diff options
Diffstat (limited to 'security')
| -rw-r--r-- | security/Kconfig | 16 | ||||
| -rw-r--r-- | security/Makefile | 2 | ||||
| -rw-r--r-- | security/capability.c | 9 | ||||
| -rw-r--r-- | security/commoncap.c | 30 | ||||
| -rw-r--r-- | security/integrity/ima/ima_crypto.c | 6 | ||||
| -rw-r--r-- | security/integrity/ima/ima_main.c | 4 | ||||
| -rw-r--r-- | security/min_addr.c | 49 | ||||
| -rw-r--r-- | security/selinux/hooks.c | 17 |
8 files changed, 119 insertions, 14 deletions
diff --git a/security/Kconfig b/security/Kconfig index d23c839..4c86534 100644 --- a/security/Kconfig +++ b/security/Kconfig @@ -113,6 +113,22 @@ config SECURITY_ROOTPLUG If you are unsure how to answer this question, answer N. +config LSM_MMAP_MIN_ADDR + int "Low address space for LSM to protect from user allocation" + depends on SECURITY && SECURITY_SELINUX + default 65536 + help + This is the portion of low virtual memory which should be protected + from userspace allocation. Keeping a user from writing to low pages + can help reduce the impact of kernel NULL pointer bugs. + + For most ia64, ppc64 and x86 users with lots of address space + a value of 65536 is reasonable and should cause no problems. + On arm and other archs it should not be higher than 32768. + Programs which use vm86 functionality or have some need to map + this low address space will need the permission specific to the + systems running LSM. + source security/selinux/Kconfig source security/smack/Kconfig source security/tomoyo/Kconfig diff --git a/security/Makefile b/security/Makefile index c67557c..b56e7f9 100644 --- a/security/Makefile +++ b/security/Makefile @@ -8,7 +8,7 @@ subdir-$(CONFIG_SECURITY_SMACK) += smack subdir-$(CONFIG_SECURITY_TOMOYO) += tomoyo # always enable default capabilities -obj-y += commoncap.o +obj-y += commoncap.o min_addr.o # Object file lists obj-$(CONFIG_SECURITY) += security.o capability.o diff --git a/security/capability.c b/security/capability.c index 21b6cea..88f752e 100644 --- a/security/capability.c +++ b/security/capability.c @@ -330,15 +330,6 @@ static int cap_file_ioctl(struct file *file, unsigned int command, return 0; } -static int cap_file_mmap(struct file *file, unsigned long reqprot, - unsigned long prot, unsigned long flags, - unsigned long addr, unsigned long addr_only) -{ - if ((addr < mmap_min_addr) && !capable(CAP_SYS_RAWIO)) - return -EACCES; - return 0; -} - static int cap_file_mprotect(struct vm_area_struct *vma, unsigned long reqprot, unsigned long prot) { diff --git a/security/commoncap.c b/security/commoncap.c index 48b7e02..e3097c0 100644 --- a/security/commoncap.c +++ b/security/commoncap.c @@ -984,3 +984,33 @@ int cap_vm_enough_memory(struct mm_struct *mm, long pages) cap_sys_admin = 1; return __vm_enough_memory(mm, pages, cap_sys_admin); } + +/* + * cap_file_mmap - check if able to map given addr + * @file: unused + * @reqprot: unused + * @prot: unused + * @flags: unused + * @addr: address attempting to be mapped + * @addr_only: unused + * + * If the process is attempting to map memory below mmap_min_addr they need + * CAP_SYS_RAWIO. The other parameters to this function are unused by the + * capability security module. Returns 0 if this mapping should be allowed + * -EPERM if not. + */ +int cap_file_mmap(struct file *file, unsigned long reqprot, + unsigned long prot, unsigned long flags, + unsigned long addr, unsigned long addr_only) +{ + int ret = 0; + + if (addr < dac_mmap_min_addr) { + ret = cap_capable(current, current_cred(), CAP_SYS_RAWIO, + SECURITY_CAP_AUDIT); + /* set PF_SUPERPRIV if it turns out we allow the low mmap */ + if (ret == 0) + current->flags |= PF_SUPERPRIV; + } + return ret; +} diff --git a/security/integrity/ima/ima_crypto.c b/security/integrity/ima/ima_crypto.c index 63003a6..46642a1 100644 --- a/security/integrity/ima/ima_crypto.c +++ b/security/integrity/ima/ima_crypto.c @@ -45,9 +45,9 @@ int ima_calc_hash(struct file *file, char *digest) { struct hash_desc desc; struct scatterlist sg[1]; - loff_t i_size; + loff_t i_size, offset = 0; char *rbuf; - int rc, offset = 0; + int rc; rc = init_desc(&desc); if (rc != 0) @@ -67,6 +67,8 @@ int ima_calc_hash(struct file *file, char *digest) rc = rbuf_len; break; } + if (rbuf_len == 0) + break; offset += rbuf_len; sg_init_one(sg, rbuf, rbuf_len); diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c index 101c512..4732f5e 100644 --- a/security/integrity/ima/ima_main.c +++ b/security/integrity/ima/ima_main.c @@ -262,6 +262,8 @@ void ima_counts_put(struct path *path, int mask) else if (mask & (MAY_READ | MAY_EXEC)) iint->readcount--; mutex_unlock(&iint->mutex); + + kref_put(&iint->refcount, iint_free); } /* @@ -291,6 +293,8 @@ void ima_counts_get(struct file *file) if (file->f_mode & FMODE_WRITE) iint->writecount++; mutex_unlock(&iint->mutex); + + kref_put(&iint->refcount, iint_free); } EXPORT_SYMBOL_GPL(ima_counts_get); diff --git a/security/min_addr.c b/security/min_addr.c new file mode 100644 index 0000000..14cc7b3 --- /dev/null +++ b/security/min_addr.c @@ -0,0 +1,49 @@ +#include <linux/init.h> +#include <linux/mm.h> +#include <linux/security.h> +#include <linux/sysctl.h> + +/* amount of vm to protect from userspace access by both DAC and the LSM*/ +unsigned long mmap_min_addr; +/* amount of vm to protect from userspace using CAP_SYS_RAWIO (DAC) */ +unsigned long dac_mmap_min_addr = CONFIG_DEFAULT_MMAP_MIN_ADDR; +/* amount of vm to protect from userspace using the LSM = CONFIG_LSM_MMAP_MIN_ADDR */ + +/* + * Update mmap_min_addr = max(dac_mmap_min_addr, CONFIG_LSM_MMAP_MIN_ADDR) + */ +static void update_mmap_min_addr(void) +{ +#ifdef CONFIG_LSM_MMAP_MIN_ADDR + if (dac_mmap_min_addr > CONFIG_LSM_MMAP_MIN_ADDR) + mmap_min_addr = dac_mmap_min_addr; + else + mmap_min_addr = CONFIG_LSM_MMAP_MIN_ADDR; +#else + mmap_min_addr = dac_mmap_min_addr; +#endif +} + +/* + * sysctl handler which just sets dac_mmap_min_addr = the new value and then + * calls update_mmap_min_addr() so non MAP_FIXED hints get rounded properly + */ +int mmap_min_addr_handler(struct ctl_table *table, int write, struct file *filp, + void __user *buffer, size_t *lenp, loff_t *ppos) +{ + int ret; + + ret = proc_doulongvec_minmax(table, write, filp, buffer, lenp, ppos); + + update_mmap_min_addr(); + + return ret; +} + +int __init init_mmap_min_addr(void) +{ + update_mmap_min_addr(); + + return 0; +} +pure_initcall(init_mmap_min_addr); diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index 15c2a08..8d8b69c 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -1285,6 +1285,8 @@ static int inode_doinit_with_dentry(struct inode *inode, struct dentry *opt_dent rc = inode->i_op->getxattr(dentry, XATTR_NAME_SELINUX, context, len); if (rc == -ERANGE) { + kfree(context); + /* Need a larger buffer. Query for the right size. */ rc = inode->i_op->getxattr(dentry, XATTR_NAME_SELINUX, NULL, 0); @@ -1292,7 +1294,6 @@ static int inode_doinit_with_dentry(struct inode *inode, struct dentry *opt_dent dput(dentry); goto out_unlock; } - kfree(context); len = rc; context = kmalloc(len+1, GFP_NOFS); if (!context) { @@ -3029,9 +3030,21 @@ static int selinux_file_mmap(struct file *file, unsigned long reqprot, int rc = 0; u32 sid = current_sid(); - if (addr < mmap_min_addr) + /* + * notice that we are intentionally putting the SELinux check before + * the secondary cap_file_mmap check. This is such a likely attempt + * at bad behaviour/exploit that we always want to get the AVC, even + * if DAC would have also denied the operation. + */ + if (addr < CONFIG_LSM_MMAP_MIN_ADDR) { rc = avc_has_perm(sid, sid, SECCLASS_MEMPROTECT, MEMPROTECT__MMAP_ZERO, NULL); + if (rc) + return rc; + } + + /* do DAC check on address space usage */ + rc = cap_file_mmap(file, reqprot, prot, flags, addr, addr_only); if (rc || addr_only) return rc; |
