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Date: Mon, 06 Oct 2008 16:52:06 -0400
From: "David P. Quigley" <dpquigl@...ho.nsa.gov>
To: "Serge E. Hallyn" <serue@...ibm.com>
Cc: hch@...radead.org, viro@...iv.linux.org.uk, casey@...aufler-ca.com,
sds@...ho.nsa.gov, matthew.dodd@...rta.com,
trond.myklebust@....uio.no, bfields@...ldses.org,
linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
linux-security-module@...r.kernel.org, selinux@...ho.nsa.gov,
labeled-nfs@...ux-nfs.org
Subject: Re: [PATCH 02/14] LSM/SELinux: inode_{get,set,notify}secctx hooks
to access LSM security context information.
Fixed.
On Tue, 2008-09-30 at 15:01 -0500, Serge E. Hallyn wrote:
> Quoting David P. Quigley (dpquigl@...ho.nsa.gov):
> > This patch introduces three new hooks. The inode_getsecctx hook is used to get
> > all relevant information from an LSM about an inode. The inode_setsecctx is
> > used to set both the in-core and on-disk state for the inode based on a context
> > derived from inode_getsecctx.The final hook inode_notifysecctx will notify the
> > LSM of a change for the in-core state of the inode in question. These hooks are
> > for use in the labeled NFS code and addresses concerns of how to set security
> > on an inode in a multi-xattr LSM. For historical reasons Stephen Smalley's
> > explanation of the reason for these hooks is pasted below.
> >
> > Quote Stephen Smalley
> >
> > inode_setsecctx: Change the security context of an inode. Updates the
> > in core security context managed by the security module and invokes the
> > fs code as needed (via __vfs_setxattr_noperm) to update any backing
> > xattrs that represent the context. Example usage: NFS server invokes
> > this hook to change the security context in its incore inode and on the
> > backing file system to a value provided by the client on a SETATTR
> > operation.
> >
> > inode_notifysecctx: Notify the security module of what the security
> > context of an inode should be. Initializes the incore security context
> > managed by the security module for this inode. Example usage: NFS
> > client invokes this hook to initialize the security context in its
> > incore inode to the value provided by the server for the file when the
> > server returned the file's attributes to the client.
> >
> > Signed-off-by: Matthew N. Dodd <Matthew.Dodd@...rta.com>
> > Signed-off-by: David P. Quigley <dpquigl@...ho.nsa.gov>
> > ---
> > include/linux/security.h | 50 ++++++++++++++++++++++++++++++++++++++++++++++
> > security/security.c | 18 ++++++++++++++++
> > security/selinux/hooks.c | 25 +++++++++++++++++++++++
> > 3 files changed, 93 insertions(+), 0 deletions(-)
> >
> > diff --git a/include/linux/security.h b/include/linux/security.h
> > index 80c4d00..8b5b041 100644
> > --- a/include/linux/security.h
> > +++ b/include/linux/security.h
> > @@ -1289,6 +1289,36 @@ static inline void security_free_mnt_opts(struct security_mnt_opts *opts)
> > * audit_rule_init.
> > * @rule contains the allocated rule
> > *
> > + * @inode_notifysecctx:
> > + * Notify the security module of what the security context of an inode
> > + * should be. Initializes the incore security context managed by the
> > + * security module for this inode. Example usage: NFS client invokes
> > + * this hook to initialize the security context in its incore inode to the
> > + * value provided by the server for the file when the server returned the
> > + * file's attributes to the client.
> > + *
> > + * @inode we wish to set the security context of.
> > + * @ctx contains the string which we wish to set in the inode.
> > + * @ctxlen contains the length of @ctx.
> > + *
> > + * @inode_setsecctx:
> > + * Change the security context of an inode. Updates the
> > + * incore security context managed by the security module and invokes the
> > + * fs code as needed (via __vfs_setxattr_noperm) to update any backing
> > + * xattrs that represent the context. Example usage: NFS server invokes
> > + * this hook to change the security context in its incore inode and on the
> > + * backing filesystem to a value provided by the client on a SETATTR
> > + * operation.
> > + *
> > + * @dentry contains the inode we wish to set the security context of.
> > + * @ctx contains the string which we wish to set in the inode.
> > + * @ctxlen contains the length of @ctx.
> > + *
> > + * @inode_getsecctx:
> > + * Returns a string containing all relavent security context information
> > + * @inode we wish to set the security context of.
> > + * @ctx is a pointer to place the allocated security context should be placed.
>
> sentence above is odd. How about
>
> @ctx is a pointer in which to place the allocated security context
>
> > + * @ctxlen points to the place to put the length of @ctx.
> > * This is the main security structure.
> > */
> > struct security_operations {
> > @@ -1479,6 +1509,10 @@ struct security_operations {
> > int (*secctx_to_secid) (const char *secdata, u32 seclen, u32 *secid);
> > void (*release_secctx) (char *secdata, u32 seclen);
> >
> > + int (*inode_notifysecctx)(struct inode *inode, void *ctx, u32 ctxlen);
> > + int (*inode_setsecctx)(struct dentry *dentry, void *ctx, u32 ctxlen);
> > + int (*inode_getsecctx)(struct inode *inode, void **ctx, u32 *ctxlen);
> > +
> > #ifdef CONFIG_SECURITY_NETWORK
> > int (*unix_stream_connect) (struct socket *sock,
> > struct socket *other, struct sock *newsk);
> > @@ -1727,6 +1761,9 @@ int security_secid_to_secctx(u32 secid, char **secdata, u32 *seclen);
> > int security_secctx_to_secid(const char *secdata, u32 seclen, u32 *secid);
> > void security_release_secctx(char *secdata, u32 seclen);
> >
> > +int security_inode_notifysecctx(struct inode *inode, void *ctx, u32 ctxlen);
> > +int security_inode_setsecctx(struct dentry *dentry, void *ctx, u32 ctxlen);
> > +int security_inode_getsecctx(struct inode *inode, void **ctx, u32 *ctxlen);
> > #else /* CONFIG_SECURITY */
> > struct security_mnt_opts {
> > };
> > @@ -2458,6 +2495,19 @@ static inline int security_secctx_to_secid(const char *secdata,
> > static inline void security_release_secctx(char *secdata, u32 seclen)
> > {
> > }
> > +
> > +static inline int security_inode_notifysecctx(struct inode *inode, void *ctx, u32 ctxlen)
> > +{
> > + return -EOPNOTSUPP;
> > +}
> > +static inline int security_inode_setsecctx(struct dentry *dentry, void *ctx, u32 ctxlen)
> > +{
> > + return -EOPNOTSUPP;
> > +}
> > +static inline int security_inode_getsecctx(struct inode *inode, void **ctx, u32 *ctxlen)
> > +{
> > + return -EOPNOTSUPP;
> > +}
> > #endif /* CONFIG_SECURITY */
> >
> > #ifdef CONFIG_SECURITY_NETWORK
> > diff --git a/security/security.c b/security/security.c
> > index 3a4b4f5..d0fd42a 100644
> > --- a/security/security.c
> > +++ b/security/security.c
> > @@ -869,6 +869,24 @@ void security_release_secctx(char *secdata, u32 seclen)
> > }
> > EXPORT_SYMBOL(security_release_secctx);
> >
> > +int security_inode_notifysecctx(struct inode *inode, void *ctx, u32 ctxlen)
> > +{
> > + return security_ops->inode_notifysecctx(inode, ctx, ctxlen);
> > +}
> > +EXPORT_SYMBOL(security_inode_notifysecctx);
> > +
> > +int security_inode_setsecctx(struct dentry *dentry, void *ctx, u32 ctxlen)
> > +{
> > + return security_ops->inode_setsecctx(dentry, ctx, ctxlen);
> > +}
> > +EXPORT_SYMBOL(security_inode_setsecctx);
> > +
> > +int security_inode_getsecctx(struct inode *inode, void **ctx, u32 *ctxlen)
> > +{
> > + return security_ops->inode_getsecctx(inode, ctx, ctxlen);
> > +}
> > +EXPORT_SYMBOL(security_inode_getsecctx);
> > +
> > #ifdef CONFIG_SECURITY_NETWORK
> >
> > int security_unix_stream_connect(struct socket *sock, struct socket *other,
> > diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
> > index 03fc6a8..b07871b 100644
> > --- a/security/selinux/hooks.c
> > +++ b/security/selinux/hooks.c
> > @@ -5285,6 +5285,28 @@ static void selinux_release_secctx(char *secdata, u32 seclen)
> > kfree(secdata);
> > }
> >
> > +/*
> > + * This hook requires that the inode i_mutex be locked
>
> 'called with inode->i_mutex locked' would make more sense here.
> Requirements on the callers would make more sense in the comments
> in include/linux/security.h, right?
>
> No code objections, though.
>
> Acked-by: Serge Hallyn <serue@...ibm.com>
>
> > + */
> > +static int selinux_inode_notifysecctx(struct inode *inode, void *ctx, u32 ctxlen)
> > +{
> > + return selinux_inode_setsecurity(inode, XATTR_SELINUX_SUFFIX, ctx, ctxlen, 0);
> > +}
> > +
> > +/*
> > + * This hook requires that the inode i_mutex be locked
> > + */
> > +static int selinux_inode_setsecctx(struct dentry *dentry, void *ctx, u32 ctxlen)
> > +{
> > + return __vfs_setxattr_noperm(dentry, XATTR_NAME_SELINUX, ctx, ctxlen, 0);
> > +}
> > +
> > +static int selinux_inode_getsecctx(struct inode *inode, void **ctx, u32 *ctxlen)
> > +{
> > + *ctxlen = selinux_inode_getsecurity(inode, XATTR_SELINUX_SUFFIX,
> > + ctx, true);
> > + return *ctxlen;
> > +}
> > #ifdef CONFIG_KEYS
> >
> > static int selinux_key_alloc(struct key *k, struct task_struct *tsk,
> > @@ -5491,6 +5513,9 @@ static struct security_operations selinux_ops = {
> > .secid_to_secctx = selinux_secid_to_secctx,
> > .secctx_to_secid = selinux_secctx_to_secid,
> > .release_secctx = selinux_release_secctx,
> > + .inode_notifysecctx = selinux_inode_notifysecctx,
> > + .inode_setsecctx = selinux_inode_setsecctx,
> > + .inode_getsecctx = selinux_inode_getsecctx,
> >
> > .unix_stream_connect = selinux_socket_unix_stream_connect,
> > .unix_may_send = selinux_socket_unix_may_send,
> > --
> > 1.5.5.1
> >
> >
> > --
> > This message was distributed to subscribers of the selinux mailing list.
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> > the words "unsubscribe selinux" without quotes as the message.
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