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authorTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>2010-02-11 09:43:20 +0900
committerJames Morris <jmorris@namei.org>2010-02-15 09:00:21 +1100
commitec8e6a4e062e2edebef91e930c20572c9f4c0dda (patch)
tree1c48fb2aa2220b3bdc138e0fb33e1ac632d0dffe /security
parentTOMOYO: Merge headers. (diff)
downloadlinux-dev-ec8e6a4e062e2edebef91e930c20572c9f4c0dda.tar.xz
linux-dev-ec8e6a4e062e2edebef91e930c20572c9f4c0dda.zip
TOMOYO: Add refcounter on domain structure.
Add refcounter to "struct tomoyo_domain_info" since garbage collector needs to determine whether this struct is referred by "struct cred"->security or not. Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Acked-by: Serge Hallyn <serue@us.ibm.com> Signed-off-by: James Morris <jmorris@namei.org>
Diffstat (limited to 'security')
-rw-r--r--security/tomoyo/common.h5
-rw-r--r--security/tomoyo/domain.c2
-rw-r--r--security/tomoyo/tomoyo.c37
3 files changed, 28 insertions, 16 deletions
diff --git a/security/tomoyo/common.h b/security/tomoyo/common.h
index f6aff59b0885..521b4b5addaf 100644
--- a/security/tomoyo/common.h
+++ b/security/tomoyo/common.h
@@ -234,6 +234,10 @@ struct tomoyo_acl_info {
* name of the domain to be created was too long or it could not allocate
* memory. If set to true, more than one process continued execve()
* without domain transition.
+ * (9) "users" is an atomic_t that holds how many "struct cred"->security
+ * are referring this "struct tomoyo_domain_info". If is_deleted == true
+ * and users == 0, this struct will be kfree()d upon next garbage
+ * collection.
*
* A domain's lifecycle is an analogy of files on / directory.
* Multiple domains with the same domainname cannot be created (as with
@@ -252,6 +256,7 @@ struct tomoyo_domain_info {
bool quota_warned; /* Quota warnning flag. */
bool ignore_global_allow_read; /* Ignore "allow_read" flag. */
bool transition_failed; /* Domain transition failed flag. */
+ atomic_t users; /* Number of referring credentials. */
};
/*
diff --git a/security/tomoyo/domain.c b/security/tomoyo/domain.c
index d60b8a61b0c8..6f74b30d6bb1 100644
--- a/security/tomoyo/domain.c
+++ b/security/tomoyo/domain.c
@@ -817,6 +817,8 @@ int tomoyo_find_next_domain(struct linux_binprm *bprm)
out:
if (!domain)
domain = old_domain;
+ /* Update reference count on "struct tomoyo_domain_info". */
+ atomic_inc(&domain->users);
bprm->cred->security = domain;
kfree(real_program_name);
kfree(symlink_program_name);
diff --git a/security/tomoyo/tomoyo.c b/security/tomoyo/tomoyo.c
index 8a0988dade79..87e82bfeac2f 100644
--- a/security/tomoyo/tomoyo.c
+++ b/security/tomoyo/tomoyo.c
@@ -21,21 +21,23 @@ static int tomoyo_cred_alloc_blank(struct cred *new, gfp_t gfp)
static int tomoyo_cred_prepare(struct cred *new, const struct cred *old,
gfp_t gfp)
{
- /*
- * Since "struct tomoyo_domain_info *" is a sharable pointer,
- * we don't need to duplicate.
- */
- new->security = old->security;
+ struct tomoyo_domain_info *domain = old->security;
+ new->security = domain;
+ if (domain)
+ atomic_inc(&domain->users);
return 0;
}
static void tomoyo_cred_transfer(struct cred *new, const struct cred *old)
{
- /*
- * Since "struct tomoyo_domain_info *" is a sharable pointer,
- * we don't need to duplicate.
- */
- new->security = old->security;
+ tomoyo_cred_prepare(new, old, 0);
+}
+
+static void tomoyo_cred_free(struct cred *cred)
+{
+ struct tomoyo_domain_info *domain = cred->security;
+ if (domain)
+ atomic_dec(&domain->users);
}
static int tomoyo_bprm_set_creds(struct linux_binprm *bprm)
@@ -59,6 +61,14 @@ static int tomoyo_bprm_set_creds(struct linux_binprm *bprm)
if (!tomoyo_policy_loaded)
tomoyo_load_policy(bprm->filename);
/*
+ * Release reference to "struct tomoyo_domain_info" stored inside
+ * "bprm->cred->security". New reference to "struct tomoyo_domain_info"
+ * stored inside "bprm->cred->security" will be acquired later inside
+ * tomoyo_find_next_domain().
+ */
+ atomic_dec(&((struct tomoyo_domain_info *)
+ bprm->cred->security)->users);
+ /*
* Tell tomoyo_bprm_check_security() is called for the first time of an
* execve operation.
*/
@@ -75,12 +85,6 @@ static int tomoyo_bprm_check_security(struct linux_binprm *bprm)
* using current domain.
*/
if (!domain) {
- /*
- * We will need to protect whole execve() operation when GC
- * starts kfree()ing "struct tomoyo_domain_info" because
- * bprm->cred->security points to "struct tomoyo_domain_info"
- * but "struct tomoyo_domain_info" does not have a refcounter.
- */
const int idx = tomoyo_read_lock();
const int err = tomoyo_find_next_domain(bprm);
tomoyo_read_unlock(idx);
@@ -265,6 +269,7 @@ static struct security_operations tomoyo_security_ops = {
.cred_alloc_blank = tomoyo_cred_alloc_blank,
.cred_prepare = tomoyo_cred_prepare,
.cred_transfer = tomoyo_cred_transfer,
+ .cred_free = tomoyo_cred_free,
.bprm_set_creds = tomoyo_bprm_set_creds,
.bprm_check_security = tomoyo_bprm_check_security,
.file_fcntl = tomoyo_file_fcntl,