This patch is for trimming N entries of the IMA event logs. It will also cleaning the hash table if ima_flush_htable is set.
It provides a userspace interface ima_trim_log that can be used to input number N to let kernel to trim N entries of IMA event logs. When read this interface, it returns number of entries trimmed last time. Signed-off-by: steven chen <[email protected]> --- .../admin-guide/kernel-parameters.txt | 4 + security/integrity/ima/ima.h | 2 + security/integrity/ima/ima_fs.c | 175 +++++++++++++++++- security/integrity/ima/ima_queue.c | 64 +++++++ 4 files changed, 241 insertions(+), 4 deletions(-) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index e92c0056e4e0..cd1a1d0bf0e2 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -2197,6 +2197,10 @@ Use the canonical format for the binary runtime measurements, instead of host native format. + ima_flush_htable [IMA] + Flush the measurement list hash table when trim all + or a part of it for deletion. + ima_hash= [IMA] Format: { md5 | sha1 | rmd160 | sha256 | sha384 | sha512 | ... } diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h index e3d71d8d56e3..ab0e30ee25ea 100644 --- a/security/integrity/ima/ima.h +++ b/security/integrity/ima/ima.h @@ -246,8 +246,10 @@ void ima_post_key_create_or_update(struct key *keyring, struct key *key, #ifdef CONFIG_IMA_KEXEC void ima_measure_kexec_event(const char *event_name); +long ima_purge_event_log(long number_logs); #else static inline void ima_measure_kexec_event(const char *event_name) {} +static inline long ima_purge_event_log(long number_logs) { return 0; } #endif /* diff --git a/security/integrity/ima/ima_fs.c b/security/integrity/ima/ima_fs.c index 87045b09f120..410f7d03c43f 100644 --- a/security/integrity/ima/ima_fs.c +++ b/security/integrity/ima/ima_fs.c @@ -21,6 +21,9 @@ #include <linux/rcupdate.h> #include <linux/parser.h> #include <linux/vmalloc.h> +#include <linux/ktime.h> +#include <linux/timekeeping.h> +#include <linux/ima.h> #include "ima.h" @@ -38,6 +41,14 @@ __setup("ima_canonical_fmt", default_canonical_fmt_setup); static int valid_policy = 1; +#define IMA_LOG_TRIM_REQ_LENGTH 11 +#define IMA_LOG_TRIM_EVENT_LEN 256 + +static long trimcount; +/* mutex protects atomicity of trimming measurement list requests */ +static DEFINE_MUTEX(ima_measure_lock); +static long ima_measure_users; + static ssize_t ima_show_htable_value(char __user *buf, size_t count, loff_t *ppos, atomic_long_t *val) { @@ -202,16 +213,65 @@ static const struct seq_operations ima_measurments_seqops = { .show = ima_measurements_show }; +static int _ima_measurements_open(struct inode *inode, struct file *file, + const struct seq_operations *seq_ops) +{ + bool write = !!(file->f_mode & FMODE_WRITE); + int ret; + + if (write && !capable(CAP_SYS_ADMIN)) + return -EPERM; + + mutex_lock(&ima_measure_lock); + if ((write && ima_measure_users != 0) || + (!write && ima_measure_users < 0)) { + mutex_unlock(&ima_measure_lock); + return -EBUSY; + } + + ret = seq_open(file, seq_ops); + if (ret < 0) { + mutex_unlock(&ima_measure_lock); + return ret; + } + + if (write) + ima_measure_users--; + else + ima_measure_users++; + + mutex_unlock(&ima_measure_lock); + return ret; +} + static int ima_measurements_open(struct inode *inode, struct file *file) { - return seq_open(file, &ima_measurments_seqops); + return _ima_measurements_open(inode, file, &ima_measurments_seqops); +} + +static int ima_measurements_release(struct inode *inode, struct file *file) +{ + bool write = !!(file->f_mode & FMODE_WRITE); + int ret; + + mutex_lock(&ima_measure_lock); + ret = seq_release(inode, file); + if (!ret) { + if (write) + ima_measure_users++; + else + ima_measure_users--; + } + + mutex_unlock(&ima_measure_lock); + return ret; } static const struct file_operations ima_measurements_ops = { .open = ima_measurements_open, .read = seq_read, .llseek = seq_lseek, - .release = seq_release, + .release = ima_measurements_release, }; void ima_print_digest(struct seq_file *m, u8 *digest, u32 size) @@ -279,14 +339,111 @@ static const struct seq_operations ima_ascii_measurements_seqops = { static int ima_ascii_measurements_open(struct inode *inode, struct file *file) { - return seq_open(file, &ima_ascii_measurements_seqops); + return _ima_measurements_open(inode, file, &ima_ascii_measurements_seqops); } static const struct file_operations ima_ascii_measurements_ops = { .open = ima_ascii_measurements_open, .read = seq_read, .llseek = seq_lseek, - .release = seq_release, + .release = ima_measurements_release, +}; + +static void ima_measure_trim_event(const long number_logs) +{ + char ima_log_trim_event[IMA_LOG_TRIM_EVENT_LEN]; + struct timespec64 ts; + u64 time_ns; + int n; + + ktime_get_real_ts64(&ts); + time_ns = (u64)ts.tv_sec * 1000000000ULL + ts.tv_nsec; + n = scnprintf(ima_log_trim_event, IMA_LOG_TRIM_EVENT_LEN, + "time=%llu; log trim this time=%lu;", + time_ns, number_logs); + + ima_measure_critical_data("ima_log_trim", "trim ima event logs", ima_log_trim_event, n, false, NULL, 0); +} + +static int ima_log_trim_open(struct inode *inode, struct file *file) +{ + bool write = !!(file->f_mode & FMODE_WRITE); + + if (!write && capable(CAP_SYS_ADMIN)) + return 0; + else if (!capable(CAP_SYS_ADMIN)) + return -EPERM; + + return _ima_measurements_open(inode, file, &ima_measurments_seqops); +} + +static ssize_t ima_log_trim_read(struct file *file, char __user *buf, size_t size, loff_t *ppos) +{ + char tmpbuf[IMA_LOG_TRIM_REQ_LENGTH]; /* greater than largest 'long' string value */ + ssize_t len; + + len = scnprintf(tmpbuf, sizeof(tmpbuf), "%li\n", trimcount); + return simple_read_from_buffer(buf, size, ppos, tmpbuf, len); +} + +static ssize_t ima_log_trim_write(struct file *file, + const char __user *buf, size_t datalen, loff_t *ppos) +{ + unsigned char req[IMA_LOG_TRIM_REQ_LENGTH]; + long count, n; + int ret; + + if (*ppos > 0 || datalen > IMA_LOG_TRIM_REQ_LENGTH || datalen < 2) { + ret = -EINVAL; + goto out; + } + + n = (int)datalen; + + ret = copy_from_user(req, buf, datalen); + if (ret < 0) + goto out; + + count = 0; + for (int i = 0; i < n; ++i) { + if (req[i] < '0' || req[i] > '9') { + ret = -EINVAL; + goto out; + } + count = count * 10 + req[i] - '0'; + } + ret = ima_purge_event_log(count); + + if (ret < 0) + goto out; + + trimcount = ret; + + if (trimcount > 0) + ima_measure_trim_event(trimcount); + + ret = datalen; +out: + return ret; +} + +static int ima_log_trim_release(struct inode *inode, struct file *file) +{ + bool write = !!(file->f_mode & FMODE_WRITE); + if (!write && capable(CAP_SYS_ADMIN)) + return 0; + else if (!capable(CAP_SYS_ADMIN)) + return -EPERM; + + return ima_measurements_release(inode, file); +} + +static const struct file_operations ima_log_trim_ops = { + .open = ima_log_trim_open, + .read = ima_log_trim_read, + .write = ima_log_trim_write, + .llseek = generic_file_llseek, + .release = ima_log_trim_release }; static ssize_t ima_read_policy(char *path) @@ -528,6 +685,16 @@ int __init ima_fs_init(void) goto out; } + dentry = securityfs_create_file("ima_trim_log", + S_IRUSR | S_IRGRP | S_IWUSR | S_IWGRP, + ima_dir, NULL, &ima_log_trim_ops); + if (IS_ERR(dentry)) { + ret = PTR_ERR(dentry); + goto out; + } + + trimcount = 0; + dentry = securityfs_create_file("runtime_measurements_count", S_IRUSR | S_IRGRP, ima_dir, NULL, &ima_measurements_count_ops); diff --git a/security/integrity/ima/ima_queue.c b/security/integrity/ima/ima_queue.c index 590637e81ad1..77ab52469727 100644 --- a/security/integrity/ima/ima_queue.c +++ b/security/integrity/ima/ima_queue.c @@ -22,6 +22,14 @@ #define AUDIT_CAUSE_LEN_MAX 32 +bool ima_flush_htable; +static int __init ima_flush_htable_setup(char *str) +{ + ima_flush_htable = true; + return 1; +} +__setup("ima_flush_htable", ima_flush_htable_setup); + /* pre-allocated array of tpm_digest structures to extend a PCR */ static struct tpm_digest *digests; @@ -220,6 +228,62 @@ int ima_add_template_entry(struct ima_template_entry *entry, int violation, return result; } +/* Delete the IMA event logs */ +long ima_purge_event_log(long number_logs) +{ + struct ima_queue_entry *qe, *qe_tmp; + LIST_HEAD(ima_measurements_staged); + unsigned int i; + long cur = number_logs; + + if (number_logs <= 0) + return number_logs; + + mutex_lock(&ima_extend_list_mutex); + + + list_for_each_entry(qe, &ima_measurements, later) { + if (--number_logs == 0) + break; + } + + if (number_logs > 0) { + mutex_unlock(&ima_extend_list_mutex); + return -ENOENT; + } + + __list_cut_position(&ima_measurements_staged, &ima_measurements, + &qe->later); + atomic_long_sub(cur, &ima_htable.len); + + if (!IS_ENABLED(CONFIG_IMA_DISABLE_HTABLE) && ima_flush_htable) { + list_for_each_entry(qe, &ima_measurements_staged, later) + /* It can race with ima_lookup_digest_entry(). */ + hlist_del_rcu(&qe->hnext); + } + + mutex_unlock(&ima_extend_list_mutex); + + + list_for_each_entry_safe(qe, qe_tmp, &ima_measurements_staged, later) { + for (i = 0; i < qe->entry->template_desc->num_fields; i++) { + kfree(qe->entry->template_data[i].data); + qe->entry->template_data[i].data = NULL; + qe->entry->template_data[i].len = 0; + } + + list_del(&qe->later); + + if (ima_flush_htable) { + kfree(qe->entry->digests); + kfree(qe->entry); + kfree(qe); + } + } + + return cur; +} + int ima_restore_measurement_entry(struct ima_template_entry *entry) { int result = 0; -- 2.43.0
