diff options
-rw-r--r-- | include/linux/cred.h | 2 | ||||
-rw-r--r-- | include/linux/sched/user.h | 7 | ||||
-rw-r--r-- | security/keys/process_keys.c | 41 | ||||
-rw-r--r-- | security/keys/request_key.c | 14 | ||||
-rw-r--r-- | security/yama/yama_lsm.c | 8 |
5 files changed, 37 insertions, 35 deletions
diff --git a/include/linux/cred.h b/include/linux/cred.h index ddd45bb74887..efb6edf32de7 100644 --- a/include/linux/cred.h +++ b/include/linux/cred.h @@ -138,7 +138,7 @@ struct cred { #ifdef CONFIG_KEYS unsigned char jit_keyring; /* default keyring to attach requested * keys to */ - struct key __rcu *session_keyring; /* keyring inherited over fork */ + struct key *session_keyring; /* keyring inherited over fork */ struct key *process_keyring; /* keyring private to this process */ struct key *thread_keyring; /* keyring private to this thread */ struct key *request_key_auth; /* assumed request_key authority */ diff --git a/include/linux/sched/user.h b/include/linux/sched/user.h index c7b5f86b91a1..468d2565a9fe 100644 --- a/include/linux/sched/user.h +++ b/include/linux/sched/user.h @@ -31,6 +31,13 @@ struct user_struct { atomic_long_t pipe_bufs; /* how many pages are allocated in pipe buffers */ #ifdef CONFIG_KEYS + /* + * These pointers can only change from NULL to a non-NULL value once. + * Writes are protected by key_user_keyring_mutex. + * Unlocked readers should use READ_ONCE() unless they know that + * install_user_keyrings() has been called successfully (which sets + * these members to non-NULL values, preventing further modifications). + */ struct key *uid_keyring; /* UID specific keyring */ struct key *session_keyring; /* UID's default session keyring */ #endif diff --git a/security/keys/process_keys.c b/security/keys/process_keys.c index 9320424c4a46..f05f7125a7d5 100644 --- a/security/keys/process_keys.c +++ b/security/keys/process_keys.c @@ -58,7 +58,7 @@ int install_user_keyrings(void) kenter("%p{%u}", user, uid); - if (user->uid_keyring && user->session_keyring) { + if (READ_ONCE(user->uid_keyring) && READ_ONCE(user->session_keyring)) { kleave(" = 0 [exist]"); return 0; } @@ -111,8 +111,10 @@ int install_user_keyrings(void) } /* install the keyrings */ - user->uid_keyring = uid_keyring; - user->session_keyring = session_keyring; + /* paired with READ_ONCE() */ + smp_store_release(&user->uid_keyring, uid_keyring); + /* paired with READ_ONCE() */ + smp_store_release(&user->session_keyring, session_keyring); } mutex_unlock(&key_user_keyring_mutex); @@ -227,6 +229,7 @@ static int install_process_keyring(void) * Install the given keyring as the session keyring of the given credentials * struct, replacing the existing one if any. If the given keyring is NULL, * then install a new anonymous session keyring. + * @cred can not be in use by any task yet. * * Return: 0 on success; -errno on failure. */ @@ -254,7 +257,7 @@ int install_session_keyring_to_cred(struct cred *cred, struct key *keyring) /* install the keyring */ old = cred->session_keyring; - rcu_assign_pointer(cred->session_keyring, keyring); + cred->session_keyring = keyring; if (old) key_put(old); @@ -339,6 +342,7 @@ void key_fsgid_changed(struct task_struct *tsk) key_ref_t search_my_process_keyrings(struct keyring_search_context *ctx) { key_ref_t key_ref, ret, err; + const struct cred *cred = ctx->cred; /* we want to return -EAGAIN or -ENOKEY if any of the keyrings were * searchable, but we failed to find a key or we found a negative key; @@ -352,9 +356,9 @@ key_ref_t search_my_process_keyrings(struct keyring_search_context *ctx) err = ERR_PTR(-EAGAIN); /* search the thread keyring first */ - if (ctx->cred->thread_keyring) { + if (cred->thread_keyring) { key_ref = keyring_search_aux( - make_key_ref(ctx->cred->thread_keyring, 1), ctx); + make_key_ref(cred->thread_keyring, 1), ctx); if (!IS_ERR(key_ref)) goto found; @@ -370,9 +374,9 @@ key_ref_t search_my_process_keyrings(struct keyring_search_context *ctx) } /* search the process keyring second */ - if (ctx->cred->process_keyring) { + if (cred->process_keyring) { key_ref = keyring_search_aux( - make_key_ref(ctx->cred->process_keyring, 1), ctx); + make_key_ref(cred->process_keyring, 1), ctx); if (!IS_ERR(key_ref)) goto found; @@ -391,12 +395,9 @@ key_ref_t search_my_process_keyrings(struct keyring_search_context *ctx) } /* search the session keyring */ - if (ctx->cred->session_keyring) { - rcu_read_lock(); + if (cred->session_keyring) { key_ref = keyring_search_aux( - make_key_ref(rcu_dereference(ctx->cred->session_keyring), 1), - ctx); - rcu_read_unlock(); + make_key_ref(cred->session_keyring, 1), ctx); if (!IS_ERR(key_ref)) goto found; @@ -415,9 +416,9 @@ key_ref_t search_my_process_keyrings(struct keyring_search_context *ctx) } } /* or search the user-session keyring */ - else if (ctx->cred->user->session_keyring) { + else if (READ_ONCE(cred->user->session_keyring)) { key_ref = keyring_search_aux( - make_key_ref(ctx->cred->user->session_keyring, 1), + make_key_ref(READ_ONCE(cred->user->session_keyring), 1), ctx); if (!IS_ERR(key_ref)) goto found; @@ -604,7 +605,7 @@ try_again: goto error; goto reget_creds; } else if (ctx.cred->session_keyring == - ctx.cred->user->session_keyring && + READ_ONCE(ctx.cred->user->session_keyring) && lflags & KEY_LOOKUP_CREATE) { ret = join_session_keyring(NULL); if (ret < 0) @@ -612,15 +613,13 @@ try_again: goto reget_creds; } - rcu_read_lock(); - key = rcu_dereference(ctx.cred->session_keyring); + key = ctx.cred->session_keyring; __key_get(key); - rcu_read_unlock(); key_ref = make_key_ref(key, 1); break; case KEY_SPEC_USER_KEYRING: - if (!ctx.cred->user->uid_keyring) { + if (!READ_ONCE(ctx.cred->user->uid_keyring)) { ret = install_user_keyrings(); if (ret < 0) goto error; @@ -632,7 +631,7 @@ try_again: break; case KEY_SPEC_USER_SESSION_KEYRING: - if (!ctx.cred->user->session_keyring) { + if (!READ_ONCE(ctx.cred->user->session_keyring)) { ret = install_user_keyrings(); if (ret < 0) goto error; diff --git a/security/keys/request_key.c b/security/keys/request_key.c index 2f17d84d46f1..75d87f9e0f49 100644 --- a/security/keys/request_key.c +++ b/security/keys/request_key.c @@ -142,12 +142,10 @@ static int call_sbin_request_key(struct key *authkey, void *aux) prkey = cred->process_keyring->serial; sprintf(keyring_str[1], "%d", prkey); - rcu_read_lock(); - session = rcu_dereference(cred->session_keyring); + session = cred->session_keyring; if (!session) session = cred->user->session_keyring; sskey = session->serial; - rcu_read_unlock(); sprintf(keyring_str[2], "%d", sskey); @@ -287,10 +285,7 @@ static int construct_get_dest_keyring(struct key **_dest_keyring) /* fall through */ case KEY_REQKEY_DEFL_SESSION_KEYRING: - rcu_read_lock(); - dest_keyring = key_get( - rcu_dereference(cred->session_keyring)); - rcu_read_unlock(); + dest_keyring = key_get(cred->session_keyring); if (dest_keyring) break; @@ -298,11 +293,12 @@ static int construct_get_dest_keyring(struct key **_dest_keyring) /* fall through */ case KEY_REQKEY_DEFL_USER_SESSION_KEYRING: dest_keyring = - key_get(cred->user->session_keyring); + key_get(READ_ONCE(cred->user->session_keyring)); break; case KEY_REQKEY_DEFL_USER_KEYRING: - dest_keyring = key_get(cred->user->uid_keyring); + dest_keyring = + key_get(READ_ONCE(cred->user->uid_keyring)); break; case KEY_REQKEY_DEFL_GROUP_KEYRING: diff --git a/security/yama/yama_lsm.c b/security/yama/yama_lsm.c index 57cc60722dd3..efac68556b45 100644 --- a/security/yama/yama_lsm.c +++ b/security/yama/yama_lsm.c @@ -206,7 +206,7 @@ static void yama_ptracer_del(struct task_struct *tracer, * yama_task_free - check for task_pid to remove from exception list * @task: task being removed */ -void yama_task_free(struct task_struct *task) +static void yama_task_free(struct task_struct *task) { yama_ptracer_del(task, task); } @@ -222,7 +222,7 @@ void yama_task_free(struct task_struct *task) * Return 0 on success, -ve on error. -ENOSYS is returned when Yama * does not handle the given option. */ -int yama_task_prctl(int option, unsigned long arg2, unsigned long arg3, +static int yama_task_prctl(int option, unsigned long arg2, unsigned long arg3, unsigned long arg4, unsigned long arg5) { int rc = -ENOSYS; @@ -401,7 +401,7 @@ static int yama_ptrace_access_check(struct task_struct *child, * * Returns 0 if following the ptrace is allowed, -ve on error. */ -int yama_ptrace_traceme(struct task_struct *parent) +static int yama_ptrace_traceme(struct task_struct *parent) { int rc = 0; @@ -452,7 +452,7 @@ static int yama_dointvec_minmax(struct ctl_table *table, int write, static int zero; static int max_scope = YAMA_SCOPE_NO_ATTACH; -struct ctl_path yama_sysctl_path[] = { +static struct ctl_path yama_sysctl_path[] = { { .procname = "kernel", }, { .procname = "yama", }, { } |