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Date: Thu, 29 Oct 2015 15:51:30 -0700
From: Casey Schaufler <casey@...aufler-ca.com>
To: Lukasz Pawelczyk <l.pawelczyk@...sung.com>,
"David S. Miller" <davem@...emloft.net>,
"Eric W. Biederman" <ebiederm@...ssion.com>,
"Serge E. Hallyn" <serge@...lyn.com>,
Al Viro <viro@...iv.linux.org.uk>,
Alexey Dobriyan <adobriyan@...il.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Andy Lutomirski <luto@...nel.org>,
Calvin Owens <calvinowens@...com>,
David Howells <dhowells@...hat.com>,
Eric Dumazet <edumazet@...gle.com>,
Eric Paris <eparis@...isplace.org>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
James Morris <james.l.morris@...cle.com>,
Jann Horn <jann@...jh.net>, Jiri Slaby <jslaby@...e.com>,
Joe Perches <joe@...ches.com>,
John Johansen <john.johansen@...onical.com>,
Jonathan Corbet <corbet@....net>,
Kees Cook <keescook@...omium.org>,
Mauro Carvalho Chehab <mchehab@....samsung.com>,
NeilBrown <neilb@...e.de>, Paul Moore <paul@...l-moore.com>,
Serge Hallyn <serge.hallyn@...onical.com>,
Stephen Smalley <sds@...ho.nsa.gov>, Tejun Heo <tj@...nel.org>,
Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
containers@...ts.linuxfoundation.org, linux-doc@...r.kernel.org,
linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-security-module@...r.kernel.org, selinux@...ho.nsa.gov
Cc: Lukasz Pawelczyk <havner@...il.com>
Subject: Re: [PATCH v4 08/11] smack: misc cleanups in preparation for a
namespace patch
On 10/14/2015 5:42 AM, Lukasz Pawelczyk wrote:
> This patch does some small miscellaneous cleanups and additions that
> should not change the code behaviour in any way. Its only purpose is to
> shape the code in a way that the smack namespace patches would be
> smaller and easier to understand.
>
> Changes:
> - four small helper functions added
> - minor code reformatting in several places for readability
> - unnecessarily increasing string size has been fixed
>
> This patch should not change the behaviour of the Smack in any way.
>
> Signed-off-by: Lukasz Pawelczyk <l.pawelczyk@...sung.com>
> Reviewed-by: Casey Schaufler <casey@...aufler-ca.com>
Acked-by: Casey Schaufler <casey@...aufler-ca.com>
> ---
> security/smack/smack.h | 47 ++++++++++++++++++++++++++++++++++-
> security/smack/smack_access.c | 18 +++++++++-----
> security/smack/smack_lsm.c | 58 ++++++++++++++++---------------------------
> security/smack/smackfs.c | 4 +--
> 4 files changed, 81 insertions(+), 46 deletions(-)
>
> diff --git a/security/smack/smack.h b/security/smack/smack.h
> index 091efc2..98bb676 100644
> --- a/security/smack/smack.h
> +++ b/security/smack/smack.h
> @@ -291,7 +291,7 @@ struct smk_audit_info {
> int smk_access_entry(char *, char *, struct list_head *);
> int smk_access(struct smack_known *, struct smack_known *,
> int, struct smk_audit_info *);
> -int smk_tskacc(struct task_smack *, struct smack_known *,
> +int smk_tskacc(struct task_struct *, struct smack_known *,
> u32, struct smk_audit_info *);
> int smk_curacc(struct smack_known *, u32, struct smk_audit_info *);
> struct smack_known *smack_from_secid(const u32);
> @@ -348,6 +348,7 @@ extern struct hlist_head smack_known_hash[SMACK_HASH_SLOTS];
> static inline int smk_inode_transmutable(const struct inode *isp)
> {
> struct inode_smack *sip = isp->i_security;
> +
> return (sip->smk_flags & SMK_INODE_TRANSMUTE) != 0;
> }
>
> @@ -357,10 +358,31 @@ static inline int smk_inode_transmutable(const struct inode *isp)
> static inline struct smack_known *smk_of_inode(const struct inode *isp)
> {
> struct inode_smack *sip = isp->i_security;
> +
> return sip->smk_inode;
> }
>
> /*
> + * Present a pointer to the smack label entry in an inode blob for an exec.
> + */
> +static inline struct smack_known *smk_of_exec(const struct inode *isp)
> +{
> + struct inode_smack *sip = isp->i_security;
> +
> + return sip->smk_task;
> +}
> +
> +/*
> + * Present a pointer to the smack label entry in an inode blob for an mmap.
> + */
> +static inline struct smack_known *smk_of_mmap(const struct inode *isp)
> +{
> + struct inode_smack *sip = isp->i_security;
> +
> + return sip->smk_mmap;
> +}
> +
> +/*
> * Present a pointer to the smack label entry in an task blob.
> */
> static inline struct smack_known *smk_of_task(const struct task_smack *tsp)
> @@ -395,6 +417,29 @@ static inline struct smack_known *smk_of_current(void)
> }
>
> /*
> + * Present a pointer to the user namespace entry in an task blob.
> + */
> +static inline
> +struct user_namespace *ns_of_task_struct(const struct task_struct *t)
> +{
> + struct user_namespace *ns;
> +
> + rcu_read_lock();
> + ns = __task_cred(t)->user_ns;
> + rcu_read_unlock();
> +
> + return ns;
> +}
> +
> +/*
> + * Present a pointer to the user namespace entry in the current task blob.
> + */
> +static inline struct user_namespace *ns_of_current(void)
> +{
> + return current_user_ns();
> +}
> +
> +/*
> * logging functions
> */
> #define SMACK_AUDIT_DENIED 0x1
> diff --git a/security/smack/smack_access.c b/security/smack/smack_access.c
> index 131c742..750aa9c 100644
> --- a/security/smack/smack_access.c
> +++ b/security/smack/smack_access.c
> @@ -167,6 +167,7 @@ int smk_access(struct smack_known *subject, struct smack_known *object,
> if (subject == &smack_known_hat)
> goto out_audit;
> }
> +
> /*
> * Beyond here an explicit relationship is required.
> * If the requested access is contained in the available
> @@ -183,6 +184,7 @@ int smk_access(struct smack_known *subject, struct smack_known *object,
> rc = -EACCES;
> goto out_audit;
> }
> +
> #ifdef CONFIG_SECURITY_SMACK_BRINGUP
> /*
> * Return a positive value if using bringup mode.
> @@ -225,10 +227,10 @@ out_audit:
> * non zero otherwise. It allows that the task may have the capability
> * to override the rules.
> */
> -int smk_tskacc(struct task_smack *tsp, struct smack_known *obj_known,
> +int smk_tskacc(struct task_struct *task, struct smack_known *obj_known,
> u32 mode, struct smk_audit_info *a)
> {
> - struct smack_known *sbj_known = smk_of_task(tsp);
> + struct smack_known *sbj_known = smk_of_task_struct(task);
> int may;
> int rc;
>
> @@ -237,13 +239,19 @@ int smk_tskacc(struct task_smack *tsp, struct smack_known *obj_known,
> */
> rc = smk_access(sbj_known, obj_known, mode, NULL);
> if (rc >= 0) {
> + struct task_smack *tsp;
> +
> /*
> * If there is an entry in the task's rule list
> * it can further restrict access.
> */
> + rcu_read_lock();
> + tsp = __task_cred(task)->security;
> may = smk_access_entry(sbj_known->smk_known,
> obj_known->smk_known,
> &tsp->smk_rules);
> + rcu_read_unlock();
> +
> if (may < 0)
> goto out_audit;
> if ((mode & may) == mode)
> @@ -280,9 +288,7 @@ out_audit:
> int smk_curacc(struct smack_known *obj_known,
> u32 mode, struct smk_audit_info *a)
> {
> - struct task_smack *tsp = current_security();
> -
> - return smk_tskacc(tsp, obj_known, mode, a);
> + return smk_tskacc(current, obj_known, mode, a);
> }
>
> #ifdef CONFIG_AUDIT
> @@ -456,7 +462,7 @@ char *smk_parse_smack(const char *string, int len)
> int i;
>
> if (len <= 0)
> - len = strlen(string) + 1;
> + len = strlen(string);
>
> /*
> * Reserve a leading '-' as an indicator that
> diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
> index 7303c37..5a59836 100644
> --- a/security/smack/smack_lsm.c
> +++ b/security/smack/smack_lsm.c
> @@ -393,8 +393,6 @@ static int smk_ptrace_rule_check(struct task_struct *tracer,
> {
> int rc;
> struct smk_audit_info ad, *saip = NULL;
> - struct task_smack *tsp;
> - struct smack_known *tracer_known;
>
> if ((mode & PTRACE_MODE_NOAUDIT) == 0) {
> smk_ad_init(&ad, func, LSM_AUDIT_DATA_TASK);
> @@ -402,13 +400,12 @@ static int smk_ptrace_rule_check(struct task_struct *tracer,
> saip = &ad;
> }
>
> - rcu_read_lock();
> - tsp = __task_cred(tracer)->security;
> - tracer_known = smk_of_task(tsp);
>
> if ((mode & PTRACE_MODE_ATTACH) &&
> (smack_ptrace_rule == SMACK_PTRACE_EXACT ||
> smack_ptrace_rule == SMACK_PTRACE_DRACONIAN)) {
> + struct smack_known *tracer_known = smk_of_task_struct(tracer);
> +
> if (tracer_known->smk_known == tracee_known->smk_known)
> rc = 0;
> else if (smack_ptrace_rule == SMACK_PTRACE_DRACONIAN)
> @@ -416,22 +413,18 @@ static int smk_ptrace_rule_check(struct task_struct *tracer,
> else if (smack_has_privilege(tracer, CAP_SYS_PTRACE))
> rc = 0;
> else
> - rc = -EACCES;
> + rc = -EPERM;
>
> if (saip)
> smack_log(tracer_known->smk_known,
> tracee_known->smk_known,
> 0, rc, saip);
>
> - rcu_read_unlock();
> return rc;
> }
>
> /* In case of rule==SMACK_PTRACE_DEFAULT or mode==PTRACE_MODE_READ */
> - rc = smk_tskacc(tsp, tracee_known, smk_ptrace_mode(mode), saip);
> -
> - rcu_read_unlock();
> - return rc;
> + return smk_tskacc(tracer, tracee_known, smk_ptrace_mode(mode), saip);
> }
>
> /*
> @@ -450,9 +443,7 @@ static int smk_ptrace_rule_check(struct task_struct *tracer,
> */
> static int smack_ptrace_access_check(struct task_struct *ctp, unsigned int mode)
> {
> - struct smack_known *skp;
> -
> - skp = smk_of_task_struct(ctp);
> + struct smack_known *skp = smk_of_task_struct(ctp);
>
> return smk_ptrace_rule_check(current, skp, mode, __func__);
> }
> @@ -467,13 +458,9 @@ static int smack_ptrace_access_check(struct task_struct *ctp, unsigned int mode)
> */
> static int smack_ptrace_traceme(struct task_struct *ptp)
> {
> - int rc;
> - struct smack_known *skp;
> -
> - skp = smk_of_task(current_security());
> + struct smack_known *skp = smk_of_current();
>
> - rc = smk_ptrace_rule_check(ptp, skp, PTRACE_MODE_ATTACH, __func__);
> - return rc;
> + return smk_ptrace_rule_check(ptp, skp, PTRACE_MODE_ATTACH, __func__);
> }
>
> /**
> @@ -1692,13 +1679,14 @@ static int smack_mmap_file(struct file *file,
> if (file == NULL)
> return 0;
>
> + tsp = current_security();
> + skp = smk_of_task(tsp);
> isp = file_inode(file)->i_security;
> - if (isp->smk_mmap == NULL)
> - return 0;
> mkp = isp->smk_mmap;
>
> - tsp = current_security();
> - skp = smk_of_current();
> + if (mkp == NULL)
> + return 0;
> +
> rc = 0;
>
> rcu_read_lock();
> @@ -3606,11 +3594,13 @@ static int smack_setprocattr(struct task_struct *p, const struct cred *f_cred,
> static int smack_unix_stream_connect(struct sock *sock,
> struct sock *other, struct sock *newsk)
> {
> - struct smack_known *skp;
> - struct smack_known *okp;
> struct socket_smack *ssp = sock->sk_security;
> struct socket_smack *osp = other->sk_security;
> struct socket_smack *nsp = newsk->sk_security;
> + struct smack_known *skp_out = ssp->smk_out;
> + struct smack_known *okp_out = osp->smk_out;
> + struct smack_known *skp_in = ssp->smk_in;
> + struct smack_known *okp_in = osp->smk_in;
> struct smk_audit_info ad;
> int rc = 0;
> #ifdef CONFIG_AUDIT
> @@ -3618,19 +3608,15 @@ static int smack_unix_stream_connect(struct sock *sock,
> #endif
>
> if (!smack_privileged(CAP_MAC_OVERRIDE)) {
> - skp = ssp->smk_out;
> - okp = osp->smk_in;
> #ifdef CONFIG_AUDIT
> smk_ad_init_net(&ad, __func__, LSM_AUDIT_DATA_NET, &net);
> smk_ad_setfield_u_net_sk(&ad, other);
> #endif
> - rc = smk_access(skp, okp, MAY_WRITE, &ad);
> - rc = smk_bu_note("UDS connect", skp, okp, MAY_WRITE, rc);
> + rc = smk_access(skp_out, okp_in, MAY_WRITE, &ad);
> + rc = smk_bu_note("UDS connect", skp_out, okp_in, MAY_WRITE, rc);
> if (rc == 0) {
> - okp = osp->smk_out;
> - skp = ssp->smk_in;
> - rc = smk_access(okp, skp, MAY_WRITE, &ad);
> - rc = smk_bu_note("UDS connect", okp, skp,
> + rc = smk_access(okp_out, skp_in, MAY_WRITE, &ad);
> + rc = smk_bu_note("UDS connect", okp_out, skp_in,
> MAY_WRITE, rc);
> }
> }
> @@ -3639,8 +3625,8 @@ static int smack_unix_stream_connect(struct sock *sock,
> * Cross reference the peer labels for SO_PEERSEC.
> */
> if (rc == 0) {
> - nsp->smk_packet = ssp->smk_out;
> - ssp->smk_packet = osp->smk_out;
> + nsp->smk_packet = skp_out;
> + ssp->smk_packet = okp_out;
> }
>
> return rc;
> diff --git a/security/smack/smackfs.c b/security/smack/smackfs.c
> index e5fb555..3149ec0 100644
> --- a/security/smack/smackfs.c
> +++ b/security/smack/smackfs.c
> @@ -1827,7 +1827,7 @@ static const struct file_operations smk_mapped_ops = {
> static ssize_t smk_read_ambient(struct file *filp, char __user *buf,
> size_t cn, loff_t *ppos)
> {
> - ssize_t rc;
> + ssize_t rc = -EINVAL;
> char *cp;
> int asize;
>
> @@ -1847,8 +1847,6 @@ static ssize_t smk_read_ambient(struct file *filp, char __user *buf,
>
> if (cn >= asize)
> rc = simple_read_from_buffer(buf, cn, ppos, cp, asize);
> - else
> - rc = -EINVAL;
>
> mutex_unlock(&smack_ambient_lock);
>
--
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