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    Subject[PATCH 01/10] Security: Add hook to calculate context based on a negative dentry.
    Date
    There is a time where we need to calculate a context without the
    inode having been created yet. To do this we take the negative dentry and
    calculate a context based on the process and the parent directory contexts.

    Signed-off-by: Matthew N. Dodd <Matthew.Dodd@sparta.com>
    Signed-off-by: David P. Quigley <dpquigl@tycho.nsa.gov>
    ---
    include/linux/security.h | 22 ++++++++++++++++++++++
    security/capability.c | 6 ++++++
    security/security.c | 7 +++++++
    security/selinux/hooks.c | 32 ++++++++++++++++++++++++++++++++
    4 files changed, 67 insertions(+), 0 deletions(-)

    diff --git a/include/linux/security.h b/include/linux/security.h
    index 3158dd9..4d01784 100644
    --- a/include/linux/security.h
    +++ b/include/linux/security.h
    @@ -322,6 +322,14 @@ static inline void security_free_mnt_opts(struct security_mnt_opts *opts)
    * Parse a string of security data filling in the opts structure
    * @options string containing all mount options known by the LSM
    * @opts binary data structure usable by the LSM
    + * @dentry_init_security:
    + * Compute a context for a dentry as the inode is not yet available
    + * since NFSv4 has no label backed by an EA anyway.
    + * @dentry dentry to use in calculating the context.
    + * @mode mode used to determine resource type.
    + * @ctx pointer to place the pointer to the resulting context in.
    + * @ctxlen point to place the length of the resulting context.
    + *
    *
    * Security hooks for inode operations.
    *
    @@ -1501,6 +1509,9 @@ struct security_operations {
    void (*sb_clone_mnt_opts) (const struct super_block *oldsb,
    struct super_block *newsb);
    int (*sb_parse_opts_str) (char *options, struct security_mnt_opts *opts);
    + int (*dentry_init_security) (struct dentry *dentry, int mode,
    + void **ctx, u32 *ctxlen);
    +

    #ifdef CONFIG_SECURITY_PATH
    int (*path_unlink) (struct path *dir, struct dentry *dentry);
    @@ -1795,6 +1806,8 @@ int security_sb_set_mnt_opts(struct super_block *sb, struct security_mnt_opts *o
    void security_sb_clone_mnt_opts(const struct super_block *oldsb,
    struct super_block *newsb);
    int security_sb_parse_opts_str(char *options, struct security_mnt_opts *opts);
    +int security_dentry_init_security (struct dentry *dentry, int mode,
    + void **ctx, u32 *ctxlen);

    int security_inode_alloc(struct inode *inode);
    void security_inode_free(struct inode *inode);
    @@ -2157,6 +2170,15 @@ static inline int security_inode_alloc(struct inode *inode)
    static inline void security_inode_free(struct inode *inode)
    { }

    +static inline int security_dentry_init_security (struct dentry *dentry,
    + int mode,
    + void **ctx,
    + u32 *ctxlen)
    +{
    + return -EOPNOTSUPP;
    +}
    +
    +
    static inline int security_inode_init_security(struct inode *inode,
    struct inode *dir,
    char **name,
    diff --git a/security/capability.c b/security/capability.c
    index 4875142..9ce1c2f 100644
    --- a/security/capability.c
    +++ b/security/capability.c
    @@ -134,6 +134,11 @@ static int cap_sb_parse_opts_str(char *options, struct security_mnt_opts *opts)
    return 0;
    }

    +static int cap_dentry_init_security(struct dentry *dentry, int mode, void **ctx, u32 *ctxlen)
    +{
    + return 0;
    +}
    +
    static int cap_inode_alloc_security(struct inode *inode)
    {
    return 0;
    @@ -952,6 +957,7 @@ void security_fixup_ops(struct security_operations *ops)
    set_to_cap_if_null(ops, sb_set_mnt_opts);
    set_to_cap_if_null(ops, sb_clone_mnt_opts);
    set_to_cap_if_null(ops, sb_parse_opts_str);
    + set_to_cap_if_null(ops, dentry_init_security);
    set_to_cap_if_null(ops, inode_alloc_security);
    set_to_cap_if_null(ops, inode_free_security);
    set_to_cap_if_null(ops, inode_init_security);
    diff --git a/security/security.c b/security/security.c
    index 687c6fd..c1b6847 100644
    --- a/security/security.c
    +++ b/security/security.c
    @@ -386,6 +386,13 @@ void security_inode_free(struct inode *inode)
    security_ops->inode_free_security(inode);
    }

    +int security_dentry_init_security (struct dentry *dentry, int mode,
    + void **ctx, u32 *ctxlen)
    +{
    + return security_ops->dentry_init_security (dentry, mode, ctx, ctxlen);
    +}
    +EXPORT_SYMBOL(security_dentry_init_security);
    +
    int security_inode_init_security(struct inode *inode, struct inode *dir,
    char **name, void **value, size_t *len)
    {
    diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
    index 5feecb4..435c51f 100644
    --- a/security/selinux/hooks.c
    +++ b/security/selinux/hooks.c
    @@ -2577,6 +2577,37 @@ static void selinux_inode_free_security(struct inode *inode)
    inode_free_security(inode);
    }

    +static int selinux_dentry_init_security(struct dentry *dentry, int mode, void **ctx, u32 *ctxlen)
    +{
    + struct cred *cred = current_cred();
    + struct task_security_struct *tsec;
    + struct inode_security_struct *dsec;
    + struct superblock_security_struct *sbsec;
    + struct inode *dir = dentry->d_parent->d_inode;
    + u32 newsid;
    + int rc;
    +
    + tsec = cred->security;
    + dsec = dir->i_security;
    + sbsec = dir->i_sb->s_security;
    +
    + if (tsec->create_sid && sbsec->behavior != SECURITY_FS_USE_MNTPOINT) {
    + newsid = tsec->create_sid;
    + } else {
    + rc = security_transition_sid(tsec->sid, dsec->sid,
    + inode_mode_to_security_class(mode),
    + &newsid);
    + if (rc) {
    + printk(KERN_WARNING "%s: "
    + "security_transition_sid failed, rc=%d\n",
    + __FUNCTION__, -rc);
    + return rc;
    + }
    + }
    +
    + return security_sid_to_context(newsid, (char **)ctx, ctxlen);
    +}
    +
    static int selinux_inode_init_security(struct inode *inode, struct inode *dir,
    char **name, void **value,
    size_t *len)
    @@ -5484,6 +5515,7 @@ static struct security_operations selinux_ops = {
    .sb_clone_mnt_opts = selinux_sb_clone_mnt_opts,
    .sb_parse_opts_str = selinux_parse_opts_str,

    + .dentry_init_security = selinux_dentry_init_security,

    .inode_alloc_security = selinux_inode_alloc_security,
    .inode_free_security = selinux_inode_free_security,
    --
    1.6.2.5


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