diff options
| -rw-r--r-- | fs/proc/base.c | 26 | ||||
| -rw-r--r-- | kernel/ptrace.c | 20 |
2 files changed, 23 insertions, 23 deletions
diff --git a/fs/proc/base.c b/fs/proc/base.c index f38da6bda269..773469703c62 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -536,29 +536,15 @@ static int proc_fd_access_allowed(struct inode *inode) { struct task_struct *task; int allowed = 0; - /* Allow access to a task's file descriptors if either we may - * use ptrace attach to the process and find out that - * information, or if the task cannot possibly be ptraced - * allow access if we have the proper capability. + /* Allow access to a task's file descriptors if it is us or we + * may use ptrace attach to the process and find out that + * information. */ task = get_proc_task(inode); - if (task == current) - allowed = 1; - if (task && !allowed) { - int alive; - - task_lock(task); - alive = !!task->mm; - task_unlock(task); - if (alive) - /* For a living task obey ptrace_may_attach */ - allowed = ptrace_may_attach(task); - else - /* For a special task simply check the capability */ - allowed = capable(CAP_SYS_PTRACE); - } - if (task) + if (task) { + allowed = ptrace_may_attach(task); put_task_struct(task); + } return allowed; } diff --git a/kernel/ptrace.c b/kernel/ptrace.c index 921c22ad16e4..6252d2fa2bf3 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; |