// 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>
*/
staticvoid 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.
*/
staticvoid 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.
*/ staticint 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.
*/ staticinlineint 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))) { conststruct 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_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;
/** * 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;
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);
}
EXPORT_SYMBOL(has_capability_noaudit);
staticbool ns_capable_common(struct user_namespace *ns, int cap, unsignedint opts)
{ int capable;
if (unlikely(!cap_valid(cap))) {
pr_crit("capable() called with invalid cap=%u\n", cap);
BUG();
}
/** * 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); #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(conststruct file *file, struct user_namespace *ns, int cap)
{
if (WARN_ON_ONCE(!cap_valid(cap))) returnfalse;
if (security_capable(file->f_cred, ns, cap, CAP_OPT_NONE) == 0) returntrue;
returnfalse;
}
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, conststruct 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, conststruct inode *inode, int cap)
{ struct user_namespace *ns = current_user_ns();
/** * ptracer_capable - Determine if the ptracer holds CAP_SYS_PTRACE in the namespace * @tsk: The task that may be ptraced * @ns: The user namespace to search for CAP_SYS_PTRACE in * * Return true if the task that is ptracing the current task had CAP_SYS_PTRACE * in the specified user namespace.
*/ bool ptracer_capable(struct task_struct *tsk, struct user_namespace *ns)
{ int ret = 0; /* An absent tracer adds no restrictions */ conststruct cred *cred;
rcu_read_lock();
cred = rcu_dereference(tsk->ptracer_cred); if (cred)
ret = security_capable(cred, ns, CAP_SYS_PTRACE,
CAP_OPT_NOAUDIT);
rcu_read_unlock(); return (ret == 0);
}
¤ Dauer der Verarbeitung: 0.19 Sekunden
(vorverarbeitet)
¤
Die Informationen auf dieser Webseite wurden
nach bestem Wissen sorgfältig zusammengestellt. Es wird jedoch weder Vollständigkeit, noch Richtigkeit,
noch Qualität der bereit gestellten Informationen zugesichert.
Bemerkung:
Die farbliche Syntaxdarstellung ist noch experimentell.
