From 0014cc04e8ec077dc482f00c87dfd949cfe2b98f Mon Sep 17 00:00:00 2001 From: Roberto Sassu Date: Mon, 27 Apr 2020 12:28:55 +0200 Subject: ima: Set file->f_mode instead of file->f_flags in ima_calc_file_hash() Commit a408e4a86b36 ("ima: open a new file instance if no read permissions") tries to create a new file descriptor to calculate a file digest if the file has not been opened with O_RDONLY flag. However, if a new file descriptor cannot be obtained, it sets the FMODE_READ flag to file->f_flags instead of file->f_mode. This patch fixes this issue by replacing f_flags with f_mode as it was before that commit. Cc: stable@vger.kernel.org # 4.20.x Fixes: a408e4a86b36 ("ima: open a new file instance if no read permissions") Signed-off-by: Roberto Sassu Reviewed-by: Goldwyn Rodrigues Signed-off-by: Mimi Zohar --- security/integrity/ima/ima_crypto.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) (limited to 'security') diff --git a/security/integrity/ima/ima_crypto.c b/security/integrity/ima/ima_crypto.c index 423c84f95a14..88b5e288f241 100644 --- a/security/integrity/ima/ima_crypto.c +++ b/security/integrity/ima/ima_crypto.c @@ -411,7 +411,7 @@ int ima_calc_file_hash(struct file *file, struct ima_digest_data *hash) loff_t i_size; int rc; struct file *f = file; - bool new_file_instance = false, modified_flags = false; + bool new_file_instance = false, modified_mode = false; /* * For consistency, fail file's opened with the O_DIRECT flag on @@ -431,13 +431,13 @@ int ima_calc_file_hash(struct file *file, struct ima_digest_data *hash) f = dentry_open(&file->f_path, flags, file->f_cred); if (IS_ERR(f)) { /* - * Cannot open the file again, lets modify f_flags + * Cannot open the file again, lets modify f_mode * of original and continue */ pr_info_ratelimited("Unable to reopen file for reading.\n"); f = file; - f->f_flags |= FMODE_READ; - modified_flags = true; + f->f_mode |= FMODE_READ; + modified_mode = true; } else { new_file_instance = true; } @@ -455,8 +455,8 @@ int ima_calc_file_hash(struct file *file, struct ima_digest_data *hash) out: if (new_file_instance) fput(f); - else if (modified_flags) - f->f_flags &= ~FMODE_READ; + else if (modified_mode) + f->f_mode &= ~FMODE_READ; return rc; } -- cgit v1.2.3 From 53de3b080d5eae31d0de219617155dcc34e7d698 Mon Sep 17 00:00:00 2001 From: Roberto Sassu Date: Mon, 27 Apr 2020 12:28:56 +0200 Subject: evm: Check also if *tfm is an error pointer in init_desc() This patch avoids a kernel panic due to accessing an error pointer set by crypto_alloc_shash(). It occurs especially when there are many files that require an unsupported algorithm, as it would increase the likelihood of the following race condition: Task A: *tfm = crypto_alloc_shash() <= error pointer Task B: if (*tfm == NULL) <= *tfm is not NULL, use it Task B: rc = crypto_shash_init(desc) <= panic Task A: *tfm = NULL This patch uses the IS_ERR_OR_NULL macro to determine whether or not a new crypto context must be created. Cc: stable@vger.kernel.org Fixes: d46eb3699502b ("evm: crypto hash replaced by shash") Co-developed-by: Krzysztof Struczynski Signed-off-by: Krzysztof Struczynski Signed-off-by: Roberto Sassu Signed-off-by: Mimi Zohar --- security/integrity/evm/evm_crypto.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'security') diff --git a/security/integrity/evm/evm_crypto.c b/security/integrity/evm/evm_crypto.c index 35682852ddea..77ad1e5a93e4 100644 --- a/security/integrity/evm/evm_crypto.c +++ b/security/integrity/evm/evm_crypto.c @@ -91,7 +91,7 @@ static struct shash_desc *init_desc(char type, uint8_t hash_algo) algo = hash_algo_name[hash_algo]; } - if (*tfm == NULL) { + if (IS_ERR_OR_NULL(*tfm)) { mutex_lock(&mutex); if (*tfm) goto out; -- cgit v1.2.3 From 2e3a34e9f409ebe83d1af7cd2f49fca7af97dfac Mon Sep 17 00:00:00 2001 From: Roberto Sassu Date: Mon, 27 Apr 2020 12:31:28 +0200 Subject: ima: Fix return value of ima_write_policy() This patch fixes the return value of ima_write_policy() when a new policy is directly passed to IMA and the current policy requires appraisal of the file containing the policy. Currently, if appraisal is not in ENFORCE mode, ima_write_policy() returns 0 and leads user space applications to an endless loop. Fix this issue by denying the operation regardless of the appraisal mode. Cc: stable@vger.kernel.org # 4.10.x Fixes: 19f8a84713edc ("ima: measure and appraise the IMA policy itself") Signed-off-by: Roberto Sassu Reviewed-by: Krzysztof Struczynski Signed-off-by: Mimi Zohar --- security/integrity/ima/ima_fs.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) (limited to 'security') diff --git a/security/integrity/ima/ima_fs.c b/security/integrity/ima/ima_fs.c index a71e822a6e92..3efc8308ad26 100644 --- a/security/integrity/ima/ima_fs.c +++ b/security/integrity/ima/ima_fs.c @@ -338,8 +338,7 @@ static ssize_t ima_write_policy(struct file *file, const char __user *buf, integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL, NULL, "policy_update", "signed policy required", 1, 0); - if (ima_appraise & IMA_APPRAISE_ENFORCE) - result = -EACCES; + result = -EACCES; } else { result = ima_parse_add_rule(data); } -- cgit v1.2.3 From 770f60586d2af0590be263f55fd079226313922c Mon Sep 17 00:00:00 2001 From: Madhuparna Bhowmik Date: Thu, 30 Apr 2020 21:32:05 +0530 Subject: evm: Fix RCU list related warnings This patch fixes the following warning and few other instances of traversal of evm_config_xattrnames list: [ 32.848432] ============================= [ 32.848707] WARNING: suspicious RCU usage [ 32.848966] 5.7.0-rc1-00006-ga8d5875ce5f0b #1 Not tainted [ 32.849308] ----------------------------- [ 32.849567] security/integrity/evm/evm_main.c:231 RCU-list traversed in non-reader section!! Since entries are only added to the list and never deleted, use list_for_each_entry_lockless() instead of list_for_each_entry_rcu for traversing the list. Also, add a relevant comment in evm_secfs.c to indicate this fact. Reported-by: kernel test robot Suggested-by: Paul E. McKenney Signed-off-by: Madhuparna Bhowmik Acked-by: Paul E. McKenney (RCU viewpoint) Signed-off-by: Mimi Zohar --- security/integrity/evm/evm_crypto.c | 2 +- security/integrity/evm/evm_main.c | 4 ++-- security/integrity/evm/evm_secfs.c | 9 ++++++++- 3 files changed, 11 insertions(+), 4 deletions(-) (limited to 'security') diff --git a/security/integrity/evm/evm_crypto.c b/security/integrity/evm/evm_crypto.c index 77ad1e5a93e4..2e1597e59606 100644 --- a/security/integrity/evm/evm_crypto.c +++ b/security/integrity/evm/evm_crypto.c @@ -207,7 +207,7 @@ static int evm_calc_hmac_or_hash(struct dentry *dentry, data->hdr.length = crypto_shash_digestsize(desc->tfm); error = -ENODATA; - list_for_each_entry_rcu(xattr, &evm_config_xattrnames, list) { + list_for_each_entry_lockless(xattr, &evm_config_xattrnames, list) { bool is_ima = false; if (strcmp(xattr->name, XATTR_NAME_IMA) == 0) diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c index d361d7fdafc4..0d36259b690d 100644 --- a/security/integrity/evm/evm_main.c +++ b/security/integrity/evm/evm_main.c @@ -97,7 +97,7 @@ static int evm_find_protected_xattrs(struct dentry *dentry) if (!(inode->i_opflags & IOP_XATTR)) return -EOPNOTSUPP; - list_for_each_entry_rcu(xattr, &evm_config_xattrnames, list) { + list_for_each_entry_lockless(xattr, &evm_config_xattrnames, list) { error = __vfs_getxattr(dentry, inode, xattr->name, NULL, 0); if (error < 0) { if (error == -ENODATA) @@ -228,7 +228,7 @@ static int evm_protected_xattr(const char *req_xattr_name) struct xattr_list *xattr; namelen = strlen(req_xattr_name); - list_for_each_entry_rcu(xattr, &evm_config_xattrnames, list) { + list_for_each_entry_lockless(xattr, &evm_config_xattrnames, list) { if ((strlen(xattr->name) == namelen) && (strncmp(req_xattr_name, xattr->name, namelen) == 0)) { found = 1; diff --git a/security/integrity/evm/evm_secfs.c b/security/integrity/evm/evm_secfs.c index 39ad1038d45d..cfc3075769bb 100644 --- a/security/integrity/evm/evm_secfs.c +++ b/security/integrity/evm/evm_secfs.c @@ -232,7 +232,14 @@ static ssize_t evm_write_xattrs(struct file *file, const char __user *buf, goto out; } - /* Guard against races in evm_read_xattrs */ + /* + * xattr_list_mutex guards against races in evm_read_xattrs(). + * Entries are only added to the evm_config_xattrnames list + * and never deleted. Therefore, the list is traversed + * using list_for_each_entry_lockless() without holding + * the mutex in evm_calc_hmac_or_hash(), evm_find_protected_xattrs() + * and evm_protected_xattr(). + */ mutex_lock(&xattr_list_mutex); list_for_each_entry(tmp, &evm_config_xattrnames, list) { if (strcmp(xattr->name, tmp->name) == 0) { -- cgit v1.2.3 From 8433856947217ebb5697a8ff9c4c9cad4639a2cf Mon Sep 17 00:00:00 2001 From: Dan Carpenter Date: Tue, 12 May 2020 16:19:17 +0300 Subject: evm: Fix a small race in init_desc() The IS_ERR_OR_NULL() function has two conditions and if we got really unlucky we could hit a race where "ptr" started as an error pointer and then was set to NULL. Both conditions would be false even though the pointer at the end was NULL. This patch fixes the problem by ensuring that "*tfm" can only be NULL or valid. I have introduced a "tmp_tfm" variable to make that work. I also reversed a condition and pulled the code in one tab. Reported-by: Roberto Sassu Fixes: 53de3b080d5e ("evm: Check also if *tfm is an error pointer in init_desc()") Signed-off-by: Dan Carpenter Acked-by: Roberto Sassu Acked-by: Krzysztof Struczynski Signed-off-by: Mimi Zohar --- security/integrity/evm/evm_crypto.c | 44 ++++++++++++++++++------------------- 1 file changed, 22 insertions(+), 22 deletions(-) (limited to 'security') diff --git a/security/integrity/evm/evm_crypto.c b/security/integrity/evm/evm_crypto.c index 2e1597e59606..764b896cd628 100644 --- a/security/integrity/evm/evm_crypto.c +++ b/security/integrity/evm/evm_crypto.c @@ -73,7 +73,7 @@ static struct shash_desc *init_desc(char type, uint8_t hash_algo) { long rc; const char *algo; - struct crypto_shash **tfm; + struct crypto_shash **tfm, *tmp_tfm; struct shash_desc *desc; if (type == EVM_XATTR_HMAC) { @@ -91,31 +91,31 @@ static struct shash_desc *init_desc(char type, uint8_t hash_algo) algo = hash_algo_name[hash_algo]; } - if (IS_ERR_OR_NULL(*tfm)) { - mutex_lock(&mutex); - if (*tfm) - goto out; - *tfm = crypto_alloc_shash(algo, 0, CRYPTO_NOLOAD); - if (IS_ERR(*tfm)) { - rc = PTR_ERR(*tfm); - pr_err("Can not allocate %s (reason: %ld)\n", algo, rc); - *tfm = NULL; + if (*tfm) + goto alloc; + mutex_lock(&mutex); + if (*tfm) + goto unlock; + + tmp_tfm = crypto_alloc_shash(algo, 0, CRYPTO_NOLOAD); + if (IS_ERR(tmp_tfm)) { + pr_err("Can not allocate %s (reason: %ld)\n", algo, + PTR_ERR(tmp_tfm)); + mutex_unlock(&mutex); + return ERR_CAST(tmp_tfm); + } + if (type == EVM_XATTR_HMAC) { + rc = crypto_shash_setkey(tmp_tfm, evmkey, evmkey_len); + if (rc) { + crypto_free_shash(tmp_tfm); mutex_unlock(&mutex); return ERR_PTR(rc); } - if (type == EVM_XATTR_HMAC) { - rc = crypto_shash_setkey(*tfm, evmkey, evmkey_len); - if (rc) { - crypto_free_shash(*tfm); - *tfm = NULL; - mutex_unlock(&mutex); - return ERR_PTR(rc); - } - } -out: - mutex_unlock(&mutex); } - + *tfm = tmp_tfm; +unlock: + mutex_unlock(&mutex); +alloc: desc = kmalloc(sizeof(*desc) + crypto_shash_descsize(*tfm), GFP_KERNEL); if (!desc) -- cgit v1.2.3