// SPDX-License-Identifier: GPL-2.0/* * 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> */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include <linux/audit.h>#include <linux/capability.h>#include <linux/mm.h>#include <linux/export.h>#include <linux/security.h>#include <linux/syscalls.h>#include <linux/pid_namespace.h>#include <linux/user_namespace.h>#include <linux/uaccess.h> 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); #ifdef CONFIG_MULTIUSER/* * 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){	pr_info_once("warning: `%s' uses 32-bit capabilities (legacy support in use)\n",		     current->comm);} /* * 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){	pr_info_once("warning: `%s' uses deprecated v2 capabilities in a way that may be insecure\n",		     current->comm);} /* * 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();		fallthrough;	/* 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;} /* * 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 != task_pid_vnr(current))) {		const struct task_struct *target; 		rcu_read_lock(); 		target = find_task_by_vpid(pid);		if (!target)			ret = -ESRCH;		else			ret = security_capget(target, pEp, pIp, pPp); 		rcu_read_unlock();	} else		ret = security_capget(current, pEp, pIp, pPp); 	return ret;} /** * 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. */SYSCALL_DEFINE2(capget, cap_user_header_t, header, cap_user_data_t, dataptr){	int ret = 0;	pid_t pid;	unsigned tocopy;	kernel_cap_t pE, pI, pP;	struct __user_cap_data_struct kdata[2]; 	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)		return ret; 	/*	 * Annoying legacy format with 64-bit capabilities exposed	 * as two sets of 32-bit fields, so we need to split the	 * capability values up.	 */	kdata[0].effective   = pE.val; kdata[1].effective   = pE.val >> 32;	kdata[0].permitted   = pP.val; kdata[1].permitted   = pP.val >> 32;	kdata[0].inheritable = pI.val; kdata[1].inheritable = pI.val >> 32; 	/*	 * 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	 * unexpectedly fail; the capget/modify/capset aborts	 * before modification is attempted and the application	 * fails.	 */	if (copy_to_user(dataptr, kdata, tocopy * sizeof(kdata[0])))		return -EFAULT; 	return 0;} static kernel_cap_t mk_kernel_cap(u32 low, u32 high){	return (kernel_cap_t) { (low | ((u64)high << 32)) & CAP_VALID_MASK };} /** * 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 the current process only.  The ability to any other * process(es) has been deprecated and removed. * * The restrictions on setting capabilities are specified as: * * 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. */SYSCALL_DEFINE2(capset, cap_user_header_t, header, const cap_user_data_t, data){	struct __user_cap_data_struct kdata[2] = { { 0, }, };	unsigned 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; 	effective   = mk_kernel_cap(kdata[0].effective,   kdata[1].effective);	permitted   = mk_kernel_cap(kdata[0].permitted,   kdata[1].permitted);	inheritable = mk_kernel_cap(kdata[0].inheritable, kdata[1].inheritable); 	new = prepare_creds();	if (!new)		return -ENOMEM; 	ret = security_capset(new, current_cred(),			      &effective, &inheritable, &permitted);	if (ret < 0)		goto error; 	audit_log_capset(new, current_cred()); 	return commit_creds(new); error:	abort_creds(new);	return ret;} /** * has_ns_capability - Does a task have a capability in a specific user ns * @t: The task in question * @ns: target user namespace * @cap: The capability to be tested for * * Return true if the specified task has the given superior capability * currently in effect to the specified user namespace, false if not. * * Note that this does not set PF_SUPERPRIV on the task. */bool has_ns_capability(struct task_struct *t,		       struct user_namespace *ns, int cap){	int ret; 	rcu_read_lock();	ret = security_capable(__task_cred(t), ns, cap, CAP_OPT_NONE);	rcu_read_unlock(); 	return (ret == 0);} /** * has_ns_capability_noaudit - Does a task have a capability (unaudited) * in a specific user ns. * @t: The task in question * @ns: target user namespace * @cap: The capability to be tested for * * Return true if the specified task has the given superior capability * currently in effect to the specified user namespace, false if not. * Do not write an audit message for the check. * * Note that this does not set PF_SUPERPRIV on the task. */bool has_ns_capability_noaudit(struct task_struct *t,			       struct user_namespace *ns, int cap){	int ret; 	rcu_read_lock();	ret = security_capable(__task_cred(t), ns, cap, CAP_OPT_NOAUDIT);	rcu_read_unlock(); 	return (ret == 0);} /** * has_capability_noaudit - Does a task have a capability (unaudited) in the * initial user ns * @t: The task in question * @cap: The capability to be tested for * * Return true if the specified task has the given superior capability * currently in effect to init_user_ns, false if not.  Don't write an * audit message for the check. * * Note that this does not set PF_SUPERPRIV on the task. */bool has_capability_noaudit(struct task_struct *t, int cap){	return has_ns_capability_noaudit(t, &init_user_ns, cap);} static bool ns_capable_common(struct user_namespace *ns,			      int cap,			      unsigned int opts){	int capable; 	if (unlikely(!cap_valid(cap))) {		pr_crit("capable() called with invalid cap=%u\n", cap);		BUG();	} 	capable = security_capable(current_cred(), ns, cap, opts);	if (capable == 0) {		current->flags |= PF_SUPERPRIV;		return true;	}	return false;} /** * ns_capable - Determine if the current task has a superior capability in effect * @ns:  The usernamespace we want the capability in * @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. */bool ns_capable(struct user_namespace *ns, int cap){	return ns_capable_common(ns, cap, CAP_OPT_NONE);}EXPORT_SYMBOL(ns_capable); /** * ns_capable_noaudit - Determine if the current task has a superior capability * (unaudited) in effect * @ns:  The usernamespace we want the capability in * @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. */bool ns_capable_noaudit(struct user_namespace *ns, int cap){	return ns_capable_common(ns, cap, CAP_OPT_NOAUDIT);}EXPORT_SYMBOL(ns_capable_noaudit); /** * ns_capable_setid - Determine if the current task has a superior capability * in effect, while signalling that this check is being done from within a * setid or setgroups syscall. * @ns:  The usernamespace we want the capability in * @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. */bool ns_capable_setid(struct user_namespace *ns, int cap){	return ns_capable_common(ns, cap, CAP_OPT_INSETID);}EXPORT_SYMBOL(ns_capable_setid); /** * 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. */bool capable(int cap){	return ns_capable(&init_user_ns, cap);}EXPORT_SYMBOL(capable); /** * capable_noaudit - Determine if the current task has a superior * capability in effect by checking the process's effective * capabilities (unaudited). * @cap: The capability to be tested for * * This is the same as capable(), except it uses CAP_OPT_NOAUDIT as to prevent * issuing spurious audit messages. * * This sets PF_SUPERPRIV on the task if the capability is available on the * assumption that it's about to be used. */bool capable_noaudit(int cap){	return ns_capable_noaudit(&init_user_ns, cap);}EXPORT_SYMBOL(capable_noaudit);#endif /* CONFIG_MULTIUSER */ /** * file_ns_capable - Determine if the file's opener had a capability in effect * @file:  The file we want to check * @ns:  The usernamespace we want the capability in * @cap: The capability to be tested for * * Return true if task that opened the file had a capability in effect * when the file was opened. * * This does not set PF_SUPERPRIV because the caller may not * actually be privileged. */bool file_ns_capable(const struct file *file, struct user_namespace *ns,		     int cap){ 	if (WARN_ON_ONCE(!cap_valid(cap)))		return false; 	if (security_capable(file->f_cred, ns, cap, CAP_OPT_NONE) == 0)		return true; 	return false;}EXPORT_SYMBOL(file_ns_capable); /** * privileged_wrt_inode_uidgid - Do capabilities in the namespace work over the inode? * @ns: The user namespace in question * @idmap: idmap of the mount @inode was found from * @inode: The inode in question * * Return true if the inode uid and gid are within the namespace. */bool privileged_wrt_inode_uidgid(struct user_namespace *ns,				 struct mnt_idmap *idmap,				 const struct inode *inode){	return vfsuid_has_mapping(ns, i_uid_into_vfsuid(idmap, inode)) &&	       vfsgid_has_mapping(ns, i_gid_into_vfsgid(idmap, inode));} /** * capable_wrt_inode_uidgid - Check nsown_capable and uid and gid mapped * @idmap: idmap of the mount @inode was found from * @inode: The inode in question * @cap: The capability in question * * Return true if the current task has the given capability targeted at * its own user namespace and that the given inode's uid and gid are * mapped into the current user namespace. */bool capable_wrt_inode_uidgid(struct mnt_idmap *idmap,			      const struct inode *inode, int cap){	struct user_namespace *ns = current_user_ns(); 	return ns_capable(ns, cap) &&	       privileged_wrt_inode_uidgid(ns, idmap, inode);}EXPORT_SYMBOL(capable_wrt_inode_uidgid); /**

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