Mimi Zohar
2022-Nov-23 17:46 UTC
[Ocfs2-devel] [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 at huawei.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 at huawei.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);
Roberto Sassu
2022-Nov-24 08:11 UTC
[Ocfs2-devel] [PATCH v5 2/6] ocfs2: Switch to security_inode_init_security()
On Wed, 2022-11-23 at 12:46 -0500, Mimi Zohar wrote:> On Wed, 2022-11-23 at 10:51 +0100, Roberto Sassu wrote: > > From: Roberto Sassu <roberto.sassu at huawei.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.Uhm, it seems unfortunately more complicated. Calling security_old_inode_init_security() allows filesystems to get the xattr, do some calculations (e.g. for reservation) and then write the xattr. The initxattrs() callback to be passed to security_inode_init_security() is meant to let filesystems provide a filesystem-specific way of writing the xattrs, just after LSMs provided them. This seems incompatible with the old behavior, as a filesystem might need to do the calculations in the middle before writing the xattrs. The initxattrs() callback, when security_old_inode_init_security() was used, is just a way of emulating the old behavior, i.e. returning the xattr to the caller. It should be possible, I guess, to handle more xattrs but if the code was designed to handle one, it would be better if the filesystem maintainers add support for it. Thanks Roberto> 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 at huawei.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);