diff options
| author | Eric W. Biederman <ebiederm@xmission.com> | 2016-11-22 21:06:50 +0300 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2018-01-01 23:52:11 +0300 |
| commit | aa3fbddbb80119b4cffbb45581c8542d9dcdec79 (patch) | |
| tree | fbb7bde50607ead102dd00bbe0cc51628957e873 /include/linux | |
| parent | a0d8337f16fb5d5dd7b963f092779bc990a1cc0e (diff) | |
| download | linux-aa3fbddbb80119b4cffbb45581c8542d9dcdec79.tar.xz | |
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>
[bwh: Backported to 3.16:
- Pass around only a write flag, not gup_flags
- Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/mm.h | 2 | ||||
| -rw-r--r-- | include/linux/ptrace.h | 3 |
2 files changed, 5 insertions, 0 deletions
diff --git a/include/linux/mm.h b/include/linux/mm.h index 35f8b59b37a7..65a4dc2da9de 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1209,6 +1209,8 @@ static inline int fixup_user_fault(struct task_struct *tsk, extern int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write); extern int access_remote_vm(struct mm_struct *mm, unsigned long addr, void *buf, int len, int write); +extern int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm, + unsigned long addr, void *buf, int len, int write); long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, unsigned long start, unsigned long nr_pages, diff --git a/include/linux/ptrace.h b/include/linux/ptrace.h index b9b35c4d687b..8e81197a28dd 100644 --- a/include/linux/ptrace.h +++ b/include/linux/ptrace.h @@ -8,6 +8,9 @@ #include <linux/pid_namespace.h> /* For task_active_pid_ns. */ #include <uapi/linux/ptrace.h> +extern int ptrace_access_vm(struct task_struct *tsk, unsigned long addr, + void *buf, int len, int write); + /* * Ptrace flags * |