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ima/evm: Fix type mismatch

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The endianness of a variable written to the measurement list cannot be
determined at compile time, as it depends on the value of the
ima_canonical_fmt global variable (set through a kernel option with the
same name if the machine is big endian).

If ima_canonical_fmt is false, the endianness of a variable is the same as
the machine; if ima_canonical_fmt is true, the endianness is little endian.
The warning arises due to this type of instruction:

var = cpu_to_leXX(var)

which tries to assign a value in little endian to a variable with native
endianness (little or big endian).

Given that the variables set with this instruction are not used in any
operation but just written to a buffer, it is safe to force the type of the
value being set to be the same of the type of the variable with:

var = (__force <var type>)cpu_to_leXX(var)

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
This commit is contained in:
Roberto Sassu 2021-06-08 14:31:22 +02:00 committed by Mimi Zohar
parent 24c9ae23bd
commit 6b26285f44
4 changed files with 12 additions and 11 deletions
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2
security/integrity/evm/evm_main.c
View File

@ -360,7 +360,7 @@ int evm_read_protected_xattrs(struct dentry *dentry, u8 *buffer,
size = sizeof(u32);
if (buffer) {
if (canonical_fmt)
rc = cpu_to_le32(rc);
rc = (__force int)cpu_to_le32(rc);
*(u32 *)(buffer + total_size) = rc;
}

4
security/integrity/ima/ima_crypto.c
View File

@ -598,8 +598,8 @@ static int ima_calc_field_array_hash_tfm(struct ima_field_data *field_data,
u8 buffer[IMA_EVENT_NAME_LEN_MAX + 1] = { 0 };
u8 *data_to_hash = field_data[i].data;
u32 datalen = field_data[i].len;
u32 datalen_to_hash =
!ima_canonical_fmt ? datalen : cpu_to_le32(datalen);
u32 datalen_to_hash = !ima_canonical_fmt ?
datalen : (__force u32)cpu_to_le32(datalen);
if (strcmp(td->name, IMA_TEMPLATE_IMA_NAME) != 0) {
rc = crypto_shash_update(shash,

6
security/integrity/ima/ima_fs.c
View File

@ -147,7 +147,7 @@ int ima_measurements_show(struct seq_file *m, void *v)
* PCR used defaults to the same (config option) in
* little-endian format, unless set in policy
*/
pcr = !ima_canonical_fmt ? e->pcr : cpu_to_le32(e->pcr);
pcr = !ima_canonical_fmt ? e->pcr : (__force u32)cpu_to_le32(e->pcr);
ima_putc(m, &pcr, sizeof(e->pcr));
/* 2nd: template digest */
@ -155,7 +155,7 @@ int ima_measurements_show(struct seq_file *m, void *v)
/* 3rd: template name size */
namelen = !ima_canonical_fmt ? strlen(template_name) :
cpu_to_le32(strlen(template_name));
(__force u32)cpu_to_le32(strlen(template_name));
ima_putc(m, &namelen, sizeof(namelen));
/* 4th: template name */
@ -167,7 +167,7 @@ int ima_measurements_show(struct seq_file *m, void *v)
if (!is_ima_template) {
template_data_len = !ima_canonical_fmt ? e->template_data_len :
cpu_to_le32(e->template_data_len);
(__force u32)cpu_to_le32(e->template_data_len);
ima_putc(m, &template_data_len, sizeof(e->template_data_len));
}

11
security/integrity/ima/ima_template_lib.c
View File

@ -133,7 +133,8 @@ static void ima_show_template_data_binary(struct seq_file *m,
strlen(field_data->data) : field_data->len;
if (show != IMA_SHOW_BINARY_NO_FIELD_LEN) {
u32 field_len = !ima_canonical_fmt ? len : cpu_to_le32(len);
u32 field_len = !ima_canonical_fmt ?
len : (__force u32)cpu_to_le32(len);
ima_putc(m, &field_len, sizeof(field_len));
}
@ -570,9 +571,9 @@ static int ima_eventinodedac_init_common(struct ima_event_data *event_data,
if (ima_canonical_fmt) {
if (sizeof(id) == sizeof(u16))
id = cpu_to_le16(id);
id = (__force u16)cpu_to_le16(id);
else
id = cpu_to_le32(id);
id = (__force u32)cpu_to_le32(id);
}
return ima_write_template_field_data((void *)&id, sizeof(id),
@ -607,7 +608,7 @@ int ima_eventinodemode_init(struct ima_event_data *event_data,
struct ima_field_data *field_data)
{
struct inode *inode;
umode_t mode;
u16 mode;
if (!event_data->file)
return 0;
@ -615,7 +616,7 @@ int ima_eventinodemode_init(struct ima_event_data *event_data,
inode = file_inode(event_data->file);
mode = inode->i_mode;
if (ima_canonical_fmt)
mode = cpu_to_le16(mode);
mode = (__force u16)cpu_to_le16(mode);
return ima_write_template_field_data((char *)&mode, sizeof(mode),
DATA_FMT_UINT, field_data);