Commit 8c81ddd2 authored by Waiman Long's avatar Waiman Long Committed by Linus Torvalds
Browse files

ipc: IPCMNI limit check for semmni 

For SysV semaphores, the semmni value is the last part of the 4-element
sem number array.  To make semmni behave in a similar way to msgmni and
shmmni, we can't directly use the _minmax handler.  Instead, a special sem
specific handler is added to check the last argument to make sure that it
is limited to the [0, IPCMNI] range.  An error will be returned if this is
not the case.

Link: http://lkml.kernel.org/r/1536352137-12003-3-git-send-email-longman@redhat.com


Signed-off-by: default avatarWaiman Long <longman@redhat.com>
Reviewed-by: default avatarDavidlohr Bueso <dave@stgolabs.net>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kees Cook <keescook@chromium.org>
Cc: Luis R. Rodriguez <mcgrof@kernel.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Takashi Iwai <tiwai@suse.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 6730e658

ipc/ipc_sysctl.c

+22 −1
Original line number Diff line number Diff line
@@ -88,12 +88,33 @@ static int proc_ipc_auto_msgmni(struct ctl_table *table, int write, 
	return proc_dointvec_minmax(&ipc_table, write, buffer, lenp, ppos);

}



static int proc_ipc_sem_dointvec(struct ctl_table *table, int write,

	void __user *buffer, size_t *lenp, loff_t *ppos)

{

	int ret, semmni;

	struct ipc_namespace *ns = current->nsproxy->ipc_ns;



	semmni = ns->sem_ctls[3];

	ret = proc_ipc_dointvec(table, write, buffer, lenp, ppos);



	if (!ret)

		ret = sem_check_semmni(current->nsproxy->ipc_ns);



	/*

	 * Reset the semmni value if an error happens.

	 */

	if (ret)

		ns->sem_ctls[3] = semmni;

	return ret;

}



#else

#define proc_ipc_doulongvec_minmax NULL

#define proc_ipc_dointvec	   NULL

#define proc_ipc_dointvec_minmax   NULL

#define proc_ipc_dointvec_minmax_orphans   NULL

#define proc_ipc_auto_msgmni	   NULL

#define proc_ipc_sem_dointvec	   NULL

#endif



static int zero;
@@ -175,7 +196,7 @@ static struct ctl_table ipc_kern_table[] = { 
		.data		= &init_ipc_ns.sem_ctls,

		.maxlen		= 4*sizeof(int),

		.mode		= 0644,

		.proc_handler	= proc_ipc_dointvec,

		.proc_handler	= proc_ipc_sem_dointvec,

	},

#ifdef CONFIG_CHECKPOINT_RESTORE

	{

ipc/util.h

+9 −0
Original line number Diff line number Diff line
@@ -217,6 +217,15 @@ int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids, 
void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,

		void (*free)(struct ipc_namespace *, struct kern_ipc_perm *));



static inline int sem_check_semmni(struct ipc_namespace *ns) {

	/*

	 * Check semmni range [0, IPCMNI]

	 * semmni is the last element of sem_ctls[4] array

	 */

	return ((ns->sem_ctls[3] < 0) || (ns->sem_ctls[3] > IPCMNI))

		? -ERANGE : 0;

}



#ifdef CONFIG_COMPAT

#include <linux/compat.h>

struct compat_ipc_perm {

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