From ad16ad00c34d3f320a5876b3d711ef6bc81362e1 Mon Sep 17 00:00:00 2001 From: Eric Paris Date: Mon, 25 Oct 2010 14:41:45 -0400 Subject: [PATCH] IMA: use inode->i_lock to protect read and write counters Currently IMA used the iint->mutex to protect the i_readcount and i_writecount. This patch uses the inode->i_lock since we are going to start using in inode objects and that is the most appropriate lock. Signed-off-by: Eric Paris Acked-by: Mimi Zohar Signed-off-by: Linus Torvalds --- security/integrity/ima/ima.h | 1 + security/integrity/ima/ima_main.c | 57 +++++++++++++------------------ 2 files changed, 24 insertions(+), 34 deletions(-) diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h index f7af0110bcde..80aca3d2cb71 100644 --- a/security/integrity/ima/ima.h +++ b/security/integrity/ima/ima.h @@ -106,6 +106,7 @@ struct ima_iint_cache { unsigned char flags; u8 digest[IMA_DIGEST_SIZE]; struct mutex mutex; /* protects: version, flags, digest */ + /* protected by inode->i_lock */ unsigned int readcount; /* measured files readcount */ unsigned int writecount;/* measured files writecount */ struct kref refcount; /* ima_iint_cache reference count */ diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c index 5a1bf3df11f8..2f9b5d50424e 100644 --- a/security/integrity/ima/ima_main.c +++ b/security/integrity/ima/ima_main.c @@ -85,42 +85,12 @@ out: return found; } -/* ima_read_write_check - reflect possible reading/writing errors in the PCR. - * - * When opening a file for read, if the file is already open for write, - * the file could change, resulting in a file measurement error. - * - * Opening a file for write, if the file is already open for read, results - * in a time of measure, time of use (ToMToU) error. - * - * In either case invalidate the PCR. - */ -enum iint_pcr_error { TOMTOU, OPEN_WRITERS }; -static void ima_read_write_check(enum iint_pcr_error error, - struct ima_iint_cache *iint, - struct inode *inode, - const unsigned char *filename) -{ - switch (error) { - case TOMTOU: - if (iint->readcount > 0) - ima_add_violation(inode, filename, "invalid_pcr", - "ToMToU"); - break; - case OPEN_WRITERS: - if (iint->writecount > 0) - ima_add_violation(inode, filename, "invalid_pcr", - "open_writers"); - break; - } -} - /* * Update the counts given an fmode_t */ static void ima_inc_counts(struct ima_iint_cache *iint, fmode_t mode) { - BUG_ON(!mutex_is_locked(&iint->mutex)); + assert_spin_locked(&iint->inode->i_lock); if ((mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ) iint->readcount++; @@ -146,6 +116,7 @@ void ima_counts_get(struct file *file) fmode_t mode = file->f_mode; struct ima_iint_cache *iint; int rc; + bool send_tomtou = false, send_writers = false; if (!iint_initialized || !S_ISREG(inode->i_mode)) return; @@ -153,22 +124,35 @@ void ima_counts_get(struct file *file) if (!iint) return; mutex_lock(&iint->mutex); + spin_lock(&inode->i_lock); + if (!ima_initialized) goto out; + rc = ima_must_measure(iint, inode, MAY_READ, FILE_CHECK); if (rc < 0) goto out; if (mode & FMODE_WRITE) { - ima_read_write_check(TOMTOU, iint, inode, dentry->d_name.name); + if (iint->readcount) + send_tomtou = true; goto out; } - ima_read_write_check(OPEN_WRITERS, iint, inode, dentry->d_name.name); + + if (atomic_read(&inode->i_writecount) > 0) + send_writers = true; out: ima_inc_counts(iint, file->f_mode); + spin_unlock(&inode->i_lock); mutex_unlock(&iint->mutex); - kref_put(&iint->refcount, iint_free); + + if (send_tomtou) + ima_add_violation(inode, dentry->d_name.name, "invalid_pcr", + "ToMToU"); + if (send_writers) + ima_add_violation(inode, dentry->d_name.name, "invalid_pcr", + "open_writers"); } /* @@ -181,6 +165,7 @@ static void ima_dec_counts(struct ima_iint_cache *iint, struct inode *inode, bool dump = false; BUG_ON(!mutex_is_locked(&iint->mutex)); + assert_spin_locked(&inode->i_lock); if ((mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ) { if (unlikely(iint->readcount == 0)) @@ -223,7 +208,11 @@ void ima_file_free(struct file *file) return; mutex_lock(&iint->mutex); + spin_lock(&inode->i_lock); + ima_dec_counts(iint, inode, file); + + spin_unlock(&inode->i_lock); mutex_unlock(&iint->mutex); kref_put(&iint->refcount, iint_free); } -- 2.20.1