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![Casey Schaufler](/assets/img/avatar_default.png)
In the embedded world there are often situations where libraries are updated from a variety of sources, for a variety of reasons, and with any number of security characteristics. These differences might include privilege required for a given library provided interface to function properly, as occurs from time to time in graphics libraries. There are also cases where it is important to limit use of libraries based on the provider of the library and the security aware application may make choices based on that criteria. These issues are addressed by providing an additional Smack label that may optionally be assigned to an object, the SMACK64MMAP attribute. An mmap operation is allowed if there is no such attribute. If there is a SMACK64MMAP attribute the mmap is permitted only if a subject with that label has all of the access permitted a subject with the current task label. Security aware applications may from time to time wish to reduce their "privilege" to avoid accidental use of privilege. One case where this arises is the environment in which multiple sources provide libraries to perform the same functions. An application may know that it should eschew services made available from a particular vendor, or of a particular version. In support of this a secondary list of Smack rules has been added that is local to the task. This list is consulted only in the case where the global list has approved access. It can only further restrict access. Unlike the global last, if no entry is found on the local list access is granted. An application can add entries to its own list by writing to /smack/load-self. The changes appear large as they involve refactoring the list handling to accomodate there being more than one rule list. Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
84 lines
3.2 KiB
C
84 lines
3.2 KiB
C
/*
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File: linux/xattr.h
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Extended attributes handling.
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Copyright (C) 2001 by Andreas Gruenbacher <a.gruenbacher@computer.org>
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Copyright (c) 2001-2002 Silicon Graphics, Inc. All Rights Reserved.
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Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com>
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*/
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#ifndef _LINUX_XATTR_H
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#define _LINUX_XATTR_H
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#define XATTR_CREATE 0x1 /* set value, fail if attr already exists */
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#define XATTR_REPLACE 0x2 /* set value, fail if attr does not exist */
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#ifdef __KERNEL__
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#include <linux/types.h>
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/* Namespaces */
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#define XATTR_OS2_PREFIX "os2."
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#define XATTR_OS2_PREFIX_LEN (sizeof (XATTR_OS2_PREFIX) - 1)
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#define XATTR_SECURITY_PREFIX "security."
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#define XATTR_SECURITY_PREFIX_LEN (sizeof (XATTR_SECURITY_PREFIX) - 1)
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#define XATTR_SYSTEM_PREFIX "system."
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#define XATTR_SYSTEM_PREFIX_LEN (sizeof (XATTR_SYSTEM_PREFIX) - 1)
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#define XATTR_TRUSTED_PREFIX "trusted."
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#define XATTR_TRUSTED_PREFIX_LEN (sizeof (XATTR_TRUSTED_PREFIX) - 1)
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#define XATTR_USER_PREFIX "user."
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#define XATTR_USER_PREFIX_LEN (sizeof (XATTR_USER_PREFIX) - 1)
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/* Security namespace */
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#define XATTR_SELINUX_SUFFIX "selinux"
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#define XATTR_NAME_SELINUX XATTR_SECURITY_PREFIX XATTR_SELINUX_SUFFIX
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#define XATTR_SMACK_SUFFIX "SMACK64"
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#define XATTR_SMACK_IPIN "SMACK64IPIN"
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#define XATTR_SMACK_IPOUT "SMACK64IPOUT"
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#define XATTR_SMACK_EXEC "SMACK64EXEC"
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#define XATTR_SMACK_TRANSMUTE "SMACK64TRANSMUTE"
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#define XATTR_SMACK_MMAP "SMACK64MMAP"
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#define XATTR_NAME_SMACK XATTR_SECURITY_PREFIX XATTR_SMACK_SUFFIX
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#define XATTR_NAME_SMACKIPIN XATTR_SECURITY_PREFIX XATTR_SMACK_IPIN
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#define XATTR_NAME_SMACKIPOUT XATTR_SECURITY_PREFIX XATTR_SMACK_IPOUT
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#define XATTR_NAME_SMACKEXEC XATTR_SECURITY_PREFIX XATTR_SMACK_EXEC
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#define XATTR_NAME_SMACKTRANSMUTE XATTR_SECURITY_PREFIX XATTR_SMACK_TRANSMUTE
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#define XATTR_NAME_SMACKMMAP XATTR_SECURITY_PREFIX XATTR_SMACK_MMAP
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#define XATTR_CAPS_SUFFIX "capability"
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#define XATTR_NAME_CAPS XATTR_SECURITY_PREFIX XATTR_CAPS_SUFFIX
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struct inode;
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struct dentry;
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struct xattr_handler {
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const char *prefix;
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int flags; /* fs private flags passed back to the handlers */
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size_t (*list)(struct dentry *dentry, char *list, size_t list_size,
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const char *name, size_t name_len, int handler_flags);
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int (*get)(struct dentry *dentry, const char *name, void *buffer,
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size_t size, int handler_flags);
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int (*set)(struct dentry *dentry, const char *name, const void *buffer,
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size_t size, int flags, int handler_flags);
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};
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ssize_t xattr_getsecurity(struct inode *, const char *, void *, size_t);
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ssize_t vfs_getxattr(struct dentry *, const char *, void *, size_t);
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ssize_t vfs_listxattr(struct dentry *d, char *list, size_t size);
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int __vfs_setxattr_noperm(struct dentry *, const char *, const void *, size_t, int);
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int vfs_setxattr(struct dentry *, const char *, const void *, size_t, int);
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int vfs_removexattr(struct dentry *, const char *);
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ssize_t generic_getxattr(struct dentry *dentry, const char *name, void *buffer, size_t size);
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ssize_t generic_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size);
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int generic_setxattr(struct dentry *dentry, const char *name, const void *value, size_t size, int flags);
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int generic_removexattr(struct dentry *dentry, const char *name);
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#endif /* __KERNEL__ */
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#endif /* _LINUX_XATTR_H */
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