From 314dabb83a547ec4da819e8cbc78fac9cec605cd Mon Sep 17 00:00:00 2001 From: James Morris Date: Mon, 10 Aug 2009 22:00:13 +1000 Subject: SELinux: fix memory leakage in /security/selinux/hooks.c Fix memory leakage in /security/selinux/hooks.c The buffer always needs to be freed here; we either error out or allocate more memory. Reported-by: iceberg Signed-off-by: James Morris Acked-by: Stephen Smalley --- security/selinux/hooks.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'security') diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index 15c2a08a66f1..1e8cfc4c2ed6 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) { -- cgit v1.2.2 From 9c0d90103c7e0eb6e638e5b649e9f6d8d9c1b4b3 Mon Sep 17 00:00:00 2001 From: Eric Paris Date: Fri, 31 Jul 2009 12:53:58 -0400 Subject: Capabilities: move cap_file_mmap to commoncap.c Currently we duplicate the mmap_min_addr test in cap_file_mmap and in security_file_mmap if !CONFIG_SECURITY. This patch moves cap_file_mmap into commoncap.c and then calls that function directly from security_file_mmap ifndef CONFIG_SECURITY like all of the other capability checks are done. Signed-off-by: Eric Paris Acked-by: Serge Hallyn Signed-off-by: James Morris --- security/capability.c | 9 --------- security/commoncap.c | 30 ++++++++++++++++++++++++++++++ 2 files changed, 30 insertions(+), 9 deletions(-) (limited to 'security') diff --git a/security/capability.c b/security/capability.c index 21b6cead6a8e..88f752e8152c 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 48b7e0228fa3..6bcf6e81e547 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 < 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; +} -- cgit v1.2.2 From 8cf948e744e0218af604c32edecde10006dc8e9e Mon Sep 17 00:00:00 2001 From: Eric Paris Date: Fri, 31 Jul 2009 12:54:05 -0400 Subject: SELinux: call cap_file_mmap in selinux_file_mmap Currently SELinux does not check CAP_SYS_RAWIO in the file_mmap hook. This means there is no DAC check on the ability to mmap low addresses in the memory space. This function adds the DAC check for CAP_SYS_RAWIO while maintaining the selinux check on mmap_zero. This means that processes which need to mmap low memory will need CAP_SYS_RAWIO and mmap_zero but will NOT need the SELinux sys_rawio capability. Signed-off-by: Eric Paris Signed-off-by: James Morris --- security/selinux/hooks.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) (limited to 'security') diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index 1e8cfc4c2ed6..e6d1432b0800 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -3030,9 +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 < 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; -- cgit v1.2.2 From 788084aba2ab7348257597496befcbccabdc98a3 Mon Sep 17 00:00:00 2001 From: Eric Paris Date: Fri, 31 Jul 2009 12:54:11 -0400 Subject: Security/SELinux: seperate lsm specific mmap_min_addr Currently SELinux enforcement of controls on the ability to map low memory is determined by the mmap_min_addr tunable. This patch causes SELinux to ignore the tunable and instead use a seperate Kconfig option specific to how much space the LSM should protect. The tunable will now only control the need for CAP_SYS_RAWIO and SELinux permissions will always protect the amount of low memory designated by CONFIG_LSM_MMAP_MIN_ADDR. This allows users who need to disable the mmap_min_addr controls (usual reason being they run WINE as a non-root user) to do so and still have SELinux controls preventing confined domains (like a web server) from being able to map some area of low memory. Signed-off-by: Eric Paris Signed-off-by: James Morris --- security/Kconfig | 16 ++++++++++++++++ security/Makefile | 2 +- security/commoncap.c | 2 +- security/min_addr.c | 49 ++++++++++++++++++++++++++++++++++++++++++++++++ security/selinux/hooks.c | 2 +- 5 files changed, 68 insertions(+), 3 deletions(-) create mode 100644 security/min_addr.c (limited to 'security') diff --git a/security/Kconfig b/security/Kconfig index d23c839038f0..9c60c346a91d 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 from user allocation" + depends on SECURITY && SECURITY_SELINUX + default 65535 + 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 c67557cdaa85..b56e7f9ecbc2 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/commoncap.c b/security/commoncap.c index 6bcf6e81e547..e3097c0a1311 100644 --- a/security/commoncap.c +++ b/security/commoncap.c @@ -1005,7 +1005,7 @@ int cap_file_mmap(struct file *file, unsigned long reqprot, { int ret = 0; - if (addr < mmap_min_addr) { + 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 */ diff --git a/security/min_addr.c b/security/min_addr.c new file mode 100644 index 000000000000..14cc7b3b8d03 --- /dev/null +++ b/security/min_addr.c @@ -0,0 +1,49 @@ +#include +#include +#include +#include + +/* 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 e6d1432b0800..8d8b69c5664e 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -3036,7 +3036,7 @@ static int selinux_file_mmap(struct file *file, unsigned long reqprot, * at bad behaviour/exploit that we always want to get the AVC, even * if DAC would have also denied the operation. */ - if (addr < mmap_min_addr) { + if (addr < CONFIG_LSM_MMAP_MIN_ADDR) { rc = avc_has_perm(sid, sid, SECCLASS_MEMPROTECT, MEMPROTECT__MMAP_ZERO, NULL); if (rc) -- cgit v1.2.2 From a58578e47f004017cf47803ad372490806630e58 Mon Sep 17 00:00:00 2001 From: Dave Jones Date: Tue, 18 Aug 2009 13:47:37 -0400 Subject: security: Make LSM_MMAP_MIN_ADDR default match its help text. Commit 788084aba2ab7348257597496befcbccabdc98a3 added the LSM_MMAP_MIN_ADDR option, whose help text states "For most ia64, ppc64 and x86 users with lots of address space a value of 65536 is reasonable and should cause no problems." Which implies that it's default setting was typoed. Signed-off-by: Dave Jones Acked-by: Eric Paris Signed-off-by: James Morris --- security/Kconfig | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'security') diff --git a/security/Kconfig b/security/Kconfig index 9c60c346a91d..bba92689b567 100644 --- a/security/Kconfig +++ b/security/Kconfig @@ -116,7 +116,7 @@ config SECURITY_ROOTPLUG config LSM_MMAP_MIN_ADDR int "Low address space for LSM to from user allocation" depends on SECURITY && SECURITY_SELINUX - default 65535 + 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 -- cgit v1.2.2 From 024e6cb408307de41cbfcb1e5a170d9af60ab2a9 Mon Sep 17 00:00:00 2001 From: Andreas Schwab Date: Tue, 18 Aug 2009 22:14:29 +0200 Subject: security: Fix prompt for LSM_MMAP_MIN_ADDR Fix prompt for LSM_MMAP_MIN_ADDR. (Verbs are cool!) Signed-off-by: Andreas Schwab Acked-by: Eric Paris Signed-off-by: James Morris --- security/Kconfig | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'security') diff --git a/security/Kconfig b/security/Kconfig index bba92689b567..4c865345caa0 100644 --- a/security/Kconfig +++ b/security/Kconfig @@ -114,7 +114,7 @@ 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 from user allocation" + int "Low address space for LSM to protect from user allocation" depends on SECURITY && SECURITY_SELINUX default 65536 help -- cgit v1.2.2