Re: FAILED: patch "[PATCH] ima: Avoid blocking in RCU read-side critical section" failed to apply to 6.6-stable tree

On Mon, 2024-06-24 at 18:47 +0200, gregkh@linuxfoundation.org wrote:

The patch below does not apply to the 6.6-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y git checkout FETCH_HEAD git cherry-pick -x 9a95c5bfbf02a0a7f5983280fe284a0ff0836c34 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2024062438-shaft-herbicide-4e7d@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^..

Possible dependencies:

9a95c5bfbf02 ("ima: Avoid blocking in RCU read-side critical section") 260017f31a8c ("lsm: use default hook return value in call_int_hook()") 923831117611 ("evm: Move to LSM infrastructure") 84594c9ecdca ("ima: Move IMA-Appraisal to LSM infrastructure") cd3cec0a02c7 ("ima: Move to LSM infrastructure") 06cca5110774 ("integrity: Move integrity_kernel_module_request() to IMA") b8d997032a46 ("security: Introduce key_post_create_or_update hook") 2d705d802414 ("security: Introduce inode_post_remove_acl hook") 8b9d0b825c65 ("security: Introduce inode_post_set_acl hook") a7811e34d100 ("security: Introduce inode_post_create_tmpfile hook") f09068b5a114 ("security: Introduce file_release hook") 8f46ff5767b0 ("security: Introduce file_post_open hook") dae52cbf5887 ("security: Introduce inode_post_removexattr hook") 77fa6f314f03 ("security: Introduce inode_post_setattr hook") 314a8dc728d0 ("security: Align inode_setattr hook definition with EVM") 779cb1947e27 ("evm: Align evm_inode_post_setxattr() definition with LSM infrastructure") 2b6a4054f8c2 ("evm: Align evm_inode_setxattr() definition with LSM infrastructure") 784111d0093e ("evm: Align evm_inode_post_setattr() definition with LSM infrastructure") fec5f85e468d ("ima: Align ima_post_read_file() definition with LSM infrastructure") 526864dd2f60 ("ima: Align ima_inode_removexattr() definition with LSM infrastructure")

The patch doesn't apply cleanly due to the '0' in security_audit_rule_init(): return call_int_hook(audit_rule_init, 0, field, op, rulestr, lsmrule);

Commit 260017f31a8c ("lsm: use default hook return value in call_int_hook()") removed it. Instead of backporting commit 260017f31a8c, adding the '0' would be simpler. This seems to be the only change needed for linux-6.8.y to 6.4.y.

For linux-6.3.y to linux-6.2.y, commit b14faf9c94a6 ("lsm: move the audit hook comments to security/security.c") also needs to be applied.

Paul, how do you normally handle backports?

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 9a95c5bfbf02a0a7f5983280fe284a0ff0836c34 Mon Sep 17 00:00:00 2001 From: GUO Zihua guozihua@huawei.com Date: Tue, 7 May 2024 01:25:41 +0000 Subject: [PATCH] ima: Avoid blocking in RCU read-side critical section

A panic happens in ima_match_policy:

BUG: unable to handle kernel NULL pointer dereference at 0000000000000010 PGD 42f873067 P4D 0 Oops: 0000 [#1] SMP NOPTI CPU: 5 PID: 1286325 Comm: kubeletmonit.sh Kdump: loaded Tainted: P Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 0.0.0 02/06/2015 RIP: 0010:ima_match_policy+0x84/0x450 Code: 49 89 fc 41 89 cf 31 ed 89 44 24 14 eb 1c 44 39 7b 18 74 26 41 83 ff 05 74 20 48 8b 1b 48 3b 1d f2 b9 f4 00 0f 84 9c 01 00 00 <44> 85 73 10 74 ea 44 8b 6b 14 41 f6 c5 01 75 d4 41 f6 c5 02 74 0f RSP: 0018:ff71570009e07a80 EFLAGS: 00010207 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000200 RDX: ffffffffad8dc7c0 RSI: 0000000024924925 RDI: ff3e27850dea2000 RBP: 0000000000000000 R08: 0000000000000000 R09: ffffffffabfce739 R10: ff3e27810cc42400 R11: 0000000000000000 R12: ff3e2781825ef970 R13: 00000000ff3e2785 R14: 000000000000000c R15: 0000000000000001 FS: 00007f5195b51740(0000) GS:ff3e278b12d40000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000010 CR3: 0000000626d24002 CR4: 0000000000361ee0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: ima_get_action+0x22/0x30 process_measurement+0xb0/0x830 ? page_add_file_rmap+0x15/0x170 ? alloc_set_pte+0x269/0x4c0 ? prep_new_page+0x81/0x140 ? simple_xattr_get+0x75/0xa0 ? selinux_file_open+0x9d/0xf0 ima_file_check+0x64/0x90 path_openat+0x571/0x1720 do_filp_open+0x9b/0x110 ? page_counter_try_charge+0x57/0xc0 ? files_cgroup_alloc_fd+0x38/0x60 ? __alloc_fd+0xd4/0x250 ? do_sys_open+0x1bd/0x250 do_sys_open+0x1bd/0x250 do_syscall_64+0x5d/0x1d0 entry_SYSCALL_64_after_hwframe+0x65/0xca

Commit c7423dbdbc9e ("ima: Handle -ESTALE returned by ima_filter_rule_match()") introduced call to ima_lsm_copy_rule within a RCU read-side critical section which contains kmalloc with GFP_KERNEL. This implies a possible sleep and violates limitations of RCU read-side critical sections on non-PREEMPT systems.

Sleeping within RCU read-side critical section might cause synchronize_rcu() returning early and break RCU protection, allowing a UAF to happen.

The root cause of this issue could be described as follows:

...

Thread A | Thread B | |ima_match_policy | | rcu_read_lock | ima_lsm_update_rule | | synchronize_rcu | | | kmalloc(GFP_KERNEL)| | sleep |

==> synchronize_rcu returns early

...

kfree(entry) | | | entry = entry->next|

==> UAF happens and entry now becomes NULL (or could be anything).

...

	|    entry->action	|

==> Accessing entry might cause panic.

To fix this issue, we are converting all kmalloc that is called within RCU read-side critical section to use GFP_ATOMIC.

Fixes: c7423dbdbc9e ("ima: Handle -ESTALE returned by ima_filter_rule_match()") Cc: stable@vger.kernel.org Signed-off-by: GUO Zihua guozihua@huawei.com Acked-by: John Johansen john.johansen@canonical.com Reviewed-by: Mimi Zohar zohar@linux.ibm.com Reviewed-by: Casey Schaufler casey@schaufler-ca.com [PM: fixed missing comment, long lines, !CONFIG_IMA_LSM_RULES case] Signed-off-by: Paul Moore paul@paul-moore.com

diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h index f804b76cde44..44488b1ab9a9 100644 --- a/include/linux/lsm_hook_defs.h +++ b/include/linux/lsm_hook_defs.h @@ -413,7 +413,7 @@ LSM_HOOK(void, LSM_RET_VOID, key_post_create_or_update, struct key *keyring, #ifdef CONFIG_AUDIT LSM_HOOK(int, 0, audit_rule_init, u32 field, u32 op, char *rulestr,

• void **lsmrule)
  

• void **lsmrule, gfp_t gfp)
  

LSM_HOOK(int, 0, audit_rule_known, struct audit_krule *krule) LSM_HOOK(int, 0, audit_rule_match, u32 secid, u32 field, u32 op, void *lsmrule) LSM_HOOK(void, LSM_RET_VOID, audit_rule_free, void *lsmrule) diff --git a/include/linux/security.h b/include/linux/security.h index 21cf70346b33..de3af33e6ff5 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -2048,7 +2048,8 @@ static inline void security_key_post_create_or_update(struct key *keyring, #ifdef CONFIG_AUDIT #ifdef CONFIG_SECURITY -int security_audit_rule_init(u32 field, u32 op, char *rulestr, void **lsmrule); +int security_audit_rule_init(u32 field, u32 op, char *rulestr, void **lsmrule,

• 	     gfp_t gfp);
  

int security_audit_rule_known(struct audit_krule *krule); int security_audit_rule_match(u32 secid, u32 field, u32 op, void *lsmrule); void security_audit_rule_free(void *lsmrule); @@ -2056,7 +2057,7 @@ void security_audit_rule_free(void *lsmrule); #else static inline int security_audit_rule_init(u32 field, u32 op, char *rulestr,

• 			   void **lsmrule)
  

• 			   void **lsmrule, gfp_t gfp)
  

{ return 0; } diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c index be8c680121e4..d6ef4f4f9cba 100644 --- a/kernel/auditfilter.c +++ b/kernel/auditfilter.c @@ -529,7 +529,8 @@ static struct audit_entry *audit_data_to_entry(struct audit_rule_data *data, entry->rule.buflen += f_val; f->lsm_str = str; err = security_audit_rule_init(f->type, f->op, str,

• 				       (void **)&f->lsm_rule);
  

• 				       (void **)&f->lsm_rule,
  

• 				       GFP_KERNEL);
  /* Keep currently invalid fields around in case they
   * become valid after a policy reload. */
  if (err == -EINVAL) {
  

@@ -799,7 +800,7 @@ static inline int audit_dupe_lsm_field(struct audit_field *df, /* our own (refreshed) copy of lsm_rule */ ret = security_audit_rule_init(df->type, df->op, df->lsm_str,

• 		       (void **)&df->lsm_rule);
  

• 		       (void **)&df->lsm_rule, GFP_KERNEL);
  

  /* Keep currently invalid fields around in case they
  • become valid after a policy reload. */
  if (ret == -EINVAL) {

diff --git a/security/apparmor/audit.c b/security/apparmor/audit.c index 45beb1c5f747..6b5181c668b5 100644 --- a/security/apparmor/audit.c +++ b/security/apparmor/audit.c @@ -217,7 +217,7 @@ void aa_audit_rule_free(void *vrule) } } -int aa_audit_rule_init(u32 field, u32 op, char *rulestr, void **vrule) +int aa_audit_rule_init(u32 field, u32 op, char *rulestr, void **vrule, gfp_t gfp) { struct aa_audit_rule *rule; @@ -230,14 +230,14 @@ int aa_audit_rule_init(u32 field, u32 op, char *rulestr, void **vrule) return -EINVAL; }

• rule = kzalloc(sizeof(struct aa_audit_rule), GFP_KERNEL);

• rule = kzalloc(sizeof(struct aa_audit_rule), gfp);

if (!rule) return -ENOMEM; /* Currently rules are treated as coming from the root ns */ rule->label = aa_label_parse(&root_ns->unconfined->label, rulestr,

• 		     GFP_KERNEL, true, false);
  

• 		     gfp, true, false);
  

  if (IS_ERR(rule->label)) { int err = PTR_ERR(rule->label); aa_audit_rule_free(rule);

diff --git a/security/apparmor/include/audit.h b/security/apparmor/include/audit.h index acbb03b9bd25..0c8cc86b417b 100644 --- a/security/apparmor/include/audit.h +++ b/security/apparmor/include/audit.h @@ -200,7 +200,7 @@ static inline int complain_error(int error) } void aa_audit_rule_free(void *vrule); -int aa_audit_rule_init(u32 field, u32 op, char *rulestr, void **vrule); +int aa_audit_rule_init(u32 field, u32 op, char *rulestr, void **vrule, gfp_t gfp); int aa_audit_rule_known(struct audit_krule *rule); int aa_audit_rule_match(u32 sid, u32 field, u32 op, void *vrule); diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h index 3e568126cd48..c51e24d24d1e 100644 --- a/security/integrity/ima/ima.h +++ b/security/integrity/ima/ima.h @@ -546,7 +546,7 @@ static inline void ima_free_modsig(struct modsig *modsig) #else static inline int ima_filter_rule_init(u32 field, u32 op, char *rulestr,

• 		       void **lsmrule)
  

• 		       void **lsmrule, gfp_t gfp)
  

{ return -EINVAL; } diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c index c0556907c2e6..09da8e639239 100644 --- a/security/integrity/ima/ima_policy.c +++ b/security/integrity/ima/ima_policy.c @@ -401,7 +401,8 @@ static void ima_free_rule(struct ima_rule_entry *entry) kfree(entry); } -static struct ima_rule_entry *ima_lsm_copy_rule(struct ima_rule_entry *entry) +static struct ima_rule_entry *ima_lsm_copy_rule(struct ima_rule_entry *entry,

• 				gfp_t gfp)
  

{ struct ima_rule_entry *nentry; int i; @@ -410,7 +411,7 @@ static struct ima_rule_entry *ima_lsm_copy_rule(struct ima_rule_entry *entry) * Immutable elements are copied over as pointers and data; only * lsm rules can change */

• nentry = kmemdup(entry, sizeof(*nentry), GFP_KERNEL);

• nentry = kmemdup(entry, sizeof(*nentry), gfp); if (!nentry) return NULL;

@@ -425,7 +426,8 @@ static struct ima_rule_entry *ima_lsm_copy_rule(struct ima_rule_entry *entry) ima_filter_rule_init(nentry->lsm[i].type, Audit_equal, nentry->lsm[i].args_p,

• 		     &nentry->lsm[i].rule);
  

• 		     &nentry->lsm[i].rule,
  

• 		     gfp);
  

  if (!nentry->lsm[i].rule) pr_warn("rule for LSM '%s' is undefined\n", nentry->lsm[i].args_p);

@@ -438,7 +440,7 @@ static int ima_lsm_update_rule(struct ima_rule_entry *entry) int i; struct ima_rule_entry *nentry;

• nentry = ima_lsm_copy_rule(entry);

• nentry = ima_lsm_copy_rule(entry, GFP_KERNEL); if (!nentry) return -ENOMEM;

@@ -664,7 +666,7 @@ static bool ima_match_rules(struct ima_rule_entry *rule, } if (rc == -ESTALE && !rule_reinitialized) {

• 	lsm_rule = ima_lsm_copy_rule(rule);
  

• 	lsm_rule = ima_lsm_copy_rule(rule, GFP_ATOMIC);
  if (lsm_rule) {
  	rule_reinitialized = true;
  	goto retry;
  

@@ -1140,7 +1142,8 @@ static int ima_lsm_rule_init(struct ima_rule_entry *entry, entry->lsm[lsm_rule].type = audit_type; result = ima_filter_rule_init(entry->lsm[lsm_rule].type, Audit_equal, entry->lsm[lsm_rule].args_p,

• 		      &entry->lsm[lsm_rule].rule);
  

• 		      &entry->lsm[lsm_rule].rule,
  

• 		      GFP_KERNEL);
  

  if (!entry->lsm[lsm_rule].rule) { pr_warn("rule for LSM '%s' is undefined\n", entry->lsm[lsm_rule].args_p);

diff --git a/security/security.c b/security/security.c index e5da848c50b9..e5ca08789f74 100644 --- a/security/security.c +++ b/security/security.c @@ -5332,15 +5332,17 @@ void security_key_post_create_or_update(struct key *keyring, struct key *key,

• @op: rule operator
• @rulestr: rule context
• @lsmrule: receive buffer for audit rule struct

• • @gfp: GFP flag used for kmalloc
  • Allocate and initialize an LSM audit rule structure.
  • Return: Return 0 if @lsmrule has been successfully set, -EINVAL in case of

  •     an invalid rule.
    

  */

-int security_audit_rule_init(u32 field, u32 op, char *rulestr, void **lsmrule) +int security_audit_rule_init(u32 field, u32 op, char *rulestr, void **lsmrule,

• 	     gfp_t gfp)
  

{

• return call_int_hook(audit_rule_init, field, op, rulestr, lsmrule);

• return call_int_hook(audit_rule_init, field, op, rulestr, lsmrule, gfp);

} /** diff --git a/security/selinux/include/audit.h b/security/selinux/include/audit.h index 52aca71210b4..29c7d4c86f6d 100644 --- a/security/selinux/include/audit.h +++ b/security/selinux/include/audit.h @@ -21,12 +21,14 @@

• @op: the operator the rule uses
• @rulestr: the text "target" of the rule
• @rule: pointer to the new rule structure returned via this

• • @gfp: GFP flag used for kmalloc
  • Returns 0 if successful, -errno if not. On success, the rule structure
  • will be allocated internally. The caller must free this structure with
  • selinux_audit_rule_free() after use.
  */

-int selinux_audit_rule_init(u32 field, u32 op, char *rulestr, void **rule); +int selinux_audit_rule_init(u32 field, u32 op, char *rulestr, void **rule,

• 	    gfp_t gfp);
  

/**

• selinux_audit_rule_free - free an selinux audit rule structure.

diff --git a/security/selinux/ss/services.c b/security/selinux/ss/services.c index f20e1968b7f7..e33e55384b75 100644 --- a/security/selinux/ss/services.c +++ b/security/selinux/ss/services.c @@ -3507,7 +3507,8 @@ void selinux_audit_rule_free(void *vrule) } } -int selinux_audit_rule_init(u32 field, u32 op, char *rulestr, void **vrule) +int selinux_audit_rule_init(u32 field, u32 op, char *rulestr, void **vrule,

• 	    gfp_t gfp)
  

{ struct selinux_state *state = &selinux_state; struct selinux_policy *policy; @@ -3548,7 +3549,7 @@ int selinux_audit_rule_init(u32 field, u32 op, char *rulestr, void **vrule) return -EINVAL; }

• tmprule = kzalloc(sizeof(struct selinux_audit_rule), GFP_KERNEL);

• tmprule = kzalloc(sizeof(struct selinux_audit_rule), gfp); if (!tmprule) return -ENOMEM; context_init(&tmprule->au_ctxt);

diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c index 70ba2841e181..f5cbec1e6a92 100644 --- a/security/smack/smack_lsm.c +++ b/security/smack/smack_lsm.c @@ -4693,11 +4693,13 @@ static int smack_post_notification(const struct cred *w_cred,

• @op: required testing operator (=, !=, >, <, ...)
• @rulestr: smack label to be audited
• @vrule: pointer to save our own audit rule representation

• • @gfp: type of the memory for the allocation
  • Prepare to audit cases where (@field @op @rulestr) is true.
  • The label to be audited is created if necessay.
  */

-static int smack_audit_rule_init(u32 field, u32 op, char *rulestr, void **vrule) +static int smack_audit_rule_init(u32 field, u32 op, char *rulestr, void **vrule,

• 		 gfp_t gfp)
  

{ struct smack_known *skp; char **rule = (char **)vrule;