forked from Minki/linux
782ebb992e
This patch improves memory use by SELinux by both reducing the avtab node
size and reducing the number of avtab nodes. The memory savings are
substantial, e.g. on a 64-bit system after boot, James Morris reported the
following data for the targeted and strict policies:
#objs objsize kernmem
Targeted:
Before: 237888 40 9.1MB
After: 19968 24 468KB
Strict:
Before: 571680 40 21.81MB
After: 221052 24 5.06MB
The improvement in memory use comes at a cost in the speed of security
server computations of access vectors, but these computations are only
required on AVC cache misses, and performance measurements by James Morris
using a number of benchmarks have shown that the change does not cause any
significant degradation.
Note that a rebuilt policy via an updated policy toolchain
(libsepol/checkpolicy) is required in order to gain the full benefits of
this patch, although some memory savings benefits are immediately applied
even to older policies (in particular, the reduction in avtab node size).
Sources for the updated toolchain are presently available from the
sourceforge CVS tree (http://sourceforge.net/cvs/?group_id=21266), and
tarballs are available from http://www.flux.utah.edu/~sds.
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: James Morris <jmorris@namei.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
79 lines
2.2 KiB
C
79 lines
2.2 KiB
C
/*
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* An extensible bitmap is a bitmap that supports an
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* arbitrary number of bits. Extensible bitmaps are
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* used to represent sets of values, such as types,
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* roles, categories, and classes.
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*
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* Each extensible bitmap is implemented as a linked
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* list of bitmap nodes, where each bitmap node has
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* an explicitly specified starting bit position within
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* the total bitmap.
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*
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* Author : Stephen Smalley, <sds@epoch.ncsc.mil>
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*/
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#ifndef _SS_EBITMAP_H_
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#define _SS_EBITMAP_H_
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#define MAPTYPE u64 /* portion of bitmap in each node */
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#define MAPSIZE (sizeof(MAPTYPE) * 8) /* number of bits in node bitmap */
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#define MAPBIT 1ULL /* a bit in the node bitmap */
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struct ebitmap_node {
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u32 startbit; /* starting position in the total bitmap */
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MAPTYPE map; /* this node's portion of the bitmap */
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struct ebitmap_node *next;
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};
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struct ebitmap {
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struct ebitmap_node *node; /* first node in the bitmap */
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u32 highbit; /* highest position in the total bitmap */
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};
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#define ebitmap_length(e) ((e)->highbit)
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#define ebitmap_startbit(e) ((e)->node ? (e)->node->startbit : 0)
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static inline unsigned int ebitmap_start(struct ebitmap *e,
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struct ebitmap_node **n)
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{
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*n = e->node;
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return ebitmap_startbit(e);
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}
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static inline void ebitmap_init(struct ebitmap *e)
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{
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memset(e, 0, sizeof(*e));
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}
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static inline unsigned int ebitmap_next(struct ebitmap_node **n,
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unsigned int bit)
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{
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if ((bit == ((*n)->startbit + MAPSIZE - 1)) &&
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(*n)->next) {
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*n = (*n)->next;
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return (*n)->startbit;
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}
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return (bit+1);
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}
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static inline int ebitmap_node_get_bit(struct ebitmap_node * n,
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unsigned int bit)
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{
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if (n->map & (MAPBIT << (bit - n->startbit)))
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return 1;
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return 0;
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}
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#define ebitmap_for_each_bit(e, n, bit) \
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for (bit = ebitmap_start(e, &n); bit < ebitmap_length(e); bit = ebitmap_next(&n, bit)) \
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int ebitmap_cmp(struct ebitmap *e1, struct ebitmap *e2);
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int ebitmap_cpy(struct ebitmap *dst, struct ebitmap *src);
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int ebitmap_contains(struct ebitmap *e1, struct ebitmap *e2);
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int ebitmap_get_bit(struct ebitmap *e, unsigned long bit);
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int ebitmap_set_bit(struct ebitmap *e, unsigned long bit, int value);
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void ebitmap_destroy(struct ebitmap *e);
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int ebitmap_read(struct ebitmap *e, void *fp);
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#endif /* _SS_EBITMAP_H_ */
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