Messages in this thread | | | Date | Tue, 26 Oct 2021 12:03:39 -0700 | From | Deven Bowers <> | Subject | Re: [RFC PATCH v7 05/16] ipe: add LSM hooks on execution and kernel read |
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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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