| /* |
| * linux/kernel/capability.c |
| * |
| * Copyright (C) 1997 Andrew Main <zefram@fysh.org> |
| * |
| * Integrated into 2.1.97+, Andrew G. Morgan <morgan@kernel.org> |
| * 30 May 2002: Cleanup, Robert M. Love <rml@tech9.net> |
| */ |
| |
| #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> |
| |
| /* |
| * This lock protects task->cap_* for all tasks including current. |
| * Locking rule: acquire this prior to tasklist_lock. |
| */ |
| static DEFINE_SPINLOCK(task_capability_lock); |
| |
| /* |
| * Leveraged for setting/resetting capabilities |
| */ |
| |
| 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); |
| |
| /* |
| * More recent versions of libcap are available from: |
| * |
| * http://www.kernel.org/pub/linux/libs/security/linux-privs/ |
| */ |
| |
| 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. |
| * |
| * 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. |
| */ |
| |
| static void warn_deprecated_v2(void) |
| { |
| static int warned; |
| |
| if (!warned) { |
| char name[sizeof(current->comm)]; |
| |
| printk(KERN_INFO "warning: `%s' uses deprecated v2" |
| " capabilities in a way that may be insecure.\n", |
| get_task_comm(name, current)); |
| warned = 1; |
| } |
| } |
| |
| /* |
| * 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; |
| } |
| |
| return 0; |
| } |
| |
| /* |
| * 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. |
| */ |
| |
| /* |
| * Atomically modify the effective capabilities returning the original |
| * value. No permission check is performed here - it is assumed that the |
| * caller is permitted to set the desired effective capabilities. |
| */ |
| kernel_cap_t cap_set_effective(const kernel_cap_t pE_new) |
| { |
| kernel_cap_t pE_old; |
| |
| spin_lock(&task_capability_lock); |
| |
| pE_old = current->cap_effective; |
| current->cap_effective = pE_new; |
| |
| spin_unlock(&task_capability_lock); |
| |
| return pE_old; |
| } |
| |
| EXPORT_SYMBOL(cap_set_effective); |
| |
| /** |
| * 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. |
| */ |
| asmlinkage long sys_capget(cap_user_header_t header, cap_user_data_t dataptr) |
| { |
| int ret = 0; |
| pid_t pid; |
| struct task_struct *target; |
| unsigned tocopy; |
| kernel_cap_t pE, pI, pP; |
| |
| ret = cap_validate_magic(header, &tocopy); |
| if (ret != 0) |
| return ret; |
| |
| if (get_user(pid, &header->pid)) |
| return -EFAULT; |
| |
| if (pid < 0) |
| return -EINVAL; |
| |
| spin_lock(&task_capability_lock); |
| read_lock(&tasklist_lock); |
| |
| if (pid && pid != task_pid_vnr(current)) { |
| target = find_task_by_vpid(pid); |
| if (!target) { |
| ret = -ESRCH; |
| goto out; |
| } |
| } else |
| target = current; |
| |
| ret = security_capget(target, &pE, &pI, &pP); |
| |
| out: |
| read_unlock(&tasklist_lock); |
| spin_unlock(&task_capability_lock); |
| |
| 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]; |
| } |
| |
| /* |
| * 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; |
| } |
| } |
| |
| 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. |
| */ |
| static inline int cap_set_pg(int pgrp_nr, kernel_cap_t *effective, |
| kernel_cap_t *inheritable, |
| kernel_cap_t *permitted) |
| { |
| struct task_struct *g, *target; |
| int ret = -EPERM; |
| int found = 0; |
| struct pid *pgrp; |
| |
| pgrp = find_vpid(pgrp_nr); |
| do_each_pid_task(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; |
| } |
| } while_each_pid_task(pgrp, PIDTYPE_PGID, g); |
| |
| if (!found) |
| ret = 0; |
| return ret; |
| } |
| |
| /* |
| * 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_container_init(target->group_leader)) |
| 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; |
| } |
| |
| /** |
| * 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. |
| * |
| * 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 |
| * |
| * Returns 0 on success and < 0 on error. |
| */ |
| asmlinkage long sys_capset(cap_user_header_t header, const cap_user_data_t data) |
| { |
| struct __user_cap_data_struct kdata[_KERNEL_CAPABILITY_U32S]; |
| unsigned i, tocopy; |
| kernel_cap_t inheritable, permitted, effective; |
| struct task_struct *target; |
| int ret; |
| pid_t pid; |
| |
| ret = cap_validate_magic(header, &tocopy); |
| if (ret != 0) |
| return ret; |
| |
| if (get_user(pid, &header->pid)) |
| return -EFAULT; |
| |
| if (pid && pid != task_pid_vnr(current) && !capable(CAP_SETPCAP)) |
| return -EPERM; |
| |
| if (copy_from_user(&kdata, data, tocopy |
| * sizeof(struct __user_cap_data_struct))) { |
| 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++; |
| } |
| |
| spin_lock(&task_capability_lock); |
| read_lock(&tasklist_lock); |
| |
| if (pid > 0 && pid != task_pid_vnr(current)) { |
| target = find_task_by_vpid(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; |
| } |
| |
| int __capable(struct task_struct *t, int cap) |
| { |
| if (security_capable(t, cap) == 0) { |
| t->flags |= PF_SUPERPRIV; |
| return 1; |
| } |
| return 0; |
| } |
| |
| int capable(int cap) |
| { |
| return __capable(current, cap); |
| } |
| EXPORT_SYMBOL(capable); |