selinux: try security xattr after genfs for kernfs filesystems
Since kernfs supports the security xattr handlers, we can simply use these to determine the inode's context, dropping the need to update it from kernfs explicitly using a security_inode_notifysecctx() call. We achieve this by setting a new sbsec flag SE_SBGENFS_XATTR to all mounts that are known to use kernfs under the hood and then fetching the xattrs after determining the fallback genfs sid in inode_doinit_with_dentry() when this flag is set. This will allow implementing full security xattr support in kernfs and removing the ...notifysecctx() call in a subsequent patch. Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com> Acked-by: Stephen Smalley <sds@tycho.nsa.gov> Acked-by: Casey Schaufler <casey@schaufler-ca.com> [PM: more manual merge fixups] Signed-off-by: Paul Moore <paul@paul-moore.com>
This commit is contained in:
Ondrej Mosnacek
Paul Moore
Родитель
d0c9c153b4
Коммит
b754026bd9
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@ -751,11 +751,13 @@ static int selinux_set_mnt_opts(struct super_block *sb,
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if (!strcmp(sb->s_type->name, "debugfs") ||
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!strcmp(sb->s_type->name, "tracefs") ||
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!strcmp(sb->s_type->name, "sysfs") ||
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!strcmp(sb->s_type->name, "pstore") ||
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!strcmp(sb->s_type->name, "pstore"))
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sbsec->flags |= SE_SBGENFS;
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if (!strcmp(sb->s_type->name, "sysfs") ||
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!strcmp(sb->s_type->name, "cgroup") ||
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!strcmp(sb->s_type->name, "cgroup2"))
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sbsec->flags |= SE_SBGENFS;
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sbsec->flags |= SE_SBGENFS | SE_SBGENFS_XATTR;
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if (!sbsec->behavior) {
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/*
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@ -1354,6 +1356,67 @@ static int selinux_genfs_get_sid(struct dentry *dentry,
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return rc;
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}
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static int inode_doinit_use_xattr(struct inode *inode, struct dentry *dentry,
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u32 def_sid, u32 *sid)
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{
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#define INITCONTEXTLEN 255
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char *context;
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unsigned int len;
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int rc;
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len = INITCONTEXTLEN;
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context = kmalloc(len + 1, GFP_NOFS);
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if (!context)
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return -ENOMEM;
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context[len] = '\0';
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rc = __vfs_getxattr(dentry, inode, XATTR_NAME_SELINUX, context, len);
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if (rc == -ERANGE) {
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kfree(context);
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/* Need a larger buffer. Query for the right size. */
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rc = __vfs_getxattr(dentry, inode, XATTR_NAME_SELINUX, NULL, 0);
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if (rc < 0)
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return rc;
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len = rc;
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context = kmalloc(len + 1, GFP_NOFS);
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if (!context)
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return -ENOMEM;
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context[len] = '\0';
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rc = __vfs_getxattr(dentry, inode, XATTR_NAME_SELINUX,
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context, len);
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}
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if (rc < 0) {
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kfree(context);
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if (rc != -ENODATA) {
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pr_warn("SELinux: %s: getxattr returned %d for dev=%s ino=%ld\n",
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__func__, -rc, inode->i_sb->s_id, inode->i_ino);
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return rc;
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}
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*sid = def_sid;
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return 0;
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}
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rc = security_context_to_sid_default(&selinux_state, context, rc, sid,
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def_sid, GFP_NOFS);
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if (rc) {
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char *dev = inode->i_sb->s_id;
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unsigned long ino = inode->i_ino;
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if (rc == -EINVAL) {
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pr_notice_ratelimited("SELinux: inode=%lu on dev=%s was found to have an invalid context=%s. This indicates you may need to relabel the inode or the filesystem in question.\n",
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ino, dev, context);
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} else {
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pr_warn("SELinux: %s: context_to_sid(%s) returned %d for dev=%s ino=%ld\n",
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__func__, context, -rc, dev, ino);
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}
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}
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kfree(context);
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return 0;
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}
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/* The inode's security attributes must be initialized before first use. */
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static int inode_doinit_with_dentry(struct inode *inode, struct dentry *opt_dentry)
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{
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@ -1362,9 +1425,6 @@ static int inode_doinit_with_dentry(struct inode *inode, struct dentry *opt_dent
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u32 task_sid, sid = 0;
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u16 sclass;
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struct dentry *dentry;
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#define INITCONTEXTLEN 255
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char *context = NULL;
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unsigned len = 0;
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int rc = 0;
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if (isec->initialized == LABEL_INITIALIZED)
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@ -1432,72 +1492,11 @@ static int inode_doinit_with_dentry(struct inode *inode, struct dentry *opt_dent
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goto out;
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}
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len = INITCONTEXTLEN;
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context = kmalloc(len+1, GFP_NOFS);
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if (!context) {
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rc = -ENOMEM;
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dput(dentry);
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goto out;
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}
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context[len] = '\0';
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rc = __vfs_getxattr(dentry, inode, XATTR_NAME_SELINUX, context, len);
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if (rc == -ERANGE) {
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kfree(context);
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/* Need a larger buffer. Query for the right size. */
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rc = __vfs_getxattr(dentry, inode, XATTR_NAME_SELINUX, NULL, 0);
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if (rc < 0) {
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dput(dentry);
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goto out;
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}
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len = rc;
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context = kmalloc(len+1, GFP_NOFS);
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if (!context) {
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rc = -ENOMEM;
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dput(dentry);
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goto out;
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}
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context[len] = '\0';
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rc = __vfs_getxattr(dentry, inode, XATTR_NAME_SELINUX, context, len);
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}
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rc = inode_doinit_use_xattr(inode, dentry, sbsec->def_sid,
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&sid);
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dput(dentry);
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if (rc < 0) {
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if (rc != -ENODATA) {
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pr_warn("SELinux: %s: getxattr returned "
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"%d for dev=%s ino=%ld\n", __func__,
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-rc, inode->i_sb->s_id, inode->i_ino);
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kfree(context);
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goto out;
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}
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/* Map ENODATA to the default file SID */
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sid = sbsec->def_sid;
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rc = 0;
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} else {
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rc = security_context_to_sid_default(&selinux_state,
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context, rc, &sid,
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sbsec->def_sid,
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GFP_NOFS);
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if (rc) {
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char *dev = inode->i_sb->s_id;
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unsigned long ino = inode->i_ino;
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if (rc == -EINVAL) {
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if (printk_ratelimit())
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pr_notice("SELinux: inode=%lu on dev=%s was found to have an invalid "
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"context=%s. This indicates you may need to relabel the inode or the "
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"filesystem in question.\n", ino, dev, context);
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} else {
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pr_warn("SELinux: %s: context_to_sid(%s) "
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"returned %d for dev=%s ino=%ld\n",
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__func__, context, -rc, dev, ino);
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}
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kfree(context);
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/* Leave with the unlabeled SID */
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rc = 0;
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break;
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}
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}
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kfree(context);
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if (rc)
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goto out;
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break;
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case SECURITY_FS_USE_TASK:
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sid = task_sid;
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@ -1548,9 +1547,21 @@ static int inode_doinit_with_dentry(struct inode *inode, struct dentry *opt_dent
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goto out;
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rc = selinux_genfs_get_sid(dentry, sclass,
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sbsec->flags, &sid);
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dput(dentry);
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if (rc)
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if (rc) {
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dput(dentry);
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goto out;
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}
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if ((sbsec->flags & SE_SBGENFS_XATTR) &&
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(inode->i_opflags & IOP_XATTR)) {
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rc = inode_doinit_use_xattr(inode, dentry,
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sid, &sid);
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if (rc) {
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dput(dentry);
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goto out;
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}
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}
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dput(dentry);
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}
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break;
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}
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@ -58,6 +58,7 @@
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#define SE_SBINITIALIZED 0x0100
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#define SE_SBPROC 0x0200
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#define SE_SBGENFS 0x0400
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#define SE_SBGENFS_XATTR 0x0800
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#define CONTEXT_STR "context"
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#define FSCONTEXT_STR "fscontext"
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