[PATCH bpf-next v4 07/20] lsm: Refactor return value of LSM hook setprocattr

Xu Kuohai
2024-07-11T11:14:06Z

From: Xu Kuohai <xukuohai@huawei.com>

To be consistent with most LSM hooks, convert the return value of
hook setprocattr to 0 or a negative error code.

Before:
- Hook setprocattr returns the number of bytes written on success
or a negative error code on failure.

After:
- Hook setprocattr returns 0 on success or a negative error code
on failure. An output parameter @wbytes is introduced to hold
the number of bytes written on success.

Signed-off-by: Xu Kuohai <xukuohai@huawei.com>
---
fs/proc/base.c | 5 +++--
include/linux/lsm_hook_defs.h | 3 ++-
include/linux/security.h | 5 +++--
security/apparmor/lsm.c | 10 +++++++---
security/security.c | 8 +++++---
security/selinux/hooks.c | 11 ++++++++---
security/smack/smack_lsm.c | 14 ++++++++++----
7 files changed, 38 insertions(+), 18 deletions(-)

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 72a1acd03675..9e1cf6cc674d 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -2740,6 +2740,7 @@ static ssize_t proc_pid_attr_write(struct file * file, const char __user * buf,
{
struct inode * inode = file_inode(file);
struct task_struct *task;
+ size_t wbytes;
void *page;
int rv;

@@ -2785,12 +2786,12 @@ static ssize_t proc_pid_attr_write(struct file * file, const char __user * buf,

rv = security_setprocattr(PROC_I(inode)->op.lsmid,
file->f_path.dentry->d_name.name, page,
- count);
+ count, &wbytes);
mutex_unlock(&current->signal->cred_guard_mutex);
out_free:
kfree(page);
out:
- return rv;
+ return rv < 0 ? rv : wbytes;
}

static const struct file_operations proc_pid_attr_operations = {
diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
index dbc16f14f42f..2628514bb19c 100644
--- a/include/linux/lsm_hook_defs.h
+++ b/include/linux/lsm_hook_defs.h
@@ -287,7 +287,8 @@ LSM_HOOK(int, -EOPNOTSUPP, setselfattr, unsigned int attr,
struct lsm_ctx *ctx, u32 size, u32 flags)
LSM_HOOK(int, -EINVAL, getprocattr, struct task_struct *p, const char *name,
char **value)
-LSM_HOOK(int, -EINVAL, setprocattr, const char *name, void *value, size_t size)
+LSM_HOOK(int, -EINVAL, setprocattr, const char *name, void *value, size_t size,
+ size_t *wbytes)
LSM_HOOK(int, 0, ismaclabel, const char *name)
LSM_HOOK(int, -EOPNOTSUPP, secid_to_secctx, u32 secid, char **secdata,
u32 *seclen)
diff --git a/include/linux/security.h b/include/linux/security.h
index 96a63e132abf..1f1a9696e65d 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -496,7 +496,8 @@ int security_setselfattr(unsigned int attr, struct lsm_ctx __user *ctx,
u32 size, u32 flags);
int security_getprocattr(struct task_struct *p, int lsmid, const char *name,
char **value);
-int security_setprocattr(int lsmid, const char *name, void *value, size_t size);
+int security_setprocattr(int lsmid, const char *name, void *value, size_t size,
+ size_t *wbytes);
int security_netlink_send(struct sock *sk, struct sk_buff *skb);
int security_ismaclabel(const char *name);
int security_secid_to_secctx(u32 secid, char **secdata, u32 *seclen);
@@ -1440,7 +1441,7 @@ static inline int security_getprocattr(struct task_struct *p, int lsmid,
}

static inline int security_setprocattr(int lsmid, char *name, void *value,
- size_t size)
+ size_t size, size_t *wbytes)
{
return -EINVAL;
}
diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c
index 72dd09993f28..6c8b1f8c5781 100644
--- a/security/apparmor/lsm.c
+++ b/security/apparmor/lsm.c
@@ -939,13 +939,17 @@ static int apparmor_setselfattr(unsigned int attr, struct lsm_ctx *ctx,
}

static int apparmor_setprocattr(const char *name, void *value,
- size_t size)
+ size_t size, size_t *wbytes)
{
+ int rc = -EINVAL;
int attr = lsm_name_to_attr(name);

if (attr)
- return do_setattr(attr, value, size);
- return -EINVAL;
+ rc = do_setattr(attr, value, size);
+ if (rc < 0)
+ return rc;
+ *wbytes = rc;
+ return 0;
}

/**
diff --git a/security/security.c b/security/security.c
index 095e78efcb32..9685096dbf16 100644
--- a/security/security.c
+++ b/security/security.c
@@ -4141,20 +4141,22 @@ int security_getprocattr(struct task_struct *p, int lsmid, const char *name,
* @name: attribute name
* @value: attribute value
* @size: attribute value size
+ * @wbytes: bytes written on success
*
* Write (set) the current task's attribute @name to @value, size @size if
* allowed.
*
- * Return: Returns bytes written on success, a negative value otherwise.
+ * Return: Returns 0 on success, a negative error code otherwise.
*/
-int security_setprocattr(int lsmid, const char *name, void *value, size_t size)
+int security_setprocattr(int lsmid, const char *name, void *value, size_t size,
+ size_t *wbytes)
{
struct security_hook_list *hp;

hlist_for_each_entry(hp, &security_hook_heads.setprocattr, list) {
if (lsmid != 0 && lsmid != hp->lsmid->id)
continue;
- return hp->hook.setprocattr(name, value, size);
+ return hp->hook.setprocattr(name, value, size, wbytes);
}
return LSM_RET_DEFAULT(setprocattr);
}
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 0d35bb93baca..7a73f3710025 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -6589,13 +6589,18 @@ static int selinux_getprocattr(struct task_struct *p,
return -EINVAL;
}

-static int selinux_setprocattr(const char *name, void *value, size_t size)
+static int selinux_setprocattr(const char *name, void *value, size_t size,
+ size_t *wbytes)
{
+ int rc = -EINVAL;
int attr = lsm_name_to_attr(name);

if (attr)
- return selinux_lsm_setattr(attr, value, size);
- return -EINVAL;
+ rc = selinux_lsm_setattr(attr, value, size);
+ if (rc < 0)
+ return rc;
+ *wbytes = rc;
+ return 0;
}

static int selinux_ismaclabel(const char *name)
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 63d9c5f456c1..4265f2639106 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -3797,19 +3797,25 @@ static int smack_setselfattr(unsigned int attr, struct lsm_ctx *ctx,
* @name: the name of the attribute in /proc/.../attr
* @value: the value to set
* @size: the size of the value
+ * @wbytes: the length of the smack label written
*
* 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
+ * Returns 0 on success or a negative error code
*/
-static int smack_setprocattr(const char *name, void *value, size_t size)
+static int smack_setprocattr(const char *name, void *value, size_t size,
+ size_t *wbytes)
{
+ int rc = -EINVAL;
int attr = lsm_name_to_attr(name);

if (attr != LSM_ATTR_UNDEF)
- return do_setattr(attr, value, size);
- return -EINVAL;
+ rc = do_setattr(attr, value, size);
+ if (rc < 0)
+ return rc;
+ *wbytes = rc;
+ return 0;
}

/**
--
2.30.2