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Subject[PATCH 3.16 077/127] ima: provide flag to identify new empty files
Date
3.16-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Dmitry Kasatkin <d.kasatkin@samsung.com>

commit b151d6b00bbb798c58f2f21305e7d43fa763f34f upstream.

On ima_file_free(), newly created empty files are not labeled with
an initial security.ima value, because the iversion did not change.
Commit dff6efc "fs: fix iversion handling" introduced a change in
iversion behavior. To verify this change use the shell command:

$ (exec >foo)
$ getfattr -h -e hex -d -m security foo

This patch defines the IMA_NEW_FILE flag. The flag is initially
set, when IMA detects that a new file is created, and subsequently
checked on the ima_file_free() hook to set the initial security.ima
value.

Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
security/integrity/ima/ima_appraise.c | 7 +++++--
security/integrity/ima/ima_main.c | 12 +++++++-----
security/integrity/integrity.h | 1 +
3 files changed, 13 insertions(+), 7 deletions(-)

--- a/security/integrity/ima/ima_appraise.c
+++ b/security/integrity/ima/ima_appraise.c
@@ -194,8 +194,11 @@ int ima_appraise_measurement(int func, s
goto out;

cause = "missing-hash";
- status =
- (inode->i_size == 0) ? INTEGRITY_PASS : INTEGRITY_NOLABEL;
+ status = INTEGRITY_NOLABEL;
+ if (inode->i_size == 0) {
+ iint->flags |= IMA_NEW_FILE;
+ status = INTEGRITY_PASS;
+ }
goto out;
}

--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -128,11 +128,13 @@ static void ima_check_last_writer(struct
return;

mutex_lock(&inode->i_mutex);
- if (atomic_read(&inode->i_writecount) == 1 &&
- iint->version != inode->i_version) {
- iint->flags &= ~IMA_DONE_MASK;
- if (iint->flags & IMA_APPRAISE)
- ima_update_xattr(iint, file);
+ if (atomic_read(&inode->i_writecount) == 1) {
+ if ((iint->version != inode->i_version) ||
+ (iint->flags & IMA_NEW_FILE)) {
+ iint->flags &= ~(IMA_DONE_MASK | IMA_NEW_FILE);
+ if (iint->flags & IMA_APPRAISE)
+ ima_update_xattr(iint, file);
+ }
}
mutex_unlock(&inode->i_mutex);
}
--- a/security/integrity/integrity.h
+++ b/security/integrity/integrity.h
@@ -31,6 +31,7 @@
#define IMA_DIGSIG 0x01000000
#define IMA_DIGSIG_REQUIRED 0x02000000
#define IMA_PERMIT_DIRECTIO 0x04000000
+#define IMA_NEW_FILE 0x08000000

#define IMA_DO_MASK (IMA_MEASURE | IMA_APPRAISE | IMA_AUDIT | \
IMA_APPRAISE_SUBMASK)



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