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

> From:deven.desai@linux.microsoft.com > [mailto:deven.desai@linux.microsoft.com] > From: Deven Bowers&lt;deven.desai(a)linux.microsoft.com&gt; > > 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&lt;deven.desai(a)linux.microsoft.com&gt; > --- > > 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).

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