diff options
Diffstat (limited to 'kernel/ptrace.c')
| -rw-r--r-- | kernel/ptrace.c | 23 |
1 files changed, 19 insertions, 4 deletions
diff --git a/kernel/ptrace.c b/kernel/ptrace.c index 921c22ad16e..335c5b932e1 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -120,8 +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) || @@ -130,7 +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); @@ -176,6 +188,8 @@ repeat: goto repeat; } + if (!task->mm) + goto bad; /* the same process cannot be attached many times */ if (task->ptrace & PT_PTRACED) goto bad; @@ -200,7 +214,7 @@ out: return retval; } -void __ptrace_detach(struct task_struct *child, unsigned int data) +static inline void __ptrace_detach(struct task_struct *child, unsigned int data) { child->exit_code = data; /* .. re-parent .. */ @@ -219,6 +233,7 @@ int ptrace_detach(struct task_struct *child, unsigned int data) ptrace_disable(child); write_lock_irq(&tasklist_lock); + /* protect against de_thread()->release_task() */ if (child->ptrace) __ptrace_detach(child, data); write_unlock_irq(&tasklist_lock); |