diff options
-rw-r--r-- | Documentation/feature-removal-schedule.txt | 10 | ||||
-rw-r--r-- | kernel/futex.c | 38 | ||||
-rw-r--r-- | kernel/futex_compat.c | 38 |
3 files changed, 40 insertions, 46 deletions
diff --git a/Documentation/feature-removal-schedule.txt b/Documentation/feature-removal-schedule.txt index 0cad480..c1be806 100644 --- a/Documentation/feature-removal-schedule.txt +++ b/Documentation/feature-removal-schedule.txt @@ -529,3 +529,13 @@ When: 3.5 Why: The old kmap_atomic() with two arguments is deprecated, we only keep it for backward compatibility for few cycles and then drop it. Who: Cong Wang <amwang@redhat.com> + +---------------------------- + +What: get_robust_list syscall +When: 2013 +Why: There appear to be no production users of the get_robust_list syscall, + and it runs the risk of leaking address locations, allowing the bypass + of ASLR. It was only ever intended for debugging, so it should be + removed. +Who: Kees Cook <keescook@chromium.org> diff --git a/kernel/futex.c b/kernel/futex.c index 72efa1e..e2b0fb9 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -59,6 +59,7 @@ #include <linux/magic.h> #include <linux/pid.h> #include <linux/nsproxy.h> +#include <linux/ptrace.h> #include <asm/futex.h> @@ -2443,40 +2444,31 @@ SYSCALL_DEFINE3(get_robust_list, int, pid, { struct robust_list_head __user *head; unsigned long ret; - const struct cred *cred = current_cred(), *pcred; + struct task_struct *p; if (!futex_cmpxchg_enabled) return -ENOSYS; + WARN_ONCE(1, "deprecated: get_robust_list will be deleted in 2013.\n"); + + rcu_read_lock(); + + ret = -ESRCH; if (!pid) - head = current->robust_list; + p = current; else { - struct task_struct *p; - - ret = -ESRCH; - rcu_read_lock(); p = find_task_by_vpid(pid); if (!p) goto err_unlock; - ret = -EPERM; - pcred = __task_cred(p); - /* If victim is in different user_ns, then uids are not - comparable, so we must have CAP_SYS_PTRACE */ - if (cred->user->user_ns != pcred->user->user_ns) { - if (!ns_capable(pcred->user->user_ns, CAP_SYS_PTRACE)) - goto err_unlock; - goto ok; - } - /* If victim is in same user_ns, then uids are comparable */ - if (cred->euid != pcred->euid && - cred->euid != pcred->uid && - !ns_capable(pcred->user->user_ns, CAP_SYS_PTRACE)) - goto err_unlock; -ok: - head = p->robust_list; - rcu_read_unlock(); } + ret = -EPERM; + if (!ptrace_may_access(p, PTRACE_MODE_READ)) + goto err_unlock; + + head = p->robust_list; + rcu_read_unlock(); + if (put_user(sizeof(*head), len_ptr)) return -EFAULT; return put_user(head, head_ptr); diff --git a/kernel/futex_compat.c b/kernel/futex_compat.c index 5f9e689..83e368b 100644 --- a/kernel/futex_compat.c +++ b/kernel/futex_compat.c @@ -10,6 +10,7 @@ #include <linux/compat.h> #include <linux/nsproxy.h> #include <linux/futex.h> +#include <linux/ptrace.h> #include <asm/uaccess.h> @@ -136,40 +137,31 @@ compat_sys_get_robust_list(int pid, compat_uptr_t __user *head_ptr, { struct compat_robust_list_head __user *head; unsigned long ret; - const struct cred *cred = current_cred(), *pcred; + struct task_struct *p; if (!futex_cmpxchg_enabled) return -ENOSYS; + WARN_ONCE(1, "deprecated: get_robust_list will be deleted in 2013.\n"); + + rcu_read_lock(); + + ret = -ESRCH; if (!pid) - head = current->compat_robust_list; + p = current; else { - struct task_struct *p; - - ret = -ESRCH; - rcu_read_lock(); p = find_task_by_vpid(pid); if (!p) goto err_unlock; - ret = -EPERM; - pcred = __task_cred(p); - /* If victim is in different user_ns, then uids are not - comparable, so we must have CAP_SYS_PTRACE */ - if (cred->user->user_ns != pcred->user->user_ns) { - if (!ns_capable(pcred->user->user_ns, CAP_SYS_PTRACE)) - goto err_unlock; - goto ok; - } - /* If victim is in same user_ns, then uids are comparable */ - if (cred->euid != pcred->euid && - cred->euid != pcred->uid && - !ns_capable(pcred->user->user_ns, CAP_SYS_PTRACE)) - goto err_unlock; -ok: - head = p->compat_robust_list; - rcu_read_unlock(); } + ret = -EPERM; + if (!ptrace_may_access(p, PTRACE_MODE_READ)) + goto err_unlock; + + head = p->compat_robust_list; + rcu_read_unlock(); + if (put_user(sizeof(*head), len_ptr)) return -EFAULT; return put_user(ptr_to_compat(head), head_ptr); |