*
* Copyright (C) 1997 Andrew Main <zefram@fysh.org>
*
- * Integrated into 2.1.97+, Andrew G. Morgan <morgan@transmeta.com>
+ * Integrated into 2.1.97+, Andrew G. Morgan <morgan@kernel.org>
* 30 May 2002: Cleanup, Robert M. Love <rml@tech9.net>
- */
+ */
+#include <linux/audit.h>
#include <linux/capability.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/security.h>
#include <linux/syscalls.h>
+#include <linux/pid_namespace.h>
#include <asm/uaccess.h>
-
-unsigned securebits = SECUREBITS_DEFAULT; /* systemwide security settings */
-kernel_cap_t cap_bset = CAP_INIT_EFF_SET;
-
-EXPORT_SYMBOL(securebits);
-EXPORT_SYMBOL(cap_bset);
+#include "cred-internals.h"
/*
- * This lock protects task->cap_* for all tasks including current.
- * Locking rule: acquire this prior to tasklist_lock.
+ * Leveraged for setting/resetting capabilities
*/
-static DEFINE_SPINLOCK(task_capability_lock);
+
+const kernel_cap_t __cap_empty_set = CAP_EMPTY_SET;
+const kernel_cap_t __cap_full_set = CAP_FULL_SET;
+const kernel_cap_t __cap_init_eff_set = CAP_INIT_EFF_SET;
+
+EXPORT_SYMBOL(__cap_empty_set);
+EXPORT_SYMBOL(__cap_full_set);
+EXPORT_SYMBOL(__cap_init_eff_set);
+
+int file_caps_enabled = 1;
+
+static int __init file_caps_disable(char *str)
+{
+ file_caps_enabled = 0;
+ return 1;
+}
+__setup("no_file_caps", file_caps_disable);
/*
- * 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.
+ * More recent versions of libcap are available from:
+ *
+ * http://www.kernel.org/pub/linux/libs/security/linux-privs/
*/
-/**
- * sys_capget - get the capabilities of a given process.
- * @header: pointer to struct that contains capability version and
- * target pid data
- * @dataptr: pointer to struct that contains the effective, permitted,
- * and inheritable capabilities that are returned
+static void warn_legacy_capability_use(void)
+{
+ static int warned;
+ if (!warned) {
+ char name[sizeof(current->comm)];
+
+ printk(KERN_INFO "warning: `%s' uses 32-bit capabilities"
+ " (legacy support in use)\n",
+ get_task_comm(name, current));
+ warned = 1;
+ }
+}
+
+/*
+ * Version 2 capabilities worked fine, but the linux/capability.h file
+ * that accompanied their introduction encouraged their use without
+ * the necessary user-space source code changes. As such, we have
+ * created a version 3 with equivalent functionality to version 2, but
+ * with a header change to protect legacy source code from using
+ * version 2 when it wanted to use version 1. If your system has code
+ * that trips the following warning, it is using version 2 specific
+ * capabilities and may be doing so insecurely.
*
- * Returns 0 on success and < 0 on error.
+ * The remedy is to either upgrade your version of libcap (to 2.10+,
+ * if the application is linked against it), or recompile your
+ * application with modern kernel headers and this warning will go
+ * away.
*/
-asmlinkage long sys_capget(cap_user_header_t header, cap_user_data_t dataptr)
+
+static void warn_deprecated_v2(void)
{
- int ret = 0;
- pid_t pid;
- __u32 version;
- struct task_struct *target;
- struct __user_cap_data_struct data;
+ static int warned;
- if (get_user(version, &header->version))
- return -EFAULT;
+ if (!warned) {
+ char name[sizeof(current->comm)];
- if (version != _LINUX_CAPABILITY_VERSION) {
- if (put_user(_LINUX_CAPABILITY_VERSION, &header->version))
- return -EFAULT;
- return -EINVAL;
- }
+ printk(KERN_INFO "warning: `%s' uses deprecated v2"
+ " capabilities in a way that may be insecure.\n",
+ get_task_comm(name, current));
+ warned = 1;
+ }
+}
- if (get_user(pid, &header->pid))
- return -EFAULT;
+/*
+ * Version check. Return the number of u32s in each capability flag
+ * array, or a negative value on error.
+ */
+static int cap_validate_magic(cap_user_header_t header, unsigned *tocopy)
+{
+ __u32 version;
+
+ if (get_user(version, &header->version))
+ return -EFAULT;
+
+ switch (version) {
+ case _LINUX_CAPABILITY_VERSION_1:
+ warn_legacy_capability_use();
+ *tocopy = _LINUX_CAPABILITY_U32S_1;
+ break;
+ case _LINUX_CAPABILITY_VERSION_2:
+ warn_deprecated_v2();
+ /*
+ * fall through - v3 is otherwise equivalent to v2.
+ */
+ case _LINUX_CAPABILITY_VERSION_3:
+ *tocopy = _LINUX_CAPABILITY_U32S_3;
+ break;
+ default:
+ if (put_user((u32)_KERNEL_CAPABILITY_VERSION, &header->version))
+ return -EFAULT;
+ return -EINVAL;
+ }
- if (pid < 0)
- return -EINVAL;
+ return 0;
+}
- spin_lock(&task_capability_lock);
- read_lock(&tasklist_lock);
+/*
+ * The only thing that can change the capabilities of the current
+ * process is the current process. As such, we can't be in this code
+ * at the same time as we are in the process of setting capabilities
+ * in this process. The net result is that we can limit our use of
+ * locks to when we are reading the caps of another process.
+ */
+static inline int cap_get_target_pid(pid_t pid, kernel_cap_t *pEp,
+ kernel_cap_t *pIp, kernel_cap_t *pPp)
+{
+ int ret;
- if (pid && pid != current->pid) {
- target = find_task_by_pid(pid);
- if (!target) {
- ret = -ESRCH;
- goto out;
- }
- } else
- target = current;
+ if (pid && (pid != task_pid_vnr(current))) {
+ struct task_struct *target;
- ret = security_capget(target, &data.effective, &data.inheritable, &data.permitted);
+ rcu_read_lock();
-out:
- read_unlock(&tasklist_lock);
- spin_unlock(&task_capability_lock);
+ target = find_task_by_vpid(pid);
+ if (!target)
+ ret = -ESRCH;
+ else
+ ret = security_capget(target, pEp, pIp, pPp);
- if (!ret && copy_to_user(dataptr, &data, sizeof data))
- return -EFAULT;
+ rcu_read_unlock();
+ } else
+ ret = security_capget(current, pEp, pIp, pPp);
- return ret;
+ return ret;
}
-/*
- * cap_set_pg - set capabilities for all processes in a given process
- * group. We call this holding task_capability_lock and tasklist_lock.
+/**
+ * sys_capget - get the capabilities of a given process.
+ * @header: pointer to struct that contains capability version and
+ * target pid data
+ * @dataptr: pointer to struct that contains the effective, permitted,
+ * and inheritable capabilities that are returned
+ *
+ * Returns 0 on success and < 0 on error.
*/
-static inline int cap_set_pg(int pgrp, kernel_cap_t *effective,
- kernel_cap_t *inheritable,
- kernel_cap_t *permitted)
+SYSCALL_DEFINE2(capget, cap_user_header_t, header, cap_user_data_t, dataptr)
{
- struct task_struct *g, *target;
- int ret = -EPERM;
- int found = 0;
-
- do_each_task_pid(pgrp, PIDTYPE_PGID, g) {
- target = g;
- while_each_thread(g, target) {
- if (!security_capset_check(target, effective,
- inheritable,
- permitted)) {
- security_capset_set(target, effective,
- inheritable,
- permitted);
- ret = 0;
- }
- found = 1;
+ int ret = 0;
+ pid_t pid;
+ unsigned tocopy;
+ kernel_cap_t pE, pI, pP;
+
+ ret = cap_validate_magic(header, &tocopy);
+ if ((dataptr == NULL) || (ret != 0))
+ return ((dataptr == NULL) && (ret == -EINVAL)) ? 0 : ret;
+
+ if (get_user(pid, &header->pid))
+ return -EFAULT;
+
+ if (pid < 0)
+ return -EINVAL;
+
+ ret = cap_get_target_pid(pid, &pE, &pI, &pP);
+ if (!ret) {
+ struct __user_cap_data_struct kdata[_KERNEL_CAPABILITY_U32S];
+ unsigned i;
+
+ for (i = 0; i < tocopy; i++) {
+ kdata[i].effective = pE.cap[i];
+ kdata[i].permitted = pP.cap[i];
+ kdata[i].inheritable = pI.cap[i];
}
- } while_each_task_pid(pgrp, PIDTYPE_PGID, g);
- if (!found)
- ret = 0;
- return ret;
-}
+ /*
+ * Note, in the case, tocopy < _KERNEL_CAPABILITY_U32S,
+ * we silently drop the upper capabilities here. This
+ * has the effect of making older libcap
+ * implementations implicitly drop upper capability
+ * bits when they perform a: capget/modify/capset
+ * sequence.
+ *
+ * This behavior is considered fail-safe
+ * behavior. Upgrading the application to a newer
+ * version of libcap will enable access to the newer
+ * capabilities.
+ *
+ * An alternative would be to return an error here
+ * (-ERANGE), but that causes legacy applications to
+ * unexpectidly fail; the capget/modify/capset aborts
+ * before modification is attempted and the application
+ * fails.
+ */
+ if (copy_to_user(dataptr, kdata, tocopy
+ * sizeof(struct __user_cap_data_struct))) {
+ return -EFAULT;
+ }
+ }
-/*
- * cap_set_all - set capabilities for all processes other than init
- * and self. We call this holding task_capability_lock and tasklist_lock.
- */
-static inline int cap_set_all(kernel_cap_t *effective,
- kernel_cap_t *inheritable,
- kernel_cap_t *permitted)
-{
- struct task_struct *g, *target;
- int ret = -EPERM;
- int found = 0;
-
- do_each_thread(g, target) {
- if (target == current || is_init(target))
- continue;
- found = 1;
- if (security_capset_check(target, effective, inheritable,
- permitted))
- continue;
- ret = 0;
- security_capset_set(target, effective, inheritable, permitted);
- } while_each_thread(g, target);
-
- if (!found)
- ret = 0;
- return ret;
+ return ret;
}
/**
- * sys_capset - set capabilities for a process or a group of processes
+ * sys_capset - set capabilities for a process or (*) a group of processes
* @header: pointer to struct that contains capability version and
* target pid data
* @data: pointer to struct that contains the effective, permitted,
* and inheritable capabilities
*
- * Set capabilities for a given process, all processes, or all
- * processes in a given process group.
+ * Set capabilities for the current process only. The ability to any other
+ * process(es) has been deprecated and removed.
*
* 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
+ * I: any raised capabilities must be a subset of the old permitted
+ * P: any raised capabilities must be a subset of the old permitted
+ * E: must be set to a subset of new permitted
*
* Returns 0 on success and < 0 on error.
*/
-asmlinkage long sys_capset(cap_user_header_t header, const cap_user_data_t data)
+SYSCALL_DEFINE2(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 ret;
- pid_t pid;
-
- if (get_user(version, &header->version))
- return -EFAULT;
-
- if (version != _LINUX_CAPABILITY_VERSION) {
- if (put_user(_LINUX_CAPABILITY_VERSION, &header->version))
- return -EFAULT;
- return -EINVAL;
- }
-
- if (get_user(pid, &header->pid))
- return -EFAULT;
-
- if (pid && pid != current->pid && !capable(CAP_SETPCAP))
- return -EPERM;
-
- if (copy_from_user(&effective, &data->effective, sizeof(effective)) ||
- copy_from_user(&inheritable, &data->inheritable, sizeof(inheritable)) ||
- copy_from_user(&permitted, &data->permitted, sizeof(permitted)))
- return -EFAULT;
-
- spin_lock(&task_capability_lock);
- read_lock(&tasklist_lock);
-
- if (pid > 0 && pid != current->pid) {
- target = find_task_by_pid(pid);
- if (!target) {
- ret = -ESRCH;
- goto out;
- }
- } else
- target = current;
-
- ret = 0;
-
- /* having verified that the proposed changes are legal,
- we now put them into effect. */
- if (pid < 0) {
- if (pid == -1) /* all procs other than current and init */
- ret = cap_set_all(&effective, &inheritable, &permitted);
-
- else /* all procs in process group */
- ret = cap_set_pg(-pid, &effective, &inheritable,
- &permitted);
- } else {
- ret = security_capset_check(target, &effective, &inheritable,
- &permitted);
- if (!ret)
- security_capset_set(target, &effective, &inheritable,
- &permitted);
- }
-
-out:
- read_unlock(&tasklist_lock);
- spin_unlock(&task_capability_lock);
-
- return ret;
+ struct __user_cap_data_struct kdata[_KERNEL_CAPABILITY_U32S];
+ unsigned i, tocopy, copybytes;
+ kernel_cap_t inheritable, permitted, effective;
+ struct cred *new;
+ int ret;
+ pid_t pid;
+
+ ret = cap_validate_magic(header, &tocopy);
+ if (ret != 0)
+ return ret;
+
+ if (get_user(pid, &header->pid))
+ return -EFAULT;
+
+ /* may only affect current now */
+ if (pid != 0 && pid != task_pid_vnr(current))
+ return -EPERM;
+
+ copybytes = tocopy * sizeof(struct __user_cap_data_struct);
+ if (copybytes > sizeof(kdata))
+ return -EFAULT;
+
+ if (copy_from_user(&kdata, data, copybytes))
+ return -EFAULT;
+
+ for (i = 0; i < tocopy; i++) {
+ effective.cap[i] = kdata[i].effective;
+ permitted.cap[i] = kdata[i].permitted;
+ inheritable.cap[i] = kdata[i].inheritable;
+ }
+ while (i < _KERNEL_CAPABILITY_U32S) {
+ effective.cap[i] = 0;
+ permitted.cap[i] = 0;
+ inheritable.cap[i] = 0;
+ i++;
+ }
+
+ new = prepare_creds();
+ if (!new)
+ return -ENOMEM;
+
+ ret = security_capset(new, current_cred(),
+ &effective, &inheritable, &permitted);
+ if (ret < 0)
+ goto error;
+
+ audit_log_capset(pid, new, current_cred());
+
+ return commit_creds(new);
+
+error:
+ abort_creds(new);
+ return ret;
}
-int __capable(struct task_struct *t, int cap)
+/**
+ * capable - Determine if the current task has a superior capability in effect
+ * @cap: The capability to be tested for
+ *
+ * Return true if the current task has the given superior capability currently
+ * available for use, false if not.
+ *
+ * This sets PF_SUPERPRIV on the task if the capability is available on the
+ * assumption that it's about to be used.
+ */
+int capable(int cap)
{
- if (security_capable(t, cap) == 0) {
- t->flags |= PF_SUPERPRIV;
+ if (unlikely(!cap_valid(cap))) {
+ printk(KERN_CRIT "capable() called with invalid cap=%u\n", cap);
+ BUG();
+ }
+
+ if (security_capable(cap) == 0) {
+ current->flags |= PF_SUPERPRIV;
return 1;
}
return 0;
}
-EXPORT_SYMBOL(__capable);
-
-int capable(int cap)
-{
- return __capable(current, cap);
-}
EXPORT_SYMBOL(capable);
Code Review / linux-2.6.git / blobdiff