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17f60a7da1
There is no way to limit the capabilities of usermodehelpers. This problem reared its head recently when someone complained that any user with cap_net_admin was able to load arbitrary kernel modules, even though the user didn't have cap_sys_module. The reason is because the actual load is done by a usermode helper and those always have the full cap set. This patch addes new sysctls which allow us to bound the permissions of usermode helpers. /proc/sys/kernel/usermodehelper/bset /proc/sys/kernel/usermodehelper/inheritable You must have CAP_SYS_MODULE and CAP_SETPCAP to change these (changes are &= ONLY). When the kernel launches a usermodehelper it will do so with these as the bset and pI. -v2: make globals static create spinlock to protect globals -v3: require both CAP_SETPCAP and CAP_SYS_MODULE -v4: fix the typo s/CAP_SET_PCAP/CAP_SETPCAP/ because I didn't commit Signed-off-by: Eric Paris <eparis@redhat.com> No-objection-from: Serge E. Hallyn <serge.hallyn@canonical.com> Acked-by: David Howells <dhowells@redhat.com> Acked-by: Serge E. Hallyn <serge.hallyn@canonical.com> Acked-by: Andrew G. Morgan <morgan@kernel.org> Signed-off-by: James Morris <jmorris@namei.org>
121 lines
3.7 KiB
C
121 lines
3.7 KiB
C
#ifndef __LINUX_KMOD_H__
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#define __LINUX_KMOD_H__
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/*
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* include/linux/kmod.h
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#include <linux/gfp.h>
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#include <linux/stddef.h>
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#include <linux/errno.h>
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#include <linux/compiler.h>
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#include <linux/workqueue.h>
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#include <linux/sysctl.h>
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#define KMOD_PATH_LEN 256
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#ifdef CONFIG_MODULES
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extern char modprobe_path[]; /* for sysctl */
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/* modprobe exit status on success, -ve on error. Return value
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* usually useless though. */
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extern int __request_module(bool wait, const char *name, ...) \
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__attribute__((format(printf, 2, 3)));
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#define request_module(mod...) __request_module(true, mod)
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#define request_module_nowait(mod...) __request_module(false, mod)
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#define try_then_request_module(x, mod...) \
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((x) ?: (__request_module(true, mod), (x)))
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#else
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static inline int request_module(const char *name, ...) { return -ENOSYS; }
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static inline int request_module_nowait(const char *name, ...) { return -ENOSYS; }
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#define try_then_request_module(x, mod...) (x)
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#endif
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struct key;
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struct file;
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enum umh_wait {
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UMH_NO_WAIT = -1, /* don't wait at all */
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UMH_WAIT_EXEC = 0, /* wait for the exec, but not the process */
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UMH_WAIT_PROC = 1, /* wait for the process to complete */
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};
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struct subprocess_info {
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struct work_struct work;
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struct completion *complete;
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char *path;
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char **argv;
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char **envp;
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enum umh_wait wait;
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int retval;
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int (*init)(struct subprocess_info *info);
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void (*cleanup)(struct subprocess_info *info);
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void *data;
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};
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/* Allocate a subprocess_info structure */
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struct subprocess_info *call_usermodehelper_setup(char *path, char **argv,
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char **envp, gfp_t gfp_mask);
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/* Set various pieces of state into the subprocess_info structure */
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void call_usermodehelper_setfns(struct subprocess_info *info,
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int (*init)(struct subprocess_info *info),
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void (*cleanup)(struct subprocess_info *info),
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void *data);
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/* Actually execute the sub-process */
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int call_usermodehelper_exec(struct subprocess_info *info, enum umh_wait wait);
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/* Free the subprocess_info. This is only needed if you're not going
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to call call_usermodehelper_exec */
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void call_usermodehelper_freeinfo(struct subprocess_info *info);
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static inline int
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call_usermodehelper_fns(char *path, char **argv, char **envp,
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enum umh_wait wait,
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int (*init)(struct subprocess_info *info),
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void (*cleanup)(struct subprocess_info *), void *data)
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{
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struct subprocess_info *info;
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gfp_t gfp_mask = (wait == UMH_NO_WAIT) ? GFP_ATOMIC : GFP_KERNEL;
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info = call_usermodehelper_setup(path, argv, envp, gfp_mask);
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if (info == NULL)
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return -ENOMEM;
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call_usermodehelper_setfns(info, init, cleanup, data);
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return call_usermodehelper_exec(info, wait);
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}
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static inline int
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call_usermodehelper(char *path, char **argv, char **envp, enum umh_wait wait)
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{
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return call_usermodehelper_fns(path, argv, envp, wait,
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NULL, NULL, NULL);
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}
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extern struct ctl_table usermodehelper_table[];
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extern void usermodehelper_init(void);
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extern int usermodehelper_disable(void);
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extern void usermodehelper_enable(void);
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#endif /* __LINUX_KMOD_H__ */
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