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path: root/fs/proc/base.c
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Diffstat (limited to 'fs/proc/base.c')
-rw-r--r--fs/proc/base.c113
1 files changed, 104 insertions, 9 deletions
diff --git a/fs/proc/base.c b/fs/proc/base.c
index c5e412a00b1..fcf02f2deeb 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;
@@ -1181,6 +1201,81 @@ static const struct file_operations proc_pid_sched_operations = {
#endif
+/*
+ * We added or removed a vma mapping the executable. The vmas are only mapped
+ * during exec and are not mapped with the mmap system call.
+ * Callers must hold down_write() on the mm's mmap_sem for these
+ */
+void added_exe_file_vma(struct mm_struct *mm)
+{
+ mm->num_exe_file_vmas++;
+}
+
+void removed_exe_file_vma(struct mm_struct *mm)
+{
+ mm->num_exe_file_vmas--;
+ if ((mm->num_exe_file_vmas == 0) && mm->exe_file){
+ fput(mm->exe_file);
+ mm->exe_file = NULL;
+ }
+
+}
+
+void set_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file)
+{
+ if (new_exe_file)
+ get_file(new_exe_file);
+ if (mm->exe_file)
+ fput(mm->exe_file);
+ mm->exe_file = new_exe_file;
+ mm->num_exe_file_vmas = 0;
+}
+
+struct file *get_mm_exe_file(struct mm_struct *mm)
+{
+ struct file *exe_file;
+
+ /* We need mmap_sem to protect against races with removal of
+ * VM_EXECUTABLE vmas */
+ down_read(&mm->mmap_sem);
+ exe_file = mm->exe_file;
+ if (exe_file)
+ get_file(exe_file);
+ up_read(&mm->mmap_sem);
+ return exe_file;
+}
+
+void dup_mm_exe_file(struct mm_struct *oldmm, struct mm_struct *newmm)
+{
+ /* It's safe to write the exe_file pointer without exe_file_lock because
+ * this is called during fork when the task is not yet in /proc */
+ newmm->exe_file = get_mm_exe_file(oldmm);
+}
+
+static int proc_exe_link(struct inode *inode, struct path *exe_path)
+{
+ struct task_struct *task;
+ struct mm_struct *mm;
+ struct file *exe_file;
+
+ task = get_proc_task(inode);
+ if (!task)
+ return -ENOENT;
+ mm = get_task_mm(task);
+ put_task_struct(task);
+ if (!mm)
+ return -ENOENT;
+ exe_file = get_mm_exe_file(mm);
+ mmput(mm);
+ if (exe_file) {
+ *exe_path = exe_file->f_path;
+ path_get(&exe_file->f_path);
+ fput(exe_file);
+ return 0;
+ } else
+ return -ENOENT;
+}
+
static void *proc_pid_follow_link(struct dentry *dentry, struct nameidata *nd)
{
struct inode *inode = dentry->d_inode;