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Commit f44d3e78 authored by Eric W. Biederman's avatar Eric W. Biederman Committed by Greg Kroah-Hartman
Browse files

sysfs: Update sysfs_setxattr so it updates secdata under the sysfs_mutex 



The sysfs_mutex is required to ensure updates are and will remain
atomic with respect to other inode iattr updates, that do not happen
through the filesystem.

Acked-by: default avatarSerge Hallyn <serue@us.ibm.com>
Acked-by: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarEric W. Biederman <ebiederm@aristanetworks.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent d3a3b0ad

fs/sysfs/inode.c

+29 −12
Original line number Diff line number Diff line
@@ -123,23 +123,39 @@ int sysfs_setattr(struct dentry * dentry, struct iattr * iattr) 
	return error;

}



static int sysfs_sd_setsecdata(struct sysfs_dirent *sd, void **secdata, u32 *secdata_len)

{

	struct sysfs_inode_attrs *iattrs;

	void *old_secdata;

	size_t old_secdata_len;



	iattrs = sd->s_iattr;

	if (!iattrs)

		iattrs = sysfs_init_inode_attrs(sd);

	if (!iattrs)

		return -ENOMEM;



	old_secdata = iattrs->ia_secdata;

	old_secdata_len = iattrs->ia_secdata_len;



	iattrs->ia_secdata = *secdata;

	iattrs->ia_secdata_len = *secdata_len;



	*secdata = old_secdata;

	*secdata_len = old_secdata_len;

	return 0;

}



int sysfs_setxattr(struct dentry *dentry, const char *name, const void *value,

		size_t size, int flags)

{

	struct sysfs_dirent *sd = dentry->d_fsdata;

	struct sysfs_inode_attrs *iattrs;

	void *secdata;

	int error;

	u32 secdata_len = 0;



	if (!sd)

		return -EINVAL;

	if (!sd->s_iattr)

		sd->s_iattr = sysfs_init_inode_attrs(sd);

	if (!sd->s_iattr)

		return -ENOMEM;



	iattrs = sd->s_iattr;



	if (!strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN)) {

		const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
@@ -151,12 +167,13 @@ int sysfs_setxattr(struct dentry *dentry, const char *name, const void *value, 
						&secdata, &secdata_len);

		if (error)

			goto out;

		if (iattrs->ia_secdata)

			security_release_secctx(iattrs->ia_secdata,

						iattrs->ia_secdata_len);

		iattrs->ia_secdata = secdata;

		iattrs->ia_secdata_len = secdata_len;



		mutex_lock(&sysfs_mutex);

		error = sysfs_sd_setsecdata(sd, &secdata, &secdata_len);

		mutex_unlock(&sysfs_mutex);



		if (secdata)

			security_release_secctx(secdata, secdata_len);

	} else

		return -EINVAL;

out: