From 864468ae309943fc9a1067606098b30959e4db33 Mon Sep 17 00:00:00 2001 From: "Borislav Petkov (AMD)" Date: Thu, 9 Oct 2025 17:45:25 +0200 Subject: [PATCH 1/3] ipe: Drop a duplicated CONFIG_ prefix in the ifdeffery Looks like it got added by mistake, perhaps editor auto-completion artifact. Drop it. No functional changes. Signed-off-by: Borislav Petkov (AMD) Signed-off-by: Fan Wu --- security/ipe/hooks.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/security/ipe/hooks.c b/security/ipe/hooks.c index d0323b81cd8f..42857c2ea2a5 100644 --- a/security/ipe/hooks.c +++ b/security/ipe/hooks.c @@ -311,4 +311,4 @@ int ipe_inode_setintegrity(const struct inode *inode, return -EINVAL; } -#endif /* CONFIG_CONFIG_IPE_PROP_FS_VERITY_BUILTIN_SIG */ +#endif /* CONFIG_IPE_PROP_FS_VERITY_BUILTIN_SIG */ From 67678189e492dc119b91c30beccd12cdbb32350e Mon Sep 17 00:00:00 2001 From: Yanzhu Huang Date: Wed, 5 Nov 2025 23:26:14 +0000 Subject: [PATCH 2/3] ipe: Add AT_EXECVE_CHECK support for script enforcement This patch adds a new ipe_bprm_creds_for_exec() hook that integrates with the AT_EXECVE_CHECK mechanism. To enable script enforcement, interpreters need to incorporate the AT_EXECVE_CHECK flag when calling execveat() on script files before execution. When a userspace interpreter calls execveat() with the AT_EXECVE_CHECK flag, this hook triggers IPE policy evaluation on the script file. The hook only triggers IPE when bprm->is_check is true, ensuring it's being called from an AT_EXECVE_CHECK context. It then builds an evaluation context for an IPE_OP_EXEC operation and invokes IPE policy. The kernel returns the policy decision to the interpreter, which can then decide whether to proceed with script execution. This extends IPE enforcement to indirectly executed scripts, permitting trusted scripts to execute while denying untrusted ones. Signed-off-by: Yanzhu Huang Signed-off-by: Fan Wu --- security/ipe/audit.c | 1 + security/ipe/hooks.c | 27 +++++++++++++++++++++++++++ security/ipe/hooks.h | 3 +++ security/ipe/ipe.c | 1 + 4 files changed, 32 insertions(+) diff --git a/security/ipe/audit.c b/security/ipe/audit.c index de5fed62592e..3f0deeb54912 100644 --- a/security/ipe/audit.c +++ b/security/ipe/audit.c @@ -46,6 +46,7 @@ static const char *const audit_op_names[__IPE_OP_MAX + 1] = { static const char *const audit_hook_names[__IPE_HOOK_MAX] = { "BPRM_CHECK", + "BPRM_CREDS_FOR_EXEC", "MMAP", "MPROTECT", "KERNEL_READ", diff --git a/security/ipe/hooks.c b/security/ipe/hooks.c index 42857c2ea2a5..2e3dc4ab22ae 100644 --- a/security/ipe/hooks.c +++ b/security/ipe/hooks.c @@ -35,6 +35,33 @@ int ipe_bprm_check_security(struct linux_binprm *bprm) return ipe_evaluate_event(&ctx); } +/** + * ipe_bprm_creds_for_exec() - ipe security hook function for bprm creds check. + * @bprm: Supplies a pointer to a linux_binprm structure to source the file + * being evaluated. + * + * This LSM hook is called when userspace signals the kernel to check a file + * for execution through the execveat syscall with the AT_EXECVE_CHECK flag. + * The hook triggers IPE policy evaluation on the script file and returns + * the policy decision to userspace. The userspace program receives the + * return code and can decide whether to proceed with script execution. + * + * Return: + * * %0 - Success + * * %-EACCES - Did not pass IPE policy + */ +int ipe_bprm_creds_for_exec(struct linux_binprm *bprm) +{ + struct ipe_eval_ctx ctx = IPE_EVAL_CTX_INIT; + + if (!bprm->is_check) + return 0; + + ipe_build_eval_ctx(&ctx, bprm->file, IPE_OP_EXEC, + IPE_HOOK_BPRM_CREDS_FOR_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. diff --git a/security/ipe/hooks.h b/security/ipe/hooks.h index 38d4a387d039..07db37332740 100644 --- a/security/ipe/hooks.h +++ b/security/ipe/hooks.h @@ -13,6 +13,7 @@ enum ipe_hook_type { IPE_HOOK_BPRM_CHECK = 0, + IPE_HOOK_BPRM_CREDS_FOR_EXEC, IPE_HOOK_MMAP, IPE_HOOK_MPROTECT, IPE_HOOK_KERNEL_READ, @@ -24,6 +25,8 @@ enum ipe_hook_type { int ipe_bprm_check_security(struct linux_binprm *bprm); +int ipe_bprm_creds_for_exec(struct linux_binprm *bprm); + int ipe_mmap_file(struct file *f, unsigned long reqprot, unsigned long prot, unsigned long flags); diff --git a/security/ipe/ipe.c b/security/ipe/ipe.c index 4317134cb0da..845e3fd7a345 100644 --- a/security/ipe/ipe.c +++ b/security/ipe/ipe.c @@ -47,6 +47,7 @@ struct ipe_inode *ipe_inode(const struct inode *inode) static struct security_hook_list ipe_hooks[] __ro_after_init = { LSM_HOOK_INIT(bprm_check_security, ipe_bprm_check_security), + LSM_HOOK_INIT(bprm_creds_for_exec, ipe_bprm_creds_for_exec), 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), From d7ba853c0e47d57805181f5269ba250270d2adde Mon Sep 17 00:00:00 2001 From: Yanzhu Huang Date: Wed, 5 Nov 2025 23:26:15 +0000 Subject: [PATCH 3/3] ipe: Update documentation for script enforcement This patch adds explanation of script enforcement mechanism in admin guide documentation. Describes how IPE supports integrity enforcement for indirectly executed scripts through the AT_EXECVE_CHECK flag, and how this differs from kernel enforcement for compiled executables. Signed-off-by: Yanzhu Huang Signed-off-by: Fan Wu --- Documentation/admin-guide/LSM/ipe.rst | 17 ++++++++++++++--- 1 file changed, 14 insertions(+), 3 deletions(-) diff --git a/Documentation/admin-guide/LSM/ipe.rst b/Documentation/admin-guide/LSM/ipe.rst index dc7088451f9d..a756d8158531 100644 --- a/Documentation/admin-guide/LSM/ipe.rst +++ b/Documentation/admin-guide/LSM/ipe.rst @@ -95,7 +95,20 @@ languages when these scripts are invoked by passing these program files to the interpreter. This is because the way interpreters execute these files; the scripts themselves are not evaluated as executable code through one of IPE's hooks, but they are merely text files that are read -(as opposed to compiled executables) [#interpreters]_. +(as opposed to compiled executables). However, with the introduction of the +``AT_EXECVE_CHECK`` flag (:doc:`AT_EXECVE_CHECK `), +interpreters can use it to signal the kernel that a script file will be executed, +and request the kernel to perform LSM security checks on it. + +IPE's EXECUTE operation enforcement differs between compiled executables and +interpreted scripts: For compiled executables, enforcement is triggered +automatically by the kernel during ``execve()``, ``execveat()``, ``mmap()`` +and ``mprotect()`` syscalls when loading executable content. For interpreted +scripts, enforcement requires explicit interpreter integration using +``execveat()`` with ``AT_EXECVE_CHECK`` flag. Unlike exec syscalls that IPE +intercepts during the execution process, this mechanism needs the interpreter +to take the initiative, and existing interpreters won't be automatically +supported unless the signal call is added. Threat Model ------------ @@ -806,8 +819,6 @@ A: .. [#digest_cache_lsm] https://lore.kernel.org/lkml/20240415142436.2545003-1-roberto.sassu@huaweicloud.com/ -.. [#interpreters] There is `some interest in solving this issue `_. - .. [#devdoc] Please see :doc:`the design docs ` for more on this topic.