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Hallyn" , "Darrick J. Wong" , Christian Brauner , Josef Bacik , Jeff Layton Cc: linux-kernel@vger.kernel.org, linux-integrity@vger.kernel.org, linux-security-module@vger.kernel.org, kernel-team@cloudflare.com, Frederick Lawler X-Mailer: b4 0.14.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=4301; i=fred@cloudflare.com; h=from:subject:message-id; bh=ztNZlDveaPUFY/UJADcT7rgx3Ng5Aaxpnl+M/Z3Ef+Q=; b=owEBbQKS/ZANAwAKAasltHYDktNtAcsmYgBpik/uqKQQioRcbHzyxd0bXzo3VM3vGk+7dbzuj N2KQ20tVoiJAjMEAAEKAB0WIQTLNBqMVmu1PHvjOe2rJbR2A5LTbQUCaYpP7gAKCRCrJbR2A5LT bdGoEADcOZn+QasfYluvP2C6autDQWR7y9dc4cDhBWt32bXHpyJE+6zt7qEk1qi8wunHSwImqOp cPfEAfzrZPvnY/6+himefudeSXKSR71TzZn1MbxL1FLxbnpxlYQpTCvKbWHzjz8Mo72wsVVbCYW OxTA5yU2K3v3Op4z7hRDfH+w1dBYF9lAtPTxX/1nr14Uqt1s5/7narziUiJb4enRb+xF0yM5VFz TheiRBJAJkdf8F/5gNPkQHYNteAQSJitZ1KziY9hQ1zHskQLpb1b1RBkIgMWs1UA9cePCgDfiXV 58g+Wv6aLuPkBQRARiWez5Rh7itkw1LSxW+8PAKVesMwWKMb6CQEYgDCjmI5dsUQ7BnTwWEpfUC wCa33F9VO4cFOn4dNS6Qtxc9/wpUCN3KYkId8XzXybAY3SYYj40By5w3noEPU+8rfHMvpMorApM RiDWXhQgTAbCpNrympaLOliuYUFrwwrgw1e5Uv3Dxn2ejjhgtILGrJKJ7wAsSUOKAsck2X1fYUD iyDG3gB3GpAXF4StVHmuA3rqeG4zaweq3Ir+al7LqzgLdicdK00NiQCALTHXYc+zJ7fqy/njV1b m2BWzyrqmNb83Bors9j0fl9KpcrECKm67FkcDfJnoObOYJ0tR2g++IkWwypLjAdYL9x+8fIaxT5 PinBdX15AGcqMYQ== X-Developer-Key: i=fred@cloudflare.com; a=openpgp; fpr=CB341A8C566BB53C7BE339EDAB25B4760392D36D IMA performs unnecessary measurements on files in file systems that do not set STATX_CHANGE_COOKIE in the vfs_getattr_nosec()'s result mask. Commit 1cf7e834a6fb ("xfs: switch to multigrain timestamps") introduced multigrain timestamps to XFS, and this made XFS no longer report an inode's i_version used by ima_collect_measurement() for change detection. Additionally, ima_check_last_writer() & integrity_inode_attributes_change() think there's a change for a file, when there may have not been. Most file systems already use ctime for change detection, therefore, make IMA fall back to compare against ctime when a file system does not report an i_version to the kstat.change_cookie. If neither fields are reported by vfs_getattr_nosec(), assume the file changed. timespec64_to_ns() is chosen to avoid adding extra storage to integrity_inode_attributes by leveraging the existing version field. XFS is just one example. There may be more file systems that adopt multigrain timestamps in the future. Link: https://lore.kernel.org/all/aTspr4_h9IU4EyrR@CMGLRV3 Fixes: 1cf7e834a6fb ("xfs: switch to multigrain timestamps") Suggested-by: Jeff Layton Signed-off-by: Frederick Lawler --- include/linux/integrity.h | 6 +++++- security/integrity/ima/ima_api.c | 11 ++++++++--- security/integrity/ima/ima_main.c | 2 +- 3 files changed, 14 insertions(+), 5 deletions(-) diff --git a/include/linux/integrity.h b/include/linux/integrity.h index 382c783f0fa3ae4a938cdf9559291ba1903a378e..ec2c94907f417c4a71ecce29ac79edac9bc2c6f8 100644 --- a/include/linux/integrity.h +++ b/include/linux/integrity.h @@ -10,6 +10,7 @@ #include #include #include +#include enum integrity_status { INTEGRITY_PASS = 0, @@ -58,6 +59,9 @@ integrity_inode_attrs_stat_changed if (stat->result_mask & STATX_CHANGE_COOKIE) return stat->change_cookie != attrs->version; + if (stat->result_mask & STATX_CTIME) + return timespec64_to_ns(&stat->ctime) != (s64)attrs->version; + return true; } @@ -84,7 +88,7 @@ integrity_inode_attrs_changed(const struct integrity_inode_attributes *attrs, * only for IMA if vfs_getattr_nosec() fails. */ if (!file || vfs_getattr_nosec(&file->f_path, &stat, - STATX_CHANGE_COOKIE, + STATX_CHANGE_COOKIE | STATX_CTIME, AT_STATX_SYNC_AS_STAT)) return !IS_I_VERSION(inode) || !inode_eq_iversion(inode, attrs->version); diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c index c35ea613c9f8d404ba4886e3b736c3bab29d1668..e47d6281febc15a0ac1bd2ea1d28fea4d0cd5c58 100644 --- a/security/integrity/ima/ima_api.c +++ b/security/integrity/ima/ima_api.c @@ -272,10 +272,15 @@ int ima_collect_measurement(struct ima_iint_cache *iint, struct file *file, * to an initial measurement/appraisal/audit, but was modified to * assume the file changed. */ - result = vfs_getattr_nosec(&file->f_path, &stat, STATX_CHANGE_COOKIE, + result = vfs_getattr_nosec(&file->f_path, &stat, + STATX_CHANGE_COOKIE | STATX_CTIME, AT_STATX_SYNC_AS_STAT); - if (!result && (stat.result_mask & STATX_CHANGE_COOKIE)) - i_version = stat.change_cookie; + if (!result) { + if (stat.result_mask & STATX_CHANGE_COOKIE) + i_version = stat.change_cookie; + else if (stat.result_mask & STATX_CTIME) + i_version = timespec64_to_ns(&stat.ctime); + } hash.hdr.algo = algo; hash.hdr.length = hash_digest_size[algo]; diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c index 8cb17c9d446caaa5a98f5ec8f027c17ba7babca8..776db158b0bd8a0d053729ac0cc15af8b6020a98 100644 --- a/security/integrity/ima/ima_main.c +++ b/security/integrity/ima/ima_main.c @@ -199,7 +199,7 @@ static void ima_check_last_writer(struct ima_iint_cache *iint, &iint->atomic_flags); if ((iint->flags & IMA_NEW_FILE) || vfs_getattr_nosec(&file->f_path, &stat, - STATX_CHANGE_COOKIE, + STATX_CHANGE_COOKIE | STATX_CTIME, AT_STATX_SYNC_AS_STAT) || integrity_inode_attrs_stat_changed(&iint->real_inode, &stat)) { -- 2.43.0