From 71ac7f6255c560716c20da8ee2c964bbd96e941f Mon Sep 17 00:00:00 2001 From: Tyler Hicks Date: Sun, 29 Sep 2013 08:39:21 -0700 Subject: [PATCH 1/2] apparmor: Use shash crypto API interface for profile hashes Use the shash interface, rather than the hash interface, when hashing AppArmor profiles. The shash interface does not use scatterlists and it is a better fit for what AppArmor needs. This fixes a kernel paging BUG when aa_calc_profile_hash() is passed a buffer from vmalloc(). The hash interface requires callers to handle vmalloc() buffers differently than what AppArmor was doing. Due to vmalloc() memory not being physically contiguous, each individual page behind the buffer must be assigned to a scatterlist with sg_set_page() and then the scatterlist passed to crypto_hash_update(). The shash interface does not have that limitation and allows vmalloc() and kmalloc() buffers to be handled in the same manner. BugLink: https://launchpad.net/bugs/1216294/ BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=62261 Signed-off-by: Tyler Hicks Acked-by: Seth Arnold Signed-off-by: John Johansen Signed-off-by: James Morris --- security/apparmor/crypto.c | 34 ++++++++++++++++------------------ 1 file changed, 16 insertions(+), 18 deletions(-) diff --git a/security/apparmor/crypto.c b/security/apparmor/crypto.c index d6222ba4e919..532471d0b3a0 100644 --- a/security/apparmor/crypto.c +++ b/security/apparmor/crypto.c @@ -15,14 +15,14 @@ * it should be. */ -#include +#include #include "include/apparmor.h" #include "include/crypto.h" static unsigned int apparmor_hash_size; -static struct crypto_hash *apparmor_tfm; +static struct crypto_shash *apparmor_tfm; unsigned int aa_hash_size(void) { @@ -32,35 +32,33 @@ unsigned int aa_hash_size(void) int aa_calc_profile_hash(struct aa_profile *profile, u32 version, void *start, size_t len) { - struct scatterlist sg[2]; - struct hash_desc desc = { - .tfm = apparmor_tfm, - .flags = 0 - }; + struct { + struct shash_desc shash; + char ctx[crypto_shash_descsize(apparmor_tfm)]; + } desc; int error = -ENOMEM; u32 le32_version = cpu_to_le32(version); if (!apparmor_tfm) return 0; - sg_init_table(sg, 2); - sg_set_buf(&sg[0], &le32_version, 4); - sg_set_buf(&sg[1], (u8 *) start, len); - profile->hash = kzalloc(apparmor_hash_size, GFP_KERNEL); if (!profile->hash) goto fail; - error = crypto_hash_init(&desc); + desc.shash.tfm = apparmor_tfm; + desc.shash.flags = 0; + + error = crypto_shash_init(&desc.shash); if (error) goto fail; - error = crypto_hash_update(&desc, &sg[0], 4); + error = crypto_shash_update(&desc.shash, (u8 *) &le32_version, 4); if (error) goto fail; - error = crypto_hash_update(&desc, &sg[1], len); + error = crypto_shash_update(&desc.shash, (u8 *) start, len); if (error) goto fail; - error = crypto_hash_final(&desc, profile->hash); + error = crypto_shash_final(&desc.shash, profile->hash); if (error) goto fail; @@ -75,19 +73,19 @@ fail: static int __init init_profile_hash(void) { - struct crypto_hash *tfm; + struct crypto_shash *tfm; if (!apparmor_initialized) return 0; - tfm = crypto_alloc_hash("sha1", 0, CRYPTO_ALG_ASYNC); + tfm = crypto_alloc_shash("sha1", 0, CRYPTO_ALG_ASYNC); if (IS_ERR(tfm)) { int error = PTR_ERR(tfm); AA_ERROR("failed to setup profile sha1 hashing: %d\n", error); return error; } apparmor_tfm = tfm; - apparmor_hash_size = crypto_hash_digestsize(apparmor_tfm); + apparmor_hash_size = crypto_shash_digestsize(apparmor_tfm); aa_info_message("AppArmor sha1 policy hashing enabled"); From 4cd4fc77032dca46fe7475d81461e29145db247a Mon Sep 17 00:00:00 2001 From: John Johansen Date: Sun, 29 Sep 2013 08:39:22 -0700 Subject: [PATCH 2/2] apparmor: fix suspicious RCU usage warning in policy.c/policy.h The recent 3.12 pull request for apparmor was missing a couple rcu _protected access modifiers. Resulting in the follow suspicious RCU usage [ 29.804534] [ INFO: suspicious RCU usage. ] [ 29.804539] 3.11.0+ #5 Not tainted [ 29.804541] ------------------------------- [ 29.804545] security/apparmor/include/policy.h:363 suspicious rcu_dereference_check() usage! [ 29.804548] [ 29.804548] other info that might help us debug this: [ 29.804548] [ 29.804553] [ 29.804553] rcu_scheduler_active = 1, debug_locks = 1 [ 29.804558] 2 locks held by apparmor_parser/1268: [ 29.804560] #0: (sb_writers#9){.+.+.+}, at: [] file_start_write+0x27/0x29 [ 29.804576] #1: (&ns->lock){+.+.+.}, at: [] aa_replace_profiles+0x166/0x57c [ 29.804589] [ 29.804589] stack backtrace: [ 29.804595] CPU: 0 PID: 1268 Comm: apparmor_parser Not tainted 3.11.0+ #5 [ 29.804599] Hardware name: ASUSTeK Computer Inc. UL50VT /UL50VT , BIOS 217 03/01/2010 [ 29.804602] 0000000000000000 ffff8800b95a1d90 ffffffff8144eb9b ffff8800b94db540 [ 29.804611] ffff8800b95a1dc0 ffffffff81087439 ffff880138cc3a18 ffff880138cc3a18 [ 29.804619] ffff8800b9464a90 ffff880138cc3a38 ffff8800b95a1df0 ffffffff811f5084 [ 29.804628] Call Trace: [ 29.804636] [] dump_stack+0x4e/0x82 [ 29.804642] [] lockdep_rcu_suspicious+0xfc/0x105 [ 29.804649] [] __aa_update_replacedby+0x53/0x7f [ 29.804655] [] __replace_profile+0x11f/0x1ed [ 29.804661] [] aa_replace_profiles+0x410/0x57c [ 29.804668] [] profile_replace+0x35/0x4c [ 29.804674] [] vfs_write+0xad/0x113 [ 29.804680] [] SyS_write+0x44/0x7a [ 29.804687] [] system_call_fastpath+0x16/0x1b [ 29.804691] [ 29.804694] =============================== [ 29.804697] [ INFO: suspicious RCU usage. ] [ 29.804700] 3.11.0+ #5 Not tainted [ 29.804703] ------------------------------- [ 29.804706] security/apparmor/policy.c:566 suspicious rcu_dereference_check() usage! [ 29.804709] [ 29.804709] other info that might help us debug this: [ 29.804709] [ 29.804714] [ 29.804714] rcu_scheduler_active = 1, debug_locks = 1 [ 29.804718] 2 locks held by apparmor_parser/1268: [ 29.804721] #0: (sb_writers#9){.+.+.+}, at: [] file_start_write+0x27/0x29 [ 29.804733] #1: (&ns->lock){+.+.+.}, at: [] aa_replace_profiles+0x166/0x57c [ 29.804744] [ 29.804744] stack backtrace: [ 29.804750] CPU: 0 PID: 1268 Comm: apparmor_parser Not tainted 3.11.0+ #5 [ 29.804753] Hardware name: ASUSTeK Computer Inc. UL50VT /UL50VT , BIOS 217 03/01/2010 [ 29.804756] 0000000000000000 ffff8800b95a1d80 ffffffff8144eb9b ffff8800b94db540 [ 29.804764] ffff8800b95a1db0 ffffffff81087439 ffff8800b95b02b0 0000000000000000 [ 29.804772] ffff8800b9efba08 ffff880138cc3a38 ffff8800b95a1dd0 ffffffff811f4f94 [ 29.804779] Call Trace: [ 29.804786] [] dump_stack+0x4e/0x82 [ 29.804791] [] lockdep_rcu_suspicious+0xfc/0x105 [ 29.804798] [] aa_free_replacedby_kref+0x4d/0x62 [ 29.804804] [] ? aa_put_namespace+0x17/0x17 [ 29.804810] [] kref_put+0x36/0x40 [ 29.804816] [] __replace_profile+0x13a/0x1ed [ 29.804822] [] aa_replace_profiles+0x410/0x57c [ 29.804829] [] profile_replace+0x35/0x4c [ 29.804835] [] vfs_write+0xad/0x113 [ 29.804840] [] SyS_write+0x44/0x7a [ 29.804847] [] system_call_fastpath+0x16/0x1b Reported-by: miles.lane@gmail.com CC: paulmck@linux.vnet.ibm.com Signed-off-by: John Johansen Signed-off-by: James Morris --- security/apparmor/include/policy.h | 4 +++- security/apparmor/policy.c | 3 ++- 2 files changed, 5 insertions(+), 2 deletions(-) diff --git a/security/apparmor/include/policy.h b/security/apparmor/include/policy.h index f2d4b6348cbc..c28b0f20ab53 100644 --- a/security/apparmor/include/policy.h +++ b/security/apparmor/include/policy.h @@ -360,7 +360,9 @@ static inline void aa_put_replacedby(struct aa_replacedby *p) static inline void __aa_update_replacedby(struct aa_profile *orig, struct aa_profile *new) { - struct aa_profile *tmp = rcu_dereference(orig->replacedby->profile); + struct aa_profile *tmp; + tmp = rcu_dereference_protected(orig->replacedby->profile, + mutex_is_locked(&orig->ns->lock)); rcu_assign_pointer(orig->replacedby->profile, aa_get_profile(new)); orig->flags |= PFLAG_INVALID; aa_put_profile(tmp); diff --git a/security/apparmor/policy.c b/security/apparmor/policy.c index 6172509fa2b7..345bec07a27d 100644 --- a/security/apparmor/policy.c +++ b/security/apparmor/policy.c @@ -563,7 +563,8 @@ void __init aa_free_root_ns(void) static void free_replacedby(struct aa_replacedby *r) { if (r) { - aa_put_profile(rcu_dereference(r->profile)); + /* r->profile will not be updated any more as r is dead */ + aa_put_profile(rcu_dereference_protected(r->profile, true)); kzfree(r); } }