/* * 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; } } /* * 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. */ /** * 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; __u32 version; struct task_struct *target; unsigned tocopy; kernel_cap_t pE, pI, pP; 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: tocopy = _LINUX_CAPABILITY_U32S_2; break; default: if (put_user(_LINUX_CAPABILITY_VERSION, &header->version)) return -EFAULT; return -EINVAL; } 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[_LINUX_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 < _LINUX_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[_LINUX_CAPABILITY_U32S]; unsigned i, tocopy; 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; switch (version) { case _LINUX_CAPABILITY_VERSION_1: warn_legacy_capability_use(); tocopy = _LINUX_CAPABILITY_U32S_1; break; case _LINUX_CAPABILITY_VERSION_2: tocopy = _LINUX_CAPABILITY_U32S_2; break; default: if (put_user(_LINUX_CAPABILITY_VERSION, &header->version)) return -EFAULT; return -EINVAL; } 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 < _LINUX_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);