[PATCH v5 28/38] SELinux: Abstract use of file security blob

From: Casey Schaufler
Date: Mon Nov 26 2018 - 18:48:51 EST


Don't use the file->f_security pointer directly.
Provide a helper function that provides the security blob pointer.

Signed-off-by: Casey Schaufler <casey@xxxxxxxxxxxxxxxx>
Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
---
security/selinux/hooks.c | 18 +++++++++---------
security/selinux/include/objsec.h | 5 +++++
2 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index ac6d8a2d00f1..ce1d37378eb5 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -393,7 +393,7 @@ static int file_alloc_security(struct file *file)

static void file_free_security(struct file *file)
{
- struct file_security_struct *fsec = file->f_security;
+ struct file_security_struct *fsec = selinux_file(file);
file->f_security = NULL;
kmem_cache_free(file_security_cache, fsec);
}
@@ -1881,7 +1881,7 @@ static int file_has_perm(const struct cred *cred,
struct file *file,
u32 av)
{
- struct file_security_struct *fsec = file->f_security;
+ struct file_security_struct *fsec = selinux_file(file);
struct inode *inode = file_inode(file);
struct common_audit_data ad;
u32 sid = cred_sid(cred);
@@ -2225,7 +2225,7 @@ static int selinux_binder_transfer_file(struct task_struct *from,
struct file *file)
{
u32 sid = task_sid(to);
- struct file_security_struct *fsec = file->f_security;
+ struct file_security_struct *fsec = selinux_file(file);
struct dentry *dentry = file->f_path.dentry;
struct inode_security_struct *isec;
struct common_audit_data ad;
@@ -3537,7 +3537,7 @@ static int selinux_revalidate_file_permission(struct file *file, int mask)
static int selinux_file_permission(struct file *file, int mask)
{
struct inode *inode = file_inode(file);
- struct file_security_struct *fsec = file->f_security;
+ struct file_security_struct *fsec = selinux_file(file);
struct inode_security_struct *isec;
u32 sid = current_sid();

@@ -3572,7 +3572,7 @@ static int ioctl_has_perm(const struct cred *cred, struct file *file,
u32 requested, u16 cmd)
{
struct common_audit_data ad;
- struct file_security_struct *fsec = file->f_security;
+ struct file_security_struct *fsec = selinux_file(file);
struct inode *inode = file_inode(file);
struct inode_security_struct *isec;
struct lsm_ioctlop_audit ioctl;
@@ -3824,7 +3824,7 @@ static void selinux_file_set_fowner(struct file *file)
{
struct file_security_struct *fsec;

- fsec = file->f_security;
+ fsec = selinux_file(file);
fsec->fown_sid = current_sid();
}

@@ -3839,7 +3839,7 @@ static int selinux_file_send_sigiotask(struct task_struct *tsk,
/* struct fown_struct is never outside the context of a struct file */
file = container_of(fown, struct file, f_owner);

- fsec = file->f_security;
+ fsec = selinux_file(file);

if (!signum)
perm = signal_to_av(SIGIO); /* as per send_sigio_to_task */
@@ -3863,7 +3863,7 @@ static int selinux_file_open(struct file *file)
struct file_security_struct *fsec;
struct inode_security_struct *isec;

- fsec = file->f_security;
+ fsec = selinux_file(file);
isec = inode_security(file_inode(file));
/*
* Save inode label and policy sequence number
@@ -4002,7 +4002,7 @@ static int selinux_kernel_module_from_file(struct file *file)
ad.type = LSM_AUDIT_DATA_FILE;
ad.u.file = file;

- fsec = file->f_security;
+ fsec = selinux_file(file);
if (sid != fsec->sid) {
rc = avc_has_perm(&selinux_state,
sid, fsec->sid, SECCLASS_FD, FD__USE, &ad);
diff --git a/security/selinux/include/objsec.h b/security/selinux/include/objsec.h
index c2974b031d05..e0ac2992e059 100644
--- a/security/selinux/include/objsec.h
+++ b/security/selinux/include/objsec.h
@@ -165,4 +165,9 @@ static inline struct task_security_struct *selinux_cred(const struct cred *cred)
return cred->security + selinux_blob_sizes.lbs_cred;
}

+static inline struct file_security_struct *selinux_file(const struct file *file)
+{
+ return file->f_security;
+}
+
#endif /* _SELINUX_OBJSEC_H_ */
--
2.14.5