diff options
Diffstat (limited to 'kernel/fork.c')
| -rw-r--r-- | kernel/fork.c | 26 |
1 files changed, 23 insertions, 3 deletions
diff --git a/kernel/fork.c b/kernel/fork.c index f253e81d0c28..1450b461d196 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -621,6 +621,12 @@ static void dup_mm_exe_file(struct mm_struct *mm, struct mm_struct *oldmm) exe_file = get_mm_exe_file(oldmm); RCU_INIT_POINTER(mm->exe_file, exe_file); + /* + * We depend on the oldmm having properly denied write access to the + * exe_file already. + */ + if (exe_file && deny_write_access(exe_file)) + pr_warn_once("deny_write_access() failed in %s\n", __func__); } #ifdef CONFIG_MMU @@ -1413,11 +1419,20 @@ int set_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file) */ old_exe_file = rcu_dereference_raw(mm->exe_file); - if (new_exe_file) + if (new_exe_file) { + /* + * We expect the caller (i.e., sys_execve) to already denied + * write access, so this is unlikely to fail. + */ + if (unlikely(deny_write_access(new_exe_file))) + return -EACCES; get_file(new_exe_file); + } rcu_assign_pointer(mm->exe_file, new_exe_file); - if (old_exe_file) + if (old_exe_file) { + allow_write_access(old_exe_file); fput(old_exe_file); + } return 0; } @@ -1456,6 +1471,9 @@ int replace_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file) return ret; } + ret = deny_write_access(new_exe_file); + if (ret) + return -EACCES; get_file(new_exe_file); /* set the new file */ @@ -1464,8 +1482,10 @@ int replace_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file) rcu_assign_pointer(mm->exe_file, new_exe_file); mmap_write_unlock(mm); - if (old_exe_file) + if (old_exe_file) { + allow_write_access(old_exe_file); fput(old_exe_file); + } return 0; } |