| Message ID | 1696457386-3010-10-git-send-email-wufan@linux.microsoft.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Delegated to: | Paul Moore |
| Headers | show |
| Series | Integrity Policy Enforcement LSM (IPE) | expand |
On Oct 4, 2023 Fan Wu <wufan@linux.microsoft.com> wrote: > > IPE, like SELinux, supports a permissive mode. This mode allows policy > authors to test and evaluate IPE policy without it effecting their > programs. When the mode is changed, a 1404 AUDIT_MAC_STATUS > be reported. > > This patch adds the following audit records: > > audit: MAC_STATUS enforcing=0 old_enforcing=1 auid=4294967295 > ses=4294967295 enabled=1 old-enabled=1 lsm=ipe res=1 > audit: MAC_STATUS enforcing=1 old_enforcing=0 auid=4294967295 > ses=4294967295 enabled=1 old-enabled=1 lsm=ipe res=1 > > The audit record only emit when the value from the user input is > different from the current enforce value. > > Signed-off-by: Deven Bowers <deven.desai@linux.microsoft.com> > Signed-off-by: Fan Wu <wufan@linux.microsoft.com> > --- > v2: > + Split evaluation loop, access control hooks, > and evaluation loop from policy parser and userspace > interface to pass mailing list character limit > > v3: > + Move ipe_load_properties to patch 04. > + Remove useless 0-initializations > + Prefix extern variables with ipe_ > + Remove kernel module parameters, as these are > exposed through sysctls. > + Add more prose to the IPE base config option > help text. > + Use GFP_KERNEL for audit_log_start. > + Remove unnecessary caching system. > + Remove comments from headers > + Use rcu_access_pointer for rcu-pointer null check > + Remove usage of reqprot; use prot only. > + Move policy load and activation audit event to 03/12 > > v4: > + Remove sysctls in favor of securityfs nodes > + Re-add kernel module parameters, as these are now > exposed through securityfs. > + Refactor property audit loop to a separate function. > > v5: > + fix minor grammatical errors > + do not group rule by curly-brace in audit record, > reconstruct the exact rule. > > v6: > + No changes > > v7: > + Further split lsm creation into a separate commit from the > evaluation loop and audit system, for easier review. > + Propagating changes to support the new ipe_context structure in the > evaluation loop. > + Split out permissive functionality into a separate patch for easier > review. > + Remove permissive switch compile-time configuration option - this > is trivial to add later. > > v8: > + Remove "IPE" prefix from permissive audit record > + align fields to the linux-audit field dictionary. This causes the > following fields to change: > enforce -> permissive > > + Remove duplicated information correlated with syscall record, that > will always be present in the audit event. > + Change audit types: > + AUDIT_TRUST_STATUS -> AUDIT_MAC_STATUS > + There is no significant difference in meaning between > these types. > > v9: > + Clean up ipe_context related code > > v10: > + Change audit format to comform with the existing format selinux is > using > + Remove the audit record emission during init to align with selinux, > which does not perform this action. > > v11: > + Remove redundant code > --- > security/ipe/audit.c | 22 ++++++++++++++ > security/ipe/audit.h | 1 + > security/ipe/eval.c | 14 +++++++-- > security/ipe/eval.h | 1 + > security/ipe/fs.c | 68 ++++++++++++++++++++++++++++++++++++++++++++ > 5 files changed, 104 insertions(+), 2 deletions(-) ... > diff --git a/security/ipe/eval.c b/security/ipe/eval.c > index 499b6b3338f2..78c54ff1fdd3 100644 > --- a/security/ipe/eval.c > +++ b/security/ipe/eval.c > @@ -167,9 +172,12 @@ int ipe_evaluate_event(const struct ipe_eval_ctx *const ctx) > ipe_audit_match(ctx, match_type, action, rule); > > if (action == IPE_ACTION_DENY) > - return -EACCES; > + rc = -EACCES; > + > + if (!enforcing) > + rc = 0; Why the local @enforcing variable? Why not: if (!READ_ONCE(enforce)) rc = 0; > - return 0; > + return rc; > } > > /** > @@ -198,3 +206,5 @@ void ipe_invalidate_pinned_sb(const struct super_block *mnt_sb) > > module_param(success_audit, bool, 0400); > MODULE_PARM_DESC(success_audit, "Start IPE with success auditing enabled"); > +module_param(enforce, bool, 0400); > +MODULE_PARM_DESC(enforce, "Start IPE in enforce or permissive mode"); "enforcing" -- paul-moore.com
On 10/23/2023 8:52 PM, Paul Moore wrote: > On Oct 4, 2023 Fan Wu <wufan@linux.microsoft.com> wrote: >> >> IPE, like SELinux, supports a permissive mode. This mode allows policy >> authors to test and evaluate IPE policy without it effecting their >> programs. When the mode is changed, a 1404 AUDIT_MAC_STATUS >> be reported. >> >> This patch adds the following audit records: >> >> audit: MAC_STATUS enforcing=0 old_enforcing=1 auid=4294967295 >> ses=4294967295 enabled=1 old-enabled=1 lsm=ipe res=1 >> audit: MAC_STATUS enforcing=1 old_enforcing=0 auid=4294967295 >> ses=4294967295 enabled=1 old-enabled=1 lsm=ipe res=1 >> >> The audit record only emit when the value from the user input is >> different from the current enforce value. >> >> Signed-off-by: Deven Bowers <deven.desai@linux.microsoft.com> >> Signed-off-by: Fan Wu <wufan@linux.microsoft.com> >> --- >> v2: >> + Split evaluation loop, access control hooks, >> and evaluation loop from policy parser and userspace >> interface to pass mailing list character limit >> >> v3: >> + Move ipe_load_properties to patch 04. >> + Remove useless 0-initializations >> + Prefix extern variables with ipe_ >> + Remove kernel module parameters, as these are >> exposed through sysctls. >> + Add more prose to the IPE base config option >> help text. >> + Use GFP_KERNEL for audit_log_start. >> + Remove unnecessary caching system. >> + Remove comments from headers >> + Use rcu_access_pointer for rcu-pointer null check >> + Remove usage of reqprot; use prot only. >> + Move policy load and activation audit event to 03/12 >> >> v4: >> + Remove sysctls in favor of securityfs nodes >> + Re-add kernel module parameters, as these are now >> exposed through securityfs. >> + Refactor property audit loop to a separate function. >> >> v5: >> + fix minor grammatical errors >> + do not group rule by curly-brace in audit record, >> reconstruct the exact rule. >> >> v6: >> + No changes >> >> v7: >> + Further split lsm creation into a separate commit from the >> evaluation loop and audit system, for easier review. >> + Propagating changes to support the new ipe_context structure in the >> evaluation loop. >> + Split out permissive functionality into a separate patch for easier >> review. >> + Remove permissive switch compile-time configuration option - this >> is trivial to add later. >> >> v8: >> + Remove "IPE" prefix from permissive audit record >> + align fields to the linux-audit field dictionary. This causes the >> following fields to change: >> enforce -> permissive >> >> + Remove duplicated information correlated with syscall record, that >> will always be present in the audit event. >> + Change audit types: >> + AUDIT_TRUST_STATUS -> AUDIT_MAC_STATUS >> + There is no significant difference in meaning between >> these types. >> >> v9: >> + Clean up ipe_context related code >> >> v10: >> + Change audit format to comform with the existing format selinux is >> using >> + Remove the audit record emission during init to align with selinux, >> which does not perform this action. >> >> v11: >> + Remove redundant code >> --- >> security/ipe/audit.c | 22 ++++++++++++++ >> security/ipe/audit.h | 1 + >> security/ipe/eval.c | 14 +++++++-- >> security/ipe/eval.h | 1 + >> security/ipe/fs.c | 68 ++++++++++++++++++++++++++++++++++++++++++++ >> 5 files changed, 104 insertions(+), 2 deletions(-) > > ... > >> diff --git a/security/ipe/eval.c b/security/ipe/eval.c >> index 499b6b3338f2..78c54ff1fdd3 100644 >> --- a/security/ipe/eval.c >> +++ b/security/ipe/eval.c >> @@ -167,9 +172,12 @@ int ipe_evaluate_event(const struct ipe_eval_ctx *const ctx) >> ipe_audit_match(ctx, match_type, action, rule); >> >> if (action == IPE_ACTION_DENY) >> - return -EACCES; >> + rc = -EACCES; >> + >> + if (!enforcing) >> + rc = 0; > > Why the local @enforcing variable? Why not: > > if (!READ_ONCE(enforce)) > rc = 0; > Yes the variable is unnecessary, I will remove it. -Fan >> - return 0; >> + return rc; >> } >> >> /** >> @@ -198,3 +206,5 @@ void ipe_invalidate_pinned_sb(const struct super_block *mnt_sb) >> >> module_param(success_audit, bool, 0400); >> MODULE_PARM_DESC(success_audit, "Start IPE with success auditing enabled"); >> +module_param(enforce, bool, 0400); >> +MODULE_PARM_DESC(enforce, "Start IPE in enforce or permissive mode"); > > "enforcing" > > -- > paul-moore.com
diff --git a/security/ipe/audit.c b/security/ipe/audit.c index e123701d5e3b..0dd5f10c318f 100644 --- a/security/ipe/audit.c +++ b/security/ipe/audit.c @@ -193,3 +193,25 @@ void ipe_audit_policy_load(const struct ipe_policy *const p) audit_log_end(ab); } + +/** + * ipe_audit_enforce - Audit a change in IPE's enforcement state. + * @new_enforce: The new value enforce to be set. + * @old_enforce: The old value currently in enforce. + */ +void ipe_audit_enforce(bool new_enforce, bool old_enforce) +{ + struct audit_buffer *ab; + + ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_MAC_STATUS); + if (!ab) + return; + + audit_log_format(ab, "enforcing=%d old_enforcing=%d auid=%u ses=%u" + " enabled=1 old-enabled=1 lsm=ipe res=1", + new_enforce, old_enforce, + from_kuid(&init_user_ns, audit_get_loginuid(current)), + audit_get_sessionid(current)); + + audit_log_end(ab); +} diff --git a/security/ipe/audit.h b/security/ipe/audit.h index 0ff5a06808de..914f001e5286 100644 --- a/security/ipe/audit.h +++ b/security/ipe/audit.h @@ -14,5 +14,6 @@ void ipe_audit_match(const struct ipe_eval_ctx *const ctx, void ipe_audit_policy_load(const struct ipe_policy *const p); void ipe_audit_policy_activation(const struct ipe_policy *const op, const struct ipe_policy *const np); +void ipe_audit_enforce(bool new_enforce, bool old_enforce); #endif /* _IPE_AUDIT_H */ diff --git a/security/ipe/eval.c b/security/ipe/eval.c index 499b6b3338f2..78c54ff1fdd3 100644 --- a/security/ipe/eval.c +++ b/security/ipe/eval.c @@ -19,6 +19,7 @@ struct ipe_policy __rcu *ipe_active_policy; bool success_audit; +bool enforce = true; static const struct super_block *pinned_sb; static DEFINE_SPINLOCK(pin_lock); @@ -114,12 +115,14 @@ static bool evaluate_property(const struct ipe_eval_ctx *const ctx, int ipe_evaluate_event(const struct ipe_eval_ctx *const ctx) { bool match = false; + bool enforcing = true; enum ipe_action_type action; enum ipe_match match_type; struct ipe_policy *pol = NULL; const struct ipe_rule *rule = NULL; const struct ipe_op_table *rules = NULL; struct ipe_prop *prop = NULL; + int rc = 0; rcu_read_lock(); @@ -129,6 +132,8 @@ int ipe_evaluate_event(const struct ipe_eval_ctx *const ctx) return 0; } + enforcing = READ_ONCE(enforce); + if (ctx->op == IPE_OP_INVALID) { rcu_read_unlock(); action = pol->parsed->global_default_action; @@ -167,9 +172,12 @@ int ipe_evaluate_event(const struct ipe_eval_ctx *const ctx) ipe_audit_match(ctx, match_type, action, rule); if (action == IPE_ACTION_DENY) - return -EACCES; + rc = -EACCES; + + if (!enforcing) + rc = 0; - return 0; + return rc; } /** @@ -198,3 +206,5 @@ void ipe_invalidate_pinned_sb(const struct super_block *mnt_sb) module_param(success_audit, bool, 0400); MODULE_PARM_DESC(success_audit, "Start IPE with success auditing enabled"); +module_param(enforce, bool, 0400); +MODULE_PARM_DESC(enforce, "Start IPE in enforce or permissive mode"); diff --git a/security/ipe/eval.h b/security/ipe/eval.h index 5473f712566c..3f7f71452618 100644 --- a/security/ipe/eval.h +++ b/security/ipe/eval.h @@ -15,6 +15,7 @@ extern struct ipe_policy __rcu *ipe_active_policy; extern bool success_audit; +extern bool enforce; struct ipe_eval_ctx { enum ipe_op_type op; diff --git a/security/ipe/fs.c b/security/ipe/fs.c index dda7a5afc60c..0a1838432bd0 100644 --- a/security/ipe/fs.c +++ b/security/ipe/fs.c @@ -16,6 +16,7 @@ static struct dentry *np __ro_after_init; static struct dentry *root __ro_after_init; struct dentry *policy_root __ro_after_init; static struct dentry *audit_node __ro_after_init; +static struct dentry *enforce_node __ro_after_init; /** * setaudit - Write handler for the securityfs node, "ipe/success_audit" @@ -67,6 +68,60 @@ static ssize_t getaudit(struct file *f, char __user *data, return simple_read_from_buffer(data, len, offset, result, 1); } +/** + * setenforce - Write handler for the securityfs node, "ipe/enforce" + * @f: Supplies a file structure representing the securityfs node. + * @data: Supplies a buffer passed to the write syscall. + * @len: Supplies the length of @data. + * @offset: unused. + * + * Return: + * * >0 - Success, Length of buffer written + * * <0 - Error + */ +static ssize_t setenforce(struct file *f, const char __user *data, + size_t len, loff_t *offset) +{ + int rc = 0; + bool new_value, old_value; + + if (!file_ns_capable(f, &init_user_ns, CAP_MAC_ADMIN)) + return -EPERM; + + old_value = READ_ONCE(enforce); + rc = kstrtobool_from_user(data, len, &new_value); + if (rc) + return rc; + + if (new_value != old_value) { + ipe_audit_enforce(new_value, old_value); + WRITE_ONCE(enforce, new_value); + } + + return len; +} + +/** + * getenforce - Read handler for the securityfs node, "ipe/enforce" + * @f: Supplies a file structure representing the securityfs node. + * @data: Supplies a buffer passed to the read syscall. + * @len: Supplies the length of @data. + * @offset: unused. + * + * Return: + * * >0 - Success, Length of buffer written + * * <0 - Error + */ +static ssize_t getenforce(struct file *f, char __user *data, + size_t len, loff_t *offset) +{ + const char *result; + + result = ((READ_ONCE(enforce)) ? "1" : "0"); + + return simple_read_from_buffer(data, len, offset, result, 1); +} + /** * new_policy - Write handler for the securityfs node, "ipe/new_policy". * @f: Supplies a file structure representing the securityfs node. @@ -120,6 +175,11 @@ static const struct file_operations audit_fops = { .read = getaudit, }; +static const struct file_operations enforce_fops = { + .write = setenforce, + .read = getenforce, +}; + /** * ipe_init_securityfs - Initialize IPE's securityfs tree at fsinit. * @@ -147,6 +207,13 @@ static int __init ipe_init_securityfs(void) goto err; } + enforce_node = securityfs_create_file("enforce", 0600, root, NULL, + &enforce_fops); + if (IS_ERR(enforce_node)) { + rc = PTR_ERR(enforce_node); + goto err; + } + policy_root = securityfs_create_dir("policies", root); if (IS_ERR(policy_root)) { rc = PTR_ERR(policy_root); @@ -163,6 +230,7 @@ static int __init ipe_init_securityfs(void) err: securityfs_remove(np); securityfs_remove(policy_root); + securityfs_remove(enforce_node); securityfs_remove(audit_node); securityfs_remove(root); return rc;