From a29c33f4e506e1dae7e0985b6328046535becbf8 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Tue, 7 Feb 2012 18:51:01 -0800 Subject: userns: Convert setting and getting uid and gid system calls to use kuid and kgid Convert setregid, setgid, setreuid, setuid, setresuid, getresuid, setresgid, getresgid, setfsuid, setfsgid, getuid, geteuid, getgid, getegid, waitpid, waitid, wait4. Convert userspace uids and gids into kuids and kgids before being placed on struct cred. Convert struct cred kuids and kgids into userspace uids and gids when returning them. Signed-off-by: Eric W. Biederman --- kernel/exit.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'kernel/exit.c') diff --git a/kernel/exit.c b/kernel/exit.c index d8bd3b425fa7..789e3c5777f7 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -1214,7 +1214,7 @@ static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p) unsigned long state; int retval, status, traced; pid_t pid = task_pid_vnr(p); - uid_t uid = __task_cred(p)->uid; + uid_t uid = from_kuid_munged(current_user_ns(), __task_cred(p)->uid); struct siginfo __user *infop; if (!likely(wo->wo_flags & WEXITED)) @@ -1427,7 +1427,7 @@ static int wait_task_stopped(struct wait_opts *wo, if (!unlikely(wo->wo_flags & WNOWAIT)) *p_code = 0; - uid = task_uid(p); + uid = from_kuid_munged(current_user_ns(), __task_cred(p)->uid); unlock_sig: spin_unlock_irq(&p->sighand->siglock); if (!exit_code) @@ -1500,7 +1500,7 @@ static int wait_task_continued(struct wait_opts *wo, struct task_struct *p) } if (!unlikely(wo->wo_flags & WNOWAIT)) p->signal->flags &= ~SIGNAL_STOP_CONTINUED; - uid = task_uid(p); + uid = from_kuid_munged(current_user_ns(), __task_cred(p)->uid); spin_unlock_irq(&p->sighand->siglock); pid = task_pid_vnr(p); -- cgit v1.2.2 From 8ca937a668d4be0b0c89c4fc9a912a5885ac06fe Mon Sep 17 00:00:00 2001 From: Sasha Levin Date: Thu, 17 May 2012 23:31:39 +0200 Subject: cred: use correct cred accessor with regards to rcu read lock Commit "userns: Convert setting and getting uid and gid system calls to use kuid and kgid has modified the accessors in wait_task_continued() and wait_task_stopped() to use __task_cred() instead of task_uid(). __task_cred() assumes that we're inside a rcu read lock, which is untrue for these two functions. Modify it to use task_uid() instead. Signed-off-by: Sasha Levin Signed-off-by: Eric W. Biederman --- kernel/exit.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'kernel/exit.c') diff --git a/kernel/exit.c b/kernel/exit.c index 789e3c5777f7..910a0716e17a 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -1427,7 +1427,7 @@ static int wait_task_stopped(struct wait_opts *wo, if (!unlikely(wo->wo_flags & WNOWAIT)) *p_code = 0; - uid = from_kuid_munged(current_user_ns(), __task_cred(p)->uid); + uid = from_kuid_munged(current_user_ns(), task_uid(p)); unlock_sig: spin_unlock_irq(&p->sighand->siglock); if (!exit_code) @@ -1500,7 +1500,7 @@ static int wait_task_continued(struct wait_opts *wo, struct task_struct *p) } if (!unlikely(wo->wo_flags & WNOWAIT)) p->signal->flags &= ~SIGNAL_STOP_CONTINUED; - uid = from_kuid_munged(current_user_ns(), __task_cred(p)->uid); + uid = from_kuid_munged(current_user_ns(), task_uid(p)); spin_unlock_irq(&p->sighand->siglock); pid = task_pid_vnr(p); -- cgit v1.2.2 From e73f8959af0439d114847eab5a8a5ce48f1217c4 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Fri, 11 May 2012 10:59:07 +1000 Subject: task_work_add: generic process-context callbacks Provide a simple mechanism that allows running code in the (nonatomic) context of the arbitrary task. The caller does task_work_add(task, task_work) and this task executes task_work->func() either from do_notify_resume() or from do_exit(). The callback can rely on PF_EXITING to detect the latter case. "struct task_work" can be embedded in another struct, still it has "void *data" to handle the most common/simple case. This allows us to kill the ->replacement_session_keyring hack, and potentially this can have more users. Performance-wise, this adds 2 "unlikely(!hlist_empty())" checks into tracehook_notify_resume() and do_exit(). But at the same time we can remove the "replacement_session_keyring != NULL" checks from arch/*/signal.c and exit_creds(). Note: task_work_add/task_work_run abuses ->pi_lock. This is only because this lock is already used by lookup_pi_state() to synchronize with do_exit() setting PF_EXITING. Fortunately the scope of this lock in task_work.c is really tiny, and the code is unlikely anyway. Signed-off-by: Oleg Nesterov Acked-by: David Howells Cc: Thomas Gleixner Cc: Richard Kuo Cc: Linus Torvalds Cc: Alexander Gordeev Cc: Chris Zankel Cc: David Smith Cc: "Frank Ch. Eigler" Cc: Geert Uytterhoeven Cc: Larry Woodman Cc: Peter Zijlstra Cc: Tejun Heo Cc: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Al Viro --- kernel/exit.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'kernel/exit.c') diff --git a/kernel/exit.c b/kernel/exit.c index 910a0716e17a..3d93325e0b1a 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -946,11 +946,14 @@ void do_exit(long code) exit_signals(tsk); /* sets PF_EXITING */ /* * tsk->flags are checked in the futex code to protect against - * an exiting task cleaning up the robust pi futexes. + * an exiting task cleaning up the robust pi futexes, and in + * task_work_add() to avoid the race with exit_task_work(). */ smp_mb(); raw_spin_unlock_wait(&tsk->pi_lock); + exit_task_work(tsk); + exit_irq_thread(); if (unlikely(in_atomic())) -- cgit v1.2.2 From 4d1d61a6b203d957777d73fcebf19d90b038b5b2 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Fri, 11 May 2012 10:59:08 +1000 Subject: genirq: reimplement exit_irq_thread() hook via task_work_add() exit_irq_thread() and task->irq_thread are needed to handle the unexpected (and unlikely) exit of irq-thread. We can use task_work instead and make this all private to kernel/irq/manage.c, cleanup plus micro-optimization. 1. rename exit_irq_thread() to irq_thread_dtor(), make it static, and move it up before irq_thread(). 2. change irq_thread() to do task_work_add(irq_thread_dtor) at the start and task_work_cancel() before return. tracehook_notify_resume() can never play with kthreads, only do_exit()->exit_task_work() can call the callback and this is what we want. 3. remove task_struct->irq_thread and the special hook in do_exit(). Signed-off-by: Oleg Nesterov Reviewed-by: Thomas Gleixner Cc: David Howells Cc: Richard Kuo Cc: Linus Torvalds Cc: Alexander Gordeev Cc: Chris Zankel Cc: David Smith Cc: "Frank Ch. Eigler" Cc: Geert Uytterhoeven Cc: Larry Woodman Cc: Peter Zijlstra Cc: Tejun Heo Cc: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Al Viro --- kernel/exit.c | 2 -- 1 file changed, 2 deletions(-) (limited to 'kernel/exit.c') diff --git a/kernel/exit.c b/kernel/exit.c index 3d93325e0b1a..3ecd096e5d4d 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -954,8 +954,6 @@ void do_exit(long code) exit_task_work(tsk); - exit_irq_thread(); - if (unlikely(in_atomic())) printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n", current->comm, task_pid_nr(current), -- cgit v1.2.2 From 43e13cc107cf6cd3c15fbe1cef849435c2223d50 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Thu, 31 May 2012 16:26:16 -0700 Subject: cred: remove task_is_dead() from __task_cred() validation Commit 8f92054e7ca1 ("CRED: Fix __task_cred()'s lockdep check and banner comment"): add the following validation condition: task->exit_state >= 0 to permit the access if the target task is dead and therefore unable to change its own credentials. OK, but afaics currently this can only help wait_task_zombie() which calls __task_cred() without rcu lock. Remove this validation and change wait_task_zombie() to use task_uid() instead. This means we do rcu_read_lock() only to shut up the lockdep, but we already do the same in, say, wait_task_stopped(). task_is_dead() should die, task->exit_state != 0 means that this task has passed exit_notify(), only do_wait-like code paths should use this. Unfortunately, we can't kill task_is_dead() right now, it has already acquired buggy users in drivers/staging. The fix already exists. Signed-off-by: Oleg Nesterov Reviewed-by: "Eric W. Biederman" Acked-by: David Howells Cc: Jiri Olsa Cc: Paul E. McKenney Cc: James Morris Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/exit.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel/exit.c') diff --git a/kernel/exit.c b/kernel/exit.c index 910a0716e17a..3281493ce7ad 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -1214,7 +1214,7 @@ static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p) unsigned long state; int retval, status, traced; pid_t pid = task_pid_vnr(p); - uid_t uid = from_kuid_munged(current_user_ns(), __task_cred(p)->uid); + uid_t uid = from_kuid_munged(current_user_ns(), task_uid(p)); struct siginfo __user *infop; if (!likely(wo->wo_flags & WEXITED)) -- cgit v1.2.2 From 168eeccbc956d2ec083c3a513f7706784ee0dc5f Mon Sep 17 00:00:00 2001 From: Tim Bird Date: Thu, 31 May 2012 16:26:16 -0700 Subject: stack usage: add pid to warning printk in check_stack_usage In embedded systems, sometimes the same program (busybox) is the cause of multiple warnings. Outputting the pid with the program name in the warning printk helps distinguish which instances of a program are using the stack most. This is a small patch, but useful. Signed-off-by: Tim Bird Cc: Oleg Nesterov Cc: Frederic Weisbecker Cc: Andrea Arcangeli Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/exit.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'kernel/exit.c') diff --git a/kernel/exit.c b/kernel/exit.c index 3281493ce7ad..6d85655353e9 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -884,9 +884,9 @@ static void check_stack_usage(void) spin_lock(&low_water_lock); if (free < lowest_to_date) { - printk(KERN_WARNING "%s used greatest stack depth: %lu bytes " - "left\n", - current->comm, free); + printk(KERN_WARNING "%s (%d) used greatest stack depth: " + "%lu bytes left\n", + current->comm, task_pid_nr(current), free); lowest_to_date = free; } spin_unlock(&low_water_lock); -- cgit v1.2.2