X-Git-Url: http://pilppa.org/gitweb/gitweb.cgi?a=blobdiff_plain;f=kernel%2Fptrace.c;h=9a111f70145c6673cddf08eeaf2e86da03dff8d8;hb=5091e746848f74c9a2c0579b4ef8d8cd1a6b135d;hp=cceaf09ac413a4da1b9ea3d27d7655cb405e785c;hpb=5367f2d67c7d0bf1faae90e6e7b4e2ac3c9b5e0f;p=linux-2.6-omap-h63xx.git diff --git a/kernel/ptrace.c b/kernel/ptrace.c index cceaf09ac41..9a111f70145 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -7,6 +7,7 @@ * to continually duplicate across every architecture. */ +#include #include #include #include @@ -27,16 +28,15 @@ * * Must be called with the tasklist lock write-held. */ -void __ptrace_link(task_t *child, task_t *new_parent) +void __ptrace_link(struct task_struct *child, struct task_struct *new_parent) { - if (!list_empty(&child->ptrace_list)) - BUG(); + BUG_ON(!list_empty(&child->ptrace_list)); if (child->parent == new_parent) return; list_add(&child->ptrace_list, &child->parent->ptrace_children); - REMOVE_LINKS(child); + remove_parent(child); child->parent = new_parent; - SET_LINKS(child); + add_parent(child); } /* @@ -46,7 +46,7 @@ void __ptrace_link(task_t *child, task_t *new_parent) * TASK_TRACED, resume it now. * Requires that irqs be disabled. */ -void ptrace_untrace(task_t *child) +void ptrace_untrace(struct task_struct *child) { spin_lock(&child->sighand->siglock); if (child->state == TASK_TRACED) { @@ -56,10 +56,6 @@ void ptrace_untrace(task_t *child) signal_wake_up(child, 1); } } - if (child->signal->flags & SIGNAL_GROUP_EXIT) { - sigaddset(&child->pending.signal, SIGKILL); - signal_wake_up(child, 1); - } spin_unlock(&child->sighand->siglock); } @@ -69,19 +65,20 @@ void ptrace_untrace(task_t *child) * * Must be called with the tasklist lock write-held. */ -void __ptrace_unlink(task_t *child) +void __ptrace_unlink(struct task_struct *child) { - if (!child->ptrace) - BUG(); + BUG_ON(!child->ptrace); + child->ptrace = 0; if (!list_empty(&child->ptrace_list)) { list_del_init(&child->ptrace_list); - REMOVE_LINKS(child); + remove_parent(child); child->parent = child->real_parent; - SET_LINKS(child); + add_parent(child); } - ptrace_untrace(child); + if (child->state == TASK_TRACED) + ptrace_untrace(child); } /* @@ -123,8 +120,18 @@ int ptrace_check_attach(struct task_struct *child, int kill) static int may_attach(struct task_struct *task) { - if (!task->mm) - return -EPERM; + /* May we inspect the given task? + * This check is used both for attaching with ptrace + * and for allowing access to sensitive information in /proc. + * + * ptrace_attach denies several cases that /proc allows + * because setting up the necessary parent/child relationship + * or halting the specified task is impossible. + */ + int dumpable = 0; + /* Don't let security modules deny introspection */ + if (task == current) + return 0; if (((current->uid != task->euid) || (current->uid != task->suid) || (current->uid != task->uid) || @@ -133,7 +140,9 @@ static int may_attach(struct task_struct *task) (current->gid != task->gid)) && !capable(CAP_SYS_PTRACE)) return -EPERM; smp_rmb(); - if (!task->mm->dumpable && !capable(CAP_SYS_PTRACE)) + if (task->mm) + dumpable = task->mm->dumpable; + if (!dumpable && !capable(CAP_SYS_PTRACE)) return -EPERM; return security_ptrace(current, task); @@ -151,11 +160,35 @@ int ptrace_may_attach(struct task_struct *task) int ptrace_attach(struct task_struct *task) { int retval; - task_lock(task); + retval = -EPERM; if (task->pid <= 1) - goto bad; + goto out; if (task->tgid == current->tgid) + goto out; + +repeat: + /* + * Nasty, nasty. + * + * We want to hold both the task-lock and the + * tasklist_lock for writing at the same time. + * But that's against the rules (tasklist_lock + * is taken for reading by interrupts on other + * cpu's that may have task_lock). + */ + task_lock(task); + local_irq_disable(); + if (!write_trylock(&tasklist_lock)) { + local_irq_enable(); + task_unlock(task); + do { + cpu_relax(); + } while (!write_can_lock(&tasklist_lock)); + goto repeat; + } + + if (!task->mm) goto bad; /* the same process cannot be attached many times */ if (task->ptrace & PT_PTRACED) @@ -169,36 +202,40 @@ int ptrace_attach(struct task_struct *task) ? PT_ATTACHED : 0); if (capable(CAP_SYS_PTRACE)) task->ptrace |= PT_PTRACE_CAP; - task_unlock(task); - write_lock_irq(&tasklist_lock); __ptrace_link(task, current); - write_unlock_irq(&tasklist_lock); force_sig_specific(SIGSTOP, task); - return 0; bad: + write_unlock_irq(&tasklist_lock); task_unlock(task); +out: return retval; } +static inline void __ptrace_detach(struct task_struct *child, unsigned int data) +{ + child->exit_code = data; + /* .. re-parent .. */ + __ptrace_unlink(child); + /* .. and wake it up. */ + if (child->exit_state != EXIT_ZOMBIE) + wake_up_process(child); +} + int ptrace_detach(struct task_struct *child, unsigned int data) { if (!valid_signal(data)) - return -EIO; + return -EIO; /* Architecture-specific hardware disable .. */ ptrace_disable(child); - /* .. re-parent .. */ - child->exit_code = data; - write_lock_irq(&tasklist_lock); - __ptrace_unlink(child); - /* .. and wake it up. */ - if (child->exit_state != EXIT_ZOMBIE) - wake_up_process(child); + /* protect against de_thread()->release_task() */ + if (child->ptrace) + __ptrace_detach(child, data); write_unlock_irq(&tasklist_lock); return 0; @@ -241,8 +278,7 @@ int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, in if (write) { copy_to_user_page(vma, page, addr, maddr + offset, buf, bytes); - if (!PageCompound(page)) - set_page_dirty_lock(page); + set_page_dirty_lock(page); } else { copy_from_user_page(vma, page, addr, buf, maddr + offset, bytes); @@ -416,21 +452,22 @@ int ptrace_request(struct task_struct *child, long request, */ int ptrace_traceme(void) { - int ret; + int ret = -EPERM; /* * Are we already being traced? */ - if (current->ptrace & PT_PTRACED) - return -EPERM; - ret = security_ptrace(current->parent, current); - if (ret) - return -EPERM; - /* - * Set the ptrace bit in the process ptrace flags. - */ - current->ptrace |= PT_PTRACED; - return 0; + task_lock(current); + if (!(current->ptrace & PT_PTRACED)) { + ret = security_ptrace(current->parent, current); + /* + * Set the ptrace bit in the process ptrace flags. + */ + if (!ret) + current->ptrace |= PT_PTRACED; + } + task_unlock(current); + return ret; } /**