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Eric Paris bade72d607 IMA: fix the ToMToU logic ... Current logic looks like this: rc = ima_must_measure(NULL, inode, MAY_READ, FILE_CHECK); if (rc < 0) goto out; if (mode & FMODE_WRITE) { if (inode->i_readcount) send_tomtou = true; goto out; } if (atomic_read(&inode->i_writecount) > 0) send_writers = true; Lets assume we have a policy which states that all files opened for read by root must be measured. Lets assume the file has permissions 777. Lets assume that root has the given file open for read. Lets assume that a non-root process opens the file write. The non-root process will get to ima_counts_get() and will check the ima_must_measure(). Since it is not supposed to measure it will goto out. We should check the i_readcount no matter what since we might be causing a ToMToU voilation! This is close to correct, but still not quite perfect. The situation could have been that root, which was interested in the mesurement opened and closed the file and another process which is not interested in the measurement is the one holding the i_readcount ATM. This is just overly strict on ToMToU violations, which is better than not strict enough... Signed-off-by: Eric Paris <eparis@redhat.com> Acked-by: Mimi Zohar <zohar@linux.vnet.ibm.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>		14 years ago
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Kconfig	ima: remove ACPI dependency	15 years ago
Makefile	…
ima.h	IMA: drop refcnt from ima_iint_cache since it isn't needed	14 years ago
ima_api.c	IMA: move read counter into struct inode	14 years ago
ima_audit.c	…
ima_crypto.c	…
ima_fs.c	ima: use generic_file_llseek for securityfs	15 years ago
ima_iint.c	IMA: explicit IMA i_flag to remove global lock on inode_delete	14 years ago
ima_init.c	…
ima_main.c	IMA: fix the ToMToU logic	14 years ago
ima_policy.c	…
ima_queue.c	…