patch-2.1.100 linux/kernel/capability.c

• Lines: 253
• Date: Wed May 6 11:01:46 1998
• Orig file: v2.1.99/linux/kernel/capability.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.1.99/linux/kernel/capability.c linux/kernel/capability.c
@@ -0,0 +1,252 @@
+/*
+ * linux/kernel/capability.c
+ *
+ * Copyright (C) 1997  Andrew Main <zefram@fysh.org>
+ * Integrated into 2.1.97+,  Andrew G. Morgan <morgan@transmeta.com>
+ */ 
+
+#include <linux/config.h>
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/capability.h>
+#include <linux/mm.h>
+#include <linux/sched.h>
+#include <linux/string.h>
+
+#include <asm/uaccess.h>
+
+static inline void cap_fromuser(kernel_cap_t *k, __u32 *u)
+{
+     copy_from_user(k, u, sizeof(*k));
+}
+
+
+static inline void cap_touser(__u32 *u, const kernel_cap_t *k)
+{
+     copy_to_user(u, k, sizeof(*k));
+}
+
+#ifdef __SMP__
+static spinlock_t task_capability_lock;
+#endif
+
+/*
+ * For sys_getproccap() and sys_setproccap(), any of the three
+ * capability set pointers may be NULL -- indicating that that set is
+ * uninteresting and/or not to be changed.
+ */
+
+asmlinkage int sys_capget(cap_user_header_t header, cap_user_data_t data)
+{
+     int error = -EINVAL, pid;
+     __u32 version;
+     struct task_struct *target;
+
+     if (!access_ok(VERIFY_WRITE, &header->version, sizeof(*header))) {
+             /* not large enough for current header so indicate error */
+             if (access_ok(VERIFY_WRITE, &header->version,
+                           sizeof(header->version))) {
+                     return error;
+             }
+             goto all_done;
+     }
+
+     copy_from_user(&version, &header->version, sizeof(header->version));
+     if (version != _LINUX_CAPABILITY_VERSION) {
+             /* if enough space for kernel version, write that */
+
+     all_done:
+             version = _LINUX_CAPABILITY_VERSION;
+             copy_to_user(&header->version, &version,
+                          sizeof(header->version));
+             return error;
+     }
+
+     if (!access_ok(VERIFY_WRITE, data, sizeof(*data))) {
+             return error;
+     }
+
+     copy_from_user(&pid, &header->pid, sizeof(header->pid));
+     if (pid < 0) {
+             return error;
+     }
+
+     spin_lock(&task_capability_lock);
+
+     if (pid && pid != current->pid) {
+             read_lock(&tasklist_lock);
+             target = find_task_by_pid(pid);  /* identify target of query */
+             if (!target) {
+                     error = -ESRCH;
+                     goto out;
+             }
+     } else {
+             target = current;
+     }
+
+     cap_touser(&data->permitted, &target->cap_permitted);
+     cap_touser(&data->inheritable, &target->cap_inheritable);
+     cap_touser(&data->effective, &target->cap_effective);
+
+     error = 0;
+
+out:
+     if (target != current) {
+             read_unlock(&tasklist_lock);
+     }
+     spin_unlock(&task_capability_lock);
+     return error;
+}
+
+/* set capabilities for all processes in a given process group */
+
+static void cap_set_pg(int pgrp,
+                    kernel_cap_t *effective,
+                    kernel_cap_t *inheritable,
+                    kernel_cap_t *permitted)
+{
+     struct task_struct *target;
+
+     /* FIXME: do we need to have a write lock here..? */
+     read_lock(&tasklist_lock);
+     for_each_task(target) {
+             if (target->pgrp != pgrp)
+                     continue;
+             target->cap_effective   = *effective;
+             target->cap_inheritable = *inheritable;
+             target->cap_permitted   = *permitted;
+     }
+     read_unlock(&tasklist_lock);
+}
+
+/* set capabilities for all processes other than 1 and self */
+
+static void cap_set_all(kernel_cap_t *effective,
+                     kernel_cap_t *inheritable,
+                     kernel_cap_t *permitted)
+{
+     struct task_struct *target;
+
+     /* FIXME: do we need to have a write lock here..? */
+     read_lock(&tasklist_lock);
+     /* ALL means everyone other than self or 'init' */
+     for_each_task(target) {
+             if (target == current || target->pid == 1)
+                     continue;
+             target->cap_effective   = *effective;
+             target->cap_inheritable = *inheritable;
+             target->cap_permitted   = *permitted;
+     }
+     read_unlock(&tasklist_lock);
+}
+
+/*
+ * The restrictions on setting capabilities are specified as:
+ *
+ * [pid is for the 'target' task.  'current' is the calling task.]
+ *
+ * I: any raised capabilities must be a subset of the (old current) Permitted
+ * P: any raised capabilities must be a subset of the (old current) permitted
+ * E: must be set to a subset of (new target) Permitted
+ */
+
+asmlinkage int sys_capset(cap_user_header_t header, const cap_user_data_t data)
+{
+     kernel_cap_t inheritable, permitted, effective;
+     __u32 version;
+     struct task_struct *target;
+     int error = -EINVAL, pid;
+
+     if (!access_ok(VERIFY_WRITE, &header->version, sizeof(*header))) {
+             /* not large enough for current header so indicate error */
+             if (!access_ok(VERIFY_WRITE, &header->version,
+                            sizeof(header->version))) {
+                     return error;
+             }
+             goto all_done;
+     }
+
+     copy_from_user(&version, &header->version, sizeof(header->version));
+     if (version != _LINUX_CAPABILITY_VERSION) {
+
+     all_done:
+             version = _LINUX_CAPABILITY_VERSION;
+             copy_to_user(&header->version, &version,
+                          sizeof(header->version));
+             return error;
+     }
+
+     if (!access_ok(VERIFY_READ, data, sizeof(*data))) {
+             return error;
+     }
+
+     /* may want to set other processes at some point -- for now demand 0 */
+     copy_from_user(&pid, &header->pid, sizeof(pid));
+
+     error = -EPERM;
+     if (pid && !capable(CAP_SETPCAP))
+             return error;
+
+     spin_lock(&task_capability_lock);
+
+     if (pid > 0 && pid != current->pid) {
+             read_lock(&tasklist_lock);
+             target = find_task_by_pid(pid);  /* identify target of query */
+             if (!target) {
+                     error = -ESRCH;
+                     goto out;
+             }
+     } else {
+             target = current;
+     }
+
+     /* copy from userspace */
+     cap_fromuser(&effective, &data->effective);
+     cap_fromuser(&inheritable, &data->inheritable);
+     cap_fromuser(&permitted, &data->permitted);
+
+     /* verify restrictions on target's new Inheritable set */
+     if (!cap_issubset(inheritable,
+                       cap_combine(target->cap_inheritable,
+                                   current->cap_permitted))) {
+             goto out;
+     }
+
+     /* verify restrictions on target's new Permitted set */
+     if (!cap_issubset(permitted,
+                       cap_combine(target->cap_permitted,
+                                   current->cap_permitted))) {
+             goto out;
+     }
+
+     /* verify the _new_Effective_ is a subset of the _new_Permitted_ */
+     if (!cap_issubset(effective, permitted)) {
+             goto out;
+     }
+
+     /* having verified that the proposed changes are legal,
+           we now put them into effect. */
+     error = 0;
+
+     if (pid < 0) {
+             if (pid == -1)  /* all procs other than current and init */
+                     cap_set_all(&effective, &inheritable, &permitted);
+
+             else            /* all procs in process group */
+                     cap_set_pg(-pid, &effective, &inheritable, &permitted);
+             goto spin_out;
+     } else {
+             /* FIXME: do we need to have a write lock here..? */
+             target->cap_effective   = effective;
+             target->cap_inheritable = inheritable;
+             target->cap_permitted   = permitted;
+     }
+
+out:
+     if (target != current) {
+             read_unlock(&tasklist_lock);
+     }
+spin_out:
+     spin_unlock(&task_capability_lock);
+     return error;
+}