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    Subject[PATCH v15 24/26] ima: Limit number of policy rules in non-init_ima_ns
    Date
    Limit the number of policy rules a user can set in non-init_ima_ns to a
    hardcoded 1024 rules. This allows to restrict the amount of kernel memory
    used for IMA's policy since now any user can create an IMA namespace and
    could try to waste kernel memory.

    Ignore added rules if the user attempts to exceed this limit by setting
    too many additional rules.

    Switch the accounting for the memory allocated for IMA policy rules to
    GFP_KERNEL_ACCOUNT so that cgroups kernel memory accounting can take
    effect. This switch has no effect on the init_ima_ns.

    Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>

    ---

    v11:
    - roll back changes to auditing too-many-rules since not auditing from
    IMA namespaces
    ---
    security/integrity/ima/ima_policy.c | 23 ++++++++++++++++++-----
    1 file changed, 18 insertions(+), 5 deletions(-)

    diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
    index bcd3227630bb..cdcc2a1506ab 100644
    --- a/security/integrity/ima/ima_policy.c
    +++ b/security/integrity/ima/ima_policy.c
    @@ -336,7 +336,8 @@ static struct ima_rule_opt_list *ima_alloc_rule_opt_list(const substring_t *src)
    return ERR_PTR(-EINVAL);
    }

    - opt_list = kzalloc(struct_size(opt_list, items, count), GFP_KERNEL);
    + opt_list = kzalloc(struct_size(opt_list, items, count),
    + GFP_KERNEL_ACCOUNT);
    if (!opt_list) {
    kfree(src_copy);
    return ERR_PTR(-ENOMEM);
    @@ -410,7 +411,7 @@ static struct ima_rule_entry *ima_lsm_copy_rule(struct ima_namespace *ns,
    * 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_KERNEL_ACCOUNT);
    if (!nentry)
    return NULL;

    @@ -889,7 +890,7 @@ static void add_rules(struct ima_namespace *ns,

    if (policy_rule & IMA_CUSTOM_POLICY) {
    entry = kmemdup(&entries[i], sizeof(*entry),
    - GFP_KERNEL);
    + GFP_KERNEL_ACCOUNT);
    if (!entry)
    continue;

    @@ -926,7 +927,7 @@ static int __init ima_init_arch_policy(struct ima_namespace *ns)

    ns->arch_policy_entry = kcalloc(arch_entries + 1,
    sizeof(*ns->arch_policy_entry),
    - GFP_KERNEL);
    + GFP_KERNEL_ACCOUNT);
    if (!ns->arch_policy_entry)
    return 0;

    @@ -1038,8 +1039,20 @@ void __init ima_init_policy(struct ima_namespace *ns)
    /* Make sure we have a valid policy, at least containing some rules. */
    int ima_check_policy(struct ima_namespace *ns)
    {
    + struct ima_rule_entry *entry;
    + size_t len1 = 0;
    + size_t len2 = 0;
    +
    if (list_empty(&ns->ima_temp_rules))
    return -EINVAL;
    + if (ns != &init_ima_ns) {
    + list_for_each_entry(entry, &ns->ima_temp_rules, list)
    + len1++;
    + list_for_each_entry(entry, &ns->ima_policy_rules, list)
    + len2++;
    + if (len1 + len2 > 1024)
    + return -ENOSPC;
    + }
    return 0;
    }

    @@ -1973,7 +1986,7 @@ ssize_t ima_parse_add_rule(struct ima_namespace *ns, char *rule)
    if (*p == '#' || *p == '\0')
    return len;

    - entry = kzalloc(sizeof(*entry), GFP_KERNEL);
    + entry = kzalloc(sizeof(*entry), GFP_KERNEL_ACCOUNT);
    if (!entry) {
    integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL,
    NULL, op, "-ENOMEM", -ENOMEM, audit_info);
    --
    2.37.3
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