6.6-stable review patch. If anyone has any objections, please let me know.
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From: Mimi Zohar zohar@linux.ibm.com
[ Upstream commit a414016218ca97140171aa3bb926b02e1f68c2cc ]
Each time a file in policy, that is already opened for read, is opened for write, a Time-of-Measure-Time-of-Use (ToMToU) integrity violation audit message is emitted and a violation record is added to the IMA measurement list. This occurs even if a ToMToU violation has already been recorded.
Limit the number of ToMToU integrity violations per file open for read.
Note: The IMA_MAY_EMIT_TOMTOU atomic flag must be set from the reader side based on policy. This may result in a per file open for read ToMToU violation.
Since IMA_MUST_MEASURE is only used for violations, rename the atomic IMA_MUST_MEASURE flag to IMA_MAY_EMIT_TOMTOU.
Cc: stable@vger.kernel.org # applies cleanly up to linux-6.6 Tested-by: Stefan Berger stefanb@linux.ibm.com Reviewed-by: Petr Vorel pvorel@suse.cz Tested-by: Petr Vorel pvorel@suse.cz Reviewed-by: Roberto Sassu roberto.sassu@huawei.com Signed-off-by: Mimi Zohar zohar@linux.ibm.com [ adapted IMA flag definitions location from ima.h to integrity.h ] Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- security/integrity/ima/ima_main.c | 16 +++++++++++----- security/integrity/integrity.h | 3 ++- 2 files changed, 13 insertions(+), 6 deletions(-)
--- a/security/integrity/ima/ima_main.c +++ b/security/integrity/ima/ima_main.c @@ -128,16 +128,22 @@ static void ima_rdwr_violation_check(str if (atomic_read(&inode->i_readcount) && IS_IMA(inode)) { if (!iint) iint = integrity_iint_find(inode); + /* IMA_MEASURE is set from reader side */ - if (iint && test_bit(IMA_MUST_MEASURE, - &iint->atomic_flags)) + if (iint && test_and_clear_bit(IMA_MAY_EMIT_TOMTOU, + &iint->atomic_flags)) send_tomtou = true; } } else { if (must_measure) - set_bit(IMA_MUST_MEASURE, &iint->atomic_flags); - if (inode_is_open_for_write(inode) && must_measure) - send_writers = true; + set_bit(IMA_MAY_EMIT_TOMTOU, &iint->atomic_flags); + + /* Limit number of open_writers violations */ + if (inode_is_open_for_write(inode) && must_measure) { + if (!test_and_set_bit(IMA_EMITTED_OPENWRITERS, + &iint->atomic_flags)) + send_writers = true; + } }
if (!send_tomtou && !send_writers) --- a/security/integrity/integrity.h +++ b/security/integrity/integrity.h @@ -74,7 +74,8 @@ #define IMA_UPDATE_XATTR 1 #define IMA_CHANGE_ATTR 2 #define IMA_DIGSIG 3 -#define IMA_MUST_MEASURE 4 +#define IMA_MAY_EMIT_TOMTOU 4 +#define IMA_EMITTED_OPENWRITERS 5
enum evm_ima_xattr_type { IMA_XATTR_DIGEST = 0x01,