Messages in this thread | | | Date | Thu, 26 Jan 2023 14:37:06 -0500 | Subject | Re: [PATCH v3 1/2] ima: Align ima_file_mmap() parameters with mmap_file LSM hook | From | Stefan Berger <> |
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On 1/26/23 11:38, Roberto Sassu wrote: > From: Roberto Sassu <roberto.sassu@huawei.com> > > Commit 98de59bfe4b2f ("take calculation of final prot in > security_mmap_file() into a helper") moved the code to update prot, to be > the actual protections applied to the kernel, to a new helper called > mmap_prot(). > > However, while without the helper ima_file_mmap() was getting the updated > prot, with the helper ima_file_mmap() gets the original prot, which > contains the protections requested by the application. > > A possible consequence of this change is that, if an application calls > mmap() with only PROT_READ, and the kernel applies PROT_EXEC in addition, > that application would have access to executable memory without having this > event recorded in the IMA measurement list. This situation would occur for > example if the application, before mmap(), calls the personality() system > call with READ_IMPLIES_EXEC as the first argument. > > Align ima_file_mmap() parameters with those of the mmap_file LSM hook, so > that IMA can receive both the requested prot and the final prot. Since the > requested protections are stored in a new variable, and the final > protections are stored in the existing variable, this effectively restores > the original behavior of the MMAP_CHECK hook. > And flags is being passed in preparation for IMA to meet the interface requirements of the LSM hooks - I suppose in preparation for IMA to become an LSM.
> Cc: stable@vger.kernel.org > Fixes: 98de59bfe4b2 ("take calculation of final prot in security_mmap_file() into a helper") > Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
> --- > include/linux/ima.h | 6 ++++-- > security/integrity/ima/ima_main.c | 7 +++++-- > security/security.c | 7 ++++--- > 3 files changed, 13 insertions(+), 7 deletions(-) > > diff --git a/include/linux/ima.h b/include/linux/ima.h > index 5a0b2a285a18..d79fee67235e 100644 > --- a/include/linux/ima.h > +++ b/include/linux/ima.h > @@ -21,7 +21,8 @@ extern int ima_file_check(struct file *file, int mask); > extern void ima_post_create_tmpfile(struct user_namespace *mnt_userns, > struct inode *inode); > extern void ima_file_free(struct file *file); > -extern int ima_file_mmap(struct file *file, unsigned long prot); > +extern int ima_file_mmap(struct file *file, unsigned long reqprot, > + unsigned long prot, unsigned long flags); > extern int ima_file_mprotect(struct vm_area_struct *vma, unsigned long prot); > extern int ima_load_data(enum kernel_load_data_id id, bool contents); > extern int ima_post_load_data(char *buf, loff_t size, > @@ -76,7 +77,8 @@ static inline void ima_file_free(struct file *file) > return; > } > > -static inline int ima_file_mmap(struct file *file, unsigned long prot) > +static inline int ima_file_mmap(struct file *file, unsigned long reqprot, > + unsigned long prot, unsigned long flags) > { > return 0; > } > diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c > index 377300973e6c..f48f4e694921 100644 > --- a/security/integrity/ima/ima_main.c > +++ b/security/integrity/ima/ima_main.c > @@ -397,7 +397,9 @@ static int process_measurement(struct file *file, const struct cred *cred, > /** > * ima_file_mmap - based on policy, collect/store measurement. > * @file: pointer to the file to be measured (May be NULL) > - * @prot: contains the protection that will be applied by the kernel. > + * @reqprot: protection requested by the application > + * @prot: protection that will be applied by the kernel > + * @flags: operational flags > * > * Measure files being mmapped executable based on the ima_must_measure() > * policy decision. > @@ -405,7 +407,8 @@ static int process_measurement(struct file *file, const struct cred *cred, > * On success return 0. On integrity appraisal error, assuming the file > * is in policy and IMA-appraisal is in enforcing mode, return -EACCES. > */ > -int ima_file_mmap(struct file *file, unsigned long prot) > +int ima_file_mmap(struct file *file, unsigned long reqprot, > + unsigned long prot, unsigned long flags) > { > u32 secid; > > diff --git a/security/security.c b/security/security.c > index d1571900a8c7..174afa4fad81 100644 > --- a/security/security.c > +++ b/security/security.c > @@ -1661,12 +1661,13 @@ static inline unsigned long mmap_prot(struct file *file, unsigned long prot) > int security_mmap_file(struct file *file, unsigned long prot, > unsigned long flags) > { > + unsigned long prot_adj = mmap_prot(file, prot); > int ret; > - ret = call_int_hook(mmap_file, 0, file, prot, > - mmap_prot(file, prot), flags); > + > + ret = call_int_hook(mmap_file, 0, file, prot, prot_adj, flags); > if (ret) > return ret; > - return ima_file_mmap(file, prot); > + return ima_file_mmap(file, prot, prot_adj, flags); > } > > int security_mmap_addr(unsigned long addr)
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