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authorTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>2010-02-10 19:43:20 -0500
committerJames Morris <jmorris@namei.org>2010-02-14 17:00:21 -0500
commitec8e6a4e062e2edebef91e930c20572c9f4c0dda (patch)
tree1c48fb2aa2220b3bdc138e0fb33e1ac632d0dffe /security
parent76bb0895d038be7bcdb6ccfcd2dd7deb30371d6b (diff)
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 f6aff59b088..521b4b5adda 100644
--- a/security/tomoyo/common.h
+++ b/security/tomoyo/common.h
@@ -234,6 +234,10 @@ struct tomoyo_acl_info {
234 * name of the domain to be created was too long or it could not allocate 234 * name of the domain to be created was too long or it could not allocate
235 * memory. If set to true, more than one process continued execve() 235 * memory. If set to true, more than one process continued execve()
236 * without domain transition. 236 * without domain transition.
237 * (9) "users" is an atomic_t that holds how many "struct cred"->security
238 * are referring this "struct tomoyo_domain_info". If is_deleted == true
239 * and users == 0, this struct will be kfree()d upon next garbage
240 * collection.
237 * 241 *
238 * A domain's lifecycle is an analogy of files on / directory. 242 * A domain's lifecycle is an analogy of files on / directory.
239 * Multiple domains with the same domainname cannot be created (as with 243 * Multiple domains with the same domainname cannot be created (as with
@@ -252,6 +256,7 @@ struct tomoyo_domain_info {
252 bool quota_warned; /* Quota warnning flag. */ 256 bool quota_warned; /* Quota warnning flag. */
253 bool ignore_global_allow_read; /* Ignore "allow_read" flag. */ 257 bool ignore_global_allow_read; /* Ignore "allow_read" flag. */
254 bool transition_failed; /* Domain transition failed flag. */ 258 bool transition_failed; /* Domain transition failed flag. */
259 atomic_t users; /* Number of referring credentials. */
255}; 260};
256 261
257/* 262/*
diff --git a/security/tomoyo/domain.c b/security/tomoyo/domain.c
index d60b8a61b0c..6f74b30d6bb 100644
--- a/security/tomoyo/domain.c
+++ b/security/tomoyo/domain.c
@@ -817,6 +817,8 @@ int tomoyo_find_next_domain(struct linux_binprm *bprm)
817 out: 817 out:
818 if (!domain) 818 if (!domain)
819 domain = old_domain; 819 domain = old_domain;
820 /* Update reference count on "struct tomoyo_domain_info". */
821 atomic_inc(&domain->users);
820 bprm->cred->security = domain; 822 bprm->cred->security = domain;
821 kfree(real_program_name); 823 kfree(real_program_name);
822 kfree(symlink_program_name); 824 kfree(symlink_program_name);
diff --git a/security/tomoyo/tomoyo.c b/security/tomoyo/tomoyo.c
index 8a0988dade7..87e82bfeac2 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)
21static int tomoyo_cred_prepare(struct cred *new, const struct cred *old, 21static int tomoyo_cred_prepare(struct cred *new, const struct cred *old,
22 gfp_t gfp) 22 gfp_t gfp)
23{ 23{
24 /* 24 struct tomoyo_domain_info *domain = old->security;
25 * Since "struct tomoyo_domain_info *" is a sharable pointer, 25 new->security = domain;
26 * we don't need to duplicate. 26 if (domain)
27 */ 27 atomic_inc(&domain->users);
28 new->security = old->security;
29 return 0; 28 return 0;
30} 29}
31 30
32static void tomoyo_cred_transfer(struct cred *new, const struct cred *old) 31static void tomoyo_cred_transfer(struct cred *new, const struct cred *old)
33{ 32{
34 /* 33 tomoyo_cred_prepare(new, old, 0);
35 * Since "struct tomoyo_domain_info *" is a sharable pointer, 34}
36 * we don't need to duplicate. 35
37 */ 36static void tomoyo_cred_free(struct cred *cred)
38 new->security = old->security; 37{
38 struct tomoyo_domain_info *domain = cred->security;
39 if (domain)
40 atomic_dec(&domain->users);
39} 41}
40 42
41static int tomoyo_bprm_set_creds(struct linux_binprm *bprm) 43static int tomoyo_bprm_set_creds(struct linux_binprm *bprm)
@@ -59,6 +61,14 @@ static int tomoyo_bprm_set_creds(struct linux_binprm *bprm)
59 if (!tomoyo_policy_loaded) 61 if (!tomoyo_policy_loaded)
60 tomoyo_load_policy(bprm->filename); 62 tomoyo_load_policy(bprm->filename);
61 /* 63 /*
64 * Release reference to "struct tomoyo_domain_info" stored inside
65 * "bprm->cred->security". New reference to "struct tomoyo_domain_info"
66 * stored inside "bprm->cred->security" will be acquired later inside
67 * tomoyo_find_next_domain().
68 */
69 atomic_dec(&((struct tomoyo_domain_info *)
70 bprm->cred->security)->users);
71 /*
62 * Tell tomoyo_bprm_check_security() is called for the first time of an 72 * Tell tomoyo_bprm_check_security() is called for the first time of an
63 * execve operation. 73 * execve operation.
64 */ 74 */
@@ -75,12 +85,6 @@ static int tomoyo_bprm_check_security(struct linux_binprm *bprm)
75 * using current domain. 85 * using current domain.
76 */ 86 */
77 if (!domain) { 87 if (!domain) {
78 /*
79 * We will need to protect whole execve() operation when GC
80 * starts kfree()ing "struct tomoyo_domain_info" because
81 * bprm->cred->security points to "struct tomoyo_domain_info"
82 * but "struct tomoyo_domain_info" does not have a refcounter.
83 */
84 const int idx = tomoyo_read_lock(); 88 const int idx = tomoyo_read_lock();
85 const int err = tomoyo_find_next_domain(bprm); 89 const int err = tomoyo_find_next_domain(bprm);
86 tomoyo_read_unlock(idx); 90 tomoyo_read_unlock(idx);
@@ -265,6 +269,7 @@ static struct security_operations tomoyo_security_ops = {
265 .cred_alloc_blank = tomoyo_cred_alloc_blank, 269 .cred_alloc_blank = tomoyo_cred_alloc_blank,
266 .cred_prepare = tomoyo_cred_prepare, 270 .cred_prepare = tomoyo_cred_prepare,
267 .cred_transfer = tomoyo_cred_transfer, 271 .cred_transfer = tomoyo_cred_transfer,
272 .cred_free = tomoyo_cred_free,
268 .bprm_set_creds = tomoyo_bprm_set_creds, 273 .bprm_set_creds = tomoyo_bprm_set_creds,
269 .bprm_check_security = tomoyo_bprm_check_security, 274 .bprm_check_security = tomoyo_bprm_check_security,
270 .file_fcntl = tomoyo_file_fcntl, 275 .file_fcntl = tomoyo_file_fcntl,