On 1/22/24 13:37, Tushar Sugandhi wrote:
Refactor ima_dump_measurement_list() to move the memory allocation part
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 function ima_dump_measurement_list() as local static to
the file, so that it can be accessed from ima_alloc_kexec_file_buf().
Make necessary changes to the function ima_add_kexec_buffer() to call the
above two functions.
Signed-off-by: Tushar Sugandhi <tusharsu@xxxxxxxxxxxxxxxxxxx>
---
security/integrity/ima/ima_kexec.c | 96 +++++++++++++++++++++---------
1 file changed, 67 insertions(+), 29 deletions(-)
diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c
index 419dc405c831..99daac355c70 100644
--- a/security/integrity/ima/ima_kexec.c
+++ b/security/integrity/ima/ima_kexec.c
@@ -15,62 +15,93 @@
#include "ima.h"
#ifdef CONFIG_IMA_KEXEC
+static struct seq_file ima_kexec_file;
+
+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 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 &&
+ ima_kexec_file.read_pos == 0 &&
+ ima_kexec_file.count == sizeof(struct ima_kexec_hdr))
+ return 0;
+
+ 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;
+ ima_kexec_file.read_pos = 0;
+ ima_kexec_file.count = sizeof(struct ima_kexec_hdr); /* reserved space */
+
+ return 0;
+}
+
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;
- /* 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) {
+ *buffer_size = 0;
+ *buffer = NULL;
+ pr_err("%s: Kexec file buf not allocated\n", __func__);
+ return -EINVAL;
}
- file.size = segment_size;
- file.read_pos = 0;
- file.count = sizeof(khdr); /* reserved space */
-
memset(&khdr, 0, sizeof(khdr));
khdr.version = 1;
+
+ /* Copy as many IMA measurements list records as possible */
list_for_each_entry_rcu(qe, &ima_measurements, later) {
- 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;
+ pr_err("%s: IMA log file is too big for Kexec buf\n",
+ __func__);
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;
-out:
- if (ret == -EINVAL)
- vfree(file.buf);
- return ret;
+ *buffer_size = ima_kexec_file.count;
+ *buffer = ima_kexec_file.buf;
+
+ return 0;
}
/*
@@ -108,13 +139,20 @@ 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("%s: Failed to dump IMA measurements. Error:%d.\n",
+ __func__, ret);
+ return;
+ }
+
kbuf.buffer = kexec_buffer;
kbuf.bufsz = kexec_buffer_size;
kbuf.memsz = kexec_segment_size;
A dent with this patch when only applying this patch:
Two consecutive kexec loads lead to this here:
[ 30.670330] IMA buffer at 0x3fff10000, size = 0xf0000
[ 32.519618] ------------[ cut here ]------------
[ 32.519669] Trying to vfree() nonexistent vm area (00000000093ae29c)
[ 32.519762] WARNING: CPU: 11 PID: 1796 at mm/vmalloc.c:2826
vfree+0x254/0x340
[ 32.519786] Modules linked in: bonding tls rfkill sunrpc
virtio_console virtio_balloon crct10dif_vpmsum fuse loop zram bochs
drm_vram_helper drm_kms_helper drm_ttm_helper ttm ibmvscsi
scsi_transport_srp drm virtio_blk virtio_net vmx_crypto net_failover
crc32c_vpmsum failover pseries_wdt drm_panel_orientation_quirks
scsi_dh_rdac scsi_dh_emc scsi_dh_alua dm_multipath
[ 32.519939] CPU: 11 PID: 1796 Comm: kexec Not tainted 6.5.0+ #112
[ 32.519953] Hardware name: IBM pSeries (emulated by qemu) POWER8E
(raw) 0x4b0201 0xf000004 of:SLOF,git-5b4c5a hv:linux,kvm pSeries
[ 32.519973] NIP: c0000000004bd004 LR: c0000000004bd000 CTR:
c00000000017ef00
[ 32.519986] REGS: c00000004593b670 TRAP: 0700 Not tainted (6.5.0+)
[ 32.519999] MSR: 8000000002029033 <SF,VEC,EE,ME,IR,DR,RI,LE> CR:
44424842 XER: 00000000
[ 32.520023] CFAR: c0000000001515b0 IRQMASK: 0
GPR00: c0000000004bd000 c00000004593b910
c000000001e17000 0000000000000038
GPR04: 00000000ffffbfff c00000004593b6e8
c00000004593b6e0 00000003f9580000
GPR08: 0000000000000027 c0000003fb707010
0000000000000001 0000000044424842
GPR12: c00000000017ef00 c00000003fff1300
0000000000000000 0000000000000000
GPR16: 0000000000000000 0000000000000000
0000000000000000 0000000000000000
GPR20: 0000000000000000 0000000000000000
0000000000000003 0000000000000004
GPR24: 00007fffeab0f68f 000000000000004c
0000000000000000 c00000002bdce400
GPR28: c000000002bf28f0 0000000000000000
c008000004770000 0000000000000000
[ 32.520180] NIP [c0000000004bd004] vfree+0x254/0x340
[ 32.520212] LR [c0000000004bd000] vfree+0x250/0x340
[ 32.520225] Call Trace:
[ 32.520232] [c00000004593b910] [c0000000004bd000] vfree+0x250/0x340
(unreliable)
[ 32.520250] [c00000004593b990] [c00000000091d590]
ima_add_kexec_buffer+0xe0/0x3c0
[ 32.520296] [c00000004593ba90] [c000000000280968]
sys_kexec_file_load+0x148/0x9b0
[ 32.520333] [c00000004593bb70] [c00000000002ea84]
system_call_exception+0x174/0x320
[ 32.520372] [c00000004593be50] [c00000000000d6a0]
system_call_common+0x160/0x2c4
[ 32.520408] --- interrupt: c00 at 0x7fffa52e7ae4
[ 32.520420] NIP: 00007fffa52e7ae4 LR: 0000000108481d8c CTR:
0000000000000000
[ 32.520452] REGS: c00000004593be80 TRAP: 0c00 Not tainted (6.5.0+)
[ 32.520483] MSR: 800000000000f033 <SF,EE,PR,FP,ME,IR,DR,RI,LE> CR:
24424202 XER: 00000000
[ 32.520507] IRQMASK: 0
GPR00: 000000000000017e 00007fffeab09470
00007fffa53f6f00 0000000000000003
GPR04: 0000000000000004 000000000000004c
00007fffeab0f68f 0000000000000000
GPR08: 0000000000000000 0000000000000000
0000000000000000 0000000000000000
GPR12: 0000000000000000 00007fffa559b280
0000000000000002 0000000000000001
GPR16: 0000000000000000 0000000000000000
0000000000000000 0000000000000000
GPR20: 00007fffa53f0454 00007fffa53f0458
0000000000000000 0000000000000001
GPR24: 0000000000000000 00007fffeab0f64d
0000000000000006 0000000000000000
GPR28: 0000000000000003 00007fffeab09530
00007fffeab09b08 0000000000000007
[ 32.520767] NIP [00007fffa52e7ae4] 0x7fffa52e7ae4
[ 32.521192] LR [0000000108481d8c] 0x108481d8c
[ 32.521587] --- interrupt: c00
[ 32.521981] Code: 3884c208 4bfc20f1 60000000 0fe00000 60000000
60000000 60420000 3c62ff94 7fc4f378 38632b20 4bc944cd 60000000
<0fe00000> eba10068 4bffff34 2c080000
[ 32.522823] ---[ end trace 0000000000000000 ]---
[ 32.536347] Removed old IMA buffer reservation.
[ 32.536473] IMA buffer at 0x3fff10000, size = 0xf0000
This vfree here probably has to go:
ret = kexec_add_buffer(&kbuf);
if (ret) {
pr_err("Error passing over kexec measurement buffer.\n");
vfree(kexec_buffer);
return;
}
