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nfs_remount(): don't leak, don't ignore LSM options quietly 

* if mount(2) passes something like "context=foo" with MS_REMOUNT
in flags (/sbin/mount.nfs will _not_ do that - you need to issue
the syscall manually), you'll get leaked copies for LSM options.
The reason is that instead of nfs_{alloc,free}_parsed_mount_data()
nfs_remount() uses kzalloc/kfree, which lacks the needed cleanup.

* selinux options are not changed on remount (as for any other
fs), but in case of NFS the failure is quiet - they are not compared
to what we used to have, with complaint in case of attempted changes.
Trivially fixed by converting to use of security_sb_remount().

Reviewed-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2018-12-10 17:30:41 -05:00
parent a65001e8a4
commit 6a0440e5b7
1 changed files with 4 additions and 2 deletions
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6
fs/nfs/super.c
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@ -2254,7 +2254,7 @@ nfs_remount(struct super_block *sb, int *flags, char *raw_data)
options->version <= 6)))) options->version <= 6))))
return 0; return 0;
data = kzalloc(sizeof(*data), GFP_KERNEL); data = nfs_alloc_parsed_mount_data();
if (data == NULL) if (data == NULL)
return -ENOMEM; return -ENOMEM;
@ -2293,8 +2293,10 @@ nfs_remount(struct super_block *sb, int *flags, char *raw_data)
/* compare new mount options with old ones */ /* compare new mount options with old ones */
error = nfs_compare_remount_data(nfss, data); error = nfs_compare_remount_data(nfss, data);
if (!error)
error = security_sb_remount(sb, &data->lsm_opts);
out: out:
kfree(data); nfs_free_parsed_mount_data(data);
return error; return error;
} }
EXPORT_SYMBOL_GPL(nfs_remount); EXPORT_SYMBOL_GPL(nfs_remount);