diff options
| author | Eric W. Biederman <ebiederm@xmission.com> | 2016-11-22 12:06:50 -0600 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-01-06 10:40:13 +0100 |
| commit | e71b4e061c9677cef1f1f38fd7236e198fab1287 (patch) | |
| tree | ca6ebd0889260f299e091cee694d79fdfea23dad /mm | |
| parent | e747b4ae3b6bca205d82e86366e140cdcbfb7731 (diff) | |
ptrace: Don't allow accessing an undumpable mm
commit 84d77d3f06e7e8dea057d10e8ec77ad71f721be3 upstream.
It is the reasonable expectation that if an executable file is not
readable there will be no way for a user without special privileges to
read the file. This is enforced in ptrace_attach but if ptrace
is already attached before exec there is no enforcement for read-only
executables.
As the only way to read such an mm is through access_process_vm
spin a variant called ptrace_access_vm that will fail if the
target process is not being ptraced by the current process, or
the current process did not have sufficient privileges when ptracing
began to read the target processes mm.
In the ptrace implementations replace access_process_vm by
ptrace_access_vm. There remain several ptrace sites that still use
access_process_vm as they are reading the target executables
instructions (for kernel consumption) or register stacks. As such it
does not appear necessary to add a permission check to those calls.
This bug has always existed in Linux.
Fixes: v1.0
Reported-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/memory.c | 2 | ||||
| -rw-r--r-- | mm/nommu.c | 2 |
2 files changed, 2 insertions, 2 deletions
diff --git a/mm/memory.c b/mm/memory.c index e18c57bdc75c..cbb1e5e5f791 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3868,7 +3868,7 @@ EXPORT_SYMBOL_GPL(generic_access_phys); * Access another process' address space as given in mm. If non-NULL, use the * given task for page fault accounting. */ -static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm, +int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm, unsigned long addr, void *buf, int len, unsigned int gup_flags) { struct vm_area_struct *vma; diff --git a/mm/nommu.c b/mm/nommu.c index 8b8faaf2a9e9..44265e00b701 100644 --- a/mm/nommu.c +++ b/mm/nommu.c @@ -1808,7 +1808,7 @@ void filemap_map_pages(struct fault_env *fe, } EXPORT_SYMBOL(filemap_map_pages); -static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm, +int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm, unsigned long addr, void *buf, int len, unsigned int gup_flags) { struct vm_area_struct *vma; |