Series comparison

-[PATCH v9 0/7] ima: kexec: measure events between kexec load and execute
+[PATCH v11 0/9] ima: kexec: measure events between kexec load and execute
 The current kernel behavior is IMA measurements snapshot is taken at
 kexec 'load' and not at kexec 'execute'.  IMA log is then carried
 over to the new kernel after kexec 'execute'.
-New events can be measured during/after the IMA log snapshot at kexec
+Currently, the kernel behavior during kexec load is to fetch the IMA
-'load' and before the system boots to the new kernel.  In this scenario,
+measurements log from TPM PCRs and store it in a buffer. When a kexec
-the TPM PCRs are extended with these events, but they are not carried
+reboot is triggered, this stored log buffer is carried over to the second
-over to the new kernel after kexec soft reboot since the snapshot is
+kernel. However, the time gap between kexec load and kexec reboot can be
-already taken.  This results in mismatch between TPM PCR quotes and the
+very long. During this time window, new events extended into TPM PCRs miss
-actual IMA measurements list after kexec soft reboot, which in turn
+the chance to be carried over to the second kernel. This results in
-results in remote attestation failure.
+mismatch between TPM PCR quotes and the actual IMA measurements list after
 kexec soft reboot, which in turn results in remote attestation failure.
 To solve this problem -
  - allocate the necessary buffer at kexec 'load' time,
  - populate the buffer with the IMA measurements at kexec 'execute' time,
  - and measure two new IMA events 'kexec_load' and 'kexec_execute' as
 ...
 V7 of this series is available here[9] for reference.
 V8 of this series is available here[10] for reference.
+V9 of this series is available here[11] for reference.
+V10 of this series is available here[12] for reference.
 References:
 -----------
 [1] [PATHC v2 5/9] ima: on soft reboot, save the measurement list
 https://lore.kernel.org/lkml/1472596811-9596-6-git-send-email-zohar@linux.vnet.ibm.com/
 ...
 [9] [PATCH v7 0/7] ima: kexec: measure events between kexec load and execute
 https://lore.kernel.org/all/20250203232033.64123-1-chenste@linux.microsoft.com/
 [10] [PATCH v8 0/7] ima: kexec: measure events between kexec load and execute
 https://lore.kernel.org/all/20250218225502.747963-1-chenste@linux.microsoft.com/
+[11] [PATCH v9 0/7] ima: kexec: measure events between kexec load and execute
+https://lore.kernel.org/all/20250304190351.96975-1-chenste@linux.microsoft.com/
+[12] [PATCH v10 0/8] ima: kexec: measure events between kexec load and execute
+https://lore.kernel.org/all/20250318010448.954-1-chenste@linux.microsoft.com/
+Change Log v11:
+ - Incorporated feedback from the community (Mimi Zohar and Baoquan He) on
+   v10 of this series[12].
+ - [PATCH V10 2/8] was splited into two [PATCH V11 2/9] and [PATCH V11 7/9].
+   Per Mimi comment on [PATCH V10 2/8].
+ - Verified all the patches are bisect-safe by booting into each
+   patch and verifying multiple kexec 'load' operations work,
+   and also verifying kexec soft reboot works, and IMA log gets
+   carried over for each patch.
+ - Updated patch descriptions as necessary.
+Change Log v10:
+ - Incorporated feedback from the community (Mimi Zohar, Baoquan He, and
+   kernel test robot) on v9 of this series[11].
+ - [PATCH V9 1/7] was splited into two [PATCH V10 1/8] and [PATCH V10 2/8].
+   Per Mimi comment on [PATCH V9 1/7].
+ - Verified all the patches are bisect-safe by booting into each
+   patch and verifying multiple kexec 'load' operations work,
+   and also verifying kexec soft reboot works, and IMA log gets
+   carried over for each patch.
 Change Log v9:
  - Incorporated feedback from the community (Stefan Berger, Mimi Zohar,
    and kernel test robot) on v8 of this series[10].
  - Rebased the patch series to mainline 6.14.0-rc3.
 ...
    compilation.
  - Used virt_to_page instead of phys_to_page.
  - Updated patch descriptions as necessary.
-steven chen (7):
+steven chen (9):
-  ima: copy only complete measurement records across kexec
+  ima: rename variable the set_file "file" to "ima_kexec_file"
   ima: define and call ima_alloc_kexec_file_buf()
   kexec: define functions to map and unmap segments
   ima: kexec: skip IMA segment validation after kexec soft reboot
   ima: kexec: define functions to copy IMA log at soft boot
   ima: kexec: move IMA log copy from kexec load to execute
+  ima: verify if the segment size has changed
   ima: make the kexec extra memory configurable
   ima: measure kexec load and exec events as critical data
  include/linux/ima.h                |   3 +
  include/linux/kexec.h              |   9 ++
  kernel/kexec_core.c                |  54 ++++++++
- kernel/kexec_file.c                |  32 +++++
+ kernel/kexec_file.c                |  33 ++++-
  security/integrity/ima/Kconfig     |  10 ++
- security/integrity/ima/ima.h       |   7 +
+ security/integrity/ima/ima.h       |   6 +
- security/integrity/ima/ima_kexec.c | 210 ++++++++++++++++++++++++-----
+ security/integrity/ima/ima_kexec.c | 193 ++++++++++++++++++++++++-----
- security/integrity/ima/ima_queue.c |   9 +-
+ security/integrity/ima/ima_queue.c |   5 +
-files changed, 297 insertions(+), 37 deletions(-)
+files changed, 279 insertions(+), 34 deletions(-)
 --
 .25.1

-New patch
+[PATCH v11 1/9] ima: rename variable the set_file "file" to "ima_kexec_file"
+The current kernel behavior is IMA measurements snapshot is taken at
+kexec 'load' and not at kexec 'execute'. IMA log is then carried
+over to the new kernel after kexec 'execute'. However, the time gap
+between kexec load and kexec reboot can be very long. During this
+time window, new events extended into TPM PCRs miss the chance
+to be carried over to the second kernel.
+To address the above, the following approach is proposed:
+  - Allocate the necessary buffer during the kexec load phase.
+  - Populate this buffer with the IMA measurements during
+    the kexec execute phase.
+In the current implementation, a local variable "file" of type seq_file
+is used in the API ima_dump_measurement_list() to store the IMA measurements
+to be carried over across kexec system call. To make this buffer accessible
+at kexec 'execute' time, rename it to "ima_kexec_file" before making it
+a file variable to better reflect its purpose.
+Renaming the local variable "file" of type seq_file defined in the
+ima_dump_measurement_list function to "ima_kexec_file" will improve code
+readability and maintainability by making the variable's role more explicit.
+Suggested-by: Mimi Zohar <zohar@linux.ibm.com>
+Signed-off-by: steven chen <chenste@linux.microsoft.com>
+Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
+---
+ security/integrity/ima/ima_kexec.c | 31 +++++++++++++++---------------
+file changed, 16 insertions(+), 15 deletions(-)
+diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c
+index XXXXXXX..XXXXXXX 100644
+--- a/security/integrity/ima/ima_kexec.c
++++ b/security/integrity/ima/ima_kexec.c
+@@ -XXX,XX +XXX,XX @@
+ static int ima_dump_measurement_list(unsigned long *buffer_size, void **buffer,
+                      unsigned long segment_size)
+ {
++    struct seq_file ima_kexec_file;
+     struct ima_queue_entry *qe;
+-    struct seq_file file;
+     struct ima_kexec_hdr khdr;
+     int ret = 0;
+     /* segment size can't change between kexec load and execute */
+-    file.buf = vmalloc(segment_size);
+-    if (!file.buf) {
++    ima_kexec_file.buf = vmalloc(segment_size);
++    if (!ima_kexec_file.buf) {
+         ret = -ENOMEM;
+         goto out;
+     }
+-    file.file = NULL;
+-    file.size = segment_size;
+-    file.read_pos = 0;
+-    file.count = sizeof(khdr);    /* reserved space */
++    ima_kexec_file.file = NULL;
++    ima_kexec_file.size = segment_size;
++    ima_kexec_file.read_pos = 0;
++    ima_kexec_file.count = sizeof(khdr);    /* reserved space */
+     memset(&khdr, 0, sizeof(khdr));
+     khdr.version = 1;
+     /* This is an append-only list, no need to hold the RCU read lock */
+     list_for_each_entry_rcu(qe, &ima_measurements, later, true) {
+-        if (file.count < file.size) {
++        if (ima_kexec_file.count < ima_kexec_file.size) {
+             khdr.count++;
+-            ima_measurements_show(&file, qe);
++            ima_measurements_show(&ima_kexec_file, qe);
+         } else {
+             ret = -EINVAL;
+             break;
+@@ -XXX,XX +XXX,XX @@ static int ima_dump_measurement_list(unsigned long *buffer_size, void **buffer,
+      * fill in reserved space with some buffer details
+      * (eg. version, buffer size, number of measurements)
+      */
+-    khdr.buffer_size = file.count;
++    khdr.buffer_size = ima_kexec_file.count;
+     if (ima_canonical_fmt) {
+         khdr.version = cpu_to_le16(khdr.version);
+         khdr.count = cpu_to_le64(khdr.count);
+         khdr.buffer_size = cpu_to_le64(khdr.buffer_size);
+     }
+-    memcpy(file.buf, &khdr, sizeof(khdr));
++    memcpy(ima_kexec_file.buf, &khdr, sizeof(khdr));
+     print_hex_dump_debug("ima dump: ", DUMP_PREFIX_NONE, 16, 1,
+-                 file.buf, file.count < 100 ? file.count : 100,
++                 ima_kexec_file.buf, ima_kexec_file.count < 100 ?
++                 ima_kexec_file.count : 100,
+                  true);
+-    *buffer_size = file.count;
+-    *buffer = file.buf;
++    *buffer_size = ima_kexec_file.count;
++    *buffer = ima_kexec_file.buf;
+ out:
+     if (ret == -EINVAL)
+-        vfree(file.buf);
++        vfree(ima_kexec_file.buf);
+     return ret;
+ }
+--
+.25.1

-[PATCH v9 1/7] ima: copy only complete measurement records across kexec
+[PATCH v11 2/9] ima: define and call ima_alloc_kexec_file_buf()
+In the current implementation, the ima_dump_measurement_list() API is
+called during the kexec "load" phase, where a buffer is allocated and
+the measurement records are copied. Due to this, new events added after
+kexec load but before kexec execute are not carried over to the new kernel
+during kexec operation
+To allow the buffer allocation and population to be separated into distinct
+steps, make the function local seq_file "ima_kexec_file" to a file variable.
 Carrying the IMA measurement list across kexec requires allocating a
 buffer and copying the measurement records.  Separate allocating the
 buffer and copying the measurement records into separate functions in
 order to allocate the buffer at kexec 'load' and copy the measurements
 at kexec 'execute'.
-This patch includes the following changes:
- - Refactor ima_dump_measurement_list() to move the memory allocation
-   to a separate function ima_alloc_kexec_file_buf() which allocates
-   buffer of size 'kexec_segment_size' at kexec 'load'.
- - Make the local variable ima_kexec_file in ima_dump_measurement_list()
-   a local static to the file, so that it can be accessed from
-   ima_alloc_kexec_file_buf(). Compare actual memory required to ensure
-   there is enough memory for the entire measurement record.
- - Copy only complete measurement records.
- - Make necessary changes to the function ima_add_kexec_buffer() to call
-   the above two functions.
- - Compared the memory size allocated with memory size of the entire
-   measurement record. Copy only complete measurement records if there
-   is enough memory. If there is not enough memory, it will not copy
-   any IMA measurement records, and this situation will result in a
-   failure of remote attestation.
-Suggested-by: Mimi Zohar <zohar@linux.ibm.com>
 Signed-off-by: Tushar Sugandhi <tusharsu@linux.microsoft.com>
 Signed-off-by: steven chen <chenste@linux.microsoft.com>
 ---
- security/integrity/ima/ima.h       |   1 +
+ security/integrity/ima/ima_kexec.c | 46 +++++++++++++++++++++++-------
- security/integrity/ima/ima_kexec.c | 105 ++++++++++++++++++++++-------
+file changed, 35 insertions(+), 11 deletions(-)
  security/integrity/ima/ima_queue.c |   4 +-
 files changed, 83 insertions(+), 27 deletions(-)
-diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
-index XXXXXXX..XXXXXXX 100644
---- a/security/integrity/ima/ima.h
-+++ b/security/integrity/ima/ima.h
-@@ -XXX,XX +XXX,XX @@ bool ima_template_has_modsig(const struct ima_template_desc *ima_template);
- int ima_restore_measurement_entry(struct ima_template_entry *entry);
- int ima_restore_measurement_list(loff_t bufsize, void *buf);
- int ima_measurements_show(struct seq_file *m, void *v);
-+int ima_get_binary_runtime_entry_size(struct ima_template_entry *entry);
- unsigned long ima_get_binary_runtime_size(void);
- int ima_init_template(void);
- void ima_init_template_list(void);
 diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c
 index XXXXXXX..XXXXXXX 100644
 --- a/security/integrity/ima/ima_kexec.c
 +++ b/security/integrity/ima/ima_kexec.c
 @@ -XXX,XX +XXX,XX @@
  #include "ima.h"
  #ifdef CONFIG_IMA_KEXEC
 +static struct seq_file ima_kexec_file;
 +
-+static void ima_reset_kexec_file(struct seq_file *sf)
++static void ima_free_kexec_file_buf(struct seq_file *sf)
 +{
++    vfree(sf->buf);
 +    sf->buf = NULL;
 +    sf->size = 0;
 +    sf->read_pos = 0;
 +    sf->count = 0;
 +}
 +
-+static void ima_free_kexec_file_buf(struct seq_file *sf)
-+{
-+    vfree(sf->buf);
-+    ima_reset_kexec_file(sf);
-+}
-+
 +static int ima_alloc_kexec_file_buf(size_t segment_size)
 +{
-+    /*
-+     * kexec 'load' may be called multiple times.
-+     * Free and realloc the buffer only if the segment_size is
-+     * changed from the previous kexec 'load' call.
-+     */
-+    if (ima_kexec_file.buf && ima_kexec_file.size == segment_size)
-+        goto out;
-+
 +    ima_free_kexec_file_buf(&ima_kexec_file);
 +
 +    /* segment size can't change between kexec load and execute */
 +    ima_kexec_file.buf = vmalloc(segment_size);
 +    if (!ima_kexec_file.buf)
 +        return -ENOMEM;
 +
 +    ima_kexec_file.size = segment_size;
-+
-+out:
 +    ima_kexec_file.read_pos = 0;
 +    ima_kexec_file.count = sizeof(struct ima_kexec_hdr);    /* reserved space */
 +
 +    return 0;
 +}
 +
-+/*
-+ * Copy the measurement list to the allocated memory
-+ * compare the size of IMA measurement list with the size of the allocated memory
-+ *    if the size of the allocated memory is not less than the size of IMA measurement list
-+ *        copy the measurement list to the allocated memory.
-+ *    else return error
-+ */
  static int ima_dump_measurement_list(unsigned long *buffer_size, void **buffer,
                       unsigned long segment_size)
  {
+-    struct seq_file ima_kexec_file;
      struct ima_queue_entry *qe;
--    struct seq_file file;
      struct ima_kexec_hdr khdr;
      int ret = 0;
-+    size_t entry_size = 0;
+     /* segment size can't change between kexec load and execute */
--    /* segment size can't change between kexec load and execute */
+-    ima_kexec_file.buf = vmalloc(segment_size);
--    file.buf = vmalloc(segment_size);
+     if (!ima_kexec_file.buf) {
 -    if (!file.buf) {
 -        ret = -ENOMEM;
 -        goto out;
-+    if (!ima_kexec_file.buf) {
 +        pr_err("Kexec file buf not allocated\n");
 +        return -EINVAL;
      }
--    file.file = NULL;
+-    ima_kexec_file.file = NULL;
--    file.size = segment_size;
+-    ima_kexec_file.size = segment_size;
--    file.read_pos = 0;
+-    ima_kexec_file.read_pos = 0;
--    file.count = sizeof(khdr);    /* reserved space */
+-    ima_kexec_file.count = sizeof(khdr);    /* reserved space */
 -
      memset(&khdr, 0, sizeof(khdr));
      khdr.version = 1;
      /* This is an append-only list, no need to hold the RCU read lock */
-     list_for_each_entry_rcu(qe, &ima_measurements, later, true) {
+@@ -XXX,XX +XXX,XX @@ static int ima_dump_measurement_list(unsigned long *buffer_size, void **buffer,
--        if (file.count < file.size) {
+     *buffer_size = ima_kexec_file.count;
-+        entry_size += ima_get_binary_runtime_entry_size(qe->entry);
+     *buffer = ima_kexec_file.buf;
 +        if (entry_size <= segment_size) {
              khdr.count++;
 -            ima_measurements_show(&file, qe);
 +            ima_measurements_show(&ima_kexec_file, qe);
          } else {
              ret = -EINVAL;
 +            pr_err("IMA log file is too big for Kexec buf\n");
              break;
          }
      }
      if (ret < 0)
          goto out;
 -
      /*
       * fill in reserved space with some buffer details
       * (eg. version, buffer size, number of measurements)
       */
 -    khdr.buffer_size = file.count;
 +    khdr.buffer_size = ima_kexec_file.count;
      if (ima_canonical_fmt) {
          khdr.version = cpu_to_le16(khdr.version);
          khdr.count = cpu_to_le64(khdr.count);
          khdr.buffer_size = cpu_to_le64(khdr.buffer_size);
      }
 -    memcpy(file.buf, &khdr, sizeof(khdr));
 +    memcpy(ima_kexec_file.buf, &khdr, sizeof(khdr));
      print_hex_dump_debug("ima dump: ", DUMP_PREFIX_NONE, 16, 1,
 -                 file.buf, file.count < 100 ? file.count : 100,
 +                 ima_kexec_file.buf, ima_kexec_file.count < 100 ?
 +                 ima_kexec_file.count : 100,
                   true);
 -    *buffer_size = file.count;
 -    *buffer = file.buf;
 +    *buffer_size = ima_kexec_file.count;
 +    *buffer = ima_kexec_file.buf;
 +
  out:
 -    if (ret == -EINVAL)
--        vfree(file.buf);
+-        vfree(ima_kexec_file.buf);
      return ret;
  }
-@@ -XXX,XX +XXX,XX @@ void ima_add_kexec_buffer(struct kimage *image)
-     /* use more understandable variable names than defined in kbuf */
-     void *kexec_buffer = NULL;
--    size_t kexec_buffer_size;
-+    size_t kexec_buffer_size = 0;
-     size_t kexec_segment_size;
-     int ret;
 @@ -XXX,XX +XXX,XX @@ void ima_add_kexec_buffer(struct kimage *image)
          return;
      }
--    ima_dump_measurement_list(&kexec_buffer_size, &kexec_buffer,
--                  kexec_segment_size);
--    if (!kexec_buffer) {
 +    ret = ima_alloc_kexec_file_buf(kexec_segment_size);
 +    if (ret < 0) {
-         pr_err("Not enough memory for the kexec measurement buffer.\n");
++        pr_err("Not enough memory for the kexec measurement buffer.\n");
          return;
      }
 +    ret = ima_dump_measurement_list(&kexec_buffer_size, &kexec_buffer,
 +                    kexec_segment_size);
 +    if (ret < 0) {
 +        pr_err("Failed to dump IMA measurements. Error:%d.\n", ret);
 +        return;
 +    }
 +
-     kbuf.buffer = kexec_buffer;
+     ima_dump_measurement_list(&kexec_buffer_size, &kexec_buffer,
-     kbuf.bufsz = kexec_buffer_size;
+                   kexec_segment_size);
-     kbuf.memsz = kexec_segment_size;
+     if (!kexec_buffer) {
@@ -XXX,XX +XXX,XX @@ void ima_add_kexec_buffer(struct kimage *image)
      image->ima_buffer_size = kexec_segment_size;
      image->ima_buffer = kexec_buffer;
 +    /*
 +     * kexec owns kexec_buffer after kexec_add_buffer() is called
 +     * and it will vfree() that buffer.
 +     */
 +    ima_reset_kexec_file(&ima_kexec_file);
 +
      kexec_dprintk("kexec measurement buffer for the loaded kernel at 0x%lx.\n",
                kbuf.mem);
  }
 diff --git a/security/integrity/ima/ima_queue.c b/security/integrity/ima/ima_queue.c
 index XXXXXXX..XXXXXXX 100644
 --- a/security/integrity/ima/ima_queue.c
 +++ b/security/integrity/ima/ima_queue.c
@@ -XXX,XX +XXX,XX @@ static struct ima_queue_entry *ima_lookup_digest_entry(u8 *digest_value,
   * binary_runtime_measurement list entry, which contains a
   * couple of variable length fields (e.g template name and data).
   */
 -static int get_binary_runtime_size(struct ima_template_entry *entry)
 +int ima_get_binary_runtime_entry_size(struct ima_template_entry *entry)
  {
      int size = 0;
@@ -XXX,XX +XXX,XX @@ static int ima_add_digest_entry(struct ima_template_entry *entry,
      if (binary_runtime_size != ULONG_MAX) {
          int size;
 -        size = get_binary_runtime_size(entry);
 +        size = ima_get_binary_runtime_entry_size(entry);
          binary_runtime_size = (binary_runtime_size < ULONG_MAX - size) ?
               binary_runtime_size + size : ULONG_MAX;
      }
 --
 .25.1

-[PATCH v9 2/7] kexec: define functions to map and unmap segments
+[PATCH v11 3/9] kexec: define functions to map and unmap segments
-The content of memory segments carried over to the new kernel during the
+Currently, the kernel behavior during kexec load is to fetch the IMA
-kexec systemcall can be changed at kexec 'execute' stage, but the size of
+measurements logs and store logs in kernel memory. When a kexec reboot is
-the memory segments cannot be changed at kexec 'execute' stage.
+triggered, these stored logs in the kernel memory are carried over to the
 second kernel. However, the time gap between kexec load and kexec reboot
 can be very long. During this time window, new events extended into TPM
 PCRs miss the chance to be carried over to the second kernel. This results
 in a mismatch between TPM PCR quotes and the actual IMA measurements list
 after kexec reboot, leading to remote attestation failure.
-To copy IMA measurement logs during the kexec operation, IMA needs to
+To solve this problem, the new design defers reading the IMA measurements
-allocate memory at the kexec 'load' stage and map the segments to the
+logs into the kexec buffer to the kexec reboot phase, while still allocating
-kimage structure. The mapped address will then be used to copy IMA
+the necessary buffer at kexec load time because it is not appropriate to
-measurements during the kexec 'execute' stage.
+allocate memory at the kexec reboot moment.
-Currently, the mechanism to map and unmap segments to the kimage
+The content of memory segments carried over to the new kernel during the
-structure is not available to subsystems outside of kexec.
+kexec system call can be changed at the kexec 'execute' stage, but the size
 of the memory segments cannot be changed at the kexec 'execute' stage.
-Implement kimage_map_segment() to enable IMA to map measurement log list to
+To copy IMA measurement logs during the kexec operation, IMA allocates
-the kimage structure during kexec 'load' stage.  This function takes a kimage
+memory at the kexec 'load' stage and map the segments to the kimage
-pointer, a memory address, and a size, then gathers the
+structure. The mapped address will then be used to copy IMA measurements
 during the kexec 'execute' stage.
 Currently, the mechanism to map and unmap segments to the kimage structure
 is not available to subsystems outside of kexec.
 Implement kimage_map_segment() to enable IMA to map the measurement log
 list to the kimage structure during the kexec 'load' stage. This function
 takes a kimage pointer, a memory address, and a size, then gathers the
 source pages within the specified address range, creates an array of page
-pointers, and maps these to a contiguous virtual address range.  The
+pointers, and maps these to a contiguous virtual address range. The
-function returns the start virtual address of this range if successful, or NULL on
+function returns the start virtual address of this range if successful,
-failure.
+or NULL on failure.
-Implement kimage_unmap_segment() for unmapping segments
+Implement kimage_unmap_segment() for unmapping segments using vunmap().
 using vunmap().
 From: Tushar Sugandhi <tusharsu@linux.microsoft.com>
 Signed-off-by: Tushar Sugandhi <tusharsu@linux.microsoft.com>
 Cc: Eric Biederman <ebiederm@xmission.com>
 Cc: Baoquan He <bhe@redhat.com>
 Cc: Vivek Goyal <vgoyal@redhat.com>
 Cc: Dave Young <dyoung@redhat.com>
 Signed-off-by: steven chen <chenste@linux.microsoft.com>
+Acked-by: Baoquan He <bhe@redhat.com>
 ---
  include/linux/kexec.h |  6 +++++
  kernel/kexec_core.c   | 54 +++++++++++++++++++++++++++++++++++++++++++
 files changed, 60 insertions(+)
 ...
  }
 +void *kimage_map_segment(struct kimage *image,
 +             unsigned long addr, unsigned long size)
 +{
++    unsigned long src_page_addr, dest_page_addr = 0;
 +    unsigned long eaddr = addr + size;
-+    unsigned long src_page_addr, dest_page_addr;
++    kimage_entry_t *ptr, entry;
 +    struct page **src_pages;
 +    unsigned int npages;
-+    struct page **src_pages;
++    void *vaddr = NULL;
 +    int i;
-+    kimage_entry_t *ptr, entry;
-+    void *vaddr = NULL;
 +
 +    /*
 +     * Collect the source pages and map them in a contiguous VA range.
 +     */
 +    npages = PFN_UP(eaddr) - PFN_DOWN(addr);
 ...

-[PATCH v9 3/7] ima: kexec: skip IMA segment validation after kexec soft reboot
+[PATCH v11 4/9] ima: kexec: skip IMA segment validation after kexec soft reboot
 ...
 kexec systemcall can be changed at kexec 'execute' stage, but the size
 and the location of the memory segments cannot be changed at kexec
 'execute' stage.
 However, during the kexec execute stage, if kexec_calculate_store_digests()
-API is call to update the digest, it does not reuse the same memory segment
+API is called to update the digest, it does not reuse the same memory
-allocated during the kexec 'load' stage and the new memory segment required
+segment allocated during the kexec 'load' stage and the new memory segment
-cannot be transferred/mapped to the new kernel.
+required cannot be transferred/mapped to the new kernel.
 As a result, digest verification will fail in verify_sha256_digest()
 after a kexec soft reboot into the new kernel. Therefore, the digest
 calculation/verification of the IMA segment needs to be skipped.
 ...
 Cc: Vivek Goyal <vgoyal@redhat.com>
 Cc: Dave Young <dyoung@redhat.com>
 Signed-off-by: steven chen <chenste@linux.microsoft.com>
 Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
 Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
+Acked-by: Baoquan He <bhe@redhat.com>
 ---
  include/linux/kexec.h              |  3 +++
  kernel/kexec_file.c                | 22 ++++++++++++++++++++++
  security/integrity/ima/ima_kexec.c |  3 +++
 files changed, 28 insertions(+)
 ...
      image->ima_buffer_size = kexec_segment_size;
      image->ima_buffer = kexec_buffer;
 +    image->ima_segment_index = image->nr_segments - 1;
 +    image->is_ima_segment_index_set = true;
-     /*
+     kexec_dprintk("kexec measurement buffer for the loaded kernel at 0x%lx.\n",
-      * kexec owns kexec_buffer after kexec_add_buffer() is called
+               kbuf.mem);
 --
 .25.1

-[PATCH v9 4/7] ima: kexec: define functions to copy IMA log at soft boot
+[PATCH v11 5/9] ima: kexec: define functions to copy IMA log at soft boot
 The IMA log is currently copied to the new kernel during kexec 'load'
-using ima_dump_measurement_list().  However, the log copied at kexec
+using ima_dump_measurement_list(). However, the log copied at kexec
 'load' may result in loss of IMA measurements that only occurred after
 kexec "load'. Therefore, the log needs to be copied during kexec
 'execute'. Setup the needed infrastructure to move the IMA log copy from
 kexec 'load' to 'execute'.
 ...
 Implement ima_kexec_post_load() function to be invoked after the new
 Kernel image has been loaded for kexec. ima_kexec_post_load() maps the
 IMA buffer to a segment in the newly loaded Kernel.  It also registers
 the reboot notifier_block to trigger ima_update_kexec_buffer() at
 kexec 'execute'.
+Set the priority of register_reboot_notifier to INT_MIN to ensure that the
+IMA log copy operation will happen at the end of the operation chain, which
+is crucial for maintaining the integrity of the logs
 Signed-off-by: Tushar Sugandhi <tusharsu@linux.microsoft.com>
 Cc: Eric Biederman <ebiederm@xmission.com>
 Cc: Baoquan He <bhe@redhat.com>
 Cc: Vivek Goyal <vgoyal@redhat.com>
 ...
 +#include <linux/reboot.h>
 +#include <asm/page.h>
  #include "ima.h"
  #ifdef CONFIG_IMA_KEXEC
++static bool ima_kexec_update_registered;
  static struct seq_file ima_kexec_file;
 +static void *ima_kexec_buffer;
-+static bool ima_kexec_update_registered;
+ static void ima_free_kexec_file_buf(struct seq_file *sf)
  static void ima_reset_kexec_file(struct seq_file *sf)
  {
 @@ -XXX,XX +XXX,XX @@ void ima_add_kexec_buffer(struct kimage *image)
      kexec_dprintk("kexec measurement buffer for the loaded kernel at 0x%lx.\n",
                kbuf.mem);
  }
 ...
 +                   unsigned long action, void *data)
 +{
 +    return NOTIFY_OK;
 +}
 +
-+struct notifier_block update_buffer_nb = {
++static struct notifier_block update_buffer_nb = {
 +    .notifier_call = ima_update_kexec_buffer,
-+    .priority = 1,
++    .priority = INT_MIN
 +};
 +
 +/*
 + * Create a mapping for the source pages that contain the IMA buffer
 + * so we can update it later.
 ...

-[PATCH v9 5/7] ima: kexec: move IMA log copy from kexec load to execute
+[PATCH v11 6/9] ima: kexec: move IMA log copy from kexec load to execute
 ima_dump_measurement_list() is called during kexec 'load', which may
 result in loss of IMA measurements during kexec soft reboot. Due to
 missed measurements that only occurred after kexec 'load', this function
 needs to be called during kexec 'execute'.
-This patch includes the following changes:
+Make the kexec_segment_size variable a local static variable within the
- - Implement kimage_file_post_load() function to be invoked after the new
+file, so it can be accessed during both kexec 'load' and 'execute'.
-   kernel image has been loaded for kexec.
- - Call kimage_file_post_load() from kexec_file_load() syscall only for
+Implement the kexec_post_load() function to be invoked after the new kernel
-   kexec soft reboot scenarios and not for KEXEC_FILE_ON_CRASH.  It will
+image has been loaded for kexec. Instead of calling machine_kexec_post_load()
-   map the IMA segment, and register reboot notifier for the function
+directly from the kexec_file_load() syscall, call kexec_post_load(), which in
-   ima_update_kexec_buffer() which would copy the IMA log at kexec soft
+turn calls machine_kexec_post_load() to maintain the original image processing.
-   reboot.
- - Make kexec_segment_size variable local static to the file so that it
+Invoke ima_kexec_post_load() within the kexec_post_load() API only for kexec
-   becomes accessible both during kexec 'load' and 'execute'.
+soft reboot scenarios, excluding KEXEC_FILE_ON_CRASH.
- - Move ima_dump_measurement_list() call from ima_add_kexec_buffer()
-   to ima_update_kexec_buffer().
+Register a reboot notifier for the ima_update_kexec_buffer() API within
- - Copy the measurement list as much as possible.
+ima_kexec_post_load() to ensure it is called upon receiving a reboot
- - Remove ima_reset_kexec_file() call from ima_add_kexec_buffer(), now
+notification.
-   that the buffer is being copied at kexec 'execute', and resetting the
-   file at kexec 'load' would corrupt the buffer.
+Move the ima_dump_measurement_list() call from ima_add_kexec_buffer() to
 ima_update_kexec_buffer() to copy the IMA log at the kexec 'execute' stage.
 When there is insufficient memory to copy all the measurement logs, copy as
 much of the measurement list as possible.
 Signed-off-by: Tushar Sugandhi <tusharsu@linux.microsoft.com>
 Cc: Eric Biederman <ebiederm@xmission.com>
 Cc: Baoquan He <bhe@redhat.com>
 Cc: Vivek Goyal <vgoyal@redhat.com>
 Cc: Dave Young <dyoung@redhat.com>
 Signed-off-by: steven chen <chenste@linux.microsoft.com>
 Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
 ---
- kernel/kexec_file.c                | 10 +++++++
+ kernel/kexec_file.c                | 11 +++++++-
- security/integrity/ima/ima_kexec.c | 48 ++++++++++++++++++------------
+ security/integrity/ima/ima_kexec.c | 43 ++++++++++++++++++++----------
-files changed, 39 insertions(+), 19 deletions(-)
+files changed, 39 insertions(+), 15 deletions(-)
 diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
 index XXXXXXX..XXXXXXX 100644
 --- a/kernel/kexec_file.c
 +++ b/kernel/kexec_file.c
 @@ -XXX,XX +XXX,XX @@ kimage_validate_signature(struct kimage *image)
  }
  #endif
-+static void kimage_file_post_load(struct kimage *image)
++static int kexec_post_load(struct kimage *image, unsigned long flags)
 +{
 +#ifdef CONFIG_IMA_KEXEC
-+    ima_kexec_post_load(image);
++    if (!(flags & KEXEC_FILE_ON_CRASH))
 +        ima_kexec_post_load(image);
 +#endif
++    return machine_kexec_post_load(image);
 +}
 +
  /*
   * In file mode list of segments is prepared by kernel. Copy relevant
   * data from user space, do error checking, prepare segment list
 @@ -XXX,XX +XXX,XX @@ SYSCALL_DEFINE5(kexec_file_load, int, kernel_fd, int, initrd_fd,
      kimage_terminate(image);
-+    if (!(flags & KEXEC_FILE_ON_CRASH))
+-    ret = machine_kexec_post_load(image);
-+        kimage_file_post_load(image);
++    ret = kexec_post_load(image, flags);
 +
      ret = machine_kexec_post_load(image);
      if (ret)
          goto out;
 diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c
 index XXXXXXX..XXXXXXX 100644
 --- a/security/integrity/ima/ima_kexec.c
 +++ b/security/integrity/ima/ima_kexec.c
 @@ -XXX,XX +XXX,XX @@
  #ifdef CONFIG_IMA_KEXEC
+ static bool ima_kexec_update_registered;
  static struct seq_file ima_kexec_file;
++static size_t kexec_segment_size;
  static void *ima_kexec_buffer;
-+static size_t kexec_segment_size;
- static bool ima_kexec_update_registered;
+ static void ima_free_kexec_file_buf(struct seq_file *sf)
  static void ima_reset_kexec_file(struct seq_file *sf)
@@ -XXX,XX +XXX,XX @@ static int ima_alloc_kexec_file_buf(size_t segment_size)
   * compare the size of IMA measurement list with the size of the allocated memory
   *    if the size of the allocated memory is not less than the size of IMA measurement list
   *        copy the measurement list to the allocated memory.
 - *    else return error
 + *    else
 + *        copy the measurement list as much as possible.
   */
  static int ima_dump_measurement_list(unsigned long *buffer_size, void **buffer,
                       unsigned long segment_size)
 @@ -XXX,XX +XXX,XX @@ static int ima_dump_measurement_list(unsigned long *buffer_size, void **buffer,
          }
      }
 -    if (ret < 0)
 -        goto out;
+-
      /*
       * fill in reserved space with some buffer details
       * (eg. version, buffer size, number of measurements)
 @@ -XXX,XX +XXX,XX @@ static int ima_dump_measurement_list(unsigned long *buffer_size, void **buffer,
      *buffer_size = ima_kexec_file.count;
      *buffer = ima_kexec_file.buf;
 -out:
++
      return ret;
  }
 @@ -XXX,XX +XXX,XX @@ void ima_add_kexec_buffer(struct kimage *image)
+     unsigned long binary_runtime_size;
      /* use more understandable variable names than defined in kbuf */
++    size_t kexec_buffer_size = 0;
      void *kexec_buffer = NULL;
-     size_t kexec_buffer_size = 0;
+-    size_t kexec_buffer_size;
 -    size_t kexec_segment_size;
      int ret;
      /*
 @@ -XXX,XX +XXX,XX @@ void ima_add_kexec_buffer(struct kimage *image)
          return;
      }
--    ret = ima_dump_measurement_list(&kexec_buffer_size, &kexec_buffer,
+-    ima_dump_measurement_list(&kexec_buffer_size, &kexec_buffer,
--                    kexec_segment_size);
+-                  kexec_segment_size);
--    if (ret < 0) {
+-    if (!kexec_buffer) {
--        pr_err("Failed to dump IMA measurements. Error:%d.\n", ret);
+-        pr_err("Not enough memory for the kexec measurement buffer.\n");
 -        return;
 -    }
 -
      kbuf.buffer = kexec_buffer;
      kbuf.bufsz = kexec_buffer_size;
      kbuf.memsz = kexec_segment_size;
 @@ -XXX,XX +XXX,XX @@ void ima_add_kexec_buffer(struct kimage *image)
-     image->ima_segment_index = image->nr_segments - 1;
-     image->is_ima_segment_index_set = true;
--    /*
--     * kexec owns kexec_buffer after kexec_add_buffer() is called
--     * and it will vfree() that buffer.
--     */
--    ima_reset_kexec_file(&ima_kexec_file);
--
-     kexec_dprintk("kexec measurement buffer for the loaded kernel at 0x%lx.\n",
-               kbuf.mem);
- }
-@@ -XXX,XX +XXX,XX @@ void ima_add_kexec_buffer(struct kimage *image)
  static int ima_update_kexec_buffer(struct notifier_block *self,
                     unsigned long action, void *data)
  {
 -    return NOTIFY_OK;
-+    void *buf = NULL;
 +    size_t buf_size = 0;
 +    int ret = NOTIFY_OK;
++    void *buf = NULL;
 +
 +    if (!kexec_in_progress) {
 +        pr_info("No kexec in progress.\n");
 +        return ret;
 +    }
 ...
 +    ima_kexec_buffer = NULL;
 +
 +    return ret;
  }
- struct notifier_block update_buffer_nb = {
+ static struct notifier_block update_buffer_nb = {
 --
 .25.1

-New patch
+[PATCH v11 7/9] ima: verify if the segment size has changed
+kexec 'load' may be called multiple times. Free and realloc the buffer
+only if the segment_size is changed from the previous kexec 'load' call.
+Signed-off-by: steven chen <chenste@linux.microsoft.com>
+---
+ security/integrity/ima/ima_kexec.c | 10 ++++++++++
+file changed, 10 insertions(+)
+diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c
+index XXXXXXX..XXXXXXX 100644
+--- a/security/integrity/ima/ima_kexec.c
++++ b/security/integrity/ima/ima_kexec.c
+@@ -XXX,XX +XXX,XX @@ static void ima_free_kexec_file_buf(struct seq_file *sf)
+ static int ima_alloc_kexec_file_buf(size_t segment_size)
+ {
++    /*
++     * kexec 'load' may be called multiple times.
++     * Free and realloc the buffer only if the segment_size is
++     * changed from the previous kexec 'load' call.
++     */
++    if (ima_kexec_file.buf && ima_kexec_file.size == segment_size)
++        goto out;
++
+     ima_free_kexec_file_buf(&ima_kexec_file);
+     /* segment size can't change between kexec load and execute */
+@@ -XXX,XX +XXX,XX @@ static int ima_alloc_kexec_file_buf(size_t segment_size)
+         return -ENOMEM;
+     ima_kexec_file.size = segment_size;
++
++out:
+     ima_kexec_file.read_pos = 0;
+     ima_kexec_file.count = sizeof(struct ima_kexec_hdr);    /* reserved space */
+--
+.25.1

-[PATCH v9 6/7] ima: make the kexec extra memory configurable
+[PATCH v11 8/9] ima: make the kexec extra memory configurable
 ...
 Signed-off-by: steven chen <chenste@linux.microsoft.com>
 Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
 Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
 ---
  security/integrity/ima/Kconfig     | 10 ++++++++++
- security/integrity/ima/ima_kexec.c | 16 ++++++++++------
+ security/integrity/ima/ima_kexec.c | 16 +++++++++++-----
-files changed, 20 insertions(+), 6 deletions(-)
+files changed, 21 insertions(+), 5 deletions(-)
 diff --git a/security/integrity/ima/Kconfig b/security/integrity/ima/Kconfig
 index XXXXXXX..XXXXXXX 100644
 --- a/security/integrity/ima/Kconfig
 +++ b/security/integrity/ima/Kconfig
 ...
 +++ b/security/integrity/ima/ima_kexec.c
 @@ -XXX,XX +XXX,XX @@ void ima_add_kexec_buffer(struct kimage *image)
                    .buf_min = 0, .buf_max = ULONG_MAX,
                    .top_down = true };
      unsigned long binary_runtime_size;
--
 +    unsigned long extra_memory;
      /* use more understandable variable names than defined in kbuf */
-     void *kexec_buffer = NULL;
      size_t kexec_buffer_size = 0;
+@@ -XXX,XX +XXX,XX @@ void ima_add_kexec_buffer(struct kimage *image)
      int ret;
      /*
 -     * Reserve an extra half page of memory for additional measurements
 -     * added during the kexec load.
 ...
 -    binary_runtime_size = ima_get_binary_runtime_size();
 +    if (CONFIG_IMA_KEXEC_EXTRA_MEMORY_KB <= 0)
 +        extra_memory = PAGE_SIZE / 2;
 +    else
 +        extra_memory = CONFIG_IMA_KEXEC_EXTRA_MEMORY_KB * 1024;
++
 +    binary_runtime_size = ima_get_binary_runtime_size() + extra_memory;
 +
      if (binary_runtime_size >= ULONG_MAX - PAGE_SIZE)
          kexec_segment_size = ULONG_MAX;
      else
 ...

-[PATCH v9 7/7] ima: measure kexec load and exec events as critical data
+[PATCH v11 9/9] ima: measure kexec load and exec events as critical data
 ...
 Signed-off-by: Tushar Sugandhi <tusharsu@linux.microsoft.com>
 Signed-off-by: steven chen <chenste@linux.microsoft.com>
 Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
 ---
  security/integrity/ima/ima.h       |  6 ++++++
- security/integrity/ima/ima_kexec.c | 20 ++++++++++++++++++++
+ security/integrity/ima/ima_kexec.c | 21 +++++++++++++++++++++
  security/integrity/ima/ima_queue.c |  5 +++++
-files changed, 31 insertions(+)
+files changed, 32 insertions(+)
 diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
 index XXXXXXX..XXXXXXX 100644
 --- a/security/integrity/ima/ima.h
 +++ b/security/integrity/ima/ima.h
 ...
  #include "ima.h"
  #ifdef CONFIG_IMA_KEXEC
 +#define IMA_KEXEC_EVENT_LEN 256
 +
+ static bool ima_kexec_update_registered;
  static struct seq_file ima_kexec_file;
- static void *ima_kexec_buffer;
  static size_t kexec_segment_size;
 @@ -XXX,XX +XXX,XX @@ static void ima_free_kexec_file_buf(struct seq_file *sf)
-     ima_reset_kexec_file(sf);
+     sf->count = 0;
  }
 +void ima_measure_kexec_event(const char *event_name)
 +{
 +    char ima_kexec_event[IMA_KEXEC_EVENT_LEN];
 +    size_t buf_size = 0;
 +    long len;
++    int n;
 +
 +    buf_size = ima_get_binary_runtime_size();
 +    len = atomic_long_read(&ima_htable.len);
 +
-+    int n = scnprintf(ima_kexec_event, IMA_KEXEC_EVENT_LEN,
++    n = scnprintf(ima_kexec_event, IMA_KEXEC_EVENT_LEN,
-+                    "kexec_segment_size=%lu;ima_binary_runtime_size=%lu;"
++              "kexec_segment_size=%lu;ima_binary_runtime_size=%lu;"
-+                    "ima_runtime_measurements_count=%ld;",
++              "ima_runtime_measurements_count=%ld;",
-+                    kexec_segment_size, buf_size, len);
++              kexec_segment_size, buf_size, len);
 +
 +    ima_measure_critical_data("ima_kexec", event_name, ima_kexec_event, n, false, NULL, 0);
 +}
 +
  static int ima_alloc_kexec_file_buf(size_t segment_size)
 ...

The current kernel behavior is IMA measurements snapshot is taken at
kexec 'load' and not at kexec 'execute'.  IMA log is then carried
over to the new kernel after kexec 'execute'.

New events can be measured during/after the IMA log snapshot at kexec 
'load' and before the system boots to the new kernel.  In this scenario,
the TPM PCRs are extended with these events, but they are not carried
over to the new kernel after kexec soft reboot since the snapshot is
already taken.  This results in mismatch between TPM PCR quotes and the
actual IMA measurements list after kexec soft reboot, which in turn
results in remote attestation failure.

To solve this problem - 
 - allocate the necessary buffer at kexec 'load' time,
 - populate the buffer with the IMA measurements at kexec 'execute' time, 
 - and measure two new IMA events 'kexec_load' and 'kexec_execute' as
   critical data to help detect missing events after kexec soft reboot.

The solution details include:
 - refactoring the existing code to allocate a buffer to hold IMA
   measurements at kexec 'load', and dump the measurements at kexec
   'execute'

- kexec functionality for mapping the segments from the current kernel
   to the subsequent one,

- necessary changes to the kexec_file_load syscall, enabling it to call
   the ima functions,

- registering a reboot notifier which gets called during kexec 'execute',

- introducing a new Kconfig option to configure the extra memory to be
   allocated for passing IMA log from the current Kernel to the next,
   
 - introducing two new events to be measured by IMA during kexec, to
   help diagnose if the IMA log was copied fully or partially, from the
   current Kernel to the next,

- excluding IMA segment while calculating and storing digest in function
   kexec_calculate_store_digests(), since IMA segment can be modified
   after the digest is computed during kexec 'load'.  This will ensure
   that the segment is not added to the 'purgatory_sha_regions', and thus
   not verified by verify_sha256_digest().

The changes proposed in this series ensure the integrity of the IMA
measurements is preserved across kexec soft reboots, thus significantly
improving the security of the kernel post kexec soft reboots.

There were previous attempts to fix this issue [1], [2], [3].  But they
were not merged into the mainline kernel.

We took inspiration from the past work [1] and [2] while working on this
patch series.

V4 of this series is available here[6] for reference.

V5 of this series is available here[7] for reference.

V6 of this series is available here[8] for reference.

V7 of this series is available here[9] for reference.

V8 of this series is available here[10] for reference.

References:
-----------

[1] [PATHC v2 5/9] ima: on soft reboot, save the measurement list
https://lore.kernel.org/lkml/1472596811-9596-6-git-send-email-zohar@linux.vnet.ibm.com/

[2] PATCH v2 4/6] kexec_file: Add mechanism to update kexec segments.
https://lkml.org/lkml/2016/8/16/577

[3] [PATCH 1/6] kexec_file: Add buffer hand-over support
https://lore.kernel.org/linuxppc-dev/1466473476-10104-6-git-send-email-bauerman@linux.vnet.ibm.com/T/

[4] [PATCH v2 0/7] ima: kexec: measure events between kexec load and execute
https://lore.kernel.org/all/20231005182602.634615-1-tusharsu@linux.microsoft.com/

[5] [PATCH v3 0/7] ima: kexec: measure events between kexec load and execute
https://lore.kernel.org/all/20231216010729.2904751-1-tusharsu@linux.microsoft.com/

[6] [PATCH v4 0/7] ima: kexec: measure events between kexec load and execute
https://lore.kernel.org/all/20240122183804.3293904-1-tusharsu@linux.microsoft.com/

[7] [PATCH v5 0/8] ima: kexec: measure events between kexec load and execute
https://lore.kernel.org/all/20240214153827.1087657-1-tusharsu@linux.microsoft.com/

[8] [PATCH v6 0/7] ima: kexec: measure events between kexec load and execute
https://lore.kernel.org/all/20250124225547.22684-1-chenste@linux.microsoft.com/

[9] [PATCH v7 0/7] ima: kexec: measure events between kexec load and execute
https://lore.kernel.org/all/20250203232033.64123-1-chenste@linux.microsoft.com/

[10] [PATCH v8 0/7] ima: kexec: measure events between kexec load and execute
https://lore.kernel.org/all/20250218225502.747963-1-chenste@linux.microsoft.com/

Change Log v9:
 - Incorporated feedback from the community (Stefan Berger, Mimi Zohar, 
   and kernel test robot) on v8 of this series[10].
 - Rebased the patch series to mainline 6.14.0-rc3.
 - Verified all the patches are bisect-safe by booting into each
   patch and verifying multiple kexec 'load' operations work,
   and also verifying kexec soft reboot works, and IMA log gets
   carried over for each patch.

Change Log v8:
 - Incorporated feedback from the community (Stefan Berger, Mimi Zohar) 
   on v7 of this series[9].
 - Rebased the patch series to mainline 6.14.0-rc1.
 - Verified all the patches are bisect-safe by booting into each
   patch and verifying multiple kexec 'load' operations work,
   and also verifying kexec soft reboot works, and IMA log gets
   carried over for each patch.

Change Log v7:
 - Incorporated feedback from the community (Stefan Berger, Tyler Hicks) 
   on v6 of this series[8].
 - Verified all the patches are bisect-safe by booting into each
   patch and verifying multiple kexec 'load' operations work,
   and also verifying kexec soft reboot works, and IMA log gets
   carried over for each patch.

Change Log v6:
 - Incorporated feedback from the community (Stefan Berger, Mimi Zohar,
   and Petr Tesařík) on v5 of this series[7].
 - Rebased the patch series to mainline 6.12.0.
 - Verified all the patches are bisect-safe by booting into each
   patch and verifying multiple kexec 'load' operations work,
   and also verifying kexec soft reboot works, and IMA log gets
   carried over for each patch.
 - Compared the memory size allocated with memory size of the entire 
   measurement record. If there is not enough memory, it will copy as many
   IMA measurement records as possible, and this situation will result
   in a failure of remote attestation.
 - [PATCH V5 6/8] was removed. Per petr comment on [PATCH V5 6/8], during
   the handover, other CPUs are taken offline (look for
   migrate_to_reboot_cpu() in kernel/kexec_core.c) and even the reboot CPU
   will be sufficiently shut down as not to be able to add any more
   measurements.

Change Log v5:
 - Incorporated feedback from the community (Stefan Berger and
   Mimi Zohar) on v4 of this series[6].
 - Rebased the patch series to mainline 6.8.0-rc1.
 - Verified all the patches are bisect-safe by booting into each
   patch and verifying multiple kexec 'load' operations work,
   and also verifying kexec soft reboot works, and IMA log gets
   carried over for each patch.
 - Divided the patch #4 in the v4 of the series[6] into two separate
   patches. One to setup the infrastructure/stub functions to prepare
   the IMA log copy from Kexec 'load' to 'execute', and another one
   to actually copy the log.
 - Updated the config description for IMA_KEXEC_EXTRA_MEMORY_KB
   to remove unnecessary references related to backwards compatibility.
 - Fixed a typo in log message/removed an extra line etc.
 - Updated patch descriptions as necessary.

Change Log v4:
 - Incorporated feedback from the community (Stefan Berger and
   Mimi Zohar) on v3 of this series[5].
 - Rearranged patches so that they remain bisect-safe i.e. the
   system can go through kexec soft reboot, and IMA log is carried
   over after each patch.
 - Verified all the patches are bisect-safe by booting into each
   patch and verifying kexec soft reboot works, and IMA log gets
   carried over.
 - Suspend-resume measurements is now a separate patch (patch #5)
   and all the relevant code is part of the same patch.
 - Excluding IMA segment from segment digest verification is now a
   separate patch. (patch #3).
 - Registering reboot notifier and functions related to move ima 
   log copy from kexec load to execute are now part of the same
   patch (patch #4) to protect bisect-safeness of the series.
 - Updated the title of patch #6 as per the feedback.
 - The default value of kexec extra memory for IMA measurements
   is set to half the PAGESIZE to maintain backwards compatibility.
 - Added number of IMA measurement records as part of 'kexec_load' 
   and 'kexec_execute' IMA critical data events.
 - Updated patch descriptions as necessary.

Change Log v3:
 - Incorporated feedback from the community (Stefan Berger and
   Mimi Zohar) on v2 of this series[4].
 - Renamed functions and removed extraneous checks and code comments.
 - Updated patch descriptions and titles as necessary.
 - Updated kexec_calculate_store_digests() in patch 2/7 to exclude ima
   segment from calculating and storing digest.
 - Updated patch 3/7 to use kmalloc_array instead of kmalloc and freed
   memory early to avoid potential memory leak.
 - Updated patch 6/7 to change Kconfig option IMA_KEXEC_EXTRA_PAGES to
   IMA_KEXEC_EXTRA_MEMORY_KB to allocate the memory in kb rather than
   in number of pages.
 - Optimized patch 7/7 not to free and alloc memory if the buffer size
   hasn't changed during multiple kexec 'load' operations.
 - Fixed a bug in patch 7/7 to measure multiple 'kexec_load' events even
   if buffer size hasn't changed.
 - Verified the patches are bisect-safe by compiling and booting into
   each patch individually.

Change Log v2:
 - Incorporated feedback from the community on v1 series.
 - Refactored the existing ima_dump_measurement_list to move buffer
   allocation functionality to ima_alloc_kexec_buf() function.
 - Introduced a new Kconfig option to configure the memory.
 - Updated the logic to copy the IMA log only in case of kexec soft 
   reboot, and not on kexec crash.
 - Updated the logic to copy as many IMA events as possible in case of
   memory constraint, rather than just bailing out.
 - Introduced two new events to be measured by IMA during kexec, to
   help diagnose if the IMA log was copied fully or partially from the
   current Kernel to the next.
 - Refactored patches to ensure no warnings during individual patch
   compilation.
 - Used virt_to_page instead of phys_to_page.
 - Updated patch descriptions as necessary.

steven chen (7):
  ima: copy only complete measurement records across kexec
  kexec: define functions to map and unmap segments
  ima: kexec: skip IMA segment validation after kexec soft reboot
  ima: kexec: define functions to copy IMA log at soft boot
  ima: kexec: move IMA log copy from kexec load to execute
  ima: make the kexec extra memory configurable
  ima: measure kexec load and exec events as critical data

-- 
2.25.1

Carrying the IMA measurement list across kexec requires allocating a
buffer and copying the measurement records.  Separate allocating the
buffer and copying the measurement records into separate functions in
order to allocate the buffer at kexec 'load' and copy the measurements
at kexec 'execute'.

This patch includes the following changes:
 - Refactor ima_dump_measurement_list() to move the memory allocation
   to a separate function ima_alloc_kexec_file_buf() which allocates
   buffer of size 'kexec_segment_size' at kexec 'load'.
 - Make the local variable ima_kexec_file in ima_dump_measurement_list()
   a local static to the file, so that it can be accessed from 
   ima_alloc_kexec_file_buf(). Compare actual memory required to ensure 
   there is enough memory for the entire measurement record.
 - Copy only complete measurement records.
 - Make necessary changes to the function ima_add_kexec_buffer() to call
   the above two functions.
 - Compared the memory size allocated with memory size of the entire 
   measurement record. Copy only complete measurement records if there 
   is enough memory. If there is not enough memory, it will not copy
   any IMA measurement records, and this situation will result in a 
   failure of remote attestation.

Suggested-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Tushar Sugandhi <tusharsu@linux.microsoft.com>
Signed-off-by: steven chen <chenste@linux.microsoft.com>
---
 security/integrity/ima/ima.h       |   1 +
 security/integrity/ima/ima_kexec.c | 105 ++++++++++++++++++++++-------
 security/integrity/ima/ima_queue.c |   4 +-
 3 files changed, 83 insertions(+), 27 deletions(-)

diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index XXXXXXX..XXXXXXX 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -XXX,XX +XXX,XX @@ bool ima_template_has_modsig(const struct ima_template_desc *ima_template);
 int ima_restore_measurement_entry(struct ima_template_entry *entry);
 int ima_restore_measurement_list(loff_t bufsize, void *buf);
 int ima_measurements_show(struct seq_file *m, void *v);
+int ima_get_binary_runtime_entry_size(struct ima_template_entry *entry);
 unsigned long ima_get_binary_runtime_size(void);
 int ima_init_template(void);
 void ima_init_template_list(void);
diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c
index XXXXXXX..XXXXXXX 100644
--- a/security/integrity/ima/ima_kexec.c
+++ b/security/integrity/ima/ima_kexec.c
@@ -XXX,XX +XXX,XX @@
 #include "ima.h"
 
 #ifdef CONFIG_IMA_KEXEC
+static struct seq_file ima_kexec_file;
+
+static void ima_reset_kexec_file(struct seq_file *sf)
+{
+	sf->buf = NULL;
+	sf->size = 0;
+	sf->read_pos = 0;
+	sf->count = 0;
+}
+
+static void ima_free_kexec_file_buf(struct seq_file *sf)
+{
+	vfree(sf->buf);
+	ima_reset_kexec_file(sf);
+}
+
+static int ima_alloc_kexec_file_buf(size_t segment_size)
+{
+	/*
+	 * kexec 'load' may be called multiple times.
+	 * Free and realloc the buffer only if the segment_size is
+	 * changed from the previous kexec 'load' call.
+	 */
+	if (ima_kexec_file.buf && ima_kexec_file.size == segment_size)
+		goto out;
+
+	ima_free_kexec_file_buf(&ima_kexec_file);
+
+	/* segment size can't change between kexec load and execute */
+	ima_kexec_file.buf = vmalloc(segment_size);
+	if (!ima_kexec_file.buf)
+		return -ENOMEM;
+
+	ima_kexec_file.size = segment_size;
+
+out:
+	ima_kexec_file.read_pos = 0;
+	ima_kexec_file.count = sizeof(struct ima_kexec_hdr);	/* reserved space */
+
+	return 0;
+}
+
+/*
+ * Copy the measurement list to the allocated memory
+ * compare the size of IMA measurement list with the size of the allocated memory
+ *    if the size of the allocated memory is not less than the size of IMA measurement list
+ *        copy the measurement list to the allocated memory.
+ *    else return error
+ */
 static int ima_dump_measurement_list(unsigned long *buffer_size, void **buffer,
 				     unsigned long segment_size)
 {
 	struct ima_queue_entry *qe;
-	struct seq_file file;
 	struct ima_kexec_hdr khdr;
 	int ret = 0;
+	size_t entry_size = 0;
 
-	/* segment size can't change between kexec load and execute */
-	file.buf = vmalloc(segment_size);
-	if (!file.buf) {
-		ret = -ENOMEM;
-		goto out;
+	if (!ima_kexec_file.buf) {
+		pr_err("Kexec file buf not allocated\n");
+		return -EINVAL;
 	}
 
-	file.file = NULL;
-	file.size = segment_size;
-	file.read_pos = 0;
-	file.count = sizeof(khdr);	/* reserved space */
-
 	memset(&khdr, 0, sizeof(khdr));
 	khdr.version = 1;
 	/* This is an append-only list, no need to hold the RCU read lock */
 	list_for_each_entry_rcu(qe, &ima_measurements, later, true) {
-		if (file.count < file.size) {
+		entry_size += ima_get_binary_runtime_entry_size(qe->entry);
+		if (entry_size <= segment_size) {
 			khdr.count++;
-			ima_measurements_show(&file, qe);
+			ima_measurements_show(&ima_kexec_file, qe);
 		} else {
 			ret = -EINVAL;
+			pr_err("IMA log file is too big for Kexec buf\n");
 			break;
 		}
 	}
 
 	if (ret < 0)
 		goto out;
-
 	/*
 	 * fill in reserved space with some buffer details
 	 * (eg. version, buffer size, number of measurements)
 	 */
-	khdr.buffer_size = file.count;
+	khdr.buffer_size = ima_kexec_file.count;
 	if (ima_canonical_fmt) {
 		khdr.version = cpu_to_le16(khdr.version);
 		khdr.count = cpu_to_le64(khdr.count);
 		khdr.buffer_size = cpu_to_le64(khdr.buffer_size);
 	}
-	memcpy(file.buf, &khdr, sizeof(khdr));
+	memcpy(ima_kexec_file.buf, &khdr, sizeof(khdr));
 
 	print_hex_dump_debug("ima dump: ", DUMP_PREFIX_NONE, 16, 1,
-			     file.buf, file.count < 100 ? file.count : 100,
+			     ima_kexec_file.buf, ima_kexec_file.count < 100 ?
+			     ima_kexec_file.count : 100,
 			     true);
 
-	*buffer_size = file.count;
-	*buffer = file.buf;
+	*buffer_size = ima_kexec_file.count;
+	*buffer = ima_kexec_file.buf;
+
 out:
-	if (ret == -EINVAL)
-		vfree(file.buf);
 	return ret;
 }
 
@@ -XXX,XX +XXX,XX @@ void ima_add_kexec_buffer(struct kimage *image)
 
 	/* use more understandable variable names than defined in kbuf */
 	void *kexec_buffer = NULL;
-	size_t kexec_buffer_size;
+	size_t kexec_buffer_size = 0;
 	size_t kexec_segment_size;
 	int ret;
 
@@ -XXX,XX +XXX,XX @@ void ima_add_kexec_buffer(struct kimage *image)
 		return;
 	}
 
-	ima_dump_measurement_list(&kexec_buffer_size, &kexec_buffer,
-				  kexec_segment_size);
-	if (!kexec_buffer) {
+	ret = ima_alloc_kexec_file_buf(kexec_segment_size);
+	if (ret < 0) {
 		pr_err("Not enough memory for the kexec measurement buffer.\n");
 		return;
 	}
 
+	ret = ima_dump_measurement_list(&kexec_buffer_size, &kexec_buffer,
+					kexec_segment_size);
+	if (ret < 0) {
+		pr_err("Failed to dump IMA measurements. Error:%d.\n", ret);
+		return;
+	}
+
 	kbuf.buffer = kexec_buffer;
 	kbuf.bufsz = kexec_buffer_size;
 	kbuf.memsz = kexec_segment_size;
@@ -XXX,XX +XXX,XX @@ void ima_add_kexec_buffer(struct kimage *image)
 	image->ima_buffer_size = kexec_segment_size;
 	image->ima_buffer = kexec_buffer;
 
+	/*
+	 * kexec owns kexec_buffer after kexec_add_buffer() is called
+	 * and it will vfree() that buffer.
+	 */
+	ima_reset_kexec_file(&ima_kexec_file);
+
 	kexec_dprintk("kexec measurement buffer for the loaded kernel at 0x%lx.\n",
 		      kbuf.mem);
 }
diff --git a/security/integrity/ima/ima_queue.c b/security/integrity/ima/ima_queue.c
index XXXXXXX..XXXXXXX 100644
--- a/security/integrity/ima/ima_queue.c
+++ b/security/integrity/ima/ima_queue.c
@@ -XXX,XX +XXX,XX @@ static struct ima_queue_entry *ima_lookup_digest_entry(u8 *digest_value,
  * binary_runtime_measurement list entry, which contains a
  * couple of variable length fields (e.g template name and data).
  */
-static int get_binary_runtime_size(struct ima_template_entry *entry)
+int ima_get_binary_runtime_entry_size(struct ima_template_entry *entry)
 {
 	int size = 0;
 
@@ -XXX,XX +XXX,XX @@ static int ima_add_digest_entry(struct ima_template_entry *entry,
 	if (binary_runtime_size != ULONG_MAX) {
 		int size;
 
-		size = get_binary_runtime_size(entry);
+		size = ima_get_binary_runtime_entry_size(entry);
 		binary_runtime_size = (binary_runtime_size < ULONG_MAX - size) ?
 		     binary_runtime_size + size : ULONG_MAX;
 	}
-- 
2.25.1

The content of memory segments carried over to the new kernel during the 
kexec systemcall can be changed at kexec 'execute' stage, but the size of
the memory segments cannot be changed at kexec 'execute' stage.

To copy IMA measurement logs during the kexec operation, IMA needs to 
allocate memory at the kexec 'load' stage and map the segments to the 
kimage structure. The mapped address will then be used to copy IMA 
measurements during the kexec 'execute' stage.

Currently, the mechanism to map and unmap segments to the kimage 
structure is not available to subsystems outside of kexec.

Implement kimage_map_segment() to enable IMA to map measurement log list to 
the kimage structure during kexec 'load' stage.  This function takes a kimage 
pointer, a memory address, and a size, then gathers the
source pages within the specified address range, creates an array of page
pointers, and maps these to a contiguous virtual address range.  The
function returns the start virtual address of this range if successful, or NULL on
failure.

Implement kimage_unmap_segment() for unmapping segments
using vunmap().

From: Tushar Sugandhi <tusharsu@linux.microsoft.com>
Signed-off-by: Tushar Sugandhi <tusharsu@linux.microsoft.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Baoquan He <bhe@redhat.com> 
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Dave Young <dyoung@redhat.com>
Signed-off-by: steven chen <chenste@linux.microsoft.com>
---
 include/linux/kexec.h |  6 +++++
 kernel/kexec_core.c   | 54 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 60 insertions(+)

diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index XXXXXXX..XXXXXXX 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -XXX,XX +XXX,XX @@ extern bool kexec_file_dbg_print;
 #define kexec_dprintk(fmt, arg...) \
         do { if (kexec_file_dbg_print) pr_info(fmt, ##arg); } while (0)
 
+extern void *kimage_map_segment(struct kimage *image, unsigned long addr, unsigned long size);
+extern void kimage_unmap_segment(void *buffer);
 #else /* !CONFIG_KEXEC_CORE */
 struct pt_regs;
 struct task_struct;
+struct kimage;
 static inline void __crash_kexec(struct pt_regs *regs) { }
 static inline void crash_kexec(struct pt_regs *regs) { }
 static inline int kexec_should_crash(struct task_struct *p) { return 0; }
 static inline int kexec_crash_loaded(void) { return 0; }
+static inline void *kimage_map_segment(struct kimage *image, unsigned long addr, unsigned long size)
+{ return NULL; }
+static inline void kimage_unmap_segment(void *buffer) { }
 #define kexec_in_progress false
 #endif /* CONFIG_KEXEC_CORE */
 
diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
index XXXXXXX..XXXXXXX 100644
--- a/kernel/kexec_core.c
+++ b/kernel/kexec_core.c
@@ -XXX,XX +XXX,XX @@ int kimage_load_segment(struct kimage *image,
 	return result;
 }
 
+void *kimage_map_segment(struct kimage *image,
+			 unsigned long addr, unsigned long size)
+{
+	unsigned long eaddr = addr + size;
+	unsigned long src_page_addr, dest_page_addr;
+	unsigned int npages;
+	struct page **src_pages;
+	int i;
+	kimage_entry_t *ptr, entry;
+	void *vaddr = NULL;
+
+	/*
+	 * Collect the source pages and map them in a contiguous VA range.
+	 */
+	npages = PFN_UP(eaddr) - PFN_DOWN(addr);
+	src_pages = kmalloc_array(npages, sizeof(*src_pages), GFP_KERNEL);
+	if (!src_pages) {
+		pr_err("Could not allocate ima pages array.\n");
+		return NULL;
+	}
+
+	i = 0;
+	for_each_kimage_entry(image, ptr, entry) {
+		if (entry & IND_DESTINATION) {
+			dest_page_addr = entry & PAGE_MASK;
+		} else if (entry & IND_SOURCE) {
+			if (dest_page_addr >= addr && dest_page_addr < eaddr) {
+				src_page_addr = entry & PAGE_MASK;
+				src_pages[i++] =
+					virt_to_page(__va(src_page_addr));
+				if (i == npages)
+					break;
+				dest_page_addr += PAGE_SIZE;
+			}
+		}
+	}
+
+	/* Sanity check. */
+	WARN_ON(i < npages);
+
+	vaddr = vmap(src_pages, npages, VM_MAP, PAGE_KERNEL);
+	kfree(src_pages);
+
+	if (!vaddr)
+		pr_err("Could not map ima buffer.\n");
+
+	return vaddr;
+}
+
+void kimage_unmap_segment(void *segment_buffer)
+{
+	vunmap(segment_buffer);
+}
+
 struct kexec_load_limit {
 	/* Mutex protects the limit count. */
 	struct mutex mutex;
-- 
2.25.1

The kexec_calculate_store_digests() function calculates and stores the
digest of the segment during the kexec_file_load syscall, where the 
IMA segment is also allocated.

With this series, the IMA segment will be updated with the measurement 
log at the kexec execute stage when a soft reboot is initiated. 
Therefore, the digests should be updated for the IMA segment in the 
normal case.

The content of memory segments carried over to the new kernel during the
kexec systemcall can be changed at kexec 'execute' stage, but the size
and the location of the memory segments cannot be changed at kexec
'execute' stage.

However, during the kexec execute stage, if kexec_calculate_store_digests()
API is call to update the digest, it does not reuse the same memory segment
allocated during the kexec 'load' stage and the new memory segment required
cannot be transferred/mapped to the new kernel.

As a result, digest verification will fail in verify_sha256_digest() 
after a kexec soft reboot into the new kernel. Therefore, the digest
calculation/verification of the IMA segment needs to be skipped.

To address this, skip the calculation and storage of the digest for the
IMA segment in kexec_calculate_store_digests() so that it is not added 
to the purgatory_sha_regions.

Since verify_sha256_digest() only verifies 'purgatory_sha_regions',
no change is needed in verify_sha256_digest() in this context.

With this change, the IMA segment is not included in the digest
calculation, storage, and verification.

Signed-off-by: Tushar Sugandhi <tusharsu@linux.microsoft.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Baoquan He <bhe@redhat.com> 
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Dave Young <dyoung@redhat.com>
Signed-off-by: steven chen <chenste@linux.microsoft.com>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
---
 include/linux/kexec.h              |  3 +++
 kernel/kexec_file.c                | 22 ++++++++++++++++++++++
 security/integrity/ima/ima_kexec.c |  3 +++
 3 files changed, 28 insertions(+)

diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index XXXXXXX..XXXXXXX 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -XXX,XX +XXX,XX @@ struct kimage {
 
 	phys_addr_t ima_buffer_addr;
 	size_t ima_buffer_size;
+
+	unsigned long ima_segment_index;
+	bool is_ima_segment_index_set;
 #endif
 
 	/* Core ELF header buffer */
diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index XXXXXXX..XXXXXXX 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -XXX,XX +XXX,XX @@ void set_kexec_sig_enforced(void)
 }
 #endif
 
+#ifdef CONFIG_IMA_KEXEC
+static bool check_ima_segment_index(struct kimage *image, int i)
+{
+	if (image->is_ima_segment_index_set && i == image->ima_segment_index)
+		return true;
+	else
+		return false;
+}
+#else
+static bool check_ima_segment_index(struct kimage *image, int i)
+{
+	return false;
+}
+#endif
+
 static int kexec_calculate_store_digests(struct kimage *image);
 
 /* Maximum size in bytes for kernel/initrd files. */
@@ -XXX,XX +XXX,XX @@ static int kexec_calculate_store_digests(struct kimage *image)
 		if (ksegment->kbuf == pi->purgatory_buf)
 			continue;
 
+		/*
+		 * Skip the segment if ima_segment_index is set and matches
+		 * the current index
+		 */
+		if (check_ima_segment_index(image, i))
+			continue;
+
 		ret = crypto_shash_update(desc, ksegment->kbuf,
 					  ksegment->bufsz);
 		if (ret)
diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c
index XXXXXXX..XXXXXXX 100644
--- a/security/integrity/ima/ima_kexec.c
+++ b/security/integrity/ima/ima_kexec.c
@@ -XXX,XX +XXX,XX @@ void ima_add_kexec_buffer(struct kimage *image)
 	kbuf.buffer = kexec_buffer;
 	kbuf.bufsz = kexec_buffer_size;
 	kbuf.memsz = kexec_segment_size;
+	image->is_ima_segment_index_set = false;
 	ret = kexec_add_buffer(&kbuf);
 	if (ret) {
 		pr_err("Error passing over kexec measurement buffer.\n");
@@ -XXX,XX +XXX,XX @@ void ima_add_kexec_buffer(struct kimage *image)
 	image->ima_buffer_addr = kbuf.mem;
 	image->ima_buffer_size = kexec_segment_size;
 	image->ima_buffer = kexec_buffer;
+	image->ima_segment_index = image->nr_segments - 1;
+	image->is_ima_segment_index_set = true;
 
 	/*
 	 * kexec owns kexec_buffer after kexec_add_buffer() is called
-- 
2.25.1

The IMA log is currently copied to the new kernel during kexec 'load' 
using ima_dump_measurement_list().  However, the log copied at kexec 
'load' may result in loss of IMA measurements that only occurred after
kexec "load'. Therefore, the log needs to be copied during kexec 
'execute'. Setup the needed infrastructure to move the IMA log copy from
kexec 'load' to 'execute'.

Define a new IMA hook ima_update_kexec_buffer() as a stub function.
It will be used to call ima_dump_measurement_list() during kexec 'execute'.

Implement ima_kexec_post_load() function to be invoked after the new 
Kernel image has been loaded for kexec. ima_kexec_post_load() maps the 
IMA buffer to a segment in the newly loaded Kernel.  It also registers 
the reboot notifier_block to trigger ima_update_kexec_buffer() at 
kexec 'execute'.

Signed-off-by: Tushar Sugandhi <tusharsu@linux.microsoft.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Baoquan He <bhe@redhat.com> 
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Dave Young <dyoung@redhat.com>
Signed-off-by: steven chen <chenste@linux.microsoft.com>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
---
 include/linux/ima.h                |  3 ++
 security/integrity/ima/ima_kexec.c | 47 ++++++++++++++++++++++++++++++
 2 files changed, 50 insertions(+)

diff --git a/include/linux/ima.h b/include/linux/ima.h
index XXXXXXX..XXXXXXX 100644
--- a/include/linux/ima.h
+++ b/include/linux/ima.h
@@ -XXX,XX +XXX,XX @@ static inline void ima_appraise_parse_cmdline(void) {}
 
 #ifdef CONFIG_IMA_KEXEC
 extern void ima_add_kexec_buffer(struct kimage *image);
+extern void ima_kexec_post_load(struct kimage *image);
+#else
+static inline void ima_kexec_post_load(struct kimage *image) {}
 #endif
 
 #else
diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c
index XXXXXXX..XXXXXXX 100644
--- a/security/integrity/ima/ima_kexec.c
+++ b/security/integrity/ima/ima_kexec.c
@@ -XXX,XX +XXX,XX @@
 #include <linux/kexec.h>
 #include <linux/of.h>
 #include <linux/ima.h>
+#include <linux/reboot.h>
+#include <asm/page.h>
 #include "ima.h"
 
 #ifdef CONFIG_IMA_KEXEC
 static struct seq_file ima_kexec_file;
+static void *ima_kexec_buffer;
+static bool ima_kexec_update_registered;
 
 static void ima_reset_kexec_file(struct seq_file *sf)
 {
@@ -XXX,XX +XXX,XX @@ void ima_add_kexec_buffer(struct kimage *image)
 	kexec_dprintk("kexec measurement buffer for the loaded kernel at 0x%lx.\n",
 		      kbuf.mem);
 }
+
+/*
+ * Called during kexec execute so that IMA can update the measurement list.
+ */
+static int ima_update_kexec_buffer(struct notifier_block *self,
+				   unsigned long action, void *data)
+{
+	return NOTIFY_OK;
+}
+
+struct notifier_block update_buffer_nb = {
+	.notifier_call = ima_update_kexec_buffer,
+	.priority = 1,
+};
+
+/*
+ * Create a mapping for the source pages that contain the IMA buffer
+ * so we can update it later.
+ */
+void ima_kexec_post_load(struct kimage *image)
+{
+	if (ima_kexec_buffer) {
+		kimage_unmap_segment(ima_kexec_buffer);
+		ima_kexec_buffer = NULL;
+	}
+
+	if (!image->ima_buffer_addr)
+		return;
+
+	ima_kexec_buffer = kimage_map_segment(image,
+					      image->ima_buffer_addr,
+					      image->ima_buffer_size);
+	if (!ima_kexec_buffer) {
+		pr_err("Could not map measurements buffer.\n");
+		return;
+	}
+
+	if (!ima_kexec_update_registered) {
+		register_reboot_notifier(&update_buffer_nb);
+		ima_kexec_update_registered = true;
+	}
+}
+
 #endif /* IMA_KEXEC */
 
 /*
-- 
2.25.1

ima_dump_measurement_list() is called during kexec 'load', which may
result in loss of IMA measurements during kexec soft reboot. Due to 
missed measurements that only occurred after kexec 'load', this function 
needs to be called during kexec 'execute'.

This patch includes the following changes:
 - Implement kimage_file_post_load() function to be invoked after the new
   kernel image has been loaded for kexec.
 - Call kimage_file_post_load() from kexec_file_load() syscall only for
   kexec soft reboot scenarios and not for KEXEC_FILE_ON_CRASH.  It will
   map the IMA segment, and register reboot notifier for the function
   ima_update_kexec_buffer() which would copy the IMA log at kexec soft
   reboot.
 - Make kexec_segment_size variable local static to the file so that it 
   becomes accessible both during kexec 'load' and 'execute'.
 - Move ima_dump_measurement_list() call from ima_add_kexec_buffer()
   to ima_update_kexec_buffer().
 - Copy the measurement list as much as possible.
 - Remove ima_reset_kexec_file() call from ima_add_kexec_buffer(), now
   that the buffer is being copied at kexec 'execute', and resetting the
   file at kexec 'load' would corrupt the buffer.

Signed-off-by: Tushar Sugandhi <tusharsu@linux.microsoft.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Baoquan He <bhe@redhat.com> 
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Dave Young <dyoung@redhat.com>
Signed-off-by: steven chen <chenste@linux.microsoft.com>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
---
 kernel/kexec_file.c                | 10 +++++++
 security/integrity/ima/ima_kexec.c | 48 ++++++++++++++++++------------
 2 files changed, 39 insertions(+), 19 deletions(-)

diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index XXXXXXX..XXXXXXX 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -XXX,XX +XXX,XX @@ kimage_validate_signature(struct kimage *image)
 }
 #endif
 
+static void kimage_file_post_load(struct kimage *image)
+{
+#ifdef CONFIG_IMA_KEXEC
+	ima_kexec_post_load(image);
+#endif
+}
+
 /*
  * In file mode list of segments is prepared by kernel. Copy relevant
  * data from user space, do error checking, prepare segment list
@@ -XXX,XX +XXX,XX @@ SYSCALL_DEFINE5(kexec_file_load, int, kernel_fd, int, initrd_fd,
 
 	kimage_terminate(image);
 
+	if (!(flags & KEXEC_FILE_ON_CRASH))
+		kimage_file_post_load(image);
+
 	ret = machine_kexec_post_load(image);
 	if (ret)
 		goto out;
diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c
index XXXXXXX..XXXXXXX 100644
--- a/security/integrity/ima/ima_kexec.c
+++ b/security/integrity/ima/ima_kexec.c
@@ -XXX,XX +XXX,XX @@
 #ifdef CONFIG_IMA_KEXEC
 static struct seq_file ima_kexec_file;
 static void *ima_kexec_buffer;
+static size_t kexec_segment_size;
 static bool ima_kexec_update_registered;
 
 static void ima_reset_kexec_file(struct seq_file *sf)
@@ -XXX,XX +XXX,XX @@ static int ima_alloc_kexec_file_buf(size_t segment_size)
  * compare the size of IMA measurement list with the size of the allocated memory
  *    if the size of the allocated memory is not less than the size of IMA measurement list
  *        copy the measurement list to the allocated memory.
- *    else return error
+ *    else
+ *        copy the measurement list as much as possible.
  */
 static int ima_dump_measurement_list(unsigned long *buffer_size, void **buffer,
 				     unsigned long segment_size)
@@ -XXX,XX +XXX,XX @@ static int ima_dump_measurement_list(unsigned long *buffer_size, void **buffer,
 		}
 	}
 
-	if (ret < 0)
-		goto out;
 	/*
 	 * fill in reserved space with some buffer details
 	 * (eg. version, buffer size, number of measurements)
@@ -XXX,XX +XXX,XX @@ static int ima_dump_measurement_list(unsigned long *buffer_size, void **buffer,
 	*buffer_size = ima_kexec_file.count;
 	*buffer = ima_kexec_file.buf;
 
-out:
 	return ret;
 }
 
@@ -XXX,XX +XXX,XX @@ void ima_add_kexec_buffer(struct kimage *image)
 	/* use more understandable variable names than defined in kbuf */
 	void *kexec_buffer = NULL;
 	size_t kexec_buffer_size = 0;
-	size_t kexec_segment_size;
 	int ret;
 
 	/*
@@ -XXX,XX +XXX,XX @@ void ima_add_kexec_buffer(struct kimage *image)
 		return;
 	}
 
-	ret = ima_dump_measurement_list(&kexec_buffer_size, &kexec_buffer,
-					kexec_segment_size);
-	if (ret < 0) {
-		pr_err("Failed to dump IMA measurements. Error:%d.\n", ret);
-		return;
-	}
-
 	kbuf.buffer = kexec_buffer;
 	kbuf.bufsz = kexec_buffer_size;
 	kbuf.memsz = kexec_segment_size;
@@ -XXX,XX +XXX,XX @@ void ima_add_kexec_buffer(struct kimage *image)
 	image->ima_segment_index = image->nr_segments - 1;
 	image->is_ima_segment_index_set = true;
 
-	/*
-	 * kexec owns kexec_buffer after kexec_add_buffer() is called
-	 * and it will vfree() that buffer.
-	 */
-	ima_reset_kexec_file(&ima_kexec_file);
-
 	kexec_dprintk("kexec measurement buffer for the loaded kernel at 0x%lx.\n",
 		      kbuf.mem);
 }
@@ -XXX,XX +XXX,XX @@ void ima_add_kexec_buffer(struct kimage *image)
 static int ima_update_kexec_buffer(struct notifier_block *self,
 				   unsigned long action, void *data)
 {
-	return NOTIFY_OK;
+	void *buf = NULL;
+	size_t buf_size = 0;
+	int ret = NOTIFY_OK;
+
+	if (!kexec_in_progress) {
+		pr_info("No kexec in progress.\n");
+		return ret;
+	}
+
+	if (!ima_kexec_buffer) {
+		pr_err("Kexec buffer not set.\n");
+		return ret;
+	}
+
+	ret = ima_dump_measurement_list(&buf_size, &buf, kexec_segment_size);
+
+	if (ret)
+		pr_err("Dump measurements failed. Error:%d\n", ret);
+
+	if (buf_size != 0)
+		memcpy(ima_kexec_buffer, buf, buf_size);
+
+	kimage_unmap_segment(ima_kexec_buffer);
+	ima_kexec_buffer = NULL;
+
+	return ret;
 }
 
 struct notifier_block update_buffer_nb = {
-- 
2.25.1

The extra memory allocated for carrying the IMA measurement list across
kexec is hard-coded as half a PAGE.  Make it configurable.

Define a Kconfig option, IMA_KEXEC_EXTRA_MEMORY_KB, to configure the
extra memory (in kb) to be allocated for IMA measurements added during
kexec soft reboot.  Ensure the default value of the option is set such
that extra half a page of memory for additional measurements is allocated
for the additional measurements.

Update ima_add_kexec_buffer() function to allocate memory based on the
Kconfig option value, rather than the currently hard-coded one.

Suggested-by: Stefan Berger <stefanb@linux.ibm.com>
Signed-off-by: Tushar Sugandhi <tusharsu@linux.microsoft.com>
Signed-off-by: steven chen <chenste@linux.microsoft.com>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
---
 security/integrity/ima/Kconfig     | 10 ++++++++++
 security/integrity/ima/ima_kexec.c | 16 ++++++++++------
 2 files changed, 20 insertions(+), 6 deletions(-)

diff --git a/security/integrity/ima/Kconfig b/security/integrity/ima/Kconfig
index XXXXXXX..XXXXXXX 100644
--- a/security/integrity/ima/Kconfig
+++ b/security/integrity/ima/Kconfig
@@ -XXX,XX +XXX,XX @@ config IMA_DISABLE_HTABLE
 	help
 	   This option disables htable to allow measurement of duplicate records.
 
+config IMA_KEXEC_EXTRA_MEMORY_KB
+	int "Extra memory for IMA measurements added during kexec soft reboot"
+	depends on IMA_KEXEC
+	default 0
+	help
+	  IMA_KEXEC_EXTRA_MEMORY_KB determines the extra memory to be
+	  allocated (in kb) for IMA measurements added during kexec soft reboot.
+	  If set to the default value of 0, an extra half page of memory for those
+	  additional measurements will be allocated.
+
 endif
diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c
index XXXXXXX..XXXXXXX 100644
--- a/security/integrity/ima/ima_kexec.c
+++ b/security/integrity/ima/ima_kexec.c
@@ -XXX,XX +XXX,XX @@ void ima_add_kexec_buffer(struct kimage *image)
 				  .buf_min = 0, .buf_max = ULONG_MAX,
 				  .top_down = true };
 	unsigned long binary_runtime_size;
-
+	unsigned long extra_memory;
 	/* use more understandable variable names than defined in kbuf */
 	void *kexec_buffer = NULL;
 	size_t kexec_buffer_size = 0;
 	int ret;
 
 	/*
-	 * Reserve an extra half page of memory for additional measurements
-	 * added during the kexec load.
+	 * Reserve extra memory for measurements added during kexec.
 	 */
-	binary_runtime_size = ima_get_binary_runtime_size();
+	if (CONFIG_IMA_KEXEC_EXTRA_MEMORY_KB <= 0)
+		extra_memory = PAGE_SIZE / 2;
+	else
+		extra_memory = CONFIG_IMA_KEXEC_EXTRA_MEMORY_KB * 1024;
+	binary_runtime_size = ima_get_binary_runtime_size() + extra_memory;
+
 	if (binary_runtime_size >= ULONG_MAX - PAGE_SIZE)
 		kexec_segment_size = ULONG_MAX;
 	else
-		kexec_segment_size = ALIGN(ima_get_binary_runtime_size() +
-					   PAGE_SIZE / 2, PAGE_SIZE);
+		kexec_segment_size = ALIGN(binary_runtime_size, PAGE_SIZE);
+
 	if ((kexec_segment_size == ULONG_MAX) ||
 	    ((kexec_segment_size >> PAGE_SHIFT) > totalram_pages() / 2)) {
 		pr_err("Binary measurement list too large.\n");
-- 
2.25.1

The amount of memory allocated at kexec load, even with the extra memory
allocated, might not be large enough for the entire measurement list.  The
indeterminate interval between kexec 'load' and 'execute' could exacerbate
this problem.

Define two new IMA events, 'kexec_load' and 'kexec_execute', to be 
measured as critical data at kexec 'load' and 'execute' respectively.
Report the allocated kexec segment size, IMA binary log size and the
runtime measurements count as part of those events.

These events, and the values reported through them, serve as markers in
the IMA log to verify the IMA events are captured during kexec soft
reboot.  The presence of a 'kexec_load' event in between the last two
'boot_aggregate' events in the IMA log implies this is a kexec soft
reboot, and not a cold-boot. And the absence of 'kexec_execute' event
after kexec soft reboot implies missing events in that window which
results in inconsistency with TPM PCR quotes, necessitating a cold boot
for a successful remote attestation.

These critical data events are displayed as hex encoded ascii in the
ascii_runtime_measurement_list.  Verifying the critical data hash requires 
calculating the hash of the decoded ascii string.

For example, to verify the 'kexec_load' data hash:

sudo cat /sys/kernel/security/integrity/ima/ascii_runtime_measurements 
| grep  kexec_load | cut -d' ' -f 6 | xxd -r -p | sha256sum

To verify the 'kexec_execute' data hash:

sudo cat /sys/kernel/security/integrity/ima/ascii_runtime_measurements 
| grep kexec_execute | cut -d' ' -f 6 | xxd -r -p | sha256sum

Signed-off-by: Tushar Sugandhi <tusharsu@linux.microsoft.com>
Signed-off-by: steven chen <chenste@linux.microsoft.com>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
---
 security/integrity/ima/ima.h       |  6 ++++++
 security/integrity/ima/ima_kexec.c | 20 ++++++++++++++++++++
 security/integrity/ima/ima_queue.c |  5 +++++
 3 files changed, 31 insertions(+)

diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index XXXXXXX..XXXXXXX 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -XXX,XX +XXX,XX @@ void ima_post_key_create_or_update(struct key *keyring, struct key *key,
 				   unsigned long flags, bool create);
 #endif
 
+#ifdef CONFIG_IMA_KEXEC
+void ima_measure_kexec_event(const char *event_name);
+#else
+static inline void ima_measure_kexec_event(const char *event_name) {}
+#endif
+
 /*
  * The default binary_runtime_measurements list format is defined as the
  * platform native format.  The canonical format is defined as little-endian.
diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c
index XXXXXXX..XXXXXXX 100644
--- a/security/integrity/ima/ima_kexec.c
+++ b/security/integrity/ima/ima_kexec.c
@@ -XXX,XX +XXX,XX @@
 #include "ima.h"
 
 #ifdef CONFIG_IMA_KEXEC
+#define IMA_KEXEC_EVENT_LEN 256
+
 static struct seq_file ima_kexec_file;
 static void *ima_kexec_buffer;
 static size_t kexec_segment_size;
@@ -XXX,XX +XXX,XX @@ static void ima_free_kexec_file_buf(struct seq_file *sf)
 	ima_reset_kexec_file(sf);
 }
 
+void ima_measure_kexec_event(const char *event_name)
+{
+	char ima_kexec_event[IMA_KEXEC_EVENT_LEN];
+	size_t buf_size = 0;
+	long len;
+
+	buf_size = ima_get_binary_runtime_size();
+	len = atomic_long_read(&ima_htable.len);
+
+	int n = scnprintf(ima_kexec_event, IMA_KEXEC_EVENT_LEN,
+					"kexec_segment_size=%lu;ima_binary_runtime_size=%lu;"
+					"ima_runtime_measurements_count=%ld;",
+					kexec_segment_size, buf_size, len);
+
+	ima_measure_critical_data("ima_kexec", event_name, ima_kexec_event, n, false, NULL, 0);
+}
+
 static int ima_alloc_kexec_file_buf(size_t segment_size)
 {
 	/*
@@ -XXX,XX +XXX,XX @@ static int ima_alloc_kexec_file_buf(size_t segment_size)
 out:
 	ima_kexec_file.read_pos = 0;
 	ima_kexec_file.count = sizeof(struct ima_kexec_hdr);	/* reserved space */
+	ima_measure_kexec_event("kexec_load");
 
 	return 0;
 }
diff --git a/security/integrity/ima/ima_queue.c b/security/integrity/ima/ima_queue.c
index XXXXXXX..XXXXXXX 100644
--- a/security/integrity/ima/ima_queue.c
+++ b/security/integrity/ima/ima_queue.c
@@ -XXX,XX +XXX,XX @@ static int ima_reboot_notifier(struct notifier_block *nb,
 			       unsigned long action,
 			       void *data)
 {
+#ifdef CONFIG_IMA_KEXEC
+	if (action == SYS_RESTART && data && !strcmp(data, "kexec reboot"))
+		ima_measure_kexec_event("kexec_execute");
+#endif
+
 	ima_measurements_suspend();
 
 	return NOTIFY_DONE;
-- 
2.25.1

The current kernel behavior is IMA measurements snapshot is taken at
kexec 'load' and not at kexec 'execute'.  IMA log is then carried
over to the new kernel after kexec 'execute'.

Currently, the kernel behavior during kexec load is to fetch the IMA
measurements log from TPM PCRs and store it in a buffer. When a kexec 
reboot is triggered, this stored log buffer is carried over to the second
kernel. However, the time gap between kexec load and kexec reboot can be
very long. During this time window, new events extended into TPM PCRs miss
the chance to be carried over to the second kernel. This results in 
mismatch between TPM PCR quotes and the actual IMA measurements list after 
kexec soft reboot, which in turn results in remote attestation failure.

The solution details include:
 - refactoring the existing code to allocate a buffer to hold IMA
   measurements at kexec 'load', and dump the measurements at kexec
   'execute'

- kexec functionality for mapping the segments from the current kernel
   to the subsequent one,

- necessary changes to the kexec_file_load syscall, enabling it to call
   the ima functions,

- registering a reboot notifier which gets called during kexec 'execute',

There were previous attempts to fix this issue [1], [2], [3].  But they
were not merged into the mainline kernel.

We took inspiration from the past work [1] and [2] while working on this
patch series.

V4 of this series is available here[6] for reference.

V5 of this series is available here[7] for reference.

V6 of this series is available here[8] for reference.

V7 of this series is available here[9] for reference.

V8 of this series is available here[10] for reference.

V9 of this series is available here[11] for reference.

V10 of this series is available here[12] for reference.