 12:23 a.m. UTC | #2
On 8/8/2019 3:22 PM, Kees Cook wrote:
> On Wed, Aug 07, 2019 at 12:44:09PM -0700, Casey Schaufler wrote:
>> Add an entry /proc/.../attr/context which displays the full
>> process security "context" in compound format:'
>> 	lsm1\0value\0lsm2\0value\0...
>> This entry is not writable.
>>
>> Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
>> ---
>>  fs/proc/base.c      |  1 +
>>  security/security.c | 45 +++++++++++++++++++++++++++++++++++++++++++++
>>  2 files changed, 46 insertions(+)
>>
>> diff --git a/fs/proc/base.c b/fs/proc/base.c
>> index 7bf70e041315..79600df5f7a2 100644
>> --- a/fs/proc/base.c
>> +++ b/fs/proc/base.c
>> @@ -2619,6 +2619,7 @@ static const struct pid_entry attr_dir_stuff[] = {
>>  	ATTR(NULL, "keycreate",		0666),
>>  	ATTR(NULL, "sockcreate",	0666),
>>  	ATTR(NULL, "display",		0666),
>> +	ATTR(NULL, "context",		0666),
>>  #ifdef CONFIG_SECURITY_SMACK
>>  	DIR("smack",			0555,
>>  	    proc_smack_attr_dir_inode_ops, proc_smack_attr_dir_ops),
>> diff --git a/security/security.c b/security/security.c
>> index 0ea7ee27e331..e9f579483d12 100644
>> --- a/security/security.c
>> +++ b/security/security.c
>> @@ -2046,6 +2046,14 @@ int security_getprocattr(struct task_struct *p, const char *lsm, char *name,
>>  				char **value)
>>  {
>>  	struct security_hook_list *hp;
>> +	char *final = NULL;
>> +	char *cp;
>> +	char *tp;
>> +	int rc = 0;
>> +	int finallen = 0;
>> +	int llen;
>> +	int clen;
>> +	int tlen;
>>  	int display = lsm_task_display(current);
>>  	int slot = 0;
>>  
>> @@ -2063,6 +2071,43 @@ int security_getprocattr(struct task_struct *p, const char *lsm, char *name,
>>  		return -ENOMEM;
>>  	}
>>  
>> +	if (!strcmp(name, "context")) {
>> +		hlist_for_each_entry(hp, &security_hook_heads.getprocattr,
>> +				     list) {
>> +			rc = hp->hook.getprocattr(p, "current", &cp);
>> +			if (rc == -EINVAL || rc == -ENOPROTOOPT)
>> +				continue;
>> +			if (rc < 0) {
>> +				kfree(final);
>> +				return rc;
>> +			}
>> +			llen = strlen(hp->lsmid->lsm) + 1;
>> +			clen = strlen(cp) + 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;
>> +		*value = final;
>> +		return finallen;
>> +	}
> Instead of a copy-paste here, please add a helper for use in both
> places...

I added an append_ctx() helper in the "full" series. I can pull it
back to here.

>
>> +
>>  	hlist_for_each_entry(hp, &security_hook_heads.getprocattr, list) {
>>  		if (lsm != NULL && strcmp(lsm, hp->lsmid->lsm))
>>  			continue;
>> -- 
>> 2.20.1
>>

Patch
diff mbox series

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 7bf70e041315..79600df5f7a2 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -2619,6 +2619,7 @@  static const struct pid_entry attr_dir_stuff[] = {
 	ATTR(NULL, "keycreate",		0666),
 	ATTR(NULL, "sockcreate",	0666),
 	ATTR(NULL, "display",		0666),
+	ATTR(NULL, "context",		0666),
 #ifdef CONFIG_SECURITY_SMACK
 	DIR("smack",			0555,
 	    proc_smack_attr_dir_inode_ops, proc_smack_attr_dir_ops),
diff --git a/security/security.c b/security/security.c
index 0ea7ee27e331..e9f579483d12 100644
--- a/security/security.c
+++ b/security/security.c
@@ -2046,6 +2046,14 @@  int security_getprocattr(struct task_struct *p, const char *lsm, char *name,
 				char **value)
 {
 	struct security_hook_list *hp;
+	char *final = NULL;
+	char *cp;
+	char *tp;
+	int rc = 0;
+	int finallen = 0;
+	int llen;
+	int clen;
+	int tlen;
 	int display = lsm_task_display(current);
 	int slot = 0;
 
@@ -2063,6 +2071,43 @@  int security_getprocattr(struct task_struct *p, const char *lsm, char *name,
 		return -ENOMEM;
 	}
 
+	if (!strcmp(name, "context")) {
+		hlist_for_each_entry(hp, &security_hook_heads.getprocattr,
+				     list) {
+			rc = hp->hook.getprocattr(p, "current", &cp);
+			if (rc == -EINVAL || rc == -ENOPROTOOPT)
+				continue;
+			if (rc < 0) {
+				kfree(final);
+				return rc;
+			}
+			llen = strlen(hp->lsmid->lsm) + 1;
+			clen = strlen(cp) + 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;
+		*value = final;
+		return finallen;
+	}
+
 	hlist_for_each_entry(hp, &security_hook_heads.getprocattr, list) {
 		if (lsm != NULL && strcmp(lsm, hp->lsmid->lsm))
 			continue;