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https://github.com/torvalds/linux
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32927393dc
Instead of having all the sysctl handlers deal with user pointers, which is rather hairy in terms of the BPF interaction, copy the input to and from userspace in common code. This also means that the strings are always NUL-terminated by the common code, making the API a little bit safer. As most handler just pass through the data to one of the common handlers a lot of the changes are mechnical. Signed-off-by: Christoph Hellwig <hch@lst.de> Acked-by: Andrey Ignatov <rdna@fb.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
144 lines
3.2 KiB
C
144 lines
3.2 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Copyright (C) 2007
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*
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* Author: Eric Biederman <ebiederm@xmision.com>
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*/
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#include <linux/export.h>
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#include <linux/uts.h>
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#include <linux/utsname.h>
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#include <linux/sysctl.h>
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#include <linux/wait.h>
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#include <linux/rwsem.h>
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#ifdef CONFIG_PROC_SYSCTL
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static void *get_uts(struct ctl_table *table)
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{
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char *which = table->data;
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struct uts_namespace *uts_ns;
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uts_ns = current->nsproxy->uts_ns;
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which = (which - (char *)&init_uts_ns) + (char *)uts_ns;
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return which;
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}
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/*
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* Special case of dostring for the UTS structure. This has locks
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* to observe. Should this be in kernel/sys.c ????
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*/
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static int proc_do_uts_string(struct ctl_table *table, int write,
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void *buffer, size_t *lenp, loff_t *ppos)
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{
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struct ctl_table uts_table;
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int r;
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char tmp_data[__NEW_UTS_LEN + 1];
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memcpy(&uts_table, table, sizeof(uts_table));
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uts_table.data = tmp_data;
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/*
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* Buffer the value in tmp_data so that proc_dostring() can be called
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* without holding any locks.
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* We also need to read the original value in the write==1 case to
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* support partial writes.
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*/
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down_read(&uts_sem);
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memcpy(tmp_data, get_uts(table), sizeof(tmp_data));
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up_read(&uts_sem);
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r = proc_dostring(&uts_table, write, buffer, lenp, ppos);
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if (write) {
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/*
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* Write back the new value.
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* Note that, since we dropped uts_sem, the result can
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* theoretically be incorrect if there are two parallel writes
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* at non-zero offsets to the same sysctl.
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*/
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down_write(&uts_sem);
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memcpy(get_uts(table), tmp_data, sizeof(tmp_data));
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up_write(&uts_sem);
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proc_sys_poll_notify(table->poll);
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}
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return r;
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}
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#else
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#define proc_do_uts_string NULL
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#endif
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static DEFINE_CTL_TABLE_POLL(hostname_poll);
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static DEFINE_CTL_TABLE_POLL(domainname_poll);
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static struct ctl_table uts_kern_table[] = {
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{
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.procname = "ostype",
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.data = init_uts_ns.name.sysname,
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.maxlen = sizeof(init_uts_ns.name.sysname),
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.mode = 0444,
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.proc_handler = proc_do_uts_string,
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},
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{
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.procname = "osrelease",
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.data = init_uts_ns.name.release,
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.maxlen = sizeof(init_uts_ns.name.release),
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.mode = 0444,
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.proc_handler = proc_do_uts_string,
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},
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{
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.procname = "version",
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.data = init_uts_ns.name.version,
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.maxlen = sizeof(init_uts_ns.name.version),
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.mode = 0444,
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.proc_handler = proc_do_uts_string,
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},
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{
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.procname = "hostname",
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.data = init_uts_ns.name.nodename,
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.maxlen = sizeof(init_uts_ns.name.nodename),
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.mode = 0644,
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.proc_handler = proc_do_uts_string,
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.poll = &hostname_poll,
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},
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{
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.procname = "domainname",
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.data = init_uts_ns.name.domainname,
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.maxlen = sizeof(init_uts_ns.name.domainname),
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.mode = 0644,
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.proc_handler = proc_do_uts_string,
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.poll = &domainname_poll,
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},
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{}
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};
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static struct ctl_table uts_root_table[] = {
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{
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.procname = "kernel",
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.mode = 0555,
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.child = uts_kern_table,
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},
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{}
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};
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#ifdef CONFIG_PROC_SYSCTL
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/*
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* Notify userspace about a change in a certain entry of uts_kern_table,
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* identified by the parameter proc.
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*/
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void uts_proc_notify(enum uts_proc proc)
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{
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struct ctl_table *table = &uts_kern_table[proc];
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proc_sys_poll_notify(table->poll);
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}
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#endif
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static int __init utsname_sysctl_init(void)
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{
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register_sysctl_table(uts_root_table);
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return 0;
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}
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device_initcall(utsname_sysctl_init);
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