On Fri, Jul 24, 2015 at 12:04:39PM +0200, Lukasz Pawelczyk wrote:
> This patch extends smack capability functions to a full list to those
> equivalent in the kernel
>
> has_ns_capability -> smack_has_ns_privilege
> has_capability -> smack_has_privilege
> ns_capable -> smack_ns_privileged
> capable -> smack_privileged
>
> It also puts the smack related part to a common function:
> smack_capability_allowed()
>
> Those functions will be needed for capability checks in the upcoming
> Smack namespace patches.
>
> Additionally there were 2 smack capability checks that used generic
> capability functions instead of specific Smack ones effectively ignoring
> the onlycap rule. This has been fixed now with the introduction of those
> new functions.
>
> This has implications on the Smack namespace as well as the additional
> Smack checks in smack_capability_allowed() will be extended beyond the
> onlycap rule. Not using Smack specific checks in those 2 places could
> mean breaking the Smack label namespace separation.
>
> Signed-off-by: Lukasz Pawelczyk <l.pawelczyk@xxxxxxxxxxx>
> Reviewed-by: Casey Schaufler <casey@xxxxxxxxxxxxxxxx>
Acked-by: Serge Hallyn <serge.hallyn@xxxxxxxxxxxxx>
> ---
> security/smack/smack.h | 5 ++++
> security/smack/smack_access.c | 64 +++++++++++++++++++++++++++++++++++++++----
> security/smack/smack_lsm.c | 4 +--
> 3 files changed, 65 insertions(+), 8 deletions(-)
>
> diff --git a/security/smack/smack.h b/security/smack/smack.h
> index 69ab9eb..e11cc13 100644
> --- a/security/smack/smack.h
> +++ b/security/smack/smack.h
> @@ -272,6 +272,11 @@ int smk_netlbl_mls(int, char *, struct netlbl_lsm_secattr *, int);
> struct smack_known *smk_import_entry(const char *, int);
> void smk_insert_entry(struct smack_known *skp);
> struct smack_known *smk_find_entry(const char *);
> +int smack_has_ns_privilege(struct task_struct *task,
> + struct user_namespace *user_ns,
> + int cap);
> +int smack_has_privilege(struct task_struct *task, int cap);
> +int smack_ns_privileged(struct user_namespace *user_ns, int cap);
> int smack_privileged(int cap);
>
> /*
> diff --git a/security/smack/smack_access.c b/security/smack/smack_access.c
> index 00f6b38..188b354 100644
> --- a/security/smack/smack_access.c
> +++ b/security/smack/smack_access.c
> @@ -629,17 +629,19 @@ LIST_HEAD(smack_onlycap_list);
> DEFINE_MUTEX(smack_onlycap_lock);
>
> /*
> - * Is the task privileged and allowed to be privileged
> - * by the onlycap rule.
> + * Internal smack capability check complimentary to the
> + * set of kernel capable() and has_capability() functions
> *
> - * Returns 1 if the task is allowed to be privileged, 0 if it's not.
> + * For a capability in smack related checks to be effective it needs to:
> + * - be allowed to be privileged by the onlycap rule.
> + * - be in the initial user ns
> */
> -int smack_privileged(int cap)
> +static int smack_capability_allowed(struct smack_known *skp,
> + struct user_namespace *user_ns)
> {
> - struct smack_known *skp = smk_of_current();
> struct smack_onlycap *sop;
>
> - if (!capable(cap))
> + if (user_ns != &init_user_ns)
> return 0;
>
> rcu_read_lock();
> @@ -658,3 +660,53 @@ int smack_privileged(int cap)
>
> return 0;
> }
> +
> +/*
> + * Is the task privileged in a namespace and allowed to be privileged
> + * by additional smack rules.
> + */
> +int smack_has_ns_privilege(struct task_struct *task,
> + struct user_namespace *user_ns,
> + int cap)
> +{
> + struct smack_known *skp = smk_of_task_struct(task);
> +
> + if (!has_ns_capability(task, user_ns, cap))
> + return 0;
> + if (smack_capability_allowed(skp, user_ns))
> + return 1;
> + return 0;
> +}
> +
> +/*
> + * Is the task privileged and allowed to be privileged
> + * by additional smack rules.
> + */
> +int smack_has_privilege(struct task_struct *task, int cap)
> +{
> + return smack_has_ns_privilege(task, &init_user_ns, cap);
> +}
> +
> +/*
> + * Is the current task privileged in a namespace and allowed to be privileged
> + * by additional smack rules.
> + */
> +int smack_ns_privileged(struct user_namespace *user_ns, int cap)
> +{
> + struct smack_known *skp = smk_of_current();
> +
> + if (!ns_capable(user_ns, cap))
> + return 0;
> + if (smack_capability_allowed(skp, user_ns))
> + return 1;
> + return 0;
> +}
> +
> +/*
> + * Is the current task privileged and allowed to be privileged
> + * by additional smack rules.
> + */
> +int smack_privileged(int cap)
> +{
> + return smack_ns_privileged(&init_user_ns, cap);
> +}
> diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
> index cdcabf4..6098518 100644
> --- a/security/smack/smack_lsm.c
> +++ b/security/smack/smack_lsm.c
> @@ -413,7 +413,7 @@ static int smk_ptrace_rule_check(struct task_struct *tracer,
> rc = 0;
> else if (smack_ptrace_rule == SMACK_PTRACE_DRACONIAN)
> rc = -EACCES;
> - else if (capable(CAP_SYS_PTRACE))
> + else if (smack_has_privilege(tracer, CAP_SYS_PTRACE))
> rc = 0;
> else
> rc = -EACCES;
> @@ -1805,7 +1805,7 @@ static int smack_file_send_sigiotask(struct task_struct *tsk,
> skp = file->f_security;
> rc = smk_access(skp, tkp, MAY_WRITE, NULL);
> rc = smk_bu_note("sigiotask", skp, tkp, MAY_WRITE, rc);
> - if (rc != 0 && has_capability(tsk, CAP_MAC_OVERRIDE))
> + if (rc != 0 && smack_has_privilege(tsk, CAP_MAC_OVERRIDE))
> rc = 0;
>
> smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_TASK);
> --
> 2.4.3
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