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    SubjectRe: [RFC PATCH v7 05/16] ipe: add LSM hooks on execution and kernel read

    On 10/25/2021 5:22 AM, Roberto Sassu wrote:
    >> From:deven.desai@linux.microsoft.com
    >> [mailto:deven.desai@linux.microsoft.com]
    >> From: Deven Bowers<deven.desai@linux.microsoft.com>
    >>
    >> IPE's initial goal is to control both execution and the loading of
    >> kernel modules based on the system's definition of trust. It
    >> accomplishes this by plugging into the security hooks for execve,
    >> mprotect, mmap, kernel_load_data and kernel_read_data.
    >>
    >> Signed-off-by: Deven Bowers<deven.desai@linux.microsoft.com>
    >> ---
    >>
    >> Relevant changes since v6:
    >> * Split up patch 02/12 into four parts:
    >> 1. context creation [01/16]
    >> 2. audit [07/16]
    >> 3. evaluation loop [03/16]
    >> 4. access control hooks [05/16] (this patch)
    >>
    >> ---
    >> security/ipe/hooks.c | 149 ++++++++++++++++++++++++++++++++++++++++++
    >> security/ipe/hooks.h | 23 ++++++-
    >> security/ipe/ipe.c | 5 ++
    >> security/ipe/policy.c | 23 +++++++
    >> security/ipe/policy.h | 12 +++-
    >> 5 files changed, 209 insertions(+), 3 deletions(-)
    >>
    >> diff --git a/security/ipe/hooks.c b/security/ipe/hooks.c
    >> index ed0c886eaa5a..216242408a80 100644
    >> --- a/security/ipe/hooks.c
    >> +++ b/security/ipe/hooks.c
    >> @@ -6,11 +6,15 @@
    >> #include "ipe.h"
    >> #include "ctx.h"
    >> #include "hooks.h"
    >> +#include "eval.h"
    >>
    >> +#include <linux/fs.h>
    >> #include <linux/sched.h>
    >> #include <linux/types.h>
    >> #include <linux/refcount.h>
    >> #include <linux/rcupdate.h>
    >> +#include <linux/binfmts.h>
    >> +#include <linux/mman.h>
    >>
    >> /**
    >> * ipe_task_alloc: Assign a new context for an associated task structure.
    >> @@ -56,3 +60,148 @@ void ipe_task_free(struct task_struct *task)
    >> ipe_put_ctx(ctx);
    >> rcu_read_unlock();
    >> }
    >> +
    >> +/**
    >> + * ipe_on_exec: LSM hook called when a process is loaded through the exec
    >> + * family of system calls.
    >> + * @bprm: Supplies a pointer to a linux_binprm structure to source the file
    >> + * being evaluated.
    >> + *
    >> + * Return:
    >> + * 0 - OK
    >> + * !0 - Error
    >> + */
    >> +int ipe_on_exec(struct linux_binprm *bprm)
    >> +{
    >> + return ipe_process_event(bprm->file, ipe_operation_exec,
    >> ipe_hook_exec);
    >> +}
    >> +
    >> +/**
    >> + * ipe_on_mmap: LSM hook called when a file is loaded through the mmap
    >> + * family of system calls.
    >> + * @f: File being mmap'd. Can be NULL in the case of anonymous memory.
    >> + * @reqprot: The requested protection on the mmap, passed from usermode.
    >> + * @prot: The effective protection on the mmap, resolved from reqprot and
    >> + * system configuration.
    >> + * @flags: Unused.
    >> + *
    >> + * Return:
    >> + * 0 - OK
    >> + * !0 - Error
    >> + */
    >> +int ipe_on_mmap(struct file *f, unsigned long reqprot, unsigned long prot,
    >> + unsigned long flags)
    >> +{
    >> + if (prot & PROT_EXEC || reqprot & PROT_EXEC)
    >> + return ipe_process_event(f, ipe_operation_exec,
    >> ipe_hook_mmap);
    >> +
    >> + return 0;
    >> +}
    >> +
    >> +/**
    >> + * ipe_on_mprotect: LSM hook called when a mmap'd region of memory is
    >> changing
    >> + * its protections via mprotect.
    >> + * @vma: Existing virtual memory area created by mmap or similar
    >> + * @reqprot: The requested protection on the mmap, passed from usermode.
    >> + * @prot: The effective protection on the mmap, resolved from reqprot and
    >> + * system configuration.
    >> + *
    >> + * Return:
    >> + * 0 - OK
    >> + * !0 - Error
    >> + */
    >> +int ipe_on_mprotect(struct vm_area_struct *vma, unsigned long reqprot,
    >> + unsigned long prot)
    >> +{
    >> + /* Already Executable */
    >> + if (vma->vm_flags & VM_EXEC)
    >> + return 0;
    >> +
    >> + if (((prot & PROT_EXEC) || reqprot & PROT_EXEC))
    >> + return ipe_process_event(vma->vm_file, ipe_operation_exec,
    >> + ipe_hook_mprotect);
    >> +
    >> + return 0;
    >> +}
    >> +
    >> +/**
    >> + * ipe_on_kernel_read: LSM hook called when a file is being read in from
    >> + * disk.
    >> + * @file: Supplies a pointer to the file structure being read in from disk
    >> + * @id: Supplies the enumeration identifying the purpose of the read.
    >> + * @contents: Unused.
    >> + *
    >> + * Return:
    >> + * 0 - OK
    >> + * !0 - Error
    >> + */
    >> +int ipe_on_kernel_read(struct file *file, enum kernel_read_file_id id,
    >> + bool contents)
    >> +{
    >> + enum ipe_operation op;
    >> +
    >> + switch (id) {
    >> + case READING_FIRMWARE:
    >> + op = ipe_operation_firmware;
    >> + break;
    >> + case READING_MODULE:
    >> + op = ipe_operation_kernel_module;
    >> + break;
    >> + case READING_KEXEC_INITRAMFS:
    >> + op = ipe_operation_kexec_initramfs;
    >> + break;
    >> + case READING_KEXEC_IMAGE:
    >> + op = ipe_operation_kexec_image;
    >> + break;
    >> + case READING_POLICY:
    >> + op = ipe_operation_ima_policy;
    >> + break;
    >> + case READING_X509_CERTIFICATE:
    >> + op = ipe_operation_ima_x509;
    >> + break;
    >> + default:
    >> + op = ipe_operation_max;
    > Possible problem here. If someone (like me) adds a new file type
    > and forgets to add a case, there will be an out of bound access
    > in evaluate():
    >
    > rules = &pol->parsed->rules[ctx->op];
    >
    > due to the static definition of the rules array in the ipe_parsed_policy
    > structure (array length: ipe_operation_max).

    Yeah, that's a problem. I can fix this down in the eval loop by matching
    the global default and emitting a WARN here.

    > Roberto
    >
    > HUAWEI TECHNOLOGIES Duesseldorf GmbH, HRB 56063
    > Managing Director: Li Peng, Zhong Ronghua
    >
    >> + }
    >> +
    >> + return ipe_process_event(file, op, ipe_hook_kernel_read);
    >> +}
    >> +
    >> +/**
    >> + * ipe_on_kernel_load_data: LSM hook called when a buffer is being read in
    >> from
    >> + * disk.
    >> + * @id: Supplies the enumeration identifying the purpose of the read.
    >> + * @contents: Unused.
    >> + *
    >> + * Return:
    >> + * 0 - OK
    >> + * !0 - Error
    >> + */
    >> +int ipe_on_kernel_load_data(enum kernel_load_data_id id, bool contents)
    >> +{
    >> + enum ipe_operation op;
    >> +
    >> + switch (id) {
    >> + case LOADING_FIRMWARE:
    >> + op = ipe_operation_firmware;
    >> + break;
    >> + case LOADING_MODULE:
    >> + op = ipe_operation_kernel_module;
    >> + break;
    >> + case LOADING_KEXEC_INITRAMFS:
    >> + op = ipe_operation_kexec_initramfs;
    >> + break;
    >> + case LOADING_KEXEC_IMAGE:
    >> + op = ipe_operation_kexec_image;
    >> + break;
    >> + case LOADING_POLICY:
    >> + op = ipe_operation_ima_policy;
    >> + break;
    >> + case LOADING_X509_CERTIFICATE:
    >> + op = ipe_operation_ima_x509;
    >> + break;
    >> + default:
    >> + op = ipe_operation_max;
    >> + }
    >> +
    >> + return ipe_process_event(NULL, op, ipe_hook_kernel_load);
    >> +}
    >> diff --git a/security/ipe/hooks.h b/security/ipe/hooks.h
    >> index 58ed4a612e26..c99a0b7f45f7 100644
    >> --- a/security/ipe/hooks.h
    >> +++ b/security/ipe/hooks.h
    >> @@ -5,11 +5,19 @@
    >> #ifndef IPE_HOOKS_H
    >> #define IPE_HOOKS_H
    >>
    >> +#include <linux/fs.h>
    >> #include <linux/types.h>
    >> #include <linux/sched.h>
    >> +#include <linux/binfmts.h>
    >> +#include <linux/security.h>
    >>
    >> enum ipe_hook {
    >> - ipe_hook_max = 0
    >> + ipe_hook_exec = 0,
    >> + ipe_hook_mmap,
    >> + ipe_hook_mprotect,
    >> + ipe_hook_kernel_read,
    >> + ipe_hook_kernel_load,
    >> + ipe_hook_max
    >> };
    >>
    >> int ipe_task_alloc(struct task_struct *task,
    >> @@ -17,4 +25,17 @@ int ipe_task_alloc(struct task_struct *task,
    >>
    >> void ipe_task_free(struct task_struct *task);
    >>
    >> +int ipe_on_exec(struct linux_binprm *bprm);
    >> +
    >> +int ipe_on_mmap(struct file *f, unsigned long reqprot, unsigned long prot,
    >> + unsigned long flags);
    >> +
    >> +int ipe_on_mprotect(struct vm_area_struct *vma, unsigned long reqprot,
    >> + unsigned long prot);
    >> +
    >> +int ipe_on_kernel_read(struct file *file, enum kernel_read_file_id id,
    >> + bool contents);
    >> +
    >> +int ipe_on_kernel_load_data(enum kernel_load_data_id id, bool contents);
    >> +
    >> #endif /* IPE_HOOKS_H */
    >> diff --git a/security/ipe/ipe.c b/security/ipe/ipe.c
    >> index b58b372327a1..3f9d43783293 100644
    >> --- a/security/ipe/ipe.c
    >> +++ b/security/ipe/ipe.c
    >> @@ -25,6 +25,11 @@ struct lsm_blob_sizes ipe_blobs __lsm_ro_after_init = {
    >> static struct security_hook_list ipe_hooks[] __lsm_ro_after_init = {
    >> LSM_HOOK_INIT(task_alloc, ipe_task_alloc),
    >> LSM_HOOK_INIT(task_free, ipe_task_free),
    >> + LSM_HOOK_INIT(bprm_check_security, ipe_on_exec),
    >> + LSM_HOOK_INIT(mmap_file, ipe_on_mmap),
    >> + LSM_HOOK_INIT(file_mprotect, ipe_on_mprotect),
    >> + LSM_HOOK_INIT(kernel_read_file, ipe_on_kernel_read),
    >> + LSM_HOOK_INIT(kernel_load_data, ipe_on_kernel_load_data),
    >> };
    >>
    >> /**
    >> diff --git a/security/ipe/policy.c b/security/ipe/policy.c
    >> index b766824cc08f..048500229365 100644
    >> --- a/security/ipe/policy.c
    >> +++ b/security/ipe/policy.c
    >> @@ -483,6 +483,14 @@ int ipe_parse_op(const struct ipe_policy_token *tok,
    >> {
    >> substring_t match[MAX_OPT_ARGS] = { 0 };
    >> const match_table_t ops = {
    >> + { ipe_operation_exec, "EXECUTE" },
    >> + { ipe_operation_firmware, "FIRMWARE" },
    >> + { ipe_operation_kernel_module, "KMODULE" },
    >> + { ipe_operation_kexec_image, "KEXEC_IMAGE" },
    >> + { ipe_operation_kexec_initramfs, "KEXEC_INITRAMFS"},
    >> + { ipe_operation_ima_policy, "IMA_POLICY" },
    >> + { ipe_operation_ima_x509, "IMA_X509_CERT" },
    >> + { ipe_op_alias_kernel_read, "KERNEL_READ" },
    >> { ipe_op_alias_max, NULL },
    >> };
    >>
    >> @@ -838,6 +846,15 @@ static int parse_policy(struct ipe_policy *p)
    >> return rc;
    >> }
    >>
    >> +static const enum ipe_operation alias_kread[] = {
    >> + ipe_operation_firmware,
    >> + ipe_operation_kernel_module,
    >> + ipe_operation_ima_policy,
    >> + ipe_operation_ima_x509,
    >> + ipe_operation_kexec_image,
    >> + ipe_operation_kexec_initramfs,
    >> +};
    >> +
    >> /**
    >> * ipe_is_op_alias: Determine if @op is an alias for one or more operations
    >> * @op: Supplies the operation to check. Should be either ipe_operation or
    >> @@ -852,9 +869,15 @@ static int parse_policy(struct ipe_policy *p)
    >> bool ipe_is_op_alias(int op, const enum ipe_operation **map, size_t *size)
    >> {
    >> switch (op) {
    >> + case ipe_op_alias_kernel_read:
    >> + *map = alias_kread;
    >> + *size = ARRAY_SIZE(alias_kread);
    >> + break;
    >> default:
    >> return false;
    >> }
    >> +
    >> + return true;
    >> }
    >>
    >> /**
    >> diff --git a/security/ipe/policy.h b/security/ipe/policy.h
    >> index 6818f6405dd0..ca37af46e5af 100644
    >> --- a/security/ipe/policy.h
    >> +++ b/security/ipe/policy.h
    >> @@ -26,7 +26,14 @@ struct ipe_policy_line {
    >> struct ipe_module;
    >>
    >> enum ipe_operation {
    >> - ipe_operation_max = 0,
    >> + ipe_operation_exec = 0,
    >> + ipe_operation_firmware,
    >> + ipe_operation_kernel_module,
    >> + ipe_operation_kexec_image,
    >> + ipe_operation_kexec_initramfs,
    >> + ipe_operation_ima_policy,
    >> + ipe_operation_ima_x509,
    >> + ipe_operation_max
    >> };
    >>
    >> /*
    >> @@ -34,7 +41,8 @@ enum ipe_operation {
    >> * that are just one or more operations under the hood
    >> */
    >> enum ipe_op_alias {
    >> - ipe_op_alias_max = ipe_operation_max,
    >> + ipe_op_alias_kernel_read = ipe_operation_max,
    >> + ipe_op_alias_max,
    >> };
    >>
    >> enum ipe_action {
    >> --
    >> 2.33.0

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      Last update: 2021-10-26 21:04    [W:2.743 / U:0.008 seconds]
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