Introduce diglim_ima_get_info() to retrieve the digest and the actions performed by IMA on the passed digest list file or buffer.
diglim_ima_get_info() requires the caller to write-lock the file to ensure that the file content the integrity status is retrieved from didn't change since the time the buffer passed as argument was filled.
Signed-off-by: Roberto Sassu roberto.sassu@huawei.com --- MAINTAINERS | 1 + security/integrity/diglim/Makefile | 2 +- security/integrity/diglim/diglim.h | 6 ++ security/integrity/diglim/ima.c | 122 +++++++++++++++++++++++++++++ security/integrity/integrity.h | 4 + 5 files changed, 134 insertions(+), 1 deletion(-) create mode 100644 security/integrity/diglim/ima.c
diff --git a/MAINTAINERS b/MAINTAINERS index f5959936d490..f10690dda734 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -5514,6 +5514,7 @@ F: Documentation/security/diglim/introduction.rst F: include/linux/diglim.h F: include/uapi/linux/diglim.h F: security/integrity/diglim/diglim.h +F: security/integrity/diglim/ima.c F: security/integrity/diglim/methods.c F: security/integrity/diglim/parser.c
diff --git a/security/integrity/diglim/Makefile b/security/integrity/diglim/Makefile index 34e4e154fff3..880dc5300792 100644 --- a/security/integrity/diglim/Makefile +++ b/security/integrity/diglim/Makefile @@ -5,4 +5,4 @@
obj-$(CONFIG_DIGLIM) += diglim.o
-diglim-y := methods.o parser.o +diglim-y := methods.o parser.o ima.o diff --git a/security/integrity/diglim/diglim.h b/security/integrity/diglim/diglim.h index afdb0affdc5e..ebe8936520b5 100644 --- a/security/integrity/diglim/diglim.h +++ b/security/integrity/diglim/diglim.h @@ -22,6 +22,8 @@ #include <linux/hash_info.h> #include <linux/diglim.h>
+#include "../integrity.h" + #define MAX_DIGEST_SIZE 64 #define HASH_BITS 10 #define DIGLIM_HTABLE_SIZE (1 << HASH_BITS) @@ -221,4 +223,8 @@ void digest_list_del(u8 *digest, enum hash_algo algo, u8 actions,
int digest_list_parse(loff_t size, void *buf, enum ops op, u8 actions, u8 *digest, enum hash_algo algo, const char *label); + +int diglim_ima_get_info(struct file *file, u8 *buffer, size_t buffer_len, + char *event_name, u8 *digest, size_t digest_len, + enum hash_algo *algo, u8 *actions); #endif /*__DIGLIM_INTERNAL_H*/ diff --git a/security/integrity/diglim/ima.c b/security/integrity/diglim/ima.c new file mode 100644 index 000000000000..2cc1ec1299f8 --- /dev/null +++ b/security/integrity/diglim/ima.c @@ -0,0 +1,122 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2021 Huawei Technologies Duesseldorf GmbH + * + * Author: Roberto Sassu roberto.sassu@huawei.com + * + * Functions to retrieve the integrity status from IMA. + */ + +#include <linux/vmalloc.h> +#include <linux/module.h> +#include <linux/ima.h> + +#include "diglim.h" + +static int diglim_ima_get_info_file(struct file *file, u8 *digest, + size_t digest_len, enum hash_algo *algo, + u8 *actions) +{ + struct integrity_iint_cache *iint; + struct inode *inode = file_inode(file); + int ret = -ENOENT; + + iint = integrity_iint_find(inode); + if (!iint) + return ret; + + mutex_lock(&iint->mutex); + /* File digest has not been calculated. */ + if (!(iint->flags & IMA_COLLECTED)) + goto out; + + ret = 0; + + if (iint->flags & IMA_MEASURED) + *actions |= 1 << COMPACT_ACTION_IMA_MEASURED; + + if (iint->flags & IMA_APPRAISED) + *actions |= 1 << COMPACT_ACTION_IMA_APPRAISED; + + if (test_bit(IMA_DIGSIG, &iint->atomic_flags)) + *actions |= 1 << COMPACT_ACTION_IMA_APPRAISED_DIGSIG; + + if (algo) + *algo = iint->ima_hash->algo; + if (digest) + memcpy(digest, iint->ima_hash->digest, hash_digest_size[*algo]); +out: + mutex_unlock(&iint->mutex); + return ret; +} + +static int diglim_ima_get_info_buffer(u8 *buffer, size_t buffer_len, + char *event_name, u8 *digest, + size_t digest_len, enum hash_algo *algo, + u8 *actions) +{ + int ret; + + ret = ima_measure_critical_data("diglim", event_name, buffer, + buffer_len, false, digest, digest_len); + if (ret < 0 && ret != -EEXIST) + return -ENOENT; + + *algo = ima_get_current_hash_algo(); + + if (!ret || ret == -EEXIST) + *actions |= 1 << COMPACT_ACTION_IMA_MEASURED; + + return 0; +} + +/** + * diglim_ima_get_info - retrieve the integrity status of digest list from IMA + * @file: file to retrieve the integrity status from + * @buffer: buffer to retrieve the integrity status from (alternative to file) + * @buffer_len: buffer length + * @event_name: name of the event to be generated by IMA for buffer measurement + * @digest: digest of the file or the buffer + * @digest_len: digest length + * @algo: digest algorithm + * @actions: actions performed on the file or the buffer + * + * This function attempts to retrieve some information from the passed digest + * list file or buffer: the digest, its algorithm, and the actions performed by + * IMA. + * + * This function first attempts to retrieve the information from the file, and + * if unsuccessful, attempts with the buffer. + * + * The caller must prevent writes to the file with deny_write_access() to ensure + * that the file content the integrity status is retrieved from didn't change + * since the time the buffer passed as argument was filled. + * + * Return: 0 if the information has been successfully retrieved, -ENOENT + * otherwise. + */ +int diglim_ima_get_info(struct file *file, u8 *buffer, size_t buffer_len, + char *event_name, u8 *digest, size_t digest_len, + enum hash_algo *algo, u8 *actions) +{ + int ret = -ENOENT; + + /* Ensure that the file is write-locked. */ + if (file && atomic_read(&file_inode(file)->i_writecount) >= 0) + return -EINVAL; + + if (file) { + ret = diglim_ima_get_info_file(file, digest, digest_len, algo, + actions); + if (!ret && (*actions & (1 << COMPACT_ACTION_IMA_MEASURED))) + return ret; + } + + if (buffer) { + ret = diglim_ima_get_info_buffer(buffer, buffer_len, event_name, + digest, digest_len, algo, + actions); + } + + return ret; +} diff --git a/security/integrity/integrity.h b/security/integrity/integrity.h index 74919b638f52..de5dde382f11 100644 --- a/security/integrity/integrity.h +++ b/security/integrity/integrity.h @@ -6,6 +6,9 @@ * Mimi Zohar zohar@us.ibm.com */
+#ifndef __INTEGRITY_H +#define __INTEGRITY_H + #ifdef pr_fmt #undef pr_fmt #endif @@ -285,3 +288,4 @@ static inline void __init add_to_platform_keyring(const char *source, { } #endif +#endif /*__INTEGRITY_H*/