diff options
| author | Eric W. Biederman <ebiederm@xmission.com> | 2016-11-22 12:06:50 -0600 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2018-01-01 20:52:11 +0000 |
| commit | aa3fbddbb80119b4cffbb45581c8542d9dcdec79 (patch) | |
| tree | fbb7bde50607ead102dd00bbe0cc51628957e873 /arch/mips | |
| parent | a0d8337f16fb5d5dd7b963f092779bc990a1cc0e (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>
[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 'arch/mips')
| -rw-r--r-- | arch/mips/kernel/ptrace32.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/mips/kernel/ptrace32.c b/arch/mips/kernel/ptrace32.c index a83fb730b387..fdd26c104c6c 100644 --- a/arch/mips/kernel/ptrace32.c +++ b/arch/mips/kernel/ptrace32.c @@ -69,7 +69,7 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request, if (get_user(addrOthers, (u32 __user * __user *) (unsigned long) addr) != 0) break; - copied = access_process_vm(child, (u64)addrOthers, &tmp, + copied = ptrace_access_vm(child, (u64)addrOthers, &tmp, sizeof(tmp), 0); if (copied != sizeof(tmp)) break; @@ -178,7 +178,7 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request, if (get_user(addrOthers, (u32 __user * __user *) (unsigned long) addr) != 0) break; ret = 0; - if (access_process_vm(child, (u64)addrOthers, &data, + if (ptrace_access_vm(child, (u64)addrOthers, &data, sizeof(data), 1) == sizeof(data)) break; ret = -EIO; |