2 files changed, 98 insertions, 0 deletions

diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 7f614ce274a9..a60943be4270 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -35,6 +35,7 @@ struct oldold_utsname;
 struct old_utsname;
 struct pollfd;
 struct rlimit;
+struct rlimit64;
 struct rusage;
 struct sched_param;
 struct sel_arg_struct;
@@ -644,6 +645,9 @@ asmlinkage long sys_old_getrlimit(unsigned int resource, struct rlimit __user *r
 #endif
 asmlinkage long sys_setrlimit(unsigned int resource,
                                 struct rlimit __user *rlim);
+asmlinkage long sys_prlimit64(pid_t pid, unsigned int resource,
+                                const struct rlimit64 __user *new_rlim,
+                                struct rlimit64 __user *old_rlim);
 asmlinkage long sys_getrusage(int who, struct rusage __user *ru);
 asmlinkage long sys_umask(int mask);
 
diff --git a/kernel/sys.c b/kernel/sys.c
index 9da98dd47276..e9ad44489828 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -1271,6 +1271,39 @@ SYSCALL_DEFINE2(old_getrlimit, unsigned int, resource,
 
 #endif
 
+static inline bool rlim64_is_infinity(__u64 rlim64)
+{
+#if BITS_PER_LONG < 64
+        return rlim64 >= ULONG_MAX;
+#else
+        return rlim64 == RLIM64_INFINITY;
+#endif
+}
+
+static void rlim_to_rlim64(const struct rlimit *rlim, struct rlimit64 *rlim64)
+{
+        if (rlim->rlim_cur == RLIM_INFINITY)
+                rlim64->rlim_cur = RLIM64_INFINITY;
+        else
+                rlim64->rlim_cur = rlim->rlim_cur;
+        if (rlim->rlim_max == RLIM_INFINITY)
+                rlim64->rlim_max = RLIM64_INFINITY;
+        else
+                rlim64->rlim_max = rlim->rlim_max;
+}
+
+static void rlim64_to_rlim(const struct rlimit64 *rlim64, struct rlimit *rlim)
+{
+        if (rlim64_is_infinity(rlim64->rlim_cur))
+                rlim->rlim_cur = RLIM_INFINITY;
+        else
+                rlim->rlim_cur = (unsigned long)rlim64->rlim_cur;
+        if (rlim64_is_infinity(rlim64->rlim_max))
+                rlim->rlim_max = RLIM_INFINITY;
+        else
+                rlim->rlim_max = (unsigned long)rlim64->rlim_max;
+}
+
 /* make sure you are allowed to change @tsk limits before calling this */
 int do_prlimit(struct task_struct *tsk, unsigned int resource,
                 struct rlimit *new_rlim, struct rlimit *old_rlim)
@@ -1336,6 +1369,67 @@ out:
         return retval;
 }
 
+/* rcu lock must be held */
+static int check_prlimit_permission(struct task_struct *task)
+{
+        const struct cred *cred = current_cred(), *tcred;
+
+        tcred = __task_cred(task);
+        if ((cred->uid != tcred->euid ||
+             cred->uid != tcred->suid ||
+             cred->uid != tcred->uid  ||
+             cred->gid != tcred->egid ||
+             cred->gid != tcred->sgid ||
+             cred->gid != tcred->gid) &&
+             !capable(CAP_SYS_RESOURCE)) {
+                return -EPERM;
+        }
+
+        return 0;
+}
+
+SYSCALL_DEFINE4(prlimit64, pid_t, pid, unsigned int, resource,
+                const struct rlimit64 __user *, new_rlim,
+                struct rlimit64 __user *, old_rlim)
+{
+        struct rlimit64 old64, new64;
+        struct rlimit old, new;
+        struct task_struct *tsk;
+        int ret;
+
+        if (new_rlim) {
+                if (copy_from_user(&new64, new_rlim, sizeof(new64)))
+                        return -EFAULT;
+                rlim64_to_rlim(&new64, &new);
+        }
+
+        rcu_read_lock();
+        tsk = pid ? find_task_by_vpid(pid) : current;
+        if (!tsk) {
+                rcu_read_unlock();
+                return -ESRCH;
+        }
+        ret = check_prlimit_permission(tsk);
+        if (ret) {
+                rcu_read_unlock();
+                return ret;
+        }
+        get_task_struct(tsk);
+        rcu_read_unlock();
+
+        ret = do_prlimit(tsk, resource, new_rlim ? &new : NULL,
+                        old_rlim ? &old : NULL);
+
+        if (!ret && old_rlim) {
+                rlim_to_rlim64(&old, &old64);
+                if (copy_to_user(old_rlim, &old64, sizeof(old64)))
+                        ret = -EFAULT;
+        }
+
+        put_task_struct(tsk);
+        return ret;
+}
+
 SYSCALL_DEFINE2(setrlimit, unsigned int, resource, struct rlimit __user *, rlim)
 {
         struct rlimit new_rlim;