From b21507e272627c434e8dd74e8d51fd8245281b59 Mon Sep 17 00:00:00 2001 From: Stephen Smalley Date: Mon, 9 Jan 2017 10:07:31 -0500 Subject: proc,security: move restriction on writing /proc/pid/attr nodes to proc Processes can only alter their own security attributes via /proc/pid/attr nodes. This is presently enforced by each individual security module and is also imposed by the Linux credentials implementation, which only allows a task to alter its own credentials. Move the check enforcing this restriction from the individual security modules to proc_pid_attr_write() before calling the security hook, and drop the unnecessary task argument to the security hook since it can only ever be the current task. Signed-off-by: Stephen Smalley Acked-by: Casey Schaufler Acked-by: John Johansen Signed-off-by: Paul Moore --- security/smack/smack_lsm.c | 11 +---------- 1 file changed, 1 insertion(+), 10 deletions(-) (limited to 'security/smack/smack_lsm.c') diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c index 94dc9d4..8da4a6b 100644 --- a/security/smack/smack_lsm.c +++ b/security/smack/smack_lsm.c @@ -3620,7 +3620,6 @@ static int smack_getprocattr(struct task_struct *p, char *name, char **value) /** * smack_setprocattr - Smack process attribute setting - * @p: the object task * @name: the name of the attribute in /proc/.../attr * @value: the value to set * @size: the size of the value @@ -3630,8 +3629,7 @@ static int smack_getprocattr(struct task_struct *p, char *name, char **value) * * Returns the length of the smack label or an error code */ -static int smack_setprocattr(struct task_struct *p, char *name, - void *value, size_t size) +static int smack_setprocattr(const char *name, void *value, size_t size) { struct task_smack *tsp = current_security(); struct cred *new; @@ -3639,13 +3637,6 @@ static int smack_setprocattr(struct task_struct *p, char *name, struct smack_known_list_elem *sklep; int rc; - /* - * Changing another process' Smack value is too dangerous - * and supports no sane use case. - */ - if (p != current) - return -EPERM; - if (!smack_privileged(CAP_MAC_ADMIN) && list_empty(&tsp->smk_relabel)) return -EPERM; -- cgit v1.1 From 3a2f5a59a695a73e0cde9a61e0feae5fa730e936 Mon Sep 17 00:00:00 2001 From: Stephen Smalley Date: Tue, 10 Jan 2017 12:28:32 -0500 Subject: security,selinux,smack: kill security_task_wait hook As reported by yangshukui, a permission denial from security_task_wait() can lead to a soft lockup in zap_pid_ns_processes() since it only expects sys_wait4() to return 0 or -ECHILD. Further, security_task_wait() can in general lead to zombies; in the absence of some way to automatically reparent a child process upon a denial, the hook is not useful. Remove the security hook and its implementations in SELinux and Smack. Smack already removed its check from its hook. Reported-by: yangshukui Signed-off-by: Stephen Smalley Acked-by: Casey Schaufler Acked-by: Oleg Nesterov Signed-off-by: Paul Moore --- security/smack/smack_lsm.c | 20 -------------------- 1 file changed, 20 deletions(-) (limited to 'security/smack/smack_lsm.c') diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c index 8da4a6b..2166373 100644 --- a/security/smack/smack_lsm.c +++ b/security/smack/smack_lsm.c @@ -2272,25 +2272,6 @@ static int smack_task_kill(struct task_struct *p, struct siginfo *info, } /** - * smack_task_wait - Smack access check for waiting - * @p: task to wait for - * - * Returns 0 - */ -static int smack_task_wait(struct task_struct *p) -{ - /* - * Allow the operation to succeed. - * Zombies are bad. - * In userless environments (e.g. phones) programs - * get marked with SMACK64EXEC and even if the parent - * and child shouldn't be talking the parent still - * may expect to know when the child exits. - */ - return 0; -} - -/** * smack_task_to_inode - copy task smack into the inode blob * @p: task to copy from * @inode: inode to copy to @@ -4658,7 +4639,6 @@ static struct security_hook_list smack_hooks[] = { LSM_HOOK_INIT(task_getscheduler, smack_task_getscheduler), LSM_HOOK_INIT(task_movememory, smack_task_movememory), LSM_HOOK_INIT(task_kill, smack_task_kill), - LSM_HOOK_INIT(task_wait, smack_task_wait), LSM_HOOK_INIT(task_to_inode, smack_task_to_inode), LSM_HOOK_INIT(ipc_permission, smack_ipc_permission), -- cgit v1.1