X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=kernel%2Fptrace.c;fp=kernel%2Fptrace.c;h=ad5df5abcd6c5f30bbb5aed5b902135fae6d6ee2;hb=43bc926fffd92024b46cafaf7350d669ba9ca884;hp=8dcb8f6288bcecf1f436a2904c0ded883f9d3862;hpb=cee37fe97739d85991964371c1f3a745c00dd236;p=linux-2.6.git diff --git a/kernel/ptrace.c b/kernel/ptrace.c index 8dcb8f628..ad5df5abc 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -7,6 +7,7 @@ * to continually duplicate across every architecture. */ +#include #include #include #include @@ -17,6 +18,7 @@ #include #include #include +#include #include #include @@ -29,14 +31,13 @@ */ void __ptrace_link(task_t *child, task_t *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); } /* @@ -67,14 +68,14 @@ void ptrace_untrace(task_t *child) */ void __ptrace_unlink(task_t *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); } if (child->state == TASK_TRACED) @@ -118,31 +119,68 @@ int ptrace_check_attach(struct task_struct *child, int kill) return ret; } +int __ptrace_may_attach(struct task_struct *task) +{ + if (!task->mm) + return -EPERM; + if (((current->uid != task->euid) || + (current->uid != task->suid) || + (current->uid != task->uid) || + (current->gid != task->egid) || + (current->gid != task->sgid) || + (current->gid != task->gid)) && !capable(CAP_SYS_PTRACE)) + return -EPERM; + smp_rmb(); + if (!task->mm->dumpable && !capable(CAP_SYS_PTRACE)) + return -EPERM; + + return security_ptrace(current, task); +} + +int ptrace_may_attach(struct task_struct *task) +{ + int err; + task_lock(task); + err = __ptrace_may_attach(task); + task_unlock(task); + return !err; +} + int ptrace_attach(struct task_struct *task) { int retval; - task_lock(task); + retval = -EPERM; if (task->pid <= 1) - goto bad; - if (task == current) - goto bad; - if (!task->mm) - goto bad; - if(((current->uid != task->euid) || - (current->uid != task->suid) || - (current->uid != task->uid) || - (current->gid != task->egid) || - (current->gid != task->sgid) || - (current->gid != task->gid)) && !capable(CAP_SYS_PTRACE)) - goto bad; - smp_rmb(); - if (!task->mm->dumpable && !capable(CAP_SYS_PTRACE)) - 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; + } + /* the same process cannot be attached many times */ if (task->ptrace & PT_PTRACED) goto bad; - retval = security_ptrace(current, task); + retval = __ptrace_may_attach(task); if (retval) goto bad; @@ -151,36 +189,39 @@ 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; } +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); + if (child->ptrace) + __ptrace_detach(child, data); write_unlock_irq(&tasklist_lock); return 0; @@ -388,3 +429,105 @@ int ptrace_request(struct task_struct *child, long request, return ret; } + +/** + * ptrace_traceme -- helper for PTRACE_TRACEME + * + * Performs checks and sets PT_PTRACED. + * Should be used by all ptrace implementations for PTRACE_TRACEME. + */ +int ptrace_traceme(void) +{ + int ret = -EPERM; + + /* + * Are we already being traced? + */ + 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; +} + +/** + * ptrace_get_task_struct -- grab a task struct reference for ptrace + * @pid: process id to grab a task_struct reference of + * + * This function is a helper for ptrace implementations. It checks + * permissions and then grabs a task struct for use of the actual + * ptrace implementation. + * + * Returns the task_struct for @pid or an ERR_PTR() on failure. + */ +struct task_struct *ptrace_get_task_struct(pid_t pid) +{ + struct task_struct *child; + + /* + * Tracing init is not allowed. + */ + if (pid == 1) + return ERR_PTR(-EPERM); + + read_lock(&tasklist_lock); + child = find_task_by_pid(pid); + if (child) + get_task_struct(child); + read_unlock(&tasklist_lock); + if (!child) + return ERR_PTR(-ESRCH); + return child; +} + +#ifndef __ARCH_SYS_PTRACE +asmlinkage long sys_ptrace(long request, long pid, long addr, long data) +{ + struct task_struct *child; + long ret; + + /* + * This lock_kernel fixes a subtle race with suid exec + */ + lock_kernel(); + if (request == PTRACE_TRACEME) { + ret = ptrace_traceme(); + goto out; + } + + child = ptrace_get_task_struct(pid); + if (IS_ERR(child)) { + ret = PTR_ERR(child); + goto out; + } + + ret = -EPERM; + if (!vx_check(vx_task_xid(child), VX_WATCH|VX_IDENT)) + goto out_put_task_struct; + + if (request == PTRACE_ATTACH) { + ret = ptrace_attach(child); + goto out_put_task_struct; + } + + ret = ptrace_check_attach(child, request == PTRACE_KILL); + if (ret < 0) + goto out_put_task_struct; + + ret = arch_ptrace(child, request, addr, data); + if (ret < 0) + goto out_put_task_struct; + + out_put_task_struct: + put_task_struct(child); + out: + unlock_kernel(); + return ret; +} +#endif /* __ARCH_SYS_PTRACE */