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SubjectRe: [RFC][PATCH 6/7] security: new LSM hook security_file_getsecid()
On 4/27/2011 5:34 AM, Roberto Sassu wrote:
> The new LSM hook security_file_getsecid() and its implementation in the
> capability module, SELinux and SMACK allows to obtain the security
> identifier associated to a file descriptor.

Why do you want a secid? You have the security information from
the file structure readily available.

What use to you intend to put this to?

> Signed-off-by: Roberto Sassu <roberto.sassu@polito.it>
> ---
> include/linux/security.h | 12 ++++++++++++
> security/capability.c | 6 ++++++
> security/security.c | 6 ++++++
> security/selinux/hooks.c | 7 +++++++
> security/smack/smack_lsm.c | 11 +++++++++++
> 5 files changed, 42 insertions(+), 0 deletions(-)
>
> diff --git a/include/linux/security.h b/include/linux/security.h
> index ca02f17..6e73a1a 100644
> --- a/include/linux/security.h
> +++ b/include/linux/security.h
> @@ -630,6 +630,11 @@ static inline void security_free_mnt_opts(struct security_mnt_opts *opts)
> * to receive an open file descriptor via socket IPC.
> * @file contains the file structure being received.
> * Return 0 if permission is granted.
> + * @file_getsecid:
> + * Get the secid associated with the file descriptor.
> + * @file contains a pointer to the file descriptor.
> + * @secid contains a pointer to the location where result will be saved.
> + * In case of failure, @secid will be set to zero.
> *
> * Security hook for dentry
> *
> @@ -1492,6 +1497,7 @@ struct security_operations {
> int (*file_send_sigiotask) (struct task_struct *tsk,
> struct fown_struct *fown, int sig);
> int (*file_receive) (struct file *file);
> + void (*file_getsecid)(const struct file *file, u32 *secid);
> int (*dentry_open) (struct file *file, const struct cred *cred);
>
> int (*task_create) (unsigned long clone_flags);
> @@ -1751,6 +1757,7 @@ int security_file_set_fowner(struct file *file);
> int security_file_send_sigiotask(struct task_struct *tsk,
> struct fown_struct *fown, int sig);
> int security_file_receive(struct file *file);
> +void security_file_getsecid(const struct file *file, u32 *secid);
> int security_dentry_open(struct file *file, const struct cred *cred);
> int security_task_create(unsigned long clone_flags);
> int security_cred_alloc_blank(struct cred *cred, gfp_t gfp);
> @@ -2251,6 +2258,11 @@ static inline int security_file_receive(struct file *file)
> return 0;
> }
>
> +static inline void security_file_getsecid(const struct file *file, u32 *secid)
> +{
> + *secid = 0;
> +}
> +
> static inline int security_dentry_open(struct file *file,
> const struct cred *cred)
> {
> diff --git a/security/capability.c b/security/capability.c
> index 2984ea4..fcb569d 100644
> --- a/security/capability.c
> +++ b/security/capability.c
> @@ -349,6 +349,11 @@ static int cap_file_receive(struct file *file)
> return 0;
> }
>
> +static void cap_file_getsecid(const struct file *file, u32 *secid)
> +{
> + *secid = 0;
> +}
> +
> static int cap_dentry_open(struct file *file, const struct cred *cred)
> {
> return 0;
> @@ -953,6 +958,7 @@ void __init security_fixup_ops(struct security_operations *ops)
> set_to_cap_if_null(ops, file_set_fowner);
> set_to_cap_if_null(ops, file_send_sigiotask);
> set_to_cap_if_null(ops, file_receive);
> + set_to_cap_if_null(ops, file_getsecid);
> set_to_cap_if_null(ops, dentry_open);
> set_to_cap_if_null(ops, task_create);
> set_to_cap_if_null(ops, cred_alloc_blank);
> diff --git a/security/security.c b/security/security.c
> index 1011423..9973dab 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -688,6 +688,12 @@ int security_file_receive(struct file *file)
> return security_ops->file_receive(file);
> }
>
> +void security_file_getsecid(const struct file *file, u32 *secid)
> +{
> + security_ops->file_getsecid(file, secid);
> +}
> +EXPORT_SYMBOL(security_file_getsecid);
> +
> int security_dentry_open(struct file *file, const struct cred *cred)
> {
> int ret;
> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
> index 6772687..e1e787c 100644
> --- a/security/selinux/hooks.c
> +++ b/security/selinux/hooks.c
> @@ -3179,6 +3179,12 @@ static int selinux_file_receive(struct file *file)
> return file_has_perm(cred, file, file_to_av(file));
> }
>
> +static void selinux_file_getsecid(const struct file *file, u32 *secid)
> +{
> + struct file_security_struct *fsec = file->f_security;
> + *secid = fsec->sid;
> +}
> +
> static int selinux_dentry_open(struct file *file, const struct cred *cred)
> {
> struct file_security_struct *fsec;
> @@ -5498,6 +5504,7 @@ static struct security_operations selinux_ops = {
> .file_set_fowner = selinux_file_set_fowner,
> .file_send_sigiotask = selinux_file_send_sigiotask,
> .file_receive = selinux_file_receive,
> + .file_getsecid = selinux_file_getsecid,
>
> .dentry_open = selinux_dentry_open,
>
> diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
> index 6612ba1..a583736 100644
> --- a/security/smack/smack_lsm.c
> +++ b/security/smack/smack_lsm.c
> @@ -1304,6 +1304,16 @@ static int smack_file_receive(struct file *file)
> return smk_curacc(file->f_security, may, &ad);
> }
>
> +/**
> + * smack_file_getsecid - Extract file descriptor's security id
> + * @file: file descriptor to extract the info from
> + * @secid: where result will be saved
> + */
> +static void smack_file_getsecid(const struct file *file, u32 *secid)
> +{
> + *secid = smack_to_secid(file->f_security);
> +}
> +
> /*
> * Task hooks
> */
> @@ -3434,6 +3444,7 @@ struct security_operations smack_ops = {
> .file_set_fowner = smack_file_set_fowner,
> .file_send_sigiotask = smack_file_send_sigiotask,
> .file_receive = smack_file_receive,
> + .file_getsecid = smack_file_getsecid,
>
> .cred_alloc_blank = smack_cred_alloc_blank,
> .cred_free = smack_cred_free,



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