X-Git-Url: http://ftp.safe.ca/?a=blobdiff_plain;f=kernel%2Fcapability.c;h=4e17041963f57073a4fb3836c415b9a681e40383;hb=1092307d582a7566d23779c304cf86f3075ac5f0;hp=bfa3c92e16f2b1c5a9971335f6500cb17a6c8a49;hpb=c59ede7b78db329949d9cdcd7064e22d357560ef;p=safe%2Fjmp%2Flinux-2.6 diff --git a/kernel/capability.c b/kernel/capability.c index bfa3c92..4e17041 100644 --- a/kernel/capability.c +++ b/kernel/capability.c @@ -3,233 +3,313 @@ * * Copyright (C) 1997 Andrew Main * - * Integrated into 2.1.97+, Andrew G. Morgan + * Integrated into 2.1.97+, Andrew G. Morgan * 30 May 2002: Cleanup, Robert M. Love - */ + */ +#include #include #include #include #include #include +#include #include - -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); + +#ifdef CONFIG_SECURITY_FILE_CAPABILITIES +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); +#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. + * 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) -{ - int ret = 0; - pid_t pid; - __u32 version; - task_t *target; - struct __user_cap_data_struct data; - if (get_user(version, &header->version)) - return -EFAULT; +static void warn_deprecated_v2(void) +{ + static int warned; - if (version != _LINUX_CAPABILITY_VERSION) { - if (put_user(_LINUX_CAPABILITY_VERSION, &header->version)) - return -EFAULT; - return -EINVAL; - } + if (!warned) { + char name[sizeof(current->comm)]; - if (get_user(pid, &header->pid)) - return -EFAULT; + 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 (pid < 0) - return -EINVAL; +/* + * 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; +} - 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); + read_lock(&tasklist_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; + read_unlock(&tasklist_lock); + } 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) { - task_t *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 (ret != 0) + return 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) -{ - task_t *g, *target; - int ret = -EPERM; - int found = 0; - - do_each_thread(g, target) { - if (target == current || target->pid == 1) - 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) +{ + struct __user_cap_data_struct kdata[_KERNEL_CAPABILITY_U32S]; + unsigned i, tocopy; + 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; + + 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++; + } + + 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; +} + +/** + * 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) { - kernel_cap_t inheritable, permitted, effective; - __u32 version; - task_t *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; + 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);