[PATCH v5 32/38] Smack: Abstract use of inode security blob

From: Casey Schaufler
Date: Mon Nov 26 2018 - 18:52:35 EST


Don't use the inode->i_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/smack/smack.h | 9 +++++++--
security/smack/smack_lsm.c | 32 ++++++++++++++++----------------
2 files changed, 23 insertions(+), 18 deletions(-)

diff --git a/security/smack/smack.h b/security/smack/smack.h
index 2007d38d0e46..436231dfae33 100644
--- a/security/smack/smack.h
+++ b/security/smack/smack.h
@@ -368,12 +368,17 @@ static inline struct smack_known **smack_file(const struct file *file)
smack_blob_sizes.lbs_file);
}

+static inline struct inode_smack *smack_inode(const struct inode *inode)
+{
+ return inode->i_security;
+}
+
/*
* Is the directory transmuting?
*/
static inline int smk_inode_transmutable(const struct inode *isp)
{
- struct inode_smack *sip = isp->i_security;
+ struct inode_smack *sip = smack_inode(isp);
return (sip->smk_flags & SMK_INODE_TRANSMUTE) != 0;
}

@@ -382,7 +387,7 @@ static inline int smk_inode_transmutable(const struct inode *isp)
*/
static inline struct smack_known *smk_of_inode(const struct inode *isp)
{
- struct inode_smack *sip = isp->i_security;
+ struct inode_smack *sip = smack_inode(isp);
return sip->smk_inode;
}

diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index c560cb8e155c..c086110cba80 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -166,7 +166,7 @@ static int smk_bu_task(struct task_struct *otp, int mode, int rc)
static int smk_bu_inode(struct inode *inode, int mode, int rc)
{
struct task_smack *tsp = smack_cred(current_cred());
- struct inode_smack *isp = inode->i_security;
+ struct inode_smack *isp = smack_inode(inode);
char acc[SMK_NUM_ACCESS_TYPE + 1];

if (isp->smk_flags & SMK_INODE_IMPURE)
@@ -198,7 +198,7 @@ static int smk_bu_file(struct file *file, int mode, int rc)
struct task_smack *tsp = smack_cred(current_cred());
struct smack_known *sskp = tsp->smk_task;
struct inode *inode = file_inode(file);
- struct inode_smack *isp = inode->i_security;
+ struct inode_smack *isp = smack_inode(inode);
char acc[SMK_NUM_ACCESS_TYPE + 1];

if (isp->smk_flags & SMK_INODE_IMPURE)
@@ -228,7 +228,7 @@ static int smk_bu_credfile(const struct cred *cred, struct file *file,
struct task_smack *tsp = smack_cred(cred);
struct smack_known *sskp = tsp->smk_task;
struct inode *inode = file_inode(file);
- struct inode_smack *isp = inode->i_security;
+ struct inode_smack *isp = smack_inode(inode);
char acc[SMK_NUM_ACCESS_TYPE + 1];

if (isp->smk_flags & SMK_INODE_IMPURE)
@@ -826,7 +826,7 @@ static int smack_set_mnt_opts(struct super_block *sb,
/*
* Initialize the root inode.
*/
- isp = inode->i_security;
+ isp = smack_inode(inode);
if (isp == NULL) {
isp = new_inode_smack(sp->smk_root);
if (isp == NULL)
@@ -914,7 +914,7 @@ static int smack_bprm_set_creds(struct linux_binprm *bprm)
if (bprm->called_set_creds)
return 0;

- isp = inode->i_security;
+ isp = smack_inode(inode);
if (isp->smk_task == NULL || isp->smk_task == bsp->smk_task)
return 0;

@@ -994,7 +994,7 @@ static void smack_inode_free_rcu(struct rcu_head *head)
*/
static void smack_inode_free_security(struct inode *inode)
{
- struct inode_smack *issp = inode->i_security;
+ struct inode_smack *issp = smack_inode(inode);

/*
* The inode may still be referenced in a path walk and
@@ -1022,7 +1022,7 @@ static int smack_inode_init_security(struct inode *inode, struct inode *dir,
const struct qstr *qstr, const char **name,
void **value, size_t *len)
{
- struct inode_smack *issp = inode->i_security;
+ struct inode_smack *issp = smack_inode(inode);
struct smack_known *skp = smk_of_current();
struct smack_known *isp = smk_of_inode(inode);
struct smack_known *dsp = smk_of_inode(dir);
@@ -1360,7 +1360,7 @@ static void smack_inode_post_setxattr(struct dentry *dentry, const char *name,
const void *value, size_t size, int flags)
{
struct smack_known *skp;
- struct inode_smack *isp = d_backing_inode(dentry)->i_security;
+ struct inode_smack *isp = smack_inode(d_backing_inode(dentry));

if (strcmp(name, XATTR_NAME_SMACKTRANSMUTE) == 0) {
isp->smk_flags |= SMK_INODE_TRANSMUTE;
@@ -1441,7 +1441,7 @@ static int smack_inode_removexattr(struct dentry *dentry, const char *name)
if (rc != 0)
return rc;

- isp = d_backing_inode(dentry)->i_security;
+ isp = smack_inode(d_backing_inode(dentry));
/*
* Don't do anything special for these.
* XATTR_NAME_SMACKIPIN
@@ -1716,7 +1716,7 @@ static int smack_mmap_file(struct file *file,
if (unlikely(IS_PRIVATE(file_inode(file))))
return 0;

- isp = file_inode(file)->i_security;
+ isp = smack_inode(file_inode(file));
if (isp->smk_mmap == NULL)
return 0;
sbsp = file_inode(file)->i_sb->s_security;
@@ -2063,7 +2063,7 @@ static int smack_kernel_act_as(struct cred *new, u32 secid)
static int smack_kernel_create_files_as(struct cred *new,
struct inode *inode)
{
- struct inode_smack *isp = inode->i_security;
+ struct inode_smack *isp = smack_inode(inode);
struct task_smack *tsp = smack_cred(new);

tsp->smk_forked = isp->smk_inode;
@@ -2263,7 +2263,7 @@ static int smack_task_kill(struct task_struct *p, struct kernel_siginfo *info,
*/
static void smack_task_to_inode(struct task_struct *p, struct inode *inode)
{
- struct inode_smack *isp = inode->i_security;
+ struct inode_smack *isp = smack_inode(inode);
struct smack_known *skp = smk_of_task_struct(p);

isp->smk_inode = skp;
@@ -2726,7 +2726,7 @@ static int smack_inode_setsecurity(struct inode *inode, const char *name,
const void *value, size_t size, int flags)
{
struct smack_known *skp;
- struct inode_smack *nsp = inode->i_security;
+ struct inode_smack *nsp = smack_inode(inode);
struct socket_smack *ssp;
struct socket *sock;
int rc = 0;
@@ -3334,7 +3334,7 @@ static void smack_d_instantiate(struct dentry *opt_dentry, struct inode *inode)
if (inode == NULL)
return;

- isp = inode->i_security;
+ isp = smack_inode(inode);

mutex_lock(&isp->smk_lock);
/*
@@ -4566,7 +4566,7 @@ static int smack_inode_copy_up(struct dentry *dentry, struct cred **new)
/*
* Get label from overlay inode and set it in create_sid
*/
- isp = d_inode(dentry->d_parent)->i_security;
+ isp = smack_inode(d_inode(dentry->d_parent));
skp = isp->smk_inode;
tsp->smk_task = skp;
*new = new_creds;
@@ -4603,7 +4603,7 @@ static int smack_dentry_create_files_as(struct dentry *dentry, int mode,
/*
* the attribute of the containing directory
*/
- isp = d_inode(dentry->d_parent)->i_security;
+ isp = smack_inode(d_inode(dentry->d_parent));

if (isp->smk_flags & SMK_INODE_TRANSMUTE) {
rcu_read_lock();
--
2.14.5