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    SubjectRe: [RFC PATCH v9 06/16] ipe: add LSM hooks on execution and kernel read
    On Mon, Jan 30, 2023 at 5:59 PM Fan Wu <wufan@linux.microsoft.com> wrote:
    >
    > 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
    > bprm_check_security, file_mprotect, mmap_file, kernel_load_data,
    > and kernel_read_data.
    >
    > Signed-off-by: Deven Bowers <deven.desai@linux.microsoft.com>
    > Signed-off-by: Fan Wu <wufan@linux.microsoft.com>

    ...

    > ---
    > security/ipe/hooks.c | 169 +++++++++++++++++++++++++++++++++++++++++++
    > security/ipe/hooks.h | 13 ++++
    > security/ipe/ipe.c | 6 ++
    > 3 files changed, 188 insertions(+)
    >
    > diff --git a/security/ipe/hooks.c b/security/ipe/hooks.c
    > index 335b773c7ae1..fd5109e29c76 100644
    > --- a/security/ipe/hooks.c
    > +++ b/security/ipe/hooks.c
    > @@ -23,3 +23,172 @@ void ipe_sb_free_security(struct super_block *mnt_sb)
    > {
    > ipe_invalidate_pinned_sb(mnt_sb);
    > }
    > +
    > +/**
    > + * ipe_bprm_check_security - ipe security hook function for bprm check.
    > + * @bprm: Supplies a pointer to a linux_binprm structure to source the file
    > + * being evaluated.
    > + *
    > + * This LSM hook is called when a binary is loaded through the exec
    > + * family of system calls.
    > + * Return:
    > + * *0 - OK
    > + * *!0 - Error
    > + */
    > +int ipe_bprm_check_security(struct linux_binprm *bprm)
    > +{
    > + struct ipe_eval_ctx ctx = { 0 };
    > +
    > + build_eval_ctx(&ctx, bprm->file, ipe_op_exec);
    > + return ipe_evaluate_event(&ctx);
    > +}
    > +
    > +/**
    > + * ipe_mmap_file - ipe security hook function for mmap check.
    > + * @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.
    > + *
    > + * This hook is called when a file is loaded through the mmap
    > + * family of system calls.
    > + *
    > + * Return:
    > + * * 0 - OK
    > + * * !0 - Error
    > + */
    > +int ipe_mmap_file(struct file *f, unsigned long reqprot, unsigned long prot,
    > + unsigned long flags)
    > +{
    > + struct ipe_eval_ctx ctx = { 0 };
    > +
    > + if (prot & PROT_EXEC || reqprot & PROT_EXEC) {

    Is there a reason why you care about @reqprot? It seems like IPE
    would only be interested in the protection flags that the kernel is
    actually using.

    I notice that in the `ipe_file_mprotect()` hook you ignore @reqprot,
    which I believe is the right thing to do.

    > + build_eval_ctx(&ctx, f, ipe_op_exec);
    > + return ipe_evaluate_event(&ctx);
    > + }
    > +
    > + return 0;
    > +}
    > +
    > +/**
    > + * ipe_file_mprotect - ipe security hook function for mprotect check.
    > + * @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.
    > + *
    > + * This LSM hook is called when a mmap'd region of memory is changing
    > + * its protections via mprotect.
    > + *
    > + * Return:
    > + * * 0 - OK
    > + * * !0 - Error
    > + */
    > +int ipe_file_mprotect(struct vm_area_struct *vma, unsigned long reqprot,
    > + unsigned long prot)
    > +{
    > + struct ipe_eval_ctx ctx = { 0 };
    > +
    > + /* Already Executable */
    > + if (vma->vm_flags & VM_EXEC)
    > + return 0;
    > +
    > + if (prot & PROT_EXEC) {
    > + build_eval_ctx(&ctx, vma->vm_file, ipe_op_exec);
    > + return ipe_evaluate_event(&ctx);
    > + }
    > +
    > + return 0;
    > +}
    > +
    > +/**
    > + * ipe_kernel_read_file - ipe security hook function for kernel read.
    > + * @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.
    > + *
    > + * This LSM hook is called when a file is being read in from disk from
    > + * the kernel.
    > + *
    > + * Return:
    > + * 0 - OK
    > + * !0 - Error
    > + */
    > +int ipe_kernel_read_file(struct file *file, enum kernel_read_file_id id,
    > + bool contents)
    > +{
    > + enum ipe_op_type op;
    > + struct ipe_eval_ctx ctx;
    > +
    > + switch (id) {
    > + case READING_FIRMWARE:
    > + op = ipe_op_firmware;
    > + break;
    > + case READING_MODULE:
    > + op = ipe_op_kernel_module;
    > + break;
    > + case READING_KEXEC_INITRAMFS:
    > + op = ipe_op_kexec_initramfs;
    > + break;
    > + case READING_KEXEC_IMAGE:
    > + op = ipe_op_kexec_image;
    > + break;
    > + case READING_POLICY:
    > + op = ipe_op_ima_policy;
    > + break;
    > + case READING_X509_CERTIFICATE:
    > + op = ipe_op_ima_x509;
    > + break;
    > + default:
    > + op = ipe_op_max;
    > + WARN(op == ipe_op_max, "no rule setup for enum %d", id);
    > + }
    > +
    > + build_eval_ctx(&ctx, file, op);
    > + return ipe_evaluate_event(&ctx);
    > +}
    > +
    > +/**
    > + * ipe_kernel_load_data - ipe security hook function for kernel load data.
    > + * @id: Supplies the enumeration identifying the purpose of the read.
    > + * @contents: Unused.
    > + *
    > + * This LSM hook is called when a buffer is being read in from disk.
    > + *
    > + * Return:
    > + * * 0 - OK
    > + * * !0 - Error
    > + */
    > +int ipe_kernel_load_data(enum kernel_load_data_id id, bool contents)
    > +{
    > + enum ipe_op_type op;
    > + struct ipe_eval_ctx ctx = { 0 };
    > +
    > + switch (id) {
    > + case LOADING_FIRMWARE:
    > + op = ipe_op_firmware;
    > + break;
    > + case LOADING_MODULE:
    > + op = ipe_op_kernel_module;
    > + break;
    > + case LOADING_KEXEC_INITRAMFS:
    > + op = ipe_op_kexec_initramfs;
    > + break;
    > + case LOADING_KEXEC_IMAGE:
    > + op = ipe_op_kexec_image;
    > + break;
    > + case LOADING_POLICY:
    > + op = ipe_op_ima_policy;
    > + break;
    > + case LOADING_X509_CERTIFICATE:
    > + op = ipe_op_ima_x509;
    > + break;
    > + default:
    > + op = ipe_op_max;
    > + WARN(op == ipe_op_max, "no rule setup for enum %d", id);
    > + }
    > +
    > + build_eval_ctx(&ctx, NULL, op);
    > + return ipe_evaluate_event(&ctx);
    > +}
    > diff --git a/security/ipe/hooks.h b/security/ipe/hooks.h
    > index 30fe455389bf..857cae69678c 100644
    > --- a/security/ipe/hooks.h
    > +++ b/security/ipe/hooks.h
    > @@ -11,4 +11,17 @@
    >
    > void ipe_sb_free_security(struct super_block *mnt_sb);
    >
    > +int ipe_bprm_check_security(struct linux_binprm *bprm);
    > +
    > +int ipe_mmap_file(struct file *f, unsigned long reqprot, unsigned long prot,
    > + unsigned long flags);
    > +
    > +int ipe_file_mprotect(struct vm_area_struct *vma, unsigned long reqprot,
    > + unsigned long prot);
    > +
    > +int ipe_kernel_read_file(struct file *file, enum kernel_read_file_id id,
    > + bool contents);
    > +
    > +int ipe_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 bef923026b50..7af2f942decd 100644
    > --- a/security/ipe/ipe.c
    > +++ b/security/ipe/ipe.c
    > @@ -4,6 +4,7 @@
    > */
    >
    > #include "ipe.h"
    > +#include "hooks.h"
    >
    > bool ipe_enabled;
    >
    > @@ -12,6 +13,11 @@ static struct lsm_blob_sizes ipe_blobs __lsm_ro_after_init = {
    >
    > static struct security_hook_list ipe_hooks[] __lsm_ro_after_init = {
    > LSM_HOOK_INIT(sb_free_security, ipe_sb_free_security),
    > + LSM_HOOK_INIT(bprm_check_security, ipe_bprm_check_security),
    > + LSM_HOOK_INIT(mmap_file, ipe_mmap_file),
    > + LSM_HOOK_INIT(file_mprotect, ipe_file_mprotect),
    > + LSM_HOOK_INIT(kernel_read_file, ipe_kernel_read_file),
    > + LSM_HOOK_INIT(kernel_load_data, ipe_kernel_load_data),
    > };
    >
    > /**
    > --
    > 2.39.0

    --
    paul-moore.com

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