From 84d77d3f06e7e8dea057d10e8ec77ad71f721be3 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Tue, 22 Nov 2016 12:06:50 -0600 Subject: ptrace: Don't allow accessing an undumpable mm 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 Cc: stable@vger.kernel.org Reported-by: Andy Lutomirski Signed-off-by: "Eric W. Biederman" --- arch/alpha/kernel/ptrace.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch/alpha') diff --git a/arch/alpha/kernel/ptrace.c b/arch/alpha/kernel/ptrace.c index 940dfb406591..04abdec7f496 100644 --- a/arch/alpha/kernel/ptrace.c +++ b/arch/alpha/kernel/ptrace.c @@ -283,7 +283,7 @@ long arch_ptrace(struct task_struct *child, long request, /* When I and D space are separate, these will need to be fixed. */ case PTRACE_PEEKTEXT: /* read word at location addr. */ case PTRACE_PEEKDATA: - copied = access_process_vm(child, addr, &tmp, sizeof(tmp), + copied = ptrace_access_vm(child, addr, &tmp, sizeof(tmp), FOLL_FORCE); ret = -EIO; if (copied != sizeof(tmp)) -- cgit v1.2.3-58-ga151