[PATCH] Smack: label for task objects

From: Jarkko Sakkinen
Date: Thu Nov 11 2010 - 11:44:26 EST

Applied against
http://gitorious.org/simplified-mandatory-access-control-kernel

This patch adds a new security attribute to Smack called
SMACK64EXEC. It defines label that is used while task is
running.

Exception: in smack_task_wait() child task is checked
for write access to parent task using label inherited
from the task that forked it.

Signed-off-by: Jarkko Sakkinen <jarkko.j.sakkinen@xxxxxxxxx>
---
include/linux/xattr.h | 2 +
security/smack/smack.h | 30 +++++++
security/smack/smack_access.c | 4 +-
security/smack/smack_lsm.c | 168 ++++++++++++++++++++++++++++++-----------
security/smack/smackfs.c | 4 +-
5 files changed, 159 insertions(+), 49 deletions(-)

diff --git a/include/linux/xattr.h b/include/linux/xattr.h
index f1e5bde..351c790 100644
--- a/include/linux/xattr.h
+++ b/include/linux/xattr.h
@@ -40,9 +40,11 @@
#define XATTR_SMACK_SUFFIX "SMACK64"
#define XATTR_SMACK_IPIN "SMACK64IPIN"
#define XATTR_SMACK_IPOUT "SMACK64IPOUT"
+#define XATTR_SMACK_EXEC "SMACK64EXEC"
#define XATTR_NAME_SMACK XATTR_SECURITY_PREFIX XATTR_SMACK_SUFFIX
#define XATTR_NAME_SMACKIPIN XATTR_SECURITY_PREFIX XATTR_SMACK_IPIN
#define XATTR_NAME_SMACKIPOUT XATTR_SECURITY_PREFIX XATTR_SMACK_IPOUT
+#define XATTR_NAME_SMACKEXEC XATTR_SECURITY_PREFIX XATTR_SMACK_EXEC
#define XATTR_CAPS_SUFFIX "capability"
#define XATTR_NAME_CAPS XATTR_SECURITY_PREFIX XATTR_CAPS_SUFFIX
diff --git a/security/smack/smack.h b/security/smack/smack.h
index 43ae747..a2e2cdf 100644
--- a/security/smack/smack.h
+++ b/security/smack/smack.h
@@ -51,10 +51,16 @@ struct socket_smack {
*/
struct inode_smack {
char *smk_inode; /* label of the fso */
+ char *smk_task; /* label of the task */
struct mutex smk_lock; /* initialization lock */
int smk_flags; /* smack inode flags */
};
+struct task_smack {
+ char *smk_task; /* label used for access control */
+ char *smk_forked; /* label when forked */
+};
+
#define SMK_INODE_INSTANT 0x01 /* inode is instantiated */
/*
@@ -243,6 +249,30 @@ static inline char *smk_of_inode(const struct inode *isp)
}
/*
+ * Present a pointer to the smack label in an task blob.
+ */
+static inline char *smk_of_task(const struct task_smack *tsp)
+{
+ return tsp->smk_task;
+}
+
+/*
+ * Present a pointer to the forked smack label in an task blob.
+ */
+static inline char *smk_of_forked(const struct task_smack *tsp)
+{
+ return tsp->smk_forked;
+}
+
+/*
+ * Present a pointer to the smack label in the curren task blob.
+ */
+static inline char *smk_of_current(void)
+{
+ return smk_of_task(current_security());
+}
+
+/*
* logging functions
*/
#define SMACK_AUDIT_DENIED 0x1
diff --git a/security/smack/smack_access.c b/security/smack/smack_access.c
index f4fac64..42becbc 100644
--- a/security/smack/smack_access.c
+++ b/security/smack/smack_access.c
@@ -185,7 +185,7 @@ out_audit:
int smk_curacc(char *obj_label, u32 mode, struct smk_audit_info *a)
{
int rc;
- char *sp = current_security();
+ char *sp = smk_of_current();
rc = smk_access(sp, obj_label, mode, NULL);
if (rc == 0)
@@ -196,7 +196,7 @@ int smk_curacc(char *obj_label, u32 mode, struct smk_audit_info *a)
* only one that gets privilege and current does not
* have that label.
*/
- if (smack_onlycap != NULL && smack_onlycap != current->cred->security)
+ if (smack_onlycap != NULL && smack_onlycap != sp)
goto out_audit;
if (capable(CAP_MAC_OVERRIDE))
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index a1bdbfa..14be2b2 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -43,7 +43,7 @@
* Returns a pointer to the master list entry for the Smack label
* or NULL if there was no label to fetch.
*/
-static char *smk_fetch(struct inode *ip, struct dentry *dp)
+static char *smk_fetch(const char *name, struct inode *ip, struct dentry *dp)
{
int rc;
char in[SMK_LABELLEN];
@@ -51,7 +51,7 @@ static char *smk_fetch(struct inode *ip, struct dentry *dp)
if (ip->i_op->getxattr == NULL)
return NULL;
- rc = ip->i_op->getxattr(dp, XATTR_NAME_SMACK, in, SMK_LABELLEN);
+ rc = ip->i_op->getxattr(dp, name, in, SMK_LABELLEN);
if (rc < 0)
return NULL;
@@ -103,8 +103,8 @@ static int smack_ptrace_access_check(struct task_struct *ctp, unsigned int mode)
if (rc != 0)
return rc;
- sp = current_security();
- tsp = task_security(ctp);
+ sp = smk_of_current();
+ tsp = smk_of_task(task_security(ctp));
smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_TASK);
smk_ad_setfield_u_tsk(&ad, ctp);
@@ -138,8 +138,8 @@ static int smack_ptrace_traceme(struct task_struct *ptp)
smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_TASK);
smk_ad_setfield_u_tsk(&ad, ptp);
- sp = current_security();
- tsp = task_security(ptp);
+ sp = smk_of_current();
+ tsp = smk_of_task(task_security(ptp));
/* we won't log here, because rc can be overriden */
rc = smk_access(tsp, sp, MAY_READWRITE, NULL);
if (rc != 0 && has_capability(ptp, CAP_MAC_OVERRIDE))
@@ -160,7 +160,7 @@ static int smack_ptrace_traceme(struct task_struct *ptp)
static int smack_syslog(int type, bool from_file)
{
int rc;
- char *sp = current_security();
+ char *sp = smk_of_current();
rc = cap_syslog(type, from_file);
if (rc != 0)
@@ -395,6 +395,40 @@ static int smack_sb_umount(struct vfsmount *mnt, int flags)
}
/*
+ * BPRM hooks
+ */
+
+static int smack_bprm_set_creds(struct linux_binprm *bprm)
+{
+ struct task_smack *tsp = bprm->cred->security;
+ struct inode_smack *isp;
+ struct dentry *dp;
+ int rc;
+
+ rc = cap_bprm_set_creds(bprm);
+ if (rc != 0)
+ return rc;
+
+ if (bprm->cred_prepared)
+ return 0;
+
+ if (bprm->file == NULL || bprm->file->f_dentry == NULL)
+ return 0;
+
+ dp = bprm->file->f_dentry;
+
+ if (dp->d_inode == NULL)
+ return 0;
+
+ isp = dp->d_inode->i_security;
+
+ if (isp->smk_task != NULL)
+ tsp->smk_task = isp->smk_task;
+
+ return 0;
+}
+
+/*
* Inode hooks
*/
@@ -406,7 +440,7 @@ static int smack_sb_umount(struct vfsmount *mnt, int flags)
*/
static int smack_inode_alloc_security(struct inode *inode)
{
- inode->i_security = new_inode_smack(current_security());
+ inode->i_security = new_inode_smack(smk_of_current());
if (inode->i_security == NULL)
return -ENOMEM;
return 0;
@@ -668,7 +702,8 @@ static int smack_inode_setxattr(struct dentry *dentry, const char *name,
if (strcmp(name, XATTR_NAME_SMACK) == 0 ||
strcmp(name, XATTR_NAME_SMACKIPIN) == 0 ||
- strcmp(name, XATTR_NAME_SMACKIPOUT) == 0) {
+ strcmp(name, XATTR_NAME_SMACKIPOUT) == 0 ||
+ strcmp(name, XATTR_NAME_SMACKEXEC) == 0) {
if (!capable(CAP_MAC_ADMIN))
rc = -EPERM;
/*
@@ -761,7 +796,8 @@ static int smack_inode_removexattr(struct dentry *dentry, const char *name)
if (strcmp(name, XATTR_NAME_SMACK) == 0 ||
strcmp(name, XATTR_NAME_SMACKIPIN) == 0 ||
- strcmp(name, XATTR_NAME_SMACKIPOUT) == 0) {
+ strcmp(name, XATTR_NAME_SMACKIPOUT) == 0 ||
+ strcmp(name, XATTR_NAME_SMACKEXEC) == 0) {
if (!capable(CAP_MAC_ADMIN))
rc = -EPERM;
} else
@@ -899,7 +935,7 @@ static int smack_file_permission(struct file *file, int mask)
*/
static int smack_file_alloc_security(struct file *file)
{
- file->f_security = current_security();
+ file->f_security = smk_of_current();
return 0;
}
@@ -1009,7 +1045,7 @@ static int smack_file_fcntl(struct file *file, unsigned int cmd,
*/
static int smack_file_set_fowner(struct file *file)
{
- file->f_security = current_security();
+ file->f_security = smk_of_current();
return 0;
}
@@ -1029,7 +1065,7 @@ static int smack_file_send_sigiotask(struct task_struct *tsk,
{
struct file *file;
int rc;
- char *tsp = tsk->cred->security;
+ char *tsp = smk_of_task(tsk->cred->security);
struct smk_audit_info ad;
/*
@@ -1086,7 +1122,9 @@ static int smack_file_receive(struct file *file)
*/
static int smack_cred_alloc_blank(struct cred *cred, gfp_t gfp)
{
- cred->security = NULL;
+ cred->security = kzalloc(sizeof(struct task_smack), gfp);
+ if (cred->security == NULL)
+ return -ENOMEM;
return 0;
}
@@ -1101,7 +1139,7 @@ static int smack_cred_alloc_blank(struct cred *cred, gfp_t gfp)
*/
static void smack_cred_free(struct cred *cred)
{
- cred->security = NULL;
+ kfree(cred->security);
}
/**
@@ -1115,7 +1153,16 @@ static void smack_cred_free(struct cred *cred)
static int smack_cred_prepare(struct cred *new, const struct cred *old,
gfp_t gfp)
{
- new->security = old->security;
+ struct task_smack *old_tsp = old->security;
+ struct task_smack *new_tsp;
+
+ new_tsp = kzalloc(sizeof(struct task_smack), gfp);
+ if (new_tsp == NULL)
+ return -ENOMEM;
+
+ new_tsp->smk_task = old_tsp->smk_task;
+ new_tsp->smk_forked = old_tsp->smk_task;
+ new->security = new_tsp;
return 0;
}
@@ -1128,7 +1175,11 @@ static int smack_cred_prepare(struct cred *new, const struct cred *old,
*/
static void smack_cred_transfer(struct cred *new, const struct cred *old)
{
- new->security = old->security;
+ struct task_smack *old_tsp = old->security;
+ struct task_smack *new_tsp = new->security;
+
+ new_tsp->smk_task = old_tsp->smk_task;
+ new_tsp->smk_forked = old_tsp->smk_task;
}
/**
@@ -1140,12 +1191,13 @@ static void smack_cred_transfer(struct cred *new, const struct cred *old)
*/
static int smack_kernel_act_as(struct cred *new, u32 secid)
{
+ struct task_smack *new_tsp = new->security;
char *smack = smack_from_secid(secid);
if (smack == NULL)
return -EINVAL;
- new->security = smack;
+ new_tsp->smk_task = smack;
return 0;
}
@@ -1161,8 +1213,10 @@ static int smack_kernel_create_files_as(struct cred *new,
struct inode *inode)
{
struct inode_smack *isp = inode->i_security;
+ struct task_smack *tsp = new->security;
- new->security = isp->smk_inode;
+ tsp->smk_forked = isp->smk_inode;
+ tsp->smk_task = isp->smk_inode;
return 0;
}
@@ -1179,7 +1233,7 @@ static int smk_curacc_on_task(struct task_struct *p, int access)
smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_TASK);
smk_ad_setfield_u_tsk(&ad, p);
- return smk_curacc(task_security(p), access, &ad);
+ return smk_curacc(smk_of_task(task_security(p)), access, &ad);
}
/**
@@ -1225,7 +1279,7 @@ static int smack_task_getsid(struct task_struct *p)
*/
static void smack_task_getsecid(struct task_struct *p, u32 *secid)
{
- *secid = smack_to_secid(task_security(p));
+ *secid = smack_to_secid(smk_of_task(task_security(p)));
}
/**
@@ -1337,14 +1391,15 @@ static int smack_task_kill(struct task_struct *p, struct siginfo *info,
* can write the receiver.
*/
if (secid == 0)
- return smk_curacc(task_security(p), MAY_WRITE, &ad);
+ return smk_curacc(smk_of_task(task_security(p)), MAY_WRITE,
+ &ad);
/*
* If the secid isn't 0 we're dealing with some USB IO
* specific behavior. This is not clean. For one thing
* we can't take privilege into account.
*/
- return smk_access(smack_from_secid(secid), task_security(p),
- MAY_WRITE, &ad);
+ return smk_access(smack_from_secid(secid),
+ smk_of_task(task_security(p)), MAY_WRITE, &ad);
}
/**
@@ -1356,12 +1411,12 @@ static int smack_task_kill(struct task_struct *p, struct siginfo *info,
static int smack_task_wait(struct task_struct *p)
{
struct smk_audit_info ad;
- char *sp = current_security();
- char *tsp = task_security(p);
+ char *sp = smk_of_current();
+ char *tsp = smk_of_forked(task_security(p));
int rc;
/* we don't log here, we can be overriden */
- rc = smk_access(sp, tsp, MAY_WRITE, NULL);
+ rc = smk_access(tsp, sp, MAY_WRITE, NULL);
if (rc == 0)
goto out_log;
@@ -1382,7 +1437,7 @@ static int smack_task_wait(struct task_struct *p)
out_log:
smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_TASK);
smk_ad_setfield_u_tsk(&ad, p);
- smack_log(sp, tsp, MAY_WRITE, rc, &ad);
+ smack_log(tsp, sp, MAY_WRITE, rc, &ad);
return rc;
}
@@ -1396,7 +1451,7 @@ static int smack_task_wait(struct task_struct *p)
static void smack_task_to_inode(struct task_struct *p, struct inode *inode)
{
struct inode_smack *isp = inode->i_security;
- isp->smk_inode = task_security(p);
+ isp->smk_inode = smk_of_task(task_security(p));
}
/*
@@ -1415,7 +1470,7 @@ static void smack_task_to_inode(struct task_struct *p, struct inode *inode)
*/
static int smack_sk_alloc_security(struct sock *sk, int family, gfp_t gfp_flags)
{
- char *csp = current_security();
+ char *csp = smk_of_current();
struct socket_smack *ssp;
ssp = kzalloc(sizeof(struct socket_smack), gfp_flags);
@@ -1756,7 +1811,7 @@ static int smack_flags_to_may(int flags)
*/
static int smack_msg_msg_alloc_security(struct msg_msg *msg)
{
- msg->security = current_security();
+ msg->security = smk_of_current();
return 0;
}
@@ -1792,7 +1847,7 @@ static int smack_shm_alloc_security(struct shmid_kernel *shp)
{
struct kern_ipc_perm *isp = &shp->shm_perm;
- isp->security = current_security();
+ isp->security = smk_of_current();
return 0;
}
@@ -1915,7 +1970,7 @@ static int smack_sem_alloc_security(struct sem_array *sma)
{
struct kern_ipc_perm *isp = &sma->sem_perm;
- isp->security = current_security();
+ isp->security = smk_of_current();
return 0;
}
@@ -2033,7 +2088,7 @@ static int smack_msg_queue_alloc_security(struct msg_queue *msq)
{
struct kern_ipc_perm *kisp = &msq->q_perm;
- kisp->security = current_security();
+ kisp->security = smk_of_current();
return 0;
}
@@ -2205,7 +2260,7 @@ static void smack_d_instantiate(struct dentry *opt_dentry, struct inode *inode)
struct super_block *sbp;
struct superblock_smack *sbsp;
struct inode_smack *isp;
- char *csp = current_security();
+ char *csp = smk_of_current();
char *fetched;
char *final;
struct dentry *dp;
@@ -2325,9 +2380,13 @@ static void smack_d_instantiate(struct dentry *opt_dentry, struct inode *inode)
* Get the dentry for xattr.
*/
dp = dget(opt_dentry);
- fetched = smk_fetch(inode, dp);
- if (fetched != NULL)
+ fetched = smk_fetch(XATTR_NAME_SMACK, inode, dp);
+ if (fetched != NULL) {
final = fetched;
+ isp->smk_task = smk_fetch(XATTR_NAME_SMACKEXEC, inode,
+ dp);
+ }
+
dput(dp);
break;
}
@@ -2362,7 +2421,7 @@ static int smack_getprocattr(struct task_struct *p, char *name, char **value)
if (strcmp(name, "current") != 0)
return -EINVAL;
- cp = kstrdup(task_security(p), GFP_KERNEL);
+ cp = kstrdup(smk_of_task(task_security(p)), GFP_KERNEL);
if (cp == NULL)
return -ENOMEM;
@@ -2386,6 +2445,7 @@ static int smack_getprocattr(struct task_struct *p, char *name, char **value)
static int smack_setprocattr(struct task_struct *p, char *name,
void *value, size_t size)
{
+ struct task_smack *tsp;
struct cred *new;
char *newsmack;
@@ -2418,7 +2478,13 @@ static int smack_setprocattr(struct task_struct *p, char *name,
new = prepare_creds();
if (new == NULL)
return -ENOMEM;
- new->security = newsmack;
+ tsp = kzalloc(sizeof(struct task_smack), GFP_KERNEL);
+ if (tsp == NULL) {
+ kfree(new);
+ return -ENOMEM;
+ }
+ tsp->smk_task = newsmack;
+ new->security = tsp;
commit_creds(new);
return size;
}
@@ -2719,7 +2785,7 @@ static void smack_sock_graft(struct sock *sk, struct socket *parent)
return;
ssp = sk->sk_security;
- ssp->smk_in = ssp->smk_out = current_security();
+ ssp->smk_in = ssp->smk_out = smk_of_current();
/* cssp->smk_packet is already set in smack_inet_csk_clone() */
}
@@ -2840,7 +2906,7 @@ static void smack_inet_csk_clone(struct sock *sk,
static int smack_key_alloc(struct key *key, const struct cred *cred,
unsigned long flags)
{
- key->security = cred->security;
+ key->security = smk_of_task(cred->security);
return 0;
}
@@ -2869,6 +2935,7 @@ static int smack_key_permission(key_ref_t key_ref,
{
struct key *keyp;
struct smk_audit_info ad;
+ char *tsp = smk_of_task(cred->security);
keyp = key_ref_to_ptr(key_ref);
if (keyp == NULL)
@@ -2882,14 +2949,14 @@ static int smack_key_permission(key_ref_t key_ref,
/*
* This should not occur
*/
- if (cred->security == NULL)
+ if (tsp == NULL)
return -EACCES;
#ifdef CONFIG_AUDIT
smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_KEY);
ad.a.u.key_struct.key = keyp->serial;
ad.a.u.key_struct.key_desc = keyp->description;
#endif
- return smk_access(cred->security, keyp->security,
+ return smk_access(tsp, keyp->security,
MAY_READWRITE, &ad);
}
#endif /* CONFIG_KEYS */
@@ -3091,6 +3158,8 @@ struct security_operations smack_ops = {
.sb_mount = smack_sb_mount,
.sb_umount = smack_sb_umount,
+ .bprm_set_creds = smack_bprm_set_creds,
+
.inode_alloc_security = smack_inode_alloc_security,
.inode_free_security = smack_inode_free_security,
.inode_init_security = smack_inode_init_security,
@@ -3227,9 +3296,16 @@ static __init void init_smack_know_list(void)
static __init int smack_init(void)
{
struct cred *cred;
+ struct task_smack *tsp;
+
+ tsp = kzalloc(sizeof(struct task_smack), GFP_KERNEL);
+ if (tsp == NULL)
+ return -ENOMEM;
- if (!security_module_enable(&smack_ops))
+ if (!security_module_enable(&smack_ops)) {
+ kfree(tsp);
return 0;
+ }
printk(KERN_INFO "Smack: Initializing.\n");
@@ -3237,7 +3313,9 @@ static __init int smack_init(void)
* Set the security state for the initial task.
*/
cred = (struct cred *) current->cred;
- cred->security = &smack_known_floor.smk_known;
+ tsp->smk_forked = smack_known_floor.smk_known;
+ tsp->smk_task = smack_known_floor.smk_known;
+ cred->security = tsp;
/* initialize the smack_know_list */
init_smack_know_list();
diff --git a/security/smack/smackfs.c b/security/smack/smackfs.c
index dc1fd62..01a0be9 100644
--- a/security/smack/smackfs.c
+++ b/security/smack/smackfs.c
@@ -121,7 +121,7 @@ static void smk_netlabel_audit_set(struct netlbl_audit *nap)
{
nap->loginuid = audit_get_loginuid(current);
nap->sessionid = audit_get_sessionid(current);
- nap->secid = smack_to_secid(current_security());
+ nap->secid = smack_to_secid(smk_of_current());
}
/*
@@ -1160,7 +1160,7 @@ static ssize_t smk_write_onlycap(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
char in[SMK_LABELLEN];
- char *sp = current->cred->security;
+ char *sp = smk_of_task(current->cred->security);
if (!capable(CAP_MAC_ADMIN))
return -EPERM;
--
1.7.1

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/