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    Subject[PATCH v5 29/38] Smack: Abstract use of file security blob
    Date
    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@schaufler-ca.com>
    Reviewed-by: Kees Cook <keescook@chromium.org>
    Signed-off-by: Kees Cook <keescook@chromium.org>
    ---
    security/smack/smack.h | 5 +++++
    security/smack/smack_lsm.c | 12 ++++++++----
    2 files changed, 13 insertions(+), 4 deletions(-)

    diff --git a/security/smack/smack.h b/security/smack/smack.h
    index b27eb252e953..50854969a391 100644
    --- a/security/smack/smack.h
    +++ b/security/smack/smack.h
    @@ -362,6 +362,11 @@ static inline struct task_smack *smack_cred(const struct cred *cred)
    return cred->security + smack_blob_sizes.lbs_cred;
    }

    +static inline struct smack_known **smack_file(const struct file *file)
    +{
    + return (struct smack_known **)&file->f_security;
    +}
    +
    /*
    * Is the directory transmuting?
    */
    diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
    index 459f7d523ca6..3e11be8cce7e 100644
    --- a/security/smack/smack_lsm.c
    +++ b/security/smack/smack_lsm.c
    @@ -1573,9 +1573,9 @@ static void smack_inode_getsecid(struct inode *inode, u32 *secid)
    */
    static int smack_file_alloc_security(struct file *file)
    {
    - struct smack_known *skp = smk_of_current();
    + struct smack_known **blob = smack_file(file);

    - file->f_security = skp;
    + *blob = smk_of_current();
    return 0;
    }

    @@ -1815,7 +1815,9 @@ static int smack_mmap_file(struct file *file,
    */
    static void smack_file_set_fowner(struct file *file)
    {
    - file->f_security = smk_of_current();
    + struct smack_known **blob = smack_file(file);
    +
    + *blob = smk_of_current();
    }

    /**
    @@ -1832,6 +1834,7 @@ static void smack_file_set_fowner(struct file *file)
    static int smack_file_send_sigiotask(struct task_struct *tsk,
    struct fown_struct *fown, int signum)
    {
    + struct smack_known **blob;
    struct smack_known *skp;
    struct smack_known *tkp = smk_of_task(smack_cred(tsk->cred));
    const struct cred *tcred;
    @@ -1845,7 +1848,8 @@ static int smack_file_send_sigiotask(struct task_struct *tsk,
    file = container_of(fown, struct file, f_owner);

    /* we don't log here as rc can be overriden */
    - skp = file->f_security;
    + blob = smack_file(file);
    + skp = *blob;
    rc = smk_access(skp, tkp, MAY_DELIVER, NULL);
    rc = smk_bu_note("sigiotask", skp, tkp, MAY_DELIVER, rc);

    --
    2.14.5
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