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507 lines
12 KiB
507 lines
12 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* Copyright (C) 2005,2006,2007,2008 IBM Corporation |
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* |
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* Authors: |
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* Kylene Hall <[email protected]> |
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* Reiner Sailer <[email protected]> |
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* Mimi Zohar <[email protected]> |
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* |
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* File: ima_fs.c |
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* implemenents security file system for reporting |
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* current measurement list and IMA statistics |
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*/ |
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|
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#include <linux/fcntl.h> |
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#include <linux/kernel_read_file.h> |
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#include <linux/slab.h> |
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#include <linux/init.h> |
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#include <linux/seq_file.h> |
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#include <linux/rculist.h> |
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#include <linux/rcupdate.h> |
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#include <linux/parser.h> |
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#include <linux/vmalloc.h> |
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#include "ima.h" |
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static DEFINE_MUTEX(ima_write_mutex); |
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bool ima_canonical_fmt; |
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static int __init default_canonical_fmt_setup(char *str) |
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{ |
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#ifdef __BIG_ENDIAN |
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ima_canonical_fmt = true; |
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#endif |
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return 1; |
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} |
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__setup("ima_canonical_fmt", default_canonical_fmt_setup); |
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static int valid_policy = 1; |
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static ssize_t ima_show_htable_value(char __user *buf, size_t count, |
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loff_t *ppos, atomic_long_t *val) |
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{ |
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char tmpbuf[32]; /* greater than largest 'long' string value */ |
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ssize_t len; |
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len = scnprintf(tmpbuf, sizeof(tmpbuf), "%li\n", atomic_long_read(val)); |
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return simple_read_from_buffer(buf, count, ppos, tmpbuf, len); |
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} |
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static ssize_t ima_show_htable_violations(struct file *filp, |
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char __user *buf, |
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size_t count, loff_t *ppos) |
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{ |
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return ima_show_htable_value(buf, count, ppos, &ima_htable.violations); |
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} |
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static const struct file_operations ima_htable_violations_ops = { |
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.read = ima_show_htable_violations, |
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.llseek = generic_file_llseek, |
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}; |
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static ssize_t ima_show_measurements_count(struct file *filp, |
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char __user *buf, |
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size_t count, loff_t *ppos) |
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{ |
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return ima_show_htable_value(buf, count, ppos, &ima_htable.len); |
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} |
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static const struct file_operations ima_measurements_count_ops = { |
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.read = ima_show_measurements_count, |
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.llseek = generic_file_llseek, |
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}; |
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/* returns pointer to hlist_node */ |
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static void *ima_measurements_start(struct seq_file *m, loff_t *pos) |
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{ |
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loff_t l = *pos; |
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struct ima_queue_entry *qe; |
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/* we need a lock since pos could point beyond last element */ |
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rcu_read_lock(); |
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list_for_each_entry_rcu(qe, &ima_measurements, later) { |
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if (!l--) { |
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rcu_read_unlock(); |
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return qe; |
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} |
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} |
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rcu_read_unlock(); |
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return NULL; |
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} |
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static void *ima_measurements_next(struct seq_file *m, void *v, loff_t *pos) |
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{ |
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struct ima_queue_entry *qe = v; |
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/* lock protects when reading beyond last element |
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* against concurrent list-extension |
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*/ |
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rcu_read_lock(); |
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qe = list_entry_rcu(qe->later.next, struct ima_queue_entry, later); |
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rcu_read_unlock(); |
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(*pos)++; |
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return (&qe->later == &ima_measurements) ? NULL : qe; |
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} |
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static void ima_measurements_stop(struct seq_file *m, void *v) |
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{ |
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} |
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void ima_putc(struct seq_file *m, void *data, int datalen) |
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{ |
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while (datalen--) |
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seq_putc(m, *(char *)data++); |
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} |
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/* print format: |
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* 32bit-le=pcr# |
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* char[20]=template digest |
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* 32bit-le=template name size |
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* char[n]=template name |
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* [eventdata length] |
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* eventdata[n]=template specific data |
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*/ |
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int ima_measurements_show(struct seq_file *m, void *v) |
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{ |
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/* the list never shrinks, so we don't need a lock here */ |
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struct ima_queue_entry *qe = v; |
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struct ima_template_entry *e; |
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char *template_name; |
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u32 pcr, namelen, template_data_len; /* temporary fields */ |
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bool is_ima_template = false; |
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int i; |
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/* get entry */ |
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e = qe->entry; |
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if (e == NULL) |
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return -1; |
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template_name = (e->template_desc->name[0] != '\0') ? |
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e->template_desc->name : e->template_desc->fmt; |
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/* |
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* 1st: PCRIndex |
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* PCR used defaults to the same (config option) in |
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* little-endian format, unless set in policy |
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*/ |
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pcr = !ima_canonical_fmt ? e->pcr : (__force u32)cpu_to_le32(e->pcr); |
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ima_putc(m, &pcr, sizeof(e->pcr)); |
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/* 2nd: template digest */ |
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ima_putc(m, e->digests[ima_sha1_idx].digest, TPM_DIGEST_SIZE); |
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/* 3rd: template name size */ |
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namelen = !ima_canonical_fmt ? strlen(template_name) : |
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(__force u32)cpu_to_le32(strlen(template_name)); |
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ima_putc(m, &namelen, sizeof(namelen)); |
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/* 4th: template name */ |
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ima_putc(m, template_name, strlen(template_name)); |
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/* 5th: template length (except for 'ima' template) */ |
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if (strcmp(template_name, IMA_TEMPLATE_IMA_NAME) == 0) |
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is_ima_template = true; |
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if (!is_ima_template) { |
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template_data_len = !ima_canonical_fmt ? e->template_data_len : |
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(__force u32)cpu_to_le32(e->template_data_len); |
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ima_putc(m, &template_data_len, sizeof(e->template_data_len)); |
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} |
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/* 6th: template specific data */ |
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for (i = 0; i < e->template_desc->num_fields; i++) { |
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enum ima_show_type show = IMA_SHOW_BINARY; |
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const struct ima_template_field *field = |
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e->template_desc->fields[i]; |
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if (is_ima_template && strcmp(field->field_id, "d") == 0) |
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show = IMA_SHOW_BINARY_NO_FIELD_LEN; |
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if (is_ima_template && strcmp(field->field_id, "n") == 0) |
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show = IMA_SHOW_BINARY_OLD_STRING_FMT; |
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field->field_show(m, show, &e->template_data[i]); |
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} |
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return 0; |
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} |
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static const struct seq_operations ima_measurments_seqops = { |
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.start = ima_measurements_start, |
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.next = ima_measurements_next, |
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.stop = ima_measurements_stop, |
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.show = ima_measurements_show |
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}; |
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static int ima_measurements_open(struct inode *inode, struct file *file) |
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{ |
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return seq_open(file, &ima_measurments_seqops); |
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} |
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static const struct file_operations ima_measurements_ops = { |
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.open = ima_measurements_open, |
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.read = seq_read, |
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.llseek = seq_lseek, |
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.release = seq_release, |
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}; |
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void ima_print_digest(struct seq_file *m, u8 *digest, u32 size) |
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{ |
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u32 i; |
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for (i = 0; i < size; i++) |
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seq_printf(m, "%02x", *(digest + i)); |
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} |
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/* print in ascii */ |
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static int ima_ascii_measurements_show(struct seq_file *m, void *v) |
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{ |
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/* the list never shrinks, so we don't need a lock here */ |
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struct ima_queue_entry *qe = v; |
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struct ima_template_entry *e; |
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char *template_name; |
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int i; |
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/* get entry */ |
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e = qe->entry; |
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if (e == NULL) |
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return -1; |
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template_name = (e->template_desc->name[0] != '\0') ? |
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e->template_desc->name : e->template_desc->fmt; |
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/* 1st: PCR used (config option) */ |
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seq_printf(m, "%2d ", e->pcr); |
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/* 2nd: SHA1 template hash */ |
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ima_print_digest(m, e->digests[ima_sha1_idx].digest, TPM_DIGEST_SIZE); |
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/* 3th: template name */ |
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seq_printf(m, " %s", template_name); |
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/* 4th: template specific data */ |
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for (i = 0; i < e->template_desc->num_fields; i++) { |
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seq_puts(m, " "); |
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if (e->template_data[i].len == 0) |
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continue; |
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e->template_desc->fields[i]->field_show(m, IMA_SHOW_ASCII, |
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&e->template_data[i]); |
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} |
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seq_puts(m, "\n"); |
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return 0; |
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} |
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static const struct seq_operations ima_ascii_measurements_seqops = { |
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.start = ima_measurements_start, |
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.next = ima_measurements_next, |
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.stop = ima_measurements_stop, |
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.show = ima_ascii_measurements_show |
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}; |
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static int ima_ascii_measurements_open(struct inode *inode, struct file *file) |
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{ |
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return seq_open(file, &ima_ascii_measurements_seqops); |
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} |
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static const struct file_operations ima_ascii_measurements_ops = { |
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.open = ima_ascii_measurements_open, |
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.read = seq_read, |
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.llseek = seq_lseek, |
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.release = seq_release, |
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}; |
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static ssize_t ima_read_policy(char *path) |
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{ |
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void *data = NULL; |
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char *datap; |
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size_t size; |
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int rc, pathlen = strlen(path); |
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char *p; |
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/* remove \n */ |
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datap = path; |
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strsep(&datap, "\n"); |
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rc = kernel_read_file_from_path(path, 0, &data, INT_MAX, NULL, |
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READING_POLICY); |
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if (rc < 0) { |
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pr_err("Unable to open file: %s (%d)", path, rc); |
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return rc; |
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} |
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size = rc; |
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rc = 0; |
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datap = data; |
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while (size > 0 && (p = strsep(&datap, "\n"))) { |
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pr_debug("rule: %s\n", p); |
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rc = ima_parse_add_rule(p); |
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if (rc < 0) |
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break; |
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size -= rc; |
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} |
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vfree(data); |
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if (rc < 0) |
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return rc; |
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else if (size) |
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return -EINVAL; |
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else |
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return pathlen; |
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} |
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static ssize_t ima_write_policy(struct file *file, const char __user *buf, |
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size_t datalen, loff_t *ppos) |
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{ |
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char *data; |
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ssize_t result; |
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if (datalen >= PAGE_SIZE) |
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datalen = PAGE_SIZE - 1; |
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/* No partial writes. */ |
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result = -EINVAL; |
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if (*ppos != 0) |
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goto out; |
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data = memdup_user_nul(buf, datalen); |
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if (IS_ERR(data)) { |
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result = PTR_ERR(data); |
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goto out; |
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} |
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result = mutex_lock_interruptible(&ima_write_mutex); |
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if (result < 0) |
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goto out_free; |
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if (data[0] == '/') { |
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result = ima_read_policy(data); |
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} else if (ima_appraise & IMA_APPRAISE_POLICY) { |
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pr_err("signed policy file (specified as an absolute pathname) required\n"); |
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integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL, NULL, |
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"policy_update", "signed policy required", |
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1, 0); |
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result = -EACCES; |
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} else { |
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result = ima_parse_add_rule(data); |
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} |
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mutex_unlock(&ima_write_mutex); |
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out_free: |
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kfree(data); |
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out: |
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if (result < 0) |
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valid_policy = 0; |
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return result; |
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} |
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static struct dentry *ima_dir; |
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static struct dentry *ima_symlink; |
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static struct dentry *binary_runtime_measurements; |
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static struct dentry *ascii_runtime_measurements; |
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static struct dentry *runtime_measurements_count; |
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static struct dentry *violations; |
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static struct dentry *ima_policy; |
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enum ima_fs_flags { |
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IMA_FS_BUSY, |
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}; |
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static unsigned long ima_fs_flags; |
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#ifdef CONFIG_IMA_READ_POLICY |
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static const struct seq_operations ima_policy_seqops = { |
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.start = ima_policy_start, |
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.next = ima_policy_next, |
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.stop = ima_policy_stop, |
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.show = ima_policy_show, |
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}; |
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#endif |
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/* |
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* ima_open_policy: sequentialize access to the policy file |
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*/ |
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static int ima_open_policy(struct inode *inode, struct file *filp) |
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{ |
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if (!(filp->f_flags & O_WRONLY)) { |
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#ifndef CONFIG_IMA_READ_POLICY |
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return -EACCES; |
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#else |
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if ((filp->f_flags & O_ACCMODE) != O_RDONLY) |
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return -EACCES; |
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if (!capable(CAP_SYS_ADMIN)) |
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return -EPERM; |
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return seq_open(filp, &ima_policy_seqops); |
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#endif |
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} |
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if (test_and_set_bit(IMA_FS_BUSY, &ima_fs_flags)) |
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return -EBUSY; |
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return 0; |
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} |
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/* |
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* ima_release_policy - start using the new measure policy rules. |
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* |
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* Initially, ima_measure points to the default policy rules, now |
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* point to the new policy rules, and remove the securityfs policy file, |
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* assuming a valid policy. |
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*/ |
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static int ima_release_policy(struct inode *inode, struct file *file) |
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{ |
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const char *cause = valid_policy ? "completed" : "failed"; |
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if ((file->f_flags & O_ACCMODE) == O_RDONLY) |
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return seq_release(inode, file); |
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if (valid_policy && ima_check_policy() < 0) { |
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cause = "failed"; |
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valid_policy = 0; |
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} |
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pr_info("policy update %s\n", cause); |
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integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL, NULL, |
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"policy_update", cause, !valid_policy, 0); |
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if (!valid_policy) { |
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ima_delete_rules(); |
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valid_policy = 1; |
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clear_bit(IMA_FS_BUSY, &ima_fs_flags); |
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return 0; |
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} |
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ima_update_policy(); |
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#if !defined(CONFIG_IMA_WRITE_POLICY) && !defined(CONFIG_IMA_READ_POLICY) |
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securityfs_remove(ima_policy); |
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ima_policy = NULL; |
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#elif defined(CONFIG_IMA_WRITE_POLICY) |
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clear_bit(IMA_FS_BUSY, &ima_fs_flags); |
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#elif defined(CONFIG_IMA_READ_POLICY) |
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inode->i_mode &= ~S_IWUSR; |
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#endif |
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return 0; |
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} |
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static const struct file_operations ima_measure_policy_ops = { |
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.open = ima_open_policy, |
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.write = ima_write_policy, |
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.read = seq_read, |
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.release = ima_release_policy, |
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.llseek = generic_file_llseek, |
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}; |
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int __init ima_fs_init(void) |
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{ |
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ima_dir = securityfs_create_dir("ima", integrity_dir); |
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if (IS_ERR(ima_dir)) |
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return -1; |
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ima_symlink = securityfs_create_symlink("ima", NULL, "integrity/ima", |
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NULL); |
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if (IS_ERR(ima_symlink)) |
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goto out; |
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binary_runtime_measurements = |
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securityfs_create_file("binary_runtime_measurements", |
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S_IRUSR | S_IRGRP, ima_dir, NULL, |
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&ima_measurements_ops); |
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if (IS_ERR(binary_runtime_measurements)) |
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goto out; |
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ascii_runtime_measurements = |
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securityfs_create_file("ascii_runtime_measurements", |
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S_IRUSR | S_IRGRP, ima_dir, NULL, |
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&ima_ascii_measurements_ops); |
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if (IS_ERR(ascii_runtime_measurements)) |
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goto out; |
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runtime_measurements_count = |
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securityfs_create_file("runtime_measurements_count", |
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S_IRUSR | S_IRGRP, ima_dir, NULL, |
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&ima_measurements_count_ops); |
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if (IS_ERR(runtime_measurements_count)) |
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goto out; |
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violations = |
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securityfs_create_file("violations", S_IRUSR | S_IRGRP, |
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ima_dir, NULL, &ima_htable_violations_ops); |
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if (IS_ERR(violations)) |
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goto out; |
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ima_policy = securityfs_create_file("policy", POLICY_FILE_FLAGS, |
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ima_dir, NULL, |
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&ima_measure_policy_ops); |
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if (IS_ERR(ima_policy)) |
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goto out; |
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return 0; |
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out: |
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securityfs_remove(violations); |
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securityfs_remove(runtime_measurements_count); |
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securityfs_remove(ascii_runtime_measurements); |
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securityfs_remove(binary_runtime_measurements); |
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securityfs_remove(ima_symlink); |
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securityfs_remove(ima_dir); |
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securityfs_remove(ima_policy); |
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return -1; |
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}
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