From 6f7c41374b62fd80bbd8aae3536c43688c54d95e Mon Sep 17 00:00:00 2001 From: Tetsuo Handa Date: Mon, 25 Nov 2019 10:46:51 +0900 Subject: [PATCH 1/2] tomoyo: Don't use nifty names on sockets. syzbot is reporting that use of SOCKET_I()->sk from open() can result in use after free problem [1], for socket's inode is still reachable via /proc/pid/fd/n despite destruction of SOCKET_I()->sk already completed. At first I thought that this race condition applies to only open/getattr permission checks. But James Morris has pointed out that there are more permission checks where this race condition applies to. Thus, get rid of tomoyo_get_socket_name() instead of conditionally bypassing permission checks on sockets. As a side effect of this patch, "socket:[family=\$:type=\$:protocol=\$]" in the policy files has to be rewritten to "socket:[\$]". [1] https://syzkaller.appspot.com/bug?id=73d590010454403d55164cca23bd0565b1eb3b74 Signed-off-by: Tetsuo Handa Reported-by: syzbot Reported-by: James Morris --- security/tomoyo/realpath.c | 32 +------------------------------- 1 file changed, 1 insertion(+), 31 deletions(-) diff --git a/security/tomoyo/realpath.c b/security/tomoyo/realpath.c index e7832448d721d..bf38fc1b59b28 100644 --- a/security/tomoyo/realpath.c +++ b/security/tomoyo/realpath.c @@ -217,31 +217,6 @@ static char *tomoyo_get_local_path(struct dentry *dentry, char * const buffer, return ERR_PTR(-ENOMEM); } -/** - * tomoyo_get_socket_name - Get the name of a socket. - * - * @path: Pointer to "struct path". - * @buffer: Pointer to buffer to return value in. - * @buflen: Sizeof @buffer. - * - * Returns the buffer. - */ -static char *tomoyo_get_socket_name(const struct path *path, char * const buffer, - const int buflen) -{ - struct inode *inode = d_backing_inode(path->dentry); - struct socket *sock = inode ? SOCKET_I(inode) : NULL; - struct sock *sk = sock ? sock->sk : NULL; - - if (sk) { - snprintf(buffer, buflen, "socket:[family=%u:type=%u:protocol=%u]", - sk->sk_family, sk->sk_type, sk->sk_protocol); - } else { - snprintf(buffer, buflen, "socket:[unknown]"); - } - return buffer; -} - /** * tomoyo_realpath_from_path - Returns realpath(3) of the given pathname but ignores chroot'ed root. * @@ -279,12 +254,7 @@ char *tomoyo_realpath_from_path(const struct path *path) break; /* To make sure that pos is '\0' terminated. */ buf[buf_len - 1] = '\0'; - /* Get better name for socket. */ - if (sb->s_magic == SOCKFS_MAGIC) { - pos = tomoyo_get_socket_name(path, buf, buf_len - 1); - goto encode; - } - /* For "pipe:[\$]". */ + /* For "pipe:[\$]" and "socket:[\$]". */ if (dentry->d_op && dentry->d_op->d_dname) { pos = dentry->d_op->d_dname(dentry, buf, buf_len - 1); goto encode; From 6bd5ce6089b561f5392460bfb654dea89356ab1b Mon Sep 17 00:00:00 2001 From: Tetsuo Handa Date: Mon, 16 Dec 2019 19:16:48 +0900 Subject: [PATCH 2/2] tomoyo: Suppress RCU warning at list_for_each_entry_rcu(). John Garry has reported that allmodconfig kernel on arm64 causes flood of "RCU-list traversed in non-reader section!!" warning. I don't know what change caused this warning, but this warning is safe because TOMOYO uses SRCU lock instead. Let's suppress this warning by explicitly telling that the caller is holding SRCU lock. Reported-and-tested-by: John Garry Signed-off-by: Tetsuo Handa --- security/tomoyo/common.c | 9 ++++++--- security/tomoyo/domain.c | 15 ++++++++++----- security/tomoyo/group.c | 9 ++++++--- security/tomoyo/util.c | 6 ++++-- 4 files changed, 26 insertions(+), 13 deletions(-) diff --git a/security/tomoyo/common.c b/security/tomoyo/common.c index dd3d5942e6692..c36bafbcd77ee 100644 --- a/security/tomoyo/common.c +++ b/security/tomoyo/common.c @@ -951,7 +951,8 @@ static bool tomoyo_manager(void) exe = tomoyo_get_exe(); if (!exe) return false; - list_for_each_entry_rcu(ptr, &tomoyo_kernel_namespace.policy_list[TOMOYO_ID_MANAGER], head.list) { + list_for_each_entry_rcu(ptr, &tomoyo_kernel_namespace.policy_list[TOMOYO_ID_MANAGER], head.list, + srcu_read_lock_held(&tomoyo_ss)) { if (!ptr->head.is_deleted && (!tomoyo_pathcmp(domainname, ptr->manager) || !strcmp(exe, ptr->manager->name))) { @@ -1095,7 +1096,8 @@ static int tomoyo_delete_domain(char *domainname) if (mutex_lock_interruptible(&tomoyo_policy_lock)) return -EINTR; /* Is there an active domain? */ - list_for_each_entry_rcu(domain, &tomoyo_domain_list, list) { + list_for_each_entry_rcu(domain, &tomoyo_domain_list, list, + srcu_read_lock_held(&tomoyo_ss)) { /* Never delete tomoyo_kernel_domain */ if (domain == &tomoyo_kernel_domain) continue; @@ -2778,7 +2780,8 @@ void tomoyo_check_profile(void) tomoyo_policy_loaded = true; pr_info("TOMOYO: 2.6.0\n"); - list_for_each_entry_rcu(domain, &tomoyo_domain_list, list) { + list_for_each_entry_rcu(domain, &tomoyo_domain_list, list, + srcu_read_lock_held(&tomoyo_ss)) { const u8 profile = domain->profile; struct tomoyo_policy_namespace *ns = domain->ns; diff --git a/security/tomoyo/domain.c b/security/tomoyo/domain.c index 8526a0a740238..7869d6a9980bf 100644 --- a/security/tomoyo/domain.c +++ b/security/tomoyo/domain.c @@ -41,7 +41,8 @@ int tomoyo_update_policy(struct tomoyo_acl_head *new_entry, const int size, if (mutex_lock_interruptible(&tomoyo_policy_lock)) return -ENOMEM; - list_for_each_entry_rcu(entry, list, list) { + list_for_each_entry_rcu(entry, list, list, + srcu_read_lock_held(&tomoyo_ss)) { if (entry->is_deleted == TOMOYO_GC_IN_PROGRESS) continue; if (!check_duplicate(entry, new_entry)) @@ -119,7 +120,8 @@ int tomoyo_update_domain(struct tomoyo_acl_info *new_entry, const int size, } if (mutex_lock_interruptible(&tomoyo_policy_lock)) goto out; - list_for_each_entry_rcu(entry, list, list) { + list_for_each_entry_rcu(entry, list, list, + srcu_read_lock_held(&tomoyo_ss)) { if (entry->is_deleted == TOMOYO_GC_IN_PROGRESS) continue; if (!tomoyo_same_acl_head(entry, new_entry) || @@ -166,7 +168,8 @@ void tomoyo_check_acl(struct tomoyo_request_info *r, u16 i = 0; retry: - list_for_each_entry_rcu(ptr, list, list) { + list_for_each_entry_rcu(ptr, list, list, + srcu_read_lock_held(&tomoyo_ss)) { if (ptr->is_deleted || ptr->type != r->param_type) continue; if (!check_entry(r, ptr)) @@ -298,7 +301,8 @@ static inline bool tomoyo_scan_transition { const struct tomoyo_transition_control *ptr; - list_for_each_entry_rcu(ptr, list, head.list) { + list_for_each_entry_rcu(ptr, list, head.list, + srcu_read_lock_held(&tomoyo_ss)) { if (ptr->head.is_deleted || ptr->type != type) continue; if (ptr->domainname) { @@ -735,7 +739,8 @@ int tomoyo_find_next_domain(struct linux_binprm *bprm) /* Check 'aggregator' directive. */ candidate = &exename; - list_for_each_entry_rcu(ptr, list, head.list) { + list_for_each_entry_rcu(ptr, list, head.list, + srcu_read_lock_held(&tomoyo_ss)) { if (ptr->head.is_deleted || !tomoyo_path_matches_pattern(&exename, ptr->original_name)) diff --git a/security/tomoyo/group.c b/security/tomoyo/group.c index a37c7dc66e444..1cecdd7975971 100644 --- a/security/tomoyo/group.c +++ b/security/tomoyo/group.c @@ -133,7 +133,8 @@ tomoyo_path_matches_group(const struct tomoyo_path_info *pathname, { struct tomoyo_path_group *member; - list_for_each_entry_rcu(member, &group->member_list, head.list) { + list_for_each_entry_rcu(member, &group->member_list, head.list, + srcu_read_lock_held(&tomoyo_ss)) { if (member->head.is_deleted) continue; if (!tomoyo_path_matches_pattern(pathname, member->member_name)) @@ -161,7 +162,8 @@ bool tomoyo_number_matches_group(const unsigned long min, struct tomoyo_number_group *member; bool matched = false; - list_for_each_entry_rcu(member, &group->member_list, head.list) { + list_for_each_entry_rcu(member, &group->member_list, head.list, + srcu_read_lock_held(&tomoyo_ss)) { if (member->head.is_deleted) continue; if (min > member->number.values[1] || @@ -191,7 +193,8 @@ bool tomoyo_address_matches_group(const bool is_ipv6, const __be32 *address, bool matched = false; const u8 size = is_ipv6 ? 16 : 4; - list_for_each_entry_rcu(member, &group->member_list, head.list) { + list_for_each_entry_rcu(member, &group->member_list, head.list, + srcu_read_lock_held(&tomoyo_ss)) { if (member->head.is_deleted) continue; if (member->address.is_ipv6 != is_ipv6) diff --git a/security/tomoyo/util.c b/security/tomoyo/util.c index 52752e1a84ed8..eba0b3395851e 100644 --- a/security/tomoyo/util.c +++ b/security/tomoyo/util.c @@ -594,7 +594,8 @@ struct tomoyo_domain_info *tomoyo_find_domain(const char *domainname) name.name = domainname; tomoyo_fill_path_info(&name); - list_for_each_entry_rcu(domain, &tomoyo_domain_list, list) { + list_for_each_entry_rcu(domain, &tomoyo_domain_list, list, + srcu_read_lock_held(&tomoyo_ss)) { if (!domain->is_deleted && !tomoyo_pathcmp(&name, domain->domainname)) return domain; @@ -1028,7 +1029,8 @@ bool tomoyo_domain_quota_is_ok(struct tomoyo_request_info *r) return false; if (!domain) return true; - list_for_each_entry_rcu(ptr, &domain->acl_info_list, list) { + list_for_each_entry_rcu(ptr, &domain->acl_info_list, list, + srcu_read_lock_held(&tomoyo_ss)) { u16 perm; u8 i;