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Message-Id: <20200324153643.15527-12-will@kernel.org> Date: Tue, 24 Mar 2020 15:36:33 +0000 From: Will Deacon <will@...nel.org> To: linux-kernel@...r.kernel.org Cc: Will Deacon <will@...nel.org>, Eric Dumazet <edumazet@...gle.com>, Jann Horn <jannh@...gle.com>, Kees Cook <keescook@...omium.org>, Maddie Stone <maddiestone@...gle.com>, Marco Elver <elver@...gle.com>, "Paul E . McKenney" <paulmck@...nel.org>, Peter Zijlstra <peterz@...radead.org>, Thomas Gleixner <tglx@...utronix.de>, kernel-team@...roid.com, kernel-hardening@...ts.openwall.com Subject: [RFC PATCH 11/21] list: Add integrity checking to hlist implementation Extend the 'hlist' implementation so that it can optionally perform integrity checking in a similar fashion to the standard 'list' code when CONFIG_CHECK_INTEGRITY_LIST=y. Cc: Kees Cook <keescook@...omium.org> Cc: Paul E. McKenney <paulmck@...nel.org> Cc: Peter Zijlstra <peterz@...radead.org> Signed-off-by: Will Deacon <will@...nel.org> --- include/linux/list.h | 41 ++++++++++++++++++++- include/linux/rculist.h | 80 ++++++++++++++++++++++------------------- lib/list_debug.c | 79 ++++++++++++++++++++++++++++++++++++++++ 3 files changed, 162 insertions(+), 38 deletions(-) diff --git a/include/linux/list.h b/include/linux/list.h index 2bef081afa69..96ede36a5614 100644 --- a/include/linux/list.h +++ b/include/linux/list.h @@ -41,6 +41,13 @@ extern bool __list_add_valid(struct list_head *new, struct list_head *prev, struct list_head *next); extern bool __list_del_entry_valid(struct list_head *entry); +extern bool __hlist_add_before_valid(struct hlist_node *new, + struct hlist_node *next); +extern bool __hlist_add_behind_valid(struct hlist_node *new, + struct hlist_node *prev); +extern bool __hlist_add_head_valid(struct hlist_node *new, + struct hlist_head *head); +extern bool __hlist_del_valid(struct hlist_node *node); #else static inline bool __list_add_valid(struct list_head *new, struct list_head *prev, @@ -52,6 +59,25 @@ static inline bool __list_del_entry_valid(struct list_head *entry) { return true; } +static inline bool __hlist_add_before_valid(struct hlist_node *new, + struct hlist_node *next) +{ + return true; +} +static inline bool __hlist_add_behind_valid(struct hlist_node *new, + struct hlist_node *prev) +{ + return true; +} +static inline bool __hlist_add_head_valid(struct hlist_node *new, + struct hlist_head *head) +{ + return true; +} +static inline bool __hlist_del_valid(struct hlist_node *node) +{ + return true; +} #endif /* @@ -796,6 +822,9 @@ static inline void __hlist_del(struct hlist_node *n) struct hlist_node *next = n->next; struct hlist_node **pprev = n->pprev; + if (!__hlist_del_valid(n)) + return; + WRITE_ONCE(*pprev, next); if (next) WRITE_ONCE(next->pprev, pprev); @@ -840,6 +869,10 @@ static inline void hlist_del_init(struct hlist_node *n) static inline void hlist_add_head(struct hlist_node *n, struct hlist_head *h) { struct hlist_node *first = h->first; + + if (!__hlist_add_head_valid(n, h)) + return; + n->next = first; if (first) first->pprev = &n->next; @@ -855,6 +888,9 @@ static inline void hlist_add_head(struct hlist_node *n, struct hlist_head *h) static inline void hlist_add_before(struct hlist_node *n, struct hlist_node *next) { + if (!__hlist_add_before_valid(n, next)) + return; + n->pprev = next->pprev; n->next = next; next->pprev = &n->next; @@ -862,13 +898,16 @@ static inline void hlist_add_before(struct hlist_node *n, } /** - * hlist_add_behing - add a new entry after the one specified + * hlist_add_behind - add a new entry after the one specified * @n: new entry to be added * @prev: hlist node to add it after, which must be non-NULL */ static inline void hlist_add_behind(struct hlist_node *n, struct hlist_node *prev) { + if (!__hlist_add_behind_valid(n, prev)) + return; + n->next = prev->next; prev->next = n; n->pprev = &prev->next; diff --git a/include/linux/rculist.h b/include/linux/rculist.h index 9f313e4999fe..6f3eb7758fd8 100644 --- a/include/linux/rculist.h +++ b/include/linux/rculist.h @@ -537,6 +537,9 @@ static inline void hlist_add_head_rcu(struct hlist_node *n, { struct hlist_node *first = h->first; + if (!__hlist_add_head_valid(n, h)) + return; + n->next = first; WRITE_ONCE(n->pprev, &h->first); rcu_assign_pointer(hlist_first_rcu(h), n); @@ -544,43 +547,6 @@ static inline void hlist_add_head_rcu(struct hlist_node *n, WRITE_ONCE(first->pprev, &n->next); } -/** - * hlist_add_tail_rcu - * @n: the element to add to the hash list. - * @h: the list to add to. - * - * Description: - * Adds the specified element to the specified hlist, - * while permitting racing traversals. - * - * The caller must take whatever precautions are necessary - * (such as holding appropriate locks) to avoid racing - * with another list-mutation primitive, such as hlist_add_head_rcu() - * or hlist_del_rcu(), running on this same list. - * However, it is perfectly legal to run concurrently with - * the _rcu list-traversal primitives, such as - * hlist_for_each_entry_rcu(), used to prevent memory-consistency - * problems on Alpha CPUs. Regardless of the type of CPU, the - * list-traversal primitive must be guarded by rcu_read_lock(). - */ -static inline void hlist_add_tail_rcu(struct hlist_node *n, - struct hlist_head *h) -{ - struct hlist_node *i, *last = NULL; - - /* Note: write side code, so rcu accessors are not needed. */ - for (i = h->first; i; i = i->next) - last = i; - - if (last) { - n->next = last->next; - WRITE_ONCE(n->pprev, &last->next); - rcu_assign_pointer(hlist_next_rcu(last), n); - } else { - hlist_add_head_rcu(n, h); - } -} - /** * hlist_add_before_rcu * @n: the new element to add to the hash list. @@ -602,6 +568,9 @@ static inline void hlist_add_tail_rcu(struct hlist_node *n, static inline void hlist_add_before_rcu(struct hlist_node *n, struct hlist_node *next) { + if (!__hlist_add_before_valid(n, next)) + return; + WRITE_ONCE(n->pprev, next->pprev); n->next = next; rcu_assign_pointer(hlist_pprev_rcu(n), n); @@ -629,6 +598,9 @@ static inline void hlist_add_before_rcu(struct hlist_node *n, static inline void hlist_add_behind_rcu(struct hlist_node *n, struct hlist_node *prev) { + if (!__hlist_add_behind_valid(n, prev)) + return; + n->next = prev->next; WRITE_ONCE(n->pprev, &prev->next); rcu_assign_pointer(hlist_next_rcu(prev), n); @@ -636,6 +608,40 @@ static inline void hlist_add_behind_rcu(struct hlist_node *n, WRITE_ONCE(n->next->pprev, &n->next); } +/** + * hlist_add_tail_rcu + * @n: the element to add to the hash list. + * @h: the list to add to. + * + * Description: + * Adds the specified element to the specified hlist, + * while permitting racing traversals. + * + * The caller must take whatever precautions are necessary + * (such as holding appropriate locks) to avoid racing + * with another list-mutation primitive, such as hlist_add_head_rcu() + * or hlist_del_rcu(), running on this same list. + * However, it is perfectly legal to run concurrently with + * the _rcu list-traversal primitives, such as + * hlist_for_each_entry_rcu(), used to prevent memory-consistency + * problems on Alpha CPUs. Regardless of the type of CPU, the + * list-traversal primitive must be guarded by rcu_read_lock(). + */ +static inline void hlist_add_tail_rcu(struct hlist_node *n, + struct hlist_head *h) +{ + struct hlist_node *i, *last = NULL; + + /* Note: write side code, so rcu accessors are not needed. */ + for (i = h->first; i; i = i->next) + last = i; + + if (last) + hlist_add_behind_rcu(n, last); + else + hlist_add_head_rcu(n, h); +} + #define __hlist_for_each_rcu(pos, head) \ for (pos = rcu_dereference(hlist_first_rcu(head)); \ pos; \ diff --git a/lib/list_debug.c b/lib/list_debug.c index 57bf685af2ef..03234ebd18c9 100644 --- a/lib/list_debug.c +++ b/lib/list_debug.c @@ -60,3 +60,82 @@ bool __list_del_entry_valid(struct list_head *entry) } EXPORT_SYMBOL(__list_del_entry_valid); + +static bool __hlist_add_valid(struct hlist_node *new, struct hlist_node *prev, + struct hlist_node *next) +{ + if (CHECK_DATA_CORRUPTION(next && next->pprev != &prev->next, + "hlist_add corruption: next->pprev should be &prev->next (%px), but was %px (next=%px)\n", + &prev->next, next->pprev, next) || + CHECK_DATA_CORRUPTION(prev->next != next, + "hlist_add corruption: prev->next should be next (%px), but was %px (prev=%px)\n", + next, prev->next, prev) || + CHECK_DATA_CORRUPTION(new == prev || new == next, + "hlist_add double add: new=%px, prev=%px, next=%px\n", + new, prev, next)) + return false; + + return true; +} + +bool __hlist_add_before_valid(struct hlist_node *new, struct hlist_node *next) +{ + struct hlist_node *prev; + + prev = container_of(next->pprev, struct hlist_node, next); + return __hlist_add_valid(new, prev, next); +} +EXPORT_SYMBOL(__hlist_add_before_valid); + +bool __hlist_add_behind_valid(struct hlist_node *new, struct hlist_node *prev) +{ + return __hlist_add_valid(new, prev, prev->next); +} +EXPORT_SYMBOL(__hlist_add_behind_valid); + +bool __hlist_add_head_valid(struct hlist_node *new, struct hlist_head *head) +{ + struct hlist_node *first = head->first; + + if (CHECK_DATA_CORRUPTION(first && first->pprev != &head->first, + "hlist_add_head corruption: first->pprev should be &head->first (%px), but was %px (first=%px)", + &head->first, first->pprev, first) || + CHECK_DATA_CORRUPTION(new == first, + "hlist_add_head double add: new (%px) == first (%px)", + new, first)) + return false; + + return true; +} +EXPORT_SYMBOL(__hlist_add_head_valid); + +bool __hlist_del_valid(struct hlist_node *node) +{ + struct hlist_node *prev, *next = node->next; + + if (CHECK_DATA_CORRUPTION(next == LIST_POISON1, + "hlist_del corruption: %px->next is LIST_POISON1 (%px)\n", + node, LIST_POISON1) || + CHECK_DATA_CORRUPTION(node->pprev == LIST_POISON2, + "hlist_del corruption: %px->pprev is LIST_POISON2 (%px)\n", + node, LIST_POISON2)) + return false; + + /* + * If we want to validate the previous node's forward linkage, + * then we must be able to treat the head like a normal node. + */ + BUILD_BUG_ON(offsetof(struct hlist_node, next) != + offsetof(struct hlist_head, first)); + prev = container_of(node->pprev, struct hlist_node, next); + if (CHECK_DATA_CORRUPTION(prev->next != node, + "hlist_del corruption: prev->next should be %px, but was %px\n", + node, prev->next) || + CHECK_DATA_CORRUPTION(next && next->pprev != &node->next, + "hlist_del corruption: next->pprev should be %px, but was %px\n", + &node->next, next->pprev)) + return false; + + return true; +} +EXPORT_SYMBOL(__hlist_del_valid); -- 2.20.1
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