On Wed, Oct 30, 2019 at 1:38 PM Ondrej Mosnacek <omosnace@xxxxxxxxxx> wrote: > > Hi Jeff, > > thank you for working on this! This is certainly a nice improvement. > See a couple quick comments below. > > On Wed, Oct 30, 2019 at 11:20 AM Jeff Vander Stoep <jeffv@xxxxxxxxxx> wrote: > > > > This replaces the reverse table lookup and reverse cache with a > > hashtable which improves cache-miss reverese-lookup times from > > spelling nit: reverse-lookup > > > O(n) to O(1) and maintains the same performance as a reverse > > cache hit. > > This is only half-true, since at some point when the number of > contexts gets too high, it becomes O(n) again > (SIDTAB_HASH_BUCKETS-times faster O(n), but still O(n) :). To make it > really O(1) you'd need to dynamically resize the hashtable (which I > recently tried to implement, but then got stuck - it is really hard to > do it without too much locking...). But of course this is just a > formal nitpick, a fixed-size hashtable is still much better than no > hashtable :) > > > > > This reduces the time needed to add a new sidtab entry from ~500us > > to 5us on a Pixel 3 when there are ~10,000 sidtab entries. > > > > The implementation uses the kernel's generic hashtable API, > > It uses the context's string represtation as the hash source, > > spelling nit: representation > > > and the kernels generic string hashing algorithm full_name_hash() > > to reduce the string to a 32 bit value. > > If I'm not mistaken, the context strings have a caveat that after a > policy reload the canonical string representation of a given context > (SID) can change slightly (IIRC it has to do with ordering of the > levels/categories). I didn't dive deep enough into the patch to be > sure if this may cause issues here, but it is definitely something to > watch out for. Stephen and Paul know the guts of SELinux better than > me, so hopefully they'll be able to provide more insight here. > I believe this is already handled. A new hash is calculated using the new string representation in context_convert(). > > > > This change also maintains the improvement introduced in commit > > ee1a84fd which removed the need to keep the current sidtab locked > > during policy reload. It does however introduce periodic locking of > > the target sidtab while converting the hashtable. Sidtab entries > > are never modified or removed, so the context struct stored in the > > sid_to_context tree can also be used for the context_to_sid > > hashtable to reduce memory usage. > > > > This bug was reported by: > > - Stephen Smally on the selinux bug tracker. > > BUG: kernel softlockup due to too many SIDs/contexts #37 > > https://github.com/SELinuxProject/selinux-kernel/issues/37 > > - Jovana Knezevic on Android's bugtracker. > > Bug: 140252993 > > "During multi-user performance testing, we create and remove users > > many times. selinux_android_restorecon_pkgdir goes from 1ms to over > > 20ms after about 200 user creations and removals. Accumulated over > > ~280 packages, that adds a significant time to user creation, > > making perf benchmarks unreliable." > > > > Signed-off-by: Jeff Vander Stoep <jeffv@xxxxxxxxxx> > > Reported-by: Stephen Smalley <sds@xxxxxxxxxxxxx> > > Reported-by: Jovana Knezevic <jovanak@xxxxxxxxxx> > > --- > > security/selinux/include/security.h | 1 + > > security/selinux/selinuxfs.c | 27 +++ > > security/selinux/ss/context.h | 9 + > > security/selinux/ss/policydb.c | 5 + > > security/selinux/ss/services.c | 81 +++++--- > > security/selinux/ss/services.h | 4 +- > > security/selinux/ss/sidtab.c | 283 ++++++++++++++++------------ > > security/selinux/ss/sidtab.h | 20 +- > > 8 files changed, 283 insertions(+), 147 deletions(-) > > > > diff --git a/security/selinux/include/security.h b/security/selinux/include/security.h > > index ae840634e3c7..8c0dbbd076c6 100644 > > --- a/security/selinux/include/security.h > > +++ b/security/selinux/include/security.h > > @@ -395,5 +395,6 @@ extern int selinux_nlmsg_lookup(u16 sclass, u16 nlmsg_type, u32 *perm); > > extern void avtab_cache_init(void); > > extern void ebitmap_cache_init(void); > > extern void hashtab_cache_init(void); > > +extern int security_sidtab_hash_stats(struct selinux_state *state, char *page); > > > > #endif /* _SELINUX_SECURITY_H_ */ > > diff --git a/security/selinux/selinuxfs.c b/security/selinux/selinuxfs.c > > index ee94fa469c29..ebdec88d9ccb 100644 > > --- a/security/selinux/selinuxfs.c > > +++ b/security/selinux/selinuxfs.c > > @@ -1482,6 +1482,32 @@ static ssize_t sel_read_avc_hash_stats(struct file *filp, char __user *buf, > > return length; > > } > > > > +static ssize_t sel_read_sidtab_hash_stats(struct file *filp, char __user *buf, > > + size_t count, loff_t *ppos) > > +{ > > + struct selinux_fs_info *fsi = file_inode(filp)->i_sb->s_fs_info; > > + struct selinux_state *state = fsi->state; > > + char *page; > > + ssize_t length; > > + > > + page = (char *)__get_free_page(GFP_KERNEL); > > + if (!page) > > + return -ENOMEM; > > + > > + length = security_sidtab_hash_stats(state, page); > > + if (length >= 0) > > + length = simple_read_from_buffer(buf, count, ppos, page, > > + length); > > + free_page((unsigned long)page); > > + > > + return length; > > +} > > + > > +static const struct file_operations sel_sidtab_hash_stats_ops = { > > + .read = sel_read_sidtab_hash_stats, > > + .llseek = generic_file_llseek, > > +}; > > + > > static const struct file_operations sel_avc_cache_threshold_ops = { > > .read = sel_read_avc_cache_threshold, > > .write = sel_write_avc_cache_threshold, > > @@ -1572,6 +1598,7 @@ static int sel_make_avc_files(struct dentry *dir) > > { "cache_threshold", > > &sel_avc_cache_threshold_ops, S_IRUGO|S_IWUSR }, > > { "hash_stats", &sel_avc_hash_stats_ops, S_IRUGO }, > > + { "sidtab_hash_stats", &sel_sidtab_hash_stats_ops, S_IRUGO }, > > #ifdef CONFIG_SECURITY_SELINUX_AVC_STATS > > { "cache_stats", &sel_avc_cache_stats_ops, S_IRUGO }, > > #endif > > diff --git a/security/selinux/ss/context.h b/security/selinux/ss/context.h > > index 513e67f48878..01fea944177d 100644 > > --- a/security/selinux/ss/context.h > > +++ b/security/selinux/ss/context.h > > @@ -31,6 +31,7 @@ struct context { > > u32 len; /* length of string in bytes */ > > struct mls_range range; > > char *str; /* string representation if context cannot be mapped. */ > > + u32 hash; /* a hash of the string representation */ > > }; > > > > static inline void mls_context_init(struct context *c) > > @@ -168,6 +169,7 @@ static inline int context_cpy(struct context *dst, struct context *src) > > kfree(dst->str); > > return rc; > > } > > + dst->hash = src->hash; > > return 0; > > } > > > > @@ -182,6 +184,8 @@ static inline void context_destroy(struct context *c) > > > > static inline int context_cmp(struct context *c1, struct context *c2) > > { > > + if (c1->hash && c2->hash && (c1->hash != c2->hash)) > > + return 0; > > if (c1->len && c2->len) > > return (c1->len == c2->len && !strcmp(c1->str, c2->str)); > > if (c1->len || c2->len) > > @@ -192,5 +196,10 @@ static inline int context_cmp(struct context *c1, struct context *c2) > > mls_context_cmp(c1, c2)); > > } > > > > +static inline unsigned int context_compute_hash(const char *s) > > +{ > > + return full_name_hash(NULL, s, strlen(s)); > > +} > > + > > #endif /* _SS_CONTEXT_H_ */ > > > > diff --git a/security/selinux/ss/policydb.c b/security/selinux/ss/policydb.c > > index e20624a68f5d..e369b0092cdf 100644 > > --- a/security/selinux/ss/policydb.c > > +++ b/security/selinux/ss/policydb.c > > @@ -878,6 +878,11 @@ int policydb_load_isids(struct policydb *p, struct sidtab *s) > > sidtab_destroy(s); > > goto out; > > } > > + rc = context_add_hash(p, &c->context[0]); > > + if (rc) { > > + sidtab_destroy(s); > > + goto out; > > + } > > > > rc = sidtab_set_initial(s, c->sid[0], &c->context[0]); > > if (rc) { > > diff --git a/security/selinux/ss/services.c b/security/selinux/ss/services.c > > index a5813c7629c1..29076c15cdf7 100644 > > --- a/security/selinux/ss/services.c > > +++ b/security/selinux/ss/services.c > > @@ -1257,6 +1257,11 @@ static int context_struct_to_string(struct policydb *p, > > > > #include "initial_sid_to_string.h" > > > > +int security_sidtab_hash_stats(struct selinux_state *state, char *page) > > +{ > > + return sidtab_hash_stats(state->ss->sidtab, page); > > +} > > + > > const char *security_get_initial_sid_context(u32 sid) > > { > > if (unlikely(sid > SECINITSID_NUM)) > > @@ -1384,6 +1389,8 @@ static int string_to_context_struct(struct policydb *pol, > > int rc = 0; > > > > context_init(ctx); > > + /* hash the string before it gets mutated */ > > + ctx->hash = context_compute_hash(scontext); > > > > /* Parse the security context. */ > > > > @@ -1442,6 +1449,7 @@ static int string_to_context_struct(struct policydb *pol, > > rc = -EINVAL; > > if (!policydb_context_isvalid(pol, ctx)) > > goto out; > > + > > rc = 0; > > out: > > if (rc) > > @@ -1449,6 +1457,42 @@ static int string_to_context_struct(struct policydb *pol, > > return rc; > > } > > > > +int context_add_hash(struct policydb *policydb, > > + struct context *context) > > +{ > > + int rc; > > + char *str; > > + int len; > > + > > + if (context->str) { > > + context->hash = context_compute_hash(context->str); > > + } else { > > + rc = context_struct_to_string(policydb, context, > > + &str, &len); > > + if (rc) > > + return rc; > > + context->hash = context_compute_hash(str); > > + kfree(str); > > + } > > + return 0; > > +} > > + > > +static int context_to_sid(struct selinux_state *state, > > + struct context *context, u32 *sid) > > +{ > > + int rc; > > + struct sidtab *sidtab = state->ss->sidtab; > > + struct policydb *policydb = &state->ss->policydb; > > + > > + if (!context->hash) { > > + rc = context_add_hash(policydb, context); > > + if (rc) > > + return rc; > > + } > > + > > + return sidtab_context_to_sid(sidtab, context, sid); > > +} > > + > > static int security_context_to_sid_core(struct selinux_state *state, > > const char *scontext, u32 scontext_len, > > u32 *sid, u32 def_sid, gfp_t gfp_flags, > > @@ -1501,7 +1545,7 @@ static int security_context_to_sid_core(struct selinux_state *state, > > str = NULL; > > } else if (rc) > > goto out_unlock; > > - rc = sidtab_context_to_sid(sidtab, &context, sid); > > + rc = context_to_sid(state, &context, sid); > > context_destroy(&context); > > out_unlock: > > read_unlock(&state->ss->policy_rwlock); > > @@ -1805,7 +1849,7 @@ static int security_compute_sid(struct selinux_state *state, > > goto out_unlock; > > } > > /* Obtain the sid for the context. */ > > - rc = sidtab_context_to_sid(sidtab, &newcontext, out_sid); > > + rc = context_to_sid(state, &newcontext, out_sid); > > out_unlock: > > read_unlock(&state->ss->policy_rwlock); > > context_destroy(&newcontext); > > @@ -2033,6 +2077,10 @@ static int convert_context(struct context *oldc, struct context *newc, void *p) > > goto bad; > > } > > > > + rc = context_add_hash(args->newp, newc); > > + if (rc) > > + goto bad; > > + > > return 0; > > bad: > > /* Map old representation to string and save it. */ > > @@ -2280,9 +2328,7 @@ int security_port_sid(struct selinux_state *state, > > > > if (c) { > > if (!c->sid[0]) { > > - rc = sidtab_context_to_sid(sidtab, > > - &c->context[0], > > - &c->sid[0]); > > + rc = context_to_sid(state, &c->context[0], &c->sid[0]); > > if (rc) > > goto out; > > } > > @@ -2374,9 +2420,7 @@ int security_ib_endport_sid(struct selinux_state *state, > > > > if (c) { > > if (!c->sid[0]) { > > - rc = sidtab_context_to_sid(sidtab, > > - &c->context[0], > > - &c->sid[0]); > > + rc = context_to_sid(state, &c->context[0], &c->sid[0]); > > if (rc) > > goto out; > > } > > @@ -2416,14 +2460,10 @@ int security_netif_sid(struct selinux_state *state, > > > > if (c) { > > if (!c->sid[0] || !c->sid[1]) { > > - rc = sidtab_context_to_sid(sidtab, > > - &c->context[0], > > - &c->sid[0]); > > + rc = context_to_sid(state, &c->context[0], &c->sid[0]); > > if (rc) > > goto out; > > - rc = sidtab_context_to_sid(sidtab, > > - &c->context[1], > > - &c->sid[1]); > > + rc = context_to_sid(state, &c->context[1], &c->sid[1]); > > if (rc) > > goto out; > > } > > @@ -2601,7 +2641,7 @@ int security_get_user_sids(struct selinux_state *state, > > &usercon)) > > continue; > > > > - rc = sidtab_context_to_sid(sidtab, &usercon, &sid); > > + rc = context_to_sid(state, &usercon, &sid); > > if (rc) > > goto out_unlock; > > if (mynel < maxnel) { > > @@ -2672,7 +2712,6 @@ static inline int __security_genfs_sid(struct selinux_state *state, > > u32 *sid) > > { > > struct policydb *policydb = &state->ss->policydb; > > - struct sidtab *sidtab = state->ss->sidtab; > > int len; > > u16 sclass; > > struct genfs *genfs; > > @@ -2707,7 +2746,7 @@ static inline int __security_genfs_sid(struct selinux_state *state, > > goto out; > > > > if (!c->sid[0]) { > > - rc = sidtab_context_to_sid(sidtab, &c->context[0], &c->sid[0]); > > + rc = context_to_sid(state, &c->context[0], &c->sid[0]); > > if (rc) > > goto out; > > } > > @@ -2770,8 +2809,7 @@ int security_fs_use(struct selinux_state *state, struct super_block *sb) > > if (c) { > > sbsec->behavior = c->v.behavior; > > if (!c->sid[0]) { > > - rc = sidtab_context_to_sid(sidtab, &c->context[0], > > - &c->sid[0]); > > + rc = context_to_sid(state, &c->context[0], &c->sid[0]); > > if (rc) > > goto out; > > } > > @@ -3026,8 +3064,7 @@ int security_sid_mls_copy(struct selinux_state *state, > > goto out_unlock; > > } > > } > > - > > - rc = sidtab_context_to_sid(sidtab, &newcon, new_sid); > > + rc = context_to_sid(state, &newcon, new_sid); > > out_unlock: > > read_unlock(&state->ss->policy_rwlock); > > context_destroy(&newcon); > > @@ -3620,7 +3657,7 @@ int security_netlbl_secattr_to_sid(struct selinux_state *state, > > if (!mls_context_isvalid(policydb, &ctx_new)) > > goto out_free; > > > > - rc = sidtab_context_to_sid(sidtab, &ctx_new, sid); > > + rc = context_to_sid(state, &ctx_new, sid); > > if (rc) > > goto out_free; > > > > diff --git a/security/selinux/ss/services.h b/security/selinux/ss/services.h > > index 9a36de860368..fc40640a9725 100644 > > --- a/security/selinux/ss/services.h > > +++ b/security/selinux/ss/services.h > > @@ -8,7 +8,7 @@ > > #define _SS_SERVICES_H_ > > > > #include "policydb.h" > > -#include "sidtab.h" > > +#include "context.h" > > > > /* Mapping for a single class */ > > struct selinux_mapping { > > @@ -39,4 +39,6 @@ void services_compute_xperms_drivers(struct extended_perms *xperms, > > void services_compute_xperms_decision(struct extended_perms_decision *xpermd, > > struct avtab_node *node); > > > > +int context_add_hash(struct policydb *policydb, struct context *context); > > + > > #endif /* _SS_SERVICES_H_ */ > > diff --git a/security/selinux/ss/sidtab.c b/security/selinux/ss/sidtab.c > > index 7d49994e8d5f..e4710f32b6d9 100644 > > --- a/security/selinux/ss/sidtab.c > > +++ b/security/selinux/ss/sidtab.c > > @@ -23,23 +23,32 @@ int sidtab_init(struct sidtab *s) > > > > memset(s->roots, 0, sizeof(s->roots)); > > > > - /* max count is SIDTAB_MAX so valid index is always < SIDTAB_MAX */ > > - for (i = 0; i < SIDTAB_RCACHE_SIZE; i++) > > - s->rcache[i] = SIDTAB_MAX; > > - > > for (i = 0; i < SECINITSID_NUM; i++) > > s->isids[i].set = 0; > > > > s->count = 0; > > s->convert = NULL; > > + hash_init(s->context_to_sid); > > > > spin_lock_init(&s->lock); > > return 0; > > } > > > > +static u32 context_to_sid(struct sidtab *s, struct context *context) > > +{ > > + struct sidtab_node *node; > > + > > + hash_for_each_possible(s->context_to_sid, node, list, context->hash) { > > + if (context_cmp(node->context, context)) > > + return node->sid; > > + } > > + return 0; > > +} > > + > > int sidtab_set_initial(struct sidtab *s, u32 sid, struct context *context) > > { > > struct sidtab_isid_entry *entry; > > + struct sidtab_node *node = NULL; > > int rc; > > > > if (sid == 0 || sid > SECINITSID_NUM) > > @@ -52,9 +61,57 @@ int sidtab_set_initial(struct sidtab *s, u32 sid, struct context *context) > > return rc; > > > > entry->set = 1; > > + > > + /* > > + * Multiple initial sids may map to the same context. Check that this > > + * context is not already represented in the context_to_sid hashtable > > + * to avoid duplicate entries and long linked lists upon hash > > + * collision. > > + */ > > + if (!context_to_sid(s, context)) { > > + node = kzalloc(sizeof(struct sidtab_node), GFP_ATOMIC); > > + if (!node) > > + return -ENOMEM; > > + node->sid = sid; > > + node->context = &entry->context; > > + hash_add(s->context_to_sid, &node->list, context->hash); > > + } > > + > > return 0; > > } > > > > +int sidtab_hash_stats(struct sidtab *sidtab, char *page) > > +{ > > + int i; > > + int chain_len = 0; > > + int slots_used = 0; > > + int entries = 0; > > + int max_chain_len = 0; > > + int cur_bucket = 0; > > + struct sidtab_node *node; > > + > > + > > + hash_for_each(sidtab->context_to_sid, i, node, list) { > > + entries++; > > + if (i == cur_bucket) { > > + chain_len++; > > + if (chain_len == 1) > > + slots_used++; > > + } else { > > + cur_bucket = i; > > + if (chain_len > max_chain_len) > > + max_chain_len = chain_len; > > + chain_len = 0; > > + } > > + } > > + if (chain_len > max_chain_len) > > + max_chain_len = chain_len; > > + return scnprintf(page, PAGE_SIZE, "%s: %d entries and %d/%d buckets " > > + "used, longest chain length %d\n", "context_to_sid", > > + entries, slots_used, SIDTAB_HASH_BUCKETS, > > + max_chain_len); > > +} > > + > > static u32 sidtab_level_from_count(u32 count) > > { > > u32 capacity = SIDTAB_LEAF_ENTRIES; > > @@ -150,7 +207,7 @@ static struct context *sidtab_search_core(struct sidtab *s, u32 sid, int force) > > > > if (sid != 0) { > > if (sid > SECINITSID_NUM) > > - context = sidtab_lookup(s, sid - (SECINITSID_NUM + 1)); > > + context = sidtab_lookup(s, sid_to_index(sid)); > > else > > context = sidtab_lookup_initial(s, sid); > > if (context && (!context->len || force)) > > @@ -170,132 +227,70 @@ struct context *sidtab_search_force(struct sidtab *s, u32 sid) > > return sidtab_search_core(s, sid, 1); > > } > > > > -static int sidtab_find_context(union sidtab_entry_inner entry, > > - u32 *pos, u32 count, u32 level, > > - struct context *context, u32 *index) > > -{ > > - int rc; > > - u32 i; > > - > > - if (level != 0) { > > - struct sidtab_node_inner *node = entry.ptr_inner; > > - > > - i = 0; > > - while (i < SIDTAB_INNER_ENTRIES && *pos < count) { > > - rc = sidtab_find_context(node->entries[i], > > - pos, count, level - 1, > > - context, index); > > - if (rc == 0) > > - return 0; > > - i++; > > - } > > - } else { > > - struct sidtab_node_leaf *node = entry.ptr_leaf; > > - > > - i = 0; > > - while (i < SIDTAB_LEAF_ENTRIES && *pos < count) { > > - if (context_cmp(&node->entries[i].context, context)) { > > - *index = *pos; > > - return 0; > > - } > > - (*pos)++; > > - i++; > > - } > > - } > > - return -ENOENT; > > -} > > - > > -static void sidtab_rcache_update(struct sidtab *s, u32 index, u32 pos) > > -{ > > - while (pos > 0) { > > - WRITE_ONCE(s->rcache[pos], READ_ONCE(s->rcache[pos - 1])); > > - --pos; > > - } > > - WRITE_ONCE(s->rcache[0], index); > > -} > > - > > -static void sidtab_rcache_push(struct sidtab *s, u32 index) > > -{ > > - sidtab_rcache_update(s, index, SIDTAB_RCACHE_SIZE - 1); > > -} > > - > > -static int sidtab_rcache_search(struct sidtab *s, struct context *context, > > - u32 *index) > > -{ > > - u32 i; > > - > > - for (i = 0; i < SIDTAB_RCACHE_SIZE; i++) { > > - u32 v = READ_ONCE(s->rcache[i]); > > - > > - if (v >= SIDTAB_MAX) > > - continue; > > - > > - if (context_cmp(sidtab_do_lookup(s, v, 0), context)) { > > - sidtab_rcache_update(s, v, i); > > - *index = v; > > - return 0; > > - } > > - } > > - return -ENOENT; > > -} > > - > > -static int sidtab_reverse_lookup(struct sidtab *s, struct context *context, > > - u32 *index) > > +int sidtab_context_to_sid(struct sidtab *s, struct context *context, > > + u32 *sid) > > { > > unsigned long flags; > > - u32 count, count_locked, level, pos; > > + u32 count; > > struct sidtab_convert_params *convert; > > struct context *dst, *dst_convert; > > + struct sidtab_node *dst_node, *dst_node_convert = NULL; > > int rc; > > > > - rc = sidtab_rcache_search(s, context, index); > > - if (rc == 0) > > - return 0; > > - > > - /* read entries only after reading count */ > > - count = smp_load_acquire(&s->count); > > - level = sidtab_level_from_count(count); > > - > > - pos = 0; > > - rc = sidtab_find_context(s->roots[level], &pos, count, level, > > - context, index); > > - if (rc == 0) { > > - sidtab_rcache_push(s, *index); > > + *sid = context_to_sid(s, context); > > + if (*sid) > > return 0; > > - } > > > > /* lock-free search failed: lock, re-search, and insert if not found */ > > spin_lock_irqsave(&s->lock, flags); > > > > + *sid = context_to_sid(s, context); > > + if (*sid) > > + goto out_unlock; > > + > > convert = s->convert; > > - count_locked = s->count; > > - level = sidtab_level_from_count(count_locked); > > - > > - /* if count has changed before we acquired the lock, then catch up */ > > - while (count < count_locked) { > > - if (context_cmp(sidtab_do_lookup(s, count, 0), context)) { > > - sidtab_rcache_push(s, count); > > - *index = count; > > - rc = 0; > > + count = s->count; > > + > > + rc = -ENOMEM; > > + dst_node = kzalloc(sizeof(struct sidtab_node), GFP_ATOMIC); > > + if (!dst_node) > > + goto out_unlock; > > + > > + if (convert) { > > + dst_node_convert = kzalloc(sizeof(struct sidtab_node), > > + GFP_ATOMIC); > > + if (!dst_node_convert) { > > + kfree(dst_node); > > goto out_unlock; > > } > > - ++count; > > } > > > > /* bail out if we already reached max entries */ > > rc = -EOVERFLOW; > > - if (count >= SIDTAB_MAX) > > + if (count >= SIDTAB_MAX) { > > + kfree(dst_node); > > + kfree(dst_node_convert); > > goto out_unlock; > > + } > > > > /* insert context into new entry */ > > rc = -ENOMEM; > > dst = sidtab_do_lookup(s, count, 1); > > - if (!dst) > > + if (!dst) { > > + kfree(dst_node); > > + kfree(dst_node_convert); > > goto out_unlock; > > + } > > + > > + dst_node->sid = index_to_sid(count); > > + dst_node->context = dst; > > > > rc = context_cpy(dst, context); > > - if (rc) > > + if (rc) { > > + kfree(dst_node); > > + kfree(dst_node_convert); > > goto out_unlock; > > + } > > > > /* > > * if we are building a new sidtab, we need to convert the context > > @@ -306,25 +301,35 @@ static int sidtab_reverse_lookup(struct sidtab *s, struct context *context, > > dst_convert = sidtab_do_lookup(convert->target, count, 1); > > if (!dst_convert) { > > context_destroy(dst); > > + kfree(dst_node); > > + kfree(dst_node_convert); > > goto out_unlock; > > } > > > > rc = convert->func(context, dst_convert, convert->args); > > if (rc) { > > context_destroy(dst); > > + kfree(dst_node); > > + kfree(dst_node_convert); > > goto out_unlock; > > } > > + dst_node_convert->sid = index_to_sid(count); > > + dst_node_convert->context = dst_convert; > > > > /* at this point we know the insert won't fail */ > > + spin_lock_irqsave(&convert->target->lock, flags); > > convert->target->count = count + 1; > > + hash_add(convert->target->context_to_sid, > > + &dst_node_convert->list, dst_convert->hash); > > + spin_unlock_irqrestore(&convert->target->lock, flags); > > } > > + hash_add(s->context_to_sid, &dst_node->list, context->hash); > > > > if (context->len) > > pr_info("SELinux: Context %s is not valid (left unmapped).\n", > > context->str); > > > > - sidtab_rcache_push(s, count); > > - *index = count; > > + *sid = index_to_sid(count); > > > > /* write entries before writing new count */ > > smp_store_release(&s->count, count + 1); > > @@ -335,27 +340,41 @@ static int sidtab_reverse_lookup(struct sidtab *s, struct context *context, > > return rc; > > } > > > > -int sidtab_context_to_sid(struct sidtab *s, struct context *context, u32 *sid) > > +static int sidtab_convert_hashnode(struct sidtab *s, u32 index) > > { > > - int rc; > > - u32 i; > > + unsigned long flags; > > + struct context *context; > > + struct sidtab_node *node; > > > > - for (i = 0; i < SECINITSID_NUM; i++) { > > - struct sidtab_isid_entry *entry = &s->isids[i]; > > + context = sidtab_do_lookup(s, index, 0); > > > > - if (entry->set && context_cmp(context, &entry->context)) { > > - *sid = i + 1; > > - return 0; > > - } > > - } > > + node = kzalloc(sizeof(struct sidtab_node), GFP_ATOMIC); > > + if (!node) > > + return -ENOMEM; > > > > - rc = sidtab_reverse_lookup(s, context, sid); > > - if (rc) > > - return rc; > > - *sid += SECINITSID_NUM + 1; > > + node->sid = index_to_sid(index); > > + node->context = context; > > + spin_lock_irqsave(&s->lock, flags); > > + hash_add(s->context_to_sid, &node->list, context->hash); > > + spin_unlock_irqrestore(&s->lock, flags); > > return 0; > > } > > > > +static int sidtab_convert_hashtable(struct sidtab *s, u32 count) > > +{ > > + u32 i; > > + int rc = 0; > > + > > + for (i = 0; i < count; i++) { > > + rc = sidtab_convert_hashnode(s, i); > > + if (rc) > > + break; > > + > > + cond_resched(); > > + } > > + return rc; > > +} > > + > > static int sidtab_convert_tree(union sidtab_entry_inner *edst, > > union sidtab_entry_inner *esrc, > > u32 *pos, u32 count, u32 level, > > @@ -400,6 +419,7 @@ static int sidtab_convert_tree(union sidtab_entry_inner *edst, > > } > > cond_resched(); > > } > > + > > return 0; > > } > > > > @@ -449,7 +469,16 @@ int sidtab_convert(struct sidtab *s, struct sidtab_convert_params *params) > > spin_lock_irqsave(&s->lock, flags); > > s->convert = NULL; > > spin_unlock_irqrestore(&s->lock, flags); > > + return rc; > > + } > > + > > + rc = sidtab_convert_hashtable(params->target, count); > > + if (rc) { > > + spin_lock_irqsave(&s->lock, flags); > > + s->convert = NULL; > > + spin_unlock_irqrestore(&s->lock, flags); > > } > > + > > return rc; > > } > > > > @@ -478,6 +507,19 @@ static void sidtab_destroy_tree(union sidtab_entry_inner entry, u32 level) > > } > > } > > > > + > > Extraneous newline? > > > +static void sidtab_destroy_hashtable(struct sidtab *s) > > +{ > > + struct sidtab_node *node; > > + struct hlist_node *tmp; > > + int i; > > + > > + hash_for_each_safe(s->context_to_sid, i, tmp, node, list) { > > + hash_del(&node->list); > > + kfree(node); > > + } > > +} > > + > > void sidtab_destroy(struct sidtab *s) > > { > > u32 i, level; > > @@ -491,4 +533,5 @@ void sidtab_destroy(struct sidtab *s) > > --level; > > > > sidtab_destroy_tree(s->roots[level], level); > > + sidtab_destroy_hashtable(s); > > } > > diff --git a/security/selinux/ss/sidtab.h b/security/selinux/ss/sidtab.h > > index 1f4763141aa1..85afef719a43 100644 > > --- a/security/selinux/ss/sidtab.h > > +++ b/security/selinux/ss/sidtab.h > > @@ -13,6 +13,7 @@ > > > > #include <linux/spinlock_types.h> > > #include <linux/log2.h> > > +#include <linux/hashtable.h> > > > > #include "context.h" > > > > @@ -66,7 +67,16 @@ struct sidtab_convert_params { > > struct sidtab *target; > > }; > > > > -#define SIDTAB_RCACHE_SIZE 3 > > +struct sidtab_node { > > + u32 sid; > > + struct context *context; > > + struct hlist_node list; > > +}; > > How about just adding the sid and hlist_node fields directly to struct > sidtab_entry_leaf and add that to the hash table? That should simplify > the code a lot and also reduce memory allocation overhead. Oh, good idea. That will definitely simplify things. > > > + > > +#define SIDTAB_HASH_BITS 9 > > +#define SIDTAB_HASH_BUCKETS (1 << SIDTAB_HASH_BITS) > > Maybe we should make SIDTAB_HASH_BITS configurable via Kconfig? > > > +#define index_to_sid(index) (index + SECINITSID_NUM + 1) > > +#define sid_to_index(sid) (sid - (SECINITSID_NUM + 1)) > > I think these last two macros should be rather defined inside > sidtab.c, since they are not useful outside sidtab internals. > > > > > struct sidtab { > > /* > > @@ -83,11 +93,11 @@ struct sidtab { > > struct sidtab_convert_params *convert; > > spinlock_t lock; > > > > - /* reverse lookup cache - access atomically via {READ|WRITE}_ONCE() */ > > - u32 rcache[SIDTAB_RCACHE_SIZE]; > > - > > /* index == SID - 1 (no entry for SECSID_NULL) */ > > struct sidtab_isid_entry isids[SECINITSID_NUM]; > > + > > + /* Hash table for fast reverse context-to-sid lookups. */ > > + DECLARE_HASHTABLE(context_to_sid, SIDTAB_HASH_BITS); > > }; > > > > int sidtab_init(struct sidtab *s); > > @@ -101,6 +111,8 @@ int sidtab_context_to_sid(struct sidtab *s, struct context *context, u32 *sid); > > > > void sidtab_destroy(struct sidtab *s); > > > > +int sidtab_hash_stats(struct sidtab *sidtab, char *page); > > + > > #endif /* _SS_SIDTAB_H_ */ > > > > > > -- > > 2.24.0.rc0.303.g954a862665-goog > > > > -- > Ondrej Mosnacek <omosnace at redhat dot com> > Software Engineer, Security Technologies > Red Hat, Inc. >
