Quoting David P. Quigley (dpquigl@xxxxxxxxxxxxx):
> 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@xxxxxxxxxx>
> Signed-off-by: David P. Quigley <dpquigl@xxxxxxxxxxxxx>
> ---
> include/linux/security.h | 14 ++++++++++++++
> security/security.c | 7 +++++++
> security/selinux/hooks.c | 36 ++++++++++++++++++++++++++++++++++++
> 3 files changed, 57 insertions(+), 0 deletions(-)
>
> diff --git a/include/linux/security.h b/include/linux/security.h
> index 8b5b041..42b9128 100644
> --- a/include/linux/security.h
> +++ b/include/linux/security.h
> @@ -1379,6 +1379,9 @@ 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);
This of course needs a description at top of include/linux/security.h.
> +
>
> int (*inode_alloc_security) (struct inode *inode);
> void (*inode_free_security) (struct inode *inode);
> @@ -1651,6 +1654,8 @@ 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);
> @@ -1994,6 +1999,15 @@ 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/security.c b/security/security.c
> index d0fd42a..b22a110 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -349,6 +349,13 @@ 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 b07871b..680db1d 100644
> --- a/security/selinux/hooks.c
> +++ b/security/selinux/hooks.c
> @@ -2504,6 +2504,41 @@ static void selinux_inode_free_security(struct inode *inode)
> inode_free_security(inode);
> }
>
> +/*
> + * For now, we need a way to compute a SID for
Just 'Compute a SID for...' ?
> + * a dentry as the inode is not yet available
> + * (and under NFSv4 has no label backed by an EA anyway.
> + */
> +static int selinux_dentry_init_security(struct dentry *dentry, int mode, void **ctx, u32 *ctxlen)
> +{
> + 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 = current->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)
> @@ -5413,6 +5448,7 @@ 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,
> --
> 1.5.5.1
>
>
> --
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