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Message-ID: <052d91687e813110cc1e1d762ea086cc8085114a.camel@linux.ibm.com>
Date: Wed, 23 Nov 2022 12:46:41 -0500
From: Mimi Zohar <zohar@...ux.ibm.com>
To: Roberto Sassu <roberto.sassu@...weicloud.com>, mark@...heh.com,
jlbec@...lplan.org, joseph.qi@...ux.alibaba.com,
dmitry.kasatkin@...il.com, paul@...l-moore.com, jmorris@...ei.org,
serge@...lyn.com, stephen.smalley.work@...il.com,
eparis@...isplace.org, Casey Schaufler <casey@...aufler-ca.com>
Cc: ocfs2-devel@....oracle.com, reiserfs-devel@...r.kernel.org,
linux-integrity@...r.kernel.org,
linux-security-module@...r.kernel.org, selinux@...r.kernel.org,
linux-kernel@...r.kernel.org, keescook@...omium.org,
nicolas.bouchinet@...p-os.org,
Roberto Sassu <roberto.sassu@...wei.com>
Subject: Re: [PATCH v5 2/6] ocfs2: Switch to security_inode_init_security()
On Wed, 2022-11-23 at 10:51 +0100, Roberto Sassu wrote:
> From: Roberto Sassu <roberto.sassu@...wei.com>
>
> In preparation for removing security_old_inode_init_security(), switch to
> security_inode_init_security().
>
> Extend the existing ocfs2_initxattrs() to take the
> ocfs2_security_xattr_info structure from fs_info, and populate the
> name/value/len triple with the first xattr provided by LSMs. Supporting
> multiple xattrs is not currently supported, as it requires non-trivial
> changes that can be done at a later time.
ocfs2 already defines ocfs2_init_security_get() as a wrapper around
calling either security_old_inode_init_security() or
security_inode_init_security(). Based on "si" one or the other hook is
called. ocfs2_initxattrs is already defined.
struct ocfs2_security_xattr_info si = {
.name = NULL,
.enable = 1,
};
The main difference between calling security_old_inode_init_security or
security_inode_init_security() is whether or not security.evm is
calculated and written.
Perhaps it is time to remove the call to
security_old_inode_init_security() in ocfs2_init_security_get(). We
need to hear back from the ocfs2 community. Mark? Joel?
As noted previously this change affects mknod and symlinks.
Mimi
>
> As fs_info was not used before, ocfs2_initxattrs() can now handle the case
> of replicating the behavior of security_old_inode_init_security(), i.e.
> just obtaining the xattr, in addition to setting all xattrs provided by
> LSMs.
>
> Finally, modify the handling of the return value from
> ocfs2_init_security_get(). As security_inode_init_security() does not
> return -EOPNOTSUPP, remove this case and directly handle the error if the
> return value is not zero.
>
> However, the previous case of receiving -EOPNOTSUPP should be still
> taken into account, as security_inode_init_security() could return zero
> without setting xattrs and ocfs2 would consider it as if the xattr was set.
>
> Instead, if security_inode_init_security() returned zero, look at the xattr
> if it was set, and behave accordingly, i.e. set si->enable to zero to
> notify to the functions following ocfs2_init_security_get() that the xattr
> is not available (same as if security_old_inode_init_security() returned
> -EOPNOTSUPP).
>
> Signed-off-by: Roberto Sassu <roberto.sassu@...wei.com>
> ---
> fs/ocfs2/namei.c | 18 ++++++------------
> fs/ocfs2/xattr.c | 30 ++++++++++++++++++++++++++----
> 2 files changed, 32 insertions(+), 16 deletions(-)
>
> diff --git a/fs/ocfs2/namei.c b/fs/ocfs2/namei.c
> index 05f32989bad6..55fba81cd2d1 100644
> --- a/fs/ocfs2/namei.c
> +++ b/fs/ocfs2/namei.c
> @@ -242,6 +242,7 @@ static int ocfs2_mknod(struct user_namespace *mnt_userns,
> int want_meta = 0;
> int xattr_credits = 0;
> struct ocfs2_security_xattr_info si = {
> + .name = NULL,
> .enable = 1,
> };
> int did_quota_inode = 0;
> @@ -315,12 +316,8 @@ static int ocfs2_mknod(struct user_namespace *mnt_userns,
> /* get security xattr */
> status = ocfs2_init_security_get(inode, dir, &dentry->d_name, &si);
> if (status) {
> - if (status == -EOPNOTSUPP)
> - si.enable = 0;
> - else {
> - mlog_errno(status);
> - goto leave;
> - }
> + mlog_errno(status);
> + goto leave;
> }
>
> /* calculate meta data/clusters for setting security and acl xattr */
> @@ -1805,6 +1802,7 @@ static int ocfs2_symlink(struct user_namespace *mnt_userns,
> int want_clusters = 0;
> int xattr_credits = 0;
> struct ocfs2_security_xattr_info si = {
> + .name = NULL,
> .enable = 1,
> };
> int did_quota = 0, did_quota_inode = 0;
> @@ -1875,12 +1873,8 @@ static int ocfs2_symlink(struct user_namespace *mnt_userns,
> /* get security xattr */
> status = ocfs2_init_security_get(inode, dir, &dentry->d_name, &si);
> if (status) {
> - if (status == -EOPNOTSUPP)
> - si.enable = 0;
> - else {
> - mlog_errno(status);
> - goto bail;
> - }
> + mlog_errno(status);
> + goto bail;
> }
>
> /* calculate meta data/clusters for setting security xattr */
> diff --git a/fs/ocfs2/xattr.c b/fs/ocfs2/xattr.c
> index 95d0611c5fc7..55699c573541 100644
> --- a/fs/ocfs2/xattr.c
> +++ b/fs/ocfs2/xattr.c
> @@ -7259,9 +7259,21 @@ static int ocfs2_xattr_security_set(const struct xattr_handler *handler,
> static int ocfs2_initxattrs(struct inode *inode, const struct xattr *xattr_array,
> void *fs_info)
> {
> + struct ocfs2_security_xattr_info *si = fs_info;
> const struct xattr *xattr;
> int err = 0;
>
> + if (si) {
> + si->value = kmemdup(xattr_array->value, xattr_array->value_len,
> + GFP_KERNEL);
> + if (!si->value)
> + return -ENOMEM;
> +
> + si->name = xattr_array->name;
> + si->value_len = xattr_array->value_len;
> + return 0;
> + }
> +
> for (xattr = xattr_array; xattr->name != NULL; xattr++) {
> err = ocfs2_xattr_set(inode, OCFS2_XATTR_INDEX_SECURITY,
> xattr->name, xattr->value,
> @@ -7277,13 +7289,23 @@ int ocfs2_init_security_get(struct inode *inode,
> const struct qstr *qstr,
> struct ocfs2_security_xattr_info *si)
> {
> + int ret;
> +
> /* check whether ocfs2 support feature xattr */
> if (!ocfs2_supports_xattr(OCFS2_SB(dir->i_sb)))
> return -EOPNOTSUPP;
> - if (si)
> - return security_old_inode_init_security(inode, dir, qstr,
> - &si->name, &si->value,
> - &si->value_len);
> + if (si) {
> + ret = security_inode_init_security(inode, dir, qstr,
> + &ocfs2_initxattrs, si);
> + /*
> + * security_inode_init_security() does not return -EOPNOTSUPP,
> + * we have to check the xattr ourselves.
> + */
> + if (!ret && !si->name)
> + si->enable = 0;
> +
> + return ret;
> + }
>
> return security_inode_init_security(inode, dir, qstr,
> &ocfs2_initxattrs, NULL);
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