| Message ID | 20201120131708.3237864-1-kpsingh@chromium.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [bpf-next,1/3] ima: Implement ima_inode_hash | expand |
On 11/20/20 5:17 AM, KP Singh wrote: > From: KP Singh <kpsingh@google.com> > > This is in preparation to add a helper for BPF LSM programs to use > IMA hashes when attached to LSM hooks. There are LSM hooks like > inode_unlink which do not have a struct file * argument and cannot > use the existing ima_file_hash API. > > An inode based API is, therefore, useful in LSM based detections like an > executable trying to delete itself which rely on the inode_unlink LSM > hook. > > Moreover, the ima_file_hash function does nothing with the struct file > pointer apart from calling file_inode on it and converting it to an > inode. > > Signed-off-by: KP Singh <kpsingh@google.com> > --- > include/linux/ima.h | 6 +++ > scripts/bpf_helpers_doc.py | 1 + > security/integrity/ima/ima_main.c | 74 ++++++++++++++++++++++--------- > 3 files changed, 59 insertions(+), 22 deletions(-) > > diff --git a/include/linux/ima.h b/include/linux/ima.h > index 8fa7bcfb2da2..7233a2751754 100644 > --- a/include/linux/ima.h > +++ b/include/linux/ima.h > @@ -29,6 +29,7 @@ extern int ima_post_read_file(struct file *file, void *buf, loff_t size, > enum kernel_read_file_id id); > extern void ima_post_path_mknod(struct dentry *dentry); > extern int ima_file_hash(struct file *file, char *buf, size_t buf_size); > +extern int ima_inode_hash(struct inode *inode, char *buf, size_t buf_size); > extern void ima_kexec_cmdline(int kernel_fd, const void *buf, int size); > > #ifdef CONFIG_IMA_KEXEC > @@ -115,6 +116,11 @@ static inline int ima_file_hash(struct file *file, char *buf, size_t buf_size) > return -EOPNOTSUPP; > } > > +static inline int ima_inode_hash(struct inode *inode, char *buf, size_t buf_size) > +{ > + return -EOPNOTSUPP; > +} > + > static inline void ima_kexec_cmdline(int kernel_fd, const void *buf, int size) {} > #endif /* CONFIG_IMA */ > > diff --git a/scripts/bpf_helpers_doc.py b/scripts/bpf_helpers_doc.py > index c5bc947a70ad..add7fcb32dcd 100755 > --- a/scripts/bpf_helpers_doc.py > +++ b/scripts/bpf_helpers_doc.py > @@ -478,6 +478,7 @@ class PrinterHelpers(Printer): > 'struct tcp_request_sock', > 'struct udp6_sock', > 'struct task_struct', > + 'struct inode', This change (bpf_helpers_doc.py) belongs to patch #2. > 'struct path', > 'struct btf_ptr', > } > diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c > index 2d1af8899cab..1dd2123b5b43 100644 > --- a/security/integrity/ima/ima_main.c > +++ b/security/integrity/ima/ima_main.c > @@ -501,37 +501,17 @@ int ima_file_check(struct file *file, int mask) > } > EXPORT_SYMBOL_GPL(ima_file_check); > > -/** > - * ima_file_hash - return the stored measurement if a file has been hashed and > - * is in the iint cache. > - * @file: pointer to the file > - * @buf: buffer in which to store the hash > - * @buf_size: length of the buffer > - * > - * On success, return the hash algorithm (as defined in the enum hash_algo). > - * If buf is not NULL, this function also outputs the hash into buf. > - * If the hash is larger than buf_size, then only buf_size bytes will be copied. > - * It generally just makes sense to pass a buffer capable of holding the largest > - * possible hash: IMA_MAX_DIGEST_SIZE. > - * The file hash returned is based on the entire file, including the appended > - * signature. > - * > - * If IMA is disabled or if no measurement is available, return -EOPNOTSUPP. > - * If the parameters are incorrect, return -EINVAL. > - */ > -int ima_file_hash(struct file *file, char *buf, size_t buf_size) > +static int __ima_inode_hash(struct inode *inode, char *buf, size_t buf_size) > { > - struct inode *inode; > struct integrity_iint_cache *iint; > int hash_algo; > > - if (!file) > + if (!inode) > return -EINVAL; Based on original code, for ima_file_hash(), inode cannot be NULL, so I prefer to remove this change here and add !inode test in ima_inode_hash. > > if (!ima_policy_flag) > return -EOPNOTSUPP; > > - inode = file_inode(file); > iint = integrity_iint_find(inode); > if (!iint) > return -EOPNOTSUPP; > @@ -558,8 +538,58 @@ int ima_file_hash(struct file *file, char *buf, size_t buf_size) > > return hash_algo; > } > + > +/** > + * ima_file_hash - return the stored measurement if a file has been hashed and > + * is in the iint cache. > + * @file: pointer to the file > + * @buf: buffer in which to store the hash > + * @buf_size: length of the buffer > + * > + * On success, return the hash algorithm (as defined in the enum hash_algo). > + * If buf is not NULL, this function also outputs the hash into buf. > + * If the hash is larger than buf_size, then only buf_size bytes will be copied. > + * It generally just makes sense to pass a buffer capable of holding the largest > + * possible hash: IMA_MAX_DIGEST_SIZE. > + * The file hash returned is based on the entire file, including the appended > + * signature. > + * > + * If IMA is disabled or if no measurement is available, return -EOPNOTSUPP. > + * If the parameters are incorrect, return -EINVAL. > + */ > +int ima_file_hash(struct file *file, char *buf, size_t buf_size) > +{ > + if (!file) > + return -EINVAL; > + > + return __ima_inode_hash(file_inode(file), buf, buf_size); > +} > EXPORT_SYMBOL_GPL(ima_file_hash); > > +/** > + * ima_inode_hash - return the stored measurement if the inode has been hashed > + * and is in the iint cache. > + * @inode: pointer to the inode > + * @buf: buffer in which to store the hash > + * @buf_size: length of the buffer > + * > + * On success, return the hash algorithm (as defined in the enum hash_algo). > + * If buf is not NULL, this function also outputs the hash into buf. > + * If the hash is larger than buf_size, then only buf_size bytes will be copied. > + * It generally just makes sense to pass a buffer capable of holding the largest > + * possible hash: IMA_MAX_DIGEST_SIZE. > + * The hash returned is based on the entire contents, including the appended > + * signature. > + * > + * If IMA is disabled or if no measurement is available, return -EOPNOTSUPP. > + * If the parameters are incorrect, return -EINVAL. > + */ > +int ima_inode_hash(struct inode *inode, char *buf, size_t buf_size) > +{ Add if (!inode) return -EINVAL; > + return __ima_inode_hash(inode, buf, buf_size); > +} > +EXPORT_SYMBOL_GPL(ima_inode_hash); > + > /** > * ima_post_create_tmpfile - mark newly created tmpfile as new > * @file : newly created tmpfile >
[...] > > > > diff --git a/scripts/bpf_helpers_doc.py b/scripts/bpf_helpers_doc.py > > index c5bc947a70ad..add7fcb32dcd 100755 > > --- a/scripts/bpf_helpers_doc.py > > +++ b/scripts/bpf_helpers_doc.py > > @@ -478,6 +478,7 @@ class PrinterHelpers(Printer): > > 'struct tcp_request_sock', > > 'struct udp6_sock', > > 'struct task_struct', > > + 'struct inode', > > This change (bpf_helpers_doc.py) belongs to patch #2. Indeed, I missed it during a rebase. Thanks! > > > 'struct path', > > 'struct btf_ptr', > > } > > diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c > > index 2d1af8899cab..1dd2123b5b43 100644 > > --- a/security/integrity/ima/ima_main.c > > +++ b/security/integrity/ima/ima_main.c > > @@ -501,37 +501,17 @@ int ima_file_check(struct file *file, int mask) > > } > > EXPORT_SYMBOL_GPL(ima_file_check); > > > > -/** > > - * ima_file_hash - return the stored measurement if a file has been hashed and > > - * is in the iint cache. > > - * @file: pointer to the file > > - * @buf: buffer in which to store the hash > > - * @buf_size: length of the buffer > > - * > > - * On success, return the hash algorithm (as defined in the enum hash_algo). > > - * If buf is not NULL, this function also outputs the hash into buf. > > - * If the hash is larger than buf_size, then only buf_size bytes will be copied. > > - * It generally just makes sense to pass a buffer capable of holding the largest > > - * possible hash: IMA_MAX_DIGEST_SIZE. > > - * The file hash returned is based on the entire file, including the appended > > - * signature. > > - * > > - * If IMA is disabled or if no measurement is available, return -EOPNOTSUPP. > > - * If the parameters are incorrect, return -EINVAL. > > - */ > > -int ima_file_hash(struct file *file, char *buf, size_t buf_size) > > +static int __ima_inode_hash(struct inode *inode, char *buf, size_t buf_size) > > { > > - struct inode *inode; > > struct integrity_iint_cache *iint; > > int hash_algo; > > > > - if (!file) > > + if (!inode) > > return -EINVAL; > > Based on original code, for ima_file_hash(), inode cannot be NULL, > so I prefer to remove this change here and add !inode test in > ima_inode_hash. Makes sense. Thanks! > > > > [...] > > + * If the parameters are incorrect, return -EINVAL. > > + */ > > +int ima_inode_hash(struct inode *inode, char *buf, size_t buf_size) > > +{ > > Add > if (!inode) > return -EINVAL; Done. > > > > + return __ima_inode_hash(inode, buf, buf_size); > > +} > > +EXPORT_SYMBOL_GPL(ima_inode_hash); > > + > > /** > > * ima_post_create_tmpfile - mark newly created tmpfile as new > > * @file : newly created tmpfile > >
diff --git a/include/linux/ima.h b/include/linux/ima.h index 8fa7bcfb2da2..7233a2751754 100644 --- a/include/linux/ima.h +++ b/include/linux/ima.h @@ -29,6 +29,7 @@ extern int ima_post_read_file(struct file *file, void *buf, loff_t size, enum kernel_read_file_id id); extern void ima_post_path_mknod(struct dentry *dentry); extern int ima_file_hash(struct file *file, char *buf, size_t buf_size); +extern int ima_inode_hash(struct inode *inode, char *buf, size_t buf_size); extern void ima_kexec_cmdline(int kernel_fd, const void *buf, int size); #ifdef CONFIG_IMA_KEXEC @@ -115,6 +116,11 @@ static inline int ima_file_hash(struct file *file, char *buf, size_t buf_size) return -EOPNOTSUPP; } +static inline int ima_inode_hash(struct inode *inode, char *buf, size_t buf_size) +{ + return -EOPNOTSUPP; +} + static inline void ima_kexec_cmdline(int kernel_fd, const void *buf, int size) {} #endif /* CONFIG_IMA */ diff --git a/scripts/bpf_helpers_doc.py b/scripts/bpf_helpers_doc.py index c5bc947a70ad..add7fcb32dcd 100755 --- a/scripts/bpf_helpers_doc.py +++ b/scripts/bpf_helpers_doc.py @@ -478,6 +478,7 @@ class PrinterHelpers(Printer): 'struct tcp_request_sock', 'struct udp6_sock', 'struct task_struct', + 'struct inode', 'struct path', 'struct btf_ptr', } diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c index 2d1af8899cab..1dd2123b5b43 100644 --- a/security/integrity/ima/ima_main.c +++ b/security/integrity/ima/ima_main.c @@ -501,37 +501,17 @@ int ima_file_check(struct file *file, int mask) } EXPORT_SYMBOL_GPL(ima_file_check); -/** - * ima_file_hash - return the stored measurement if a file has been hashed and - * is in the iint cache. - * @file: pointer to the file - * @buf: buffer in which to store the hash - * @buf_size: length of the buffer - * - * On success, return the hash algorithm (as defined in the enum hash_algo). - * If buf is not NULL, this function also outputs the hash into buf. - * If the hash is larger than buf_size, then only buf_size bytes will be copied. - * It generally just makes sense to pass a buffer capable of holding the largest - * possible hash: IMA_MAX_DIGEST_SIZE. - * The file hash returned is based on the entire file, including the appended - * signature. - * - * If IMA is disabled or if no measurement is available, return -EOPNOTSUPP. - * If the parameters are incorrect, return -EINVAL. - */ -int ima_file_hash(struct file *file, char *buf, size_t buf_size) +static int __ima_inode_hash(struct inode *inode, char *buf, size_t buf_size) { - struct inode *inode; struct integrity_iint_cache *iint; int hash_algo; - if (!file) + if (!inode) return -EINVAL; if (!ima_policy_flag) return -EOPNOTSUPP; - inode = file_inode(file); iint = integrity_iint_find(inode); if (!iint) return -EOPNOTSUPP; @@ -558,8 +538,58 @@ int ima_file_hash(struct file *file, char *buf, size_t buf_size) return hash_algo; } + +/** + * ima_file_hash - return the stored measurement if a file has been hashed and + * is in the iint cache. + * @file: pointer to the file + * @buf: buffer in which to store the hash + * @buf_size: length of the buffer + * + * On success, return the hash algorithm (as defined in the enum hash_algo). + * If buf is not NULL, this function also outputs the hash into buf. + * If the hash is larger than buf_size, then only buf_size bytes will be copied. + * It generally just makes sense to pass a buffer capable of holding the largest + * possible hash: IMA_MAX_DIGEST_SIZE. + * The file hash returned is based on the entire file, including the appended + * signature. + * + * If IMA is disabled or if no measurement is available, return -EOPNOTSUPP. + * If the parameters are incorrect, return -EINVAL. + */ +int ima_file_hash(struct file *file, char *buf, size_t buf_size) +{ + if (!file) + return -EINVAL; + + return __ima_inode_hash(file_inode(file), buf, buf_size); +} EXPORT_SYMBOL_GPL(ima_file_hash); +/** + * ima_inode_hash - return the stored measurement if the inode has been hashed + * and is in the iint cache. + * @inode: pointer to the inode + * @buf: buffer in which to store the hash + * @buf_size: length of the buffer + * + * On success, return the hash algorithm (as defined in the enum hash_algo). + * If buf is not NULL, this function also outputs the hash into buf. + * If the hash is larger than buf_size, then only buf_size bytes will be copied. + * It generally just makes sense to pass a buffer capable of holding the largest + * possible hash: IMA_MAX_DIGEST_SIZE. + * The hash returned is based on the entire contents, including the appended + * signature. + * + * If IMA is disabled or if no measurement is available, return -EOPNOTSUPP. + * If the parameters are incorrect, return -EINVAL. + */ +int ima_inode_hash(struct inode *inode, char *buf, size_t buf_size) +{ + return __ima_inode_hash(inode, buf, buf_size); +} +EXPORT_SYMBOL_GPL(ima_inode_hash); + /** * ima_post_create_tmpfile - mark newly created tmpfile as new * @file : newly created tmpfile