diff mbox series

[v15,08/11] Smack: implement setselfattr and getselfattr hooks

Message ID 20230912205658.3432-9-casey@schaufler-ca.com (mailing list archive)
State Accepted
Delegated to: Paul Moore
Headers show
Series LSM: Three basic syscalls | expand

Commit Message

Casey Schaufler Sept. 12, 2023, 8:56 p.m. UTC 
Implement Smack support for security_[gs]etselfattr.
Refactor the setprocattr hook to avoid code duplication.

Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Reviewed-by: John Johansen <john.johansen@canonical.com>
---
 security/smack/smack_lsm.c | 95 ++++++++++++++++++++++++++++++++++++--
 1 file changed, 90 insertions(+), 5 deletions(-)

Comments

Mickaël Salaün Oct. 3, 2023, 2:28 p.m. UTC | #1 
On Tue, Sep 12, 2023 at 01:56:53PM -0700, Casey Schaufler wrote:
> Implement Smack support for security_[gs]etselfattr.
> Refactor the setprocattr hook to avoid code duplication.
> 
> Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
> Reviewed-by: John Johansen <john.johansen@canonical.com>
> ---
>  security/smack/smack_lsm.c | 95 ++++++++++++++++++++++++++++++++++++--
>  1 file changed, 90 insertions(+), 5 deletions(-)
> 
> diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
> index f73f9a2834eb..12160d060cc1 100644
> --- a/security/smack/smack_lsm.c
> +++ b/security/smack/smack_lsm.c
> @@ -3626,6 +3626,46 @@ static void smack_d_instantiate(struct dentry *opt_dentry, struct inode *inode)
>  	return;
>  }
>  
> +/**
> + * smack_getselfattr - Smack current process attribute
> + * @attr: which attribute to fetch
> + * @ctx: buffer to receive the result
> + * @size: available size in, actual size out
> + * @flags: unused
> + *
> + * Fill the passed user space @ctx with the details of the requested
> + * attribute.
> + *
> + * Returns the number of attributes on success, an error code otherwise.
> + * There will only ever be one attribute.
> + */
> +static int smack_getselfattr(unsigned int attr, struct lsm_ctx __user *ctx,
> +			     size_t *size, u32 flags)
> +{
> +	struct smack_known *skp = smk_of_current();
> +	int total;
> +	int slen;
> +	int rc;
> +
> +	if (attr != LSM_ATTR_CURRENT)
> +		return -EOPNOTSUPP;
> +
> +	slen = strlen(skp->smk_known) + 1;


> +	total = ALIGN(slen + sizeof(*ctx), 8);
> +	if (total > *size)
> +		rc = -E2BIG;
> +	else if (ctx)
> +		rc = lsm_fill_user_ctx(ctx, skp->smk_known, slen, LSM_ID_SMACK,
> +				       0);
> +	else
> +		rc = 1;

Can we move these checks into lsm_fill_user_ctx()? They are similar for
AppArmor and SELinux.

> +
> +	*size = total;
> +	if (rc >= 0)
> +		return 1;
> +	return rc;
> +}
Casey Schaufler Oct. 20, 2023, 7:40 p.m. UTC | #2 
On 10/3/2023 7:28 AM, Mickaël Salaün wrote:
> On Tue, Sep 12, 2023 at 01:56:53PM -0700, Casey Schaufler wrote:
>> Implement Smack support for security_[gs]etselfattr.
>> Refactor the setprocattr hook to avoid code duplication.
>>
>> Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
>> Reviewed-by: John Johansen <john.johansen@canonical.com>
>> ---
>>  security/smack/smack_lsm.c | 95 ++++++++++++++++++++++++++++++++++++--
>>  1 file changed, 90 insertions(+), 5 deletions(-)
>>
>> diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
>> index f73f9a2834eb..12160d060cc1 100644
>> --- a/security/smack/smack_lsm.c
>> +++ b/security/smack/smack_lsm.c
>> @@ -3626,6 +3626,46 @@ static void smack_d_instantiate(struct dentry *opt_dentry, struct inode *inode)
>>  	return;
>>  }
>>  
>> +/**
>> + * smack_getselfattr - Smack current process attribute
>> + * @attr: which attribute to fetch
>> + * @ctx: buffer to receive the result
>> + * @size: available size in, actual size out
>> + * @flags: unused
>> + *
>> + * Fill the passed user space @ctx with the details of the requested
>> + * attribute.
>> + *
>> + * Returns the number of attributes on success, an error code otherwise.
>> + * There will only ever be one attribute.
>> + */
>> +static int smack_getselfattr(unsigned int attr, struct lsm_ctx __user *ctx,
>> +			     size_t *size, u32 flags)
>> +{
>> +	struct smack_known *skp = smk_of_current();
>> +	int total;
>> +	int slen;
>> +	int rc;
>> +
>> +	if (attr != LSM_ATTR_CURRENT)
>> +		return -EOPNOTSUPP;
>> +
>> +	slen = strlen(skp->smk_known) + 1;
>
>> +	total = ALIGN(slen + sizeof(*ctx), 8);
>> +	if (total > *size)
>> +		rc = -E2BIG;
>> +	else if (ctx)
>> +		rc = lsm_fill_user_ctx(ctx, skp->smk_known, slen, LSM_ID_SMACK,
>> +				       0);
>> +	else
>> +		rc = 1;
> Can we move these checks into lsm_fill_user_ctx()? They are similar for
> AppArmor and SELinux.
>
>> +
>> +	*size = total;
>> +	if (rc >= 0)
>> +		return 1;
>> +	return rc;
>> +}
Casey Schaufler Oct. 20, 2023, 7:42 p.m. UTC | #3 
On 10/3/2023 7:28 AM, Mickaël Salaün wrote:
> On Tue, Sep 12, 2023 at 01:56:53PM -0700, Casey Schaufler wrote:
>> Implement Smack support for security_[gs]etselfattr.
>> Refactor the setprocattr hook to avoid code duplication.
>>
>> Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
>> Reviewed-by: John Johansen <john.johansen@canonical.com>
>> ---
>>  security/smack/smack_lsm.c | 95 ++++++++++++++++++++++++++++++++++++--
>>  1 file changed, 90 insertions(+), 5 deletions(-)
>>
>> diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
>> index f73f9a2834eb..12160d060cc1 100644
>> --- a/security/smack/smack_lsm.c
>> +++ b/security/smack/smack_lsm.c
>> @@ -3626,6 +3626,46 @@ static void smack_d_instantiate(struct dentry *opt_dentry, struct inode *inode)
>>  	return;
>>  }
>>  
>> +/**
>> + * smack_getselfattr - Smack current process attribute
>> + * @attr: which attribute to fetch
>> + * @ctx: buffer to receive the result
>> + * @size: available size in, actual size out
>> + * @flags: unused
>> + *
>> + * Fill the passed user space @ctx with the details of the requested
>> + * attribute.
>> + *
>> + * Returns the number of attributes on success, an error code otherwise.
>> + * There will only ever be one attribute.
>> + */
>> +static int smack_getselfattr(unsigned int attr, struct lsm_ctx __user *ctx,
>> +			     size_t *size, u32 flags)
>> +{
>> +	struct smack_known *skp = smk_of_current();
>> +	int total;
>> +	int slen;
>> +	int rc;
>> +
>> +	if (attr != LSM_ATTR_CURRENT)
>> +		return -EOPNOTSUPP;
>> +
>> +	slen = strlen(skp->smk_known) + 1;
>
>> +	total = ALIGN(slen + sizeof(*ctx), 8);
>> +	if (total > *size)
>> +		rc = -E2BIG;
>> +	else if (ctx)
>> +		rc = lsm_fill_user_ctx(ctx, skp->smk_known, slen, LSM_ID_SMACK,
>> +				       0);
>> +	else
>> +		rc = 1;
> Can we move these checks into lsm_fill_user_ctx()? They are similar for
> AppArmor and SELinux.

Possibly, but that would make lsm_fill_user_ctx() into lsm_validiate_and_fill_user_ctx(),
and I don't want to do that.

>
>> +
>> +	*size = total;
>> +	if (rc >= 0)
>> +		return 1;
>> +	return rc;
>> +}
diff mbox series

Patch

diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index f73f9a2834eb..12160d060cc1 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -3626,6 +3626,46 @@  static void smack_d_instantiate(struct dentry *opt_dentry, struct inode *inode)
 	return;
 }
 
+/**
+ * smack_getselfattr - Smack current process attribute
+ * @attr: which attribute to fetch
+ * @ctx: buffer to receive the result
+ * @size: available size in, actual size out
+ * @flags: unused
+ *
+ * Fill the passed user space @ctx with the details of the requested
+ * attribute.
+ *
+ * Returns the number of attributes on success, an error code otherwise.
+ * There will only ever be one attribute.
+ */
+static int smack_getselfattr(unsigned int attr, struct lsm_ctx __user *ctx,
+			     size_t *size, u32 flags)
+{
+	struct smack_known *skp = smk_of_current();
+	int total;
+	int slen;
+	int rc;
+
+	if (attr != LSM_ATTR_CURRENT)
+		return -EOPNOTSUPP;
+
+	slen = strlen(skp->smk_known) + 1;
+	total = ALIGN(slen + sizeof(*ctx), 8);
+	if (total > *size)
+		rc = -E2BIG;
+	else if (ctx)
+		rc = lsm_fill_user_ctx(ctx, skp->smk_known, slen, LSM_ID_SMACK,
+				       0);
+	else
+		rc = 1;
+
+	*size = total;
+	if (rc >= 0)
+		return 1;
+	return rc;
+}
+
 /**
  * smack_getprocattr - Smack process attribute access
  * @p: the object task
@@ -3655,8 +3695,8 @@  static int smack_getprocattr(struct task_struct *p, const char *name, char **val
 }
 
 /**
- * smack_setprocattr - Smack process attribute setting
- * @name: the name of the attribute in /proc/.../attr
+ * do_setattr - Smack process attribute setting
+ * @attr: the ID of the attribute
  * @value: the value to set
  * @size: the size of the value
  *
@@ -3665,7 +3705,7 @@  static int smack_getprocattr(struct task_struct *p, const char *name, char **val
  *
  * Returns the length of the smack label or an error code
  */
-static int smack_setprocattr(const char *name, void *value, size_t size)
+static int do_setattr(u64 attr, void *value, size_t size)
 {
 	struct task_smack *tsp = smack_cred(current_cred());
 	struct cred *new;
@@ -3679,8 +3719,8 @@  static int smack_setprocattr(const char *name, void *value, size_t size)
 	if (value == NULL || size == 0 || size >= SMK_LONGLABEL)
 		return -EINVAL;
 
-	if (strcmp(name, "current") != 0)
-		return -EINVAL;
+	if (attr != LSM_ATTR_CURRENT)
+		return -EOPNOTSUPP;
 
 	skp = smk_import_entry(value, size);
 	if (IS_ERR(skp))
@@ -3719,6 +3759,49 @@  static int smack_setprocattr(const char *name, void *value, size_t size)
 	return size;
 }
 
+/**
+ * smack_setselfattr - Set a Smack process attribute
+ * @attr: which attribute to set
+ * @ctx: buffer containing the data
+ * @size: size of @ctx
+ * @flags: unused
+ *
+ * Fill the passed user space @ctx with the details of the requested
+ * attribute.
+ *
+ * Returns 0 on success, an error code otherwise.
+ */
+static int smack_setselfattr(unsigned int attr, struct lsm_ctx *ctx,
+			     size_t size, u32 flags)
+{
+	int rc;
+
+	rc = do_setattr(attr, ctx->ctx, ctx->ctx_len);
+	if (rc > 0)
+		return 0;
+	return rc;
+}
+
+/**
+ * smack_setprocattr - Smack process attribute setting
+ * @name: the name of the attribute in /proc/.../attr
+ * @value: the value to set
+ * @size: the size of the value
+ *
+ * Sets the Smack value of the task. Only setting self
+ * is permitted and only with privilege
+ *
+ * Returns the length of the smack label or an error code
+ */
+static int smack_setprocattr(const char *name, void *value, size_t size)
+{
+	int attr = lsm_name_to_attr(name);
+
+	if (attr != LSM_ATTR_UNDEF)
+		return do_setattr(attr, value, size);
+	return -EINVAL;
+}
+
 /**
  * smack_unix_stream_connect - Smack access on UDS
  * @sock: one sock
@@ -5033,6 +5116,8 @@  static struct security_hook_list smack_hooks[] __ro_after_init = {
 
 	LSM_HOOK_INIT(d_instantiate, smack_d_instantiate),
 
+	LSM_HOOK_INIT(getselfattr, smack_getselfattr),
+	LSM_HOOK_INIT(setselfattr, smack_setselfattr),
 	LSM_HOOK_INIT(getprocattr, smack_getprocattr),
 	LSM_HOOK_INIT(setprocattr, smack_setprocattr),