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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: Serge Hallyn <serue@us.ibm.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Eric W. Biederman <ebiederm@aristanetworks.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Eric W. Biederman 2009-11-07 23:26:59 -08:00 committed by Greg Kroah-Hartman
parent d3a3b0adad
commit f44d3e7857
1 changed files with 29 additions and 12 deletions
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41
fs/sysfs/inode.c
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@ -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: