diff options
| -rw-r--r-- | fs/proc/base.c | 38 |
1 files changed, 29 insertions, 9 deletions
diff --git a/fs/proc/base.c b/fs/proc/base.c index b48ddb119945..fcf02f2deeba 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -195,12 +195,32 @@ static int proc_root_link(struct inode *inode, struct path *path) return result; } -#define MAY_PTRACE(task) \ - (task == current || \ - (task->parent == current && \ - (task->ptrace & PT_PTRACED) && \ - (task_is_stopped_or_traced(task)) && \ - security_ptrace(current,task) == 0)) +/* + * Return zero if current may access user memory in @task, -error if not. + */ +static int check_mem_permission(struct task_struct *task) +{ + /* + * A task can always look at itself, in case it chooses + * to use system calls instead of load instructions. + */ + if (task == current) + return 0; + + /* + * If current is actively ptrace'ing, and would also be + * permitted to freshly attach with ptrace now, permit it. + */ + if (task->parent == current && (task->ptrace & PT_PTRACED) && + task_is_stopped_or_traced(task) && + ptrace_may_attach(task)) + return 0; + + /* + * Noone else is allowed. + */ + return -EPERM; +} struct mm_struct *mm_for_maps(struct task_struct *task) { @@ -722,7 +742,7 @@ static ssize_t mem_read(struct file * file, char __user * buf, if (!task) goto out_no_task; - if (!MAY_PTRACE(task) || !ptrace_may_attach(task)) + if (check_mem_permission(task)) goto out; ret = -ENOMEM; @@ -748,7 +768,7 @@ static ssize_t mem_read(struct file * file, char __user * buf, this_len = (count > PAGE_SIZE) ? PAGE_SIZE : count; retval = access_process_vm(task, src, page, this_len, 0); - if (!retval || !MAY_PTRACE(task) || !ptrace_may_attach(task)) { + if (!retval || check_mem_permission(task)) { if (!ret) ret = -EIO; break; @@ -792,7 +812,7 @@ static ssize_t mem_write(struct file * file, const char __user *buf, if (!task) goto out_no_task; - if (!MAY_PTRACE(task) || !ptrace_may_attach(task)) + if (check_mem_permission(task)) goto out; copied = -ENOMEM; |