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author | paul.moore@hp.com <paul.moore@hp.com> | 2006-10-04 11:46:31 -0400 |
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committer | David S. Miller <davem@sunset.davemloft.net> | 2006-10-11 23:59:29 -0700 |
commit | ffb733c65000ee701294f7b80c4eca2a5f335637 (patch) | |
tree | edda8e25792fe4a7bf0c619787949291276b9ed7 /include/net/netlabel.h | |
parent | c25d5180441e344a3368d100c57f0a481c6944f7 (diff) | |
download | kernel_samsung_espresso10-ffb733c65000ee701294f7b80c4eca2a5f335637.zip kernel_samsung_espresso10-ffb733c65000ee701294f7b80c4eca2a5f335637.tar.gz kernel_samsung_espresso10-ffb733c65000ee701294f7b80c4eca2a5f335637.tar.bz2 |
NetLabel: fix a cache race condition
Testing revealed a problem with the NetLabel cache where a cached entry could
be freed while in use by the LSM layer causing an oops and other problems.
This patch fixes that problem by introducing a reference counter to the cache
entry so that it is only freed when it is no longer in use.
Signed-off-by: Paul Moore <paul.moore@hp.com>
Signed-off-by: James Morris <jmorris@namei.org>
Diffstat (limited to 'include/net/netlabel.h')
-rw-r--r-- | include/net/netlabel.h | 62 |
1 files changed, 47 insertions, 15 deletions
diff --git a/include/net/netlabel.h b/include/net/netlabel.h index c63a580..113337c 100644 --- a/include/net/netlabel.h +++ b/include/net/netlabel.h @@ -34,6 +34,7 @@ #include <linux/net.h> #include <linux/skbuff.h> #include <net/netlink.h> +#include <asm/atomic.h> /* * NetLabel - A management interface for maintaining network packet label @@ -106,6 +107,7 @@ int netlbl_domhsh_remove(const char *domain, struct netlbl_audit *audit_info); /* LSM security attributes */ struct netlbl_lsm_cache { + atomic_t refcount; void (*free) (const void *data); void *data; }; @@ -117,7 +119,7 @@ struct netlbl_lsm_secattr { unsigned char *mls_cat; size_t mls_cat_len; - struct netlbl_lsm_cache cache; + struct netlbl_lsm_cache *cache; }; /* @@ -126,6 +128,43 @@ struct netlbl_lsm_secattr { /** + * netlbl_secattr_cache_alloc - Allocate and initialize a secattr cache + * @flags: the memory allocation flags + * + * Description: + * Allocate and initialize a netlbl_lsm_cache structure. Returns a pointer + * on success, NULL on failure. + * + */ +static inline struct netlbl_lsm_cache *netlbl_secattr_cache_alloc(int flags) +{ + struct netlbl_lsm_cache *cache; + + cache = kzalloc(sizeof(*cache), flags); + if (cache) + atomic_set(&cache->refcount, 1); + return cache; +} + +/** + * netlbl_secattr_cache_free - Frees a netlbl_lsm_cache struct + * @cache: the struct to free + * + * Description: + * Frees @secattr including all of the internal buffers. + * + */ +static inline void netlbl_secattr_cache_free(struct netlbl_lsm_cache *cache) +{ + if (!atomic_dec_and_test(&cache->refcount)) + return; + + if (cache->free) + cache->free(cache->data); + kfree(cache); +} + +/** * netlbl_secattr_init - Initialize a netlbl_lsm_secattr struct * @secattr: the struct to initialize * @@ -143,20 +182,16 @@ static inline int netlbl_secattr_init(struct netlbl_lsm_secattr *secattr) /** * netlbl_secattr_destroy - Clears a netlbl_lsm_secattr struct * @secattr: the struct to clear - * @clear_cache: cache clear flag * * Description: * Destroys the @secattr struct, including freeing all of the internal buffers. - * If @clear_cache is true then free the cache fields, otherwise leave them - * intact. The struct must be reset with a call to netlbl_secattr_init() - * before reuse. + * The struct must be reset with a call to netlbl_secattr_init() before reuse. * */ -static inline void netlbl_secattr_destroy(struct netlbl_lsm_secattr *secattr, - u32 clear_cache) +static inline void netlbl_secattr_destroy(struct netlbl_lsm_secattr *secattr) { - if (clear_cache && secattr->cache.data != NULL && secattr->cache.free) - secattr->cache.free(secattr->cache.data); + if (secattr->cache) + netlbl_secattr_cache_free(secattr->cache); kfree(secattr->domain); kfree(secattr->mls_cat); } @@ -178,17 +213,14 @@ static inline struct netlbl_lsm_secattr *netlbl_secattr_alloc(int flags) /** * netlbl_secattr_free - Frees a netlbl_lsm_secattr struct * @secattr: the struct to free - * @clear_cache: cache clear flag * * Description: - * Frees @secattr including all of the internal buffers. If @clear_cache is - * true then free the cache fields, otherwise leave them intact. + * Frees @secattr including all of the internal buffers. * */ -static inline void netlbl_secattr_free(struct netlbl_lsm_secattr *secattr, - u32 clear_cache) +static inline void netlbl_secattr_free(struct netlbl_lsm_secattr *secattr) { - netlbl_secattr_destroy(secattr, clear_cache); + netlbl_secattr_destroy(secattr); kfree(secattr); } |