| Message ID | 1706654228-17180-11-git-send-email-wufan@linux.microsoft.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Integrity Policy Enforcement LSM (IPE) | expand |
On Jan 30, 2024 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 > > v12: > + Remove redundant code > --- > security/ipe/audit.c | 27 ++++++++++++++++-- > security/ipe/audit.h | 1 + > security/ipe/eval.c | 11 +++++-- > security/ipe/eval.h | 1 + > security/ipe/fs.c | 68 ++++++++++++++++++++++++++++++++++++++++++++ > 5 files changed, 104 insertions(+), 4 deletions(-) > > diff --git a/security/ipe/audit.c b/security/ipe/audit.c > index 79b7af25085c..ed390d32c641 100644 > --- a/security/ipe/audit.c > +++ b/security/ipe/audit.c > @@ -27,6 +27,9 @@ > "new_active_pol_version=%hu.%hu.%hu "\ > "new_policy_digest=" IPE_AUDIT_HASH_ALG ":" > > +#define AUDIT_ENFORCE_CHANGE_FMT "enforcing=%d old_enforcing=%d auid=%u ses=%u "\ > + "enabled=1 old-enabled=1 lsm=ipe res=1" It looks like you only ever use this in one place, it would probably be better to skip the macro definition in this case as it can make it easier to have a disconnect between the format string and the data. > static const char *const audit_op_names[__IPE_OP_MAX + 1] = { > "EXECUTE", > "FIRMWARE", > @@ -95,8 +98,8 @@ void ipe_audit_match(const struct ipe_eval_ctx *const ctx, > if (!ab) > return; > > - audit_log_format(ab, "ipe_op=%s ipe_hook=%s pid=%d comm=", > - op, audit_hook_names[ctx->hook], > + audit_log_format(ab, "ipe_op=%s ipe_hook=%s enforcing=%d pid=%d comm=", > + op, audit_hook_names[ctx->hook], READ_ONCE(enforce), > task_tgid_nr(current)); > audit_log_untrustedstring(ab, get_task_comm(comm, current)); > > @@ -210,3 +213,23 @@ 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, AUDIT_ENFORCE_CHANGE_FMT, new_enforce, old_enforce, > + from_kuid(&init_user_ns, audit_get_loginuid(current)), > + audit_get_sessionid(current)); > + > + audit_log_end(ab); > +} -- paul-moore.com
diff --git a/security/ipe/audit.c b/security/ipe/audit.c index 79b7af25085c..ed390d32c641 100644 --- a/security/ipe/audit.c +++ b/security/ipe/audit.c @@ -27,6 +27,9 @@ "new_active_pol_version=%hu.%hu.%hu "\ "new_policy_digest=" IPE_AUDIT_HASH_ALG ":" +#define AUDIT_ENFORCE_CHANGE_FMT "enforcing=%d old_enforcing=%d auid=%u ses=%u "\ + "enabled=1 old-enabled=1 lsm=ipe res=1" + static const char *const audit_op_names[__IPE_OP_MAX + 1] = { "EXECUTE", "FIRMWARE", @@ -95,8 +98,8 @@ void ipe_audit_match(const struct ipe_eval_ctx *const ctx, if (!ab) return; - audit_log_format(ab, "ipe_op=%s ipe_hook=%s pid=%d comm=", - op, audit_hook_names[ctx->hook], + audit_log_format(ab, "ipe_op=%s ipe_hook=%s enforcing=%d pid=%d comm=", + op, audit_hook_names[ctx->hook], READ_ONCE(enforce), task_tgid_nr(current)); audit_log_untrustedstring(ab, get_task_comm(comm, current)); @@ -210,3 +213,23 @@ 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, AUDIT_ENFORCE_CHANGE_FMT, 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 85cccc3d0bdf..49338b35f126 100644 --- a/security/ipe/eval.c +++ b/security/ipe/eval.c @@ -18,6 +18,7 @@ struct ipe_policy __rcu *ipe_active_policy; bool success_audit; +bool enforce = true; #define FILE_SUPERBLOCK(f) ((f)->f_path.mnt->mnt_sb) @@ -137,6 +138,7 @@ int ipe_evaluate_event(const struct ipe_eval_ctx *const ctx) const struct ipe_rule *rule = NULL; const struct ipe_op_table *rules = NULL; struct ipe_prop *prop = NULL; + int rc = 0; rcu_read_lock(); @@ -189,9 +191,12 @@ 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; - return 0; + if (!READ_ONCE(enforce)) + rc = 0; + + return rc; } /* Set the right module name */ @@ -202,3 +207,5 @@ int ipe_evaluate_event(const struct ipe_eval_ctx *const ctx) 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 0be9aadec9f8..84adf1a0e514 100644 --- a/security/ipe/eval.h +++ b/security/ipe/eval.h @@ -16,6 +16,7 @@ extern struct ipe_policy __rcu *ipe_active_policy; extern bool success_audit; +extern bool enforce; #ifdef CONFIG_BLK_DEV_INITRD struct ipe_sb { diff --git a/security/ipe/fs.c b/security/ipe/fs.c index 95407997cf0c..b16d87443a3b 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;