From afdb09c720b62b8090584c11151d856df330e57d Mon Sep 17 00:00:00 2001 From: Chenbo Feng Date: Wed, 18 Oct 2017 13:00:24 -0700 Subject: security: bpf: Add LSM hooks for bpf object related syscall Introduce several LSM hooks for the syscalls that will allow the userspace to access to eBPF object such as eBPF programs and eBPF maps. The security check is aimed to enforce a per object security protection for eBPF object so only processes with the right priviliges can read/write to a specific map or use a specific eBPF program. Besides that, a general security hook is added before the multiplexer of bpf syscall to check the cmd and the attribute used for the command. The actual security module can decide which command need to be checked and how the cmd should be checked. Signed-off-by: Chenbo Feng Acked-by: James Morris Signed-off-by: David S. Miller --- security/security.c | 32 ++++++++++++++++++++++++++++++++ 1 file changed, 32 insertions(+) (limited to 'security') diff --git a/security/security.c b/security/security.c index 4bf0f571b4ef..1cd8526cb0b7 100644 --- a/security/security.c +++ b/security/security.c @@ -12,6 +12,7 @@ * (at your option) any later version. */ +#include #include #include #include @@ -1703,3 +1704,34 @@ int security_audit_rule_match(u32 secid, u32 field, u32 op, void *lsmrule, actx); } #endif /* CONFIG_AUDIT */ + +#ifdef CONFIG_BPF_SYSCALL +int security_bpf(int cmd, union bpf_attr *attr, unsigned int size) +{ + return call_int_hook(bpf, 0, cmd, attr, size); +} +int security_bpf_map(struct bpf_map *map, fmode_t fmode) +{ + return call_int_hook(bpf_map, 0, map, fmode); +} +int security_bpf_prog(struct bpf_prog *prog) +{ + return call_int_hook(bpf_prog, 0, prog); +} +int security_bpf_map_alloc(struct bpf_map *map) +{ + return call_int_hook(bpf_map_alloc_security, 0, map); +} +int security_bpf_prog_alloc(struct bpf_prog_aux *aux) +{ + return call_int_hook(bpf_prog_alloc_security, 0, aux); +} +void security_bpf_map_free(struct bpf_map *map) +{ + call_void_hook(bpf_map_free_security, map); +} +void security_bpf_prog_free(struct bpf_prog_aux *aux) +{ + call_void_hook(bpf_prog_free_security, aux); +} +#endif /* CONFIG_BPF_SYSCALL */ -- cgit From ec27c3568a34c7fe5fcf4ac0a354eda77687f7eb Mon Sep 17 00:00:00 2001 From: Chenbo Feng Date: Wed, 18 Oct 2017 13:00:25 -0700 Subject: selinux: bpf: Add selinux check for eBPF syscall operations Implement the actual checks introduced to eBPF related syscalls. This implementation use the security field inside bpf object to store a sid that identify the bpf object. And when processes try to access the object, selinux will check if processes have the right privileges. The creation of eBPF object are also checked at the general bpf check hook and new cmd introduced to eBPF domain can also be checked there. Signed-off-by: Chenbo Feng Acked-by: Alexei Starovoitov Reviewed-by: James Morris Signed-off-by: David S. Miller --- security/selinux/hooks.c | 111 ++++++++++++++++++++++++++++++++++++ security/selinux/include/classmap.h | 2 + security/selinux/include/objsec.h | 4 ++ 3 files changed, 117 insertions(+) (limited to 'security') diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index f5d304736852..12cf7de8cbed 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -85,6 +85,7 @@ #include #include #include +#include #include "avc.h" #include "objsec.h" @@ -6252,6 +6253,106 @@ static void selinux_ib_free_security(void *ib_sec) } #endif +#ifdef CONFIG_BPF_SYSCALL +static int selinux_bpf(int cmd, union bpf_attr *attr, + unsigned int size) +{ + u32 sid = current_sid(); + int ret; + + switch (cmd) { + case BPF_MAP_CREATE: + ret = avc_has_perm(sid, sid, SECCLASS_BPF, BPF__MAP_CREATE, + NULL); + break; + case BPF_PROG_LOAD: + ret = avc_has_perm(sid, sid, SECCLASS_BPF, BPF__PROG_LOAD, + NULL); + break; + default: + ret = 0; + break; + } + + return ret; +} + +static u32 bpf_map_fmode_to_av(fmode_t fmode) +{ + u32 av = 0; + + if (fmode & FMODE_READ) + av |= BPF__MAP_READ; + if (fmode & FMODE_WRITE) + av |= BPF__MAP_WRITE; + return av; +} + +static int selinux_bpf_map(struct bpf_map *map, fmode_t fmode) +{ + u32 sid = current_sid(); + struct bpf_security_struct *bpfsec; + + bpfsec = map->security; + return avc_has_perm(sid, bpfsec->sid, SECCLASS_BPF, + bpf_map_fmode_to_av(fmode), NULL); +} + +static int selinux_bpf_prog(struct bpf_prog *prog) +{ + u32 sid = current_sid(); + struct bpf_security_struct *bpfsec; + + bpfsec = prog->aux->security; + return avc_has_perm(sid, bpfsec->sid, SECCLASS_BPF, + BPF__PROG_RUN, NULL); +} + +static int selinux_bpf_map_alloc(struct bpf_map *map) +{ + struct bpf_security_struct *bpfsec; + + bpfsec = kzalloc(sizeof(*bpfsec), GFP_KERNEL); + if (!bpfsec) + return -ENOMEM; + + bpfsec->sid = current_sid(); + map->security = bpfsec; + + return 0; +} + +static void selinux_bpf_map_free(struct bpf_map *map) +{ + struct bpf_security_struct *bpfsec = map->security; + + map->security = NULL; + kfree(bpfsec); +} + +static int selinux_bpf_prog_alloc(struct bpf_prog_aux *aux) +{ + struct bpf_security_struct *bpfsec; + + bpfsec = kzalloc(sizeof(*bpfsec), GFP_KERNEL); + if (!bpfsec) + return -ENOMEM; + + bpfsec->sid = current_sid(); + aux->security = bpfsec; + + return 0; +} + +static void selinux_bpf_prog_free(struct bpf_prog_aux *aux) +{ + struct bpf_security_struct *bpfsec = aux->security; + + aux->security = NULL; + kfree(bpfsec); +} +#endif + static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = { LSM_HOOK_INIT(binder_set_context_mgr, selinux_binder_set_context_mgr), LSM_HOOK_INIT(binder_transaction, selinux_binder_transaction), @@ -6471,6 +6572,16 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = { LSM_HOOK_INIT(audit_rule_match, selinux_audit_rule_match), LSM_HOOK_INIT(audit_rule_free, selinux_audit_rule_free), #endif + +#ifdef CONFIG_BPF_SYSCALL + LSM_HOOK_INIT(bpf, selinux_bpf), + LSM_HOOK_INIT(bpf_map, selinux_bpf_map), + LSM_HOOK_INIT(bpf_prog, selinux_bpf_prog), + LSM_HOOK_INIT(bpf_map_alloc_security, selinux_bpf_map_alloc), + LSM_HOOK_INIT(bpf_prog_alloc_security, selinux_bpf_prog_alloc), + LSM_HOOK_INIT(bpf_map_free_security, selinux_bpf_map_free), + LSM_HOOK_INIT(bpf_prog_free_security, selinux_bpf_prog_free), +#endif }; static __init int selinux_init(void) diff --git a/security/selinux/include/classmap.h b/security/selinux/include/classmap.h index 35ffb29a69cb..0a7023b5f000 100644 --- a/security/selinux/include/classmap.h +++ b/security/selinux/include/classmap.h @@ -237,6 +237,8 @@ struct security_class_mapping secclass_map[] = { { "access", NULL } }, { "infiniband_endport", { "manage_subnet", NULL } }, + { "bpf", + {"map_create", "map_read", "map_write", "prog_load", "prog_run"} }, { NULL } }; diff --git a/security/selinux/include/objsec.h b/security/selinux/include/objsec.h index 1649cd18eb0b..3d54468ce334 100644 --- a/security/selinux/include/objsec.h +++ b/security/selinux/include/objsec.h @@ -150,6 +150,10 @@ struct pkey_security_struct { u32 sid; /* SID of pkey */ }; +struct bpf_security_struct { + u32 sid; /*SID of bpf obj creater*/ +}; + extern unsigned int selinux_checkreqprot; #endif /* _SELINUX_OBJSEC_H_ */ -- cgit From f66e448cfda021b0bcd884f26709796fe19c7cc1 Mon Sep 17 00:00:00 2001 From: Chenbo Feng Date: Wed, 18 Oct 2017 13:00:26 -0700 Subject: selinux: bpf: Add addtional check for bpf object file receive Introduce a bpf object related check when sending and receiving files through unix domain socket as well as binder. It checks if the receiving process have privilege to read/write the bpf map or use the bpf program. This check is necessary because the bpf maps and programs are using a anonymous inode as their shared inode so the normal way of checking the files and sockets when passing between processes cannot work properly on eBPF object. This check only works when the BPF_SYSCALL is configured. Signed-off-by: Chenbo Feng Acked-by: Stephen Smalley Reviewed-by: James Morris Signed-off-by: David S. Miller --- security/selinux/hooks.c | 49 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 49 insertions(+) (limited to 'security') diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index 12cf7de8cbed..2e3a627fc0b1 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -1815,6 +1815,10 @@ static inline int file_path_has_perm(const struct cred *cred, return inode_has_perm(cred, file_inode(file), av, &ad); } +#ifdef CONFIG_BPF_SYSCALL +static int bpf_fd_pass(struct file *file, u32 sid); +#endif + /* Check whether a task can use an open file descriptor to access an inode in a given way. Check access to the descriptor itself, and then use dentry_has_perm to @@ -1845,6 +1849,12 @@ static int file_has_perm(const struct cred *cred, goto out; } +#ifdef CONFIG_BPF_SYSCALL + rc = bpf_fd_pass(file, cred_sid(cred)); + if (rc) + return rc; +#endif + /* av is zero if only checking access to the descriptor. */ rc = 0; if (av) @@ -2165,6 +2175,12 @@ static int selinux_binder_transfer_file(struct task_struct *from, return rc; } +#ifdef CONFIG_BPF_SYSCALL + rc = bpf_fd_pass(file, sid); + if (rc) + return rc; +#endif + if (unlikely(IS_PRIVATE(d_backing_inode(dentry)))) return 0; @@ -6288,6 +6304,39 @@ static u32 bpf_map_fmode_to_av(fmode_t fmode) return av; } +/* This function will check the file pass through unix socket or binder to see + * if it is a bpf related object. And apply correspinding checks on the bpf + * object based on the type. The bpf maps and programs, not like other files and + * socket, are using a shared anonymous inode inside the kernel as their inode. + * So checking that inode cannot identify if the process have privilege to + * access the bpf object and that's why we have to add this additional check in + * selinux_file_receive and selinux_binder_transfer_files. + */ +static int bpf_fd_pass(struct file *file, u32 sid) +{ + struct bpf_security_struct *bpfsec; + struct bpf_prog *prog; + struct bpf_map *map; + int ret; + + if (file->f_op == &bpf_map_fops) { + map = file->private_data; + bpfsec = map->security; + ret = avc_has_perm(sid, bpfsec->sid, SECCLASS_BPF, + bpf_map_fmode_to_av(file->f_mode), NULL); + if (ret) + return ret; + } else if (file->f_op == &bpf_prog_fops) { + prog = file->private_data; + bpfsec = prog->aux->security; + ret = avc_has_perm(sid, bpfsec->sid, SECCLASS_BPF, + BPF__PROG_RUN, NULL); + if (ret) + return ret; + } + return 0; +} + static int selinux_bpf_map(struct bpf_map *map, fmode_t fmode) { u32 sid = current_sid(); -- cgit From 67e306fdbed71ab0a6e0d5985e088a49061c523f Mon Sep 17 00:00:00 2001 From: Roman Gushchin Date: Sun, 5 Nov 2017 08:15:30 -0500 Subject: device_cgroup: add DEVCG_ prefix to ACC_* and DEV_* constants Rename device type and access type constants defined in security/device_cgroup.c by adding the DEVCG_ prefix. The reason behind this renaming is to make them global namespace friendly, as they will be moved to the corresponding header file by following patches. Signed-off-by: Roman Gushchin Cc: David S. Miller Cc: Tejun Heo Cc: Alexei Starovoitov Cc: Daniel Borkmann Signed-off-by: David S. Miller --- security/device_cgroup.c | 72 ++++++++++++++++++++++++------------------------ 1 file changed, 36 insertions(+), 36 deletions(-) (limited to 'security') diff --git a/security/device_cgroup.c b/security/device_cgroup.c index 5ef7e5240563..968c21557ba7 100644 --- a/security/device_cgroup.c +++ b/security/device_cgroup.c @@ -15,14 +15,14 @@ #include #include -#define ACC_MKNOD 1 -#define ACC_READ 2 -#define ACC_WRITE 4 -#define ACC_MASK (ACC_MKNOD | ACC_READ | ACC_WRITE) +#define DEVCG_ACC_MKNOD 1 +#define DEVCG_ACC_READ 2 +#define DEVCG_ACC_WRITE 4 +#define DEVCG_ACC_MASK (DEVCG_ACC_MKNOD | DEVCG_ACC_READ | DEVCG_ACC_WRITE) -#define DEV_BLOCK 1 -#define DEV_CHAR 2 -#define DEV_ALL 4 /* this represents all devices */ +#define DEVCG_DEV_BLOCK 1 +#define DEVCG_DEV_CHAR 2 +#define DEVCG_DEV_ALL 4 /* this represents all devices */ static DEFINE_MUTEX(devcgroup_mutex); @@ -246,21 +246,21 @@ static void set_access(char *acc, short access) { int idx = 0; memset(acc, 0, ACCLEN); - if (access & ACC_READ) + if (access & DEVCG_ACC_READ) acc[idx++] = 'r'; - if (access & ACC_WRITE) + if (access & DEVCG_ACC_WRITE) acc[idx++] = 'w'; - if (access & ACC_MKNOD) + if (access & DEVCG_ACC_MKNOD) acc[idx++] = 'm'; } static char type_to_char(short type) { - if (type == DEV_ALL) + if (type == DEVCG_DEV_ALL) return 'a'; - if (type == DEV_CHAR) + if (type == DEVCG_DEV_CHAR) return 'c'; - if (type == DEV_BLOCK) + if (type == DEVCG_DEV_BLOCK) return 'b'; return 'X'; } @@ -287,10 +287,10 @@ static int devcgroup_seq_show(struct seq_file *m, void *v) * This way, the file remains as a "whitelist of devices" */ if (devcgroup->behavior == DEVCG_DEFAULT_ALLOW) { - set_access(acc, ACC_MASK); + set_access(acc, DEVCG_ACC_MASK); set_majmin(maj, ~0); set_majmin(min, ~0); - seq_printf(m, "%c %s:%s %s\n", type_to_char(DEV_ALL), + seq_printf(m, "%c %s:%s %s\n", type_to_char(DEVCG_DEV_ALL), maj, min, acc); } else { list_for_each_entry_rcu(ex, &devcgroup->exceptions, list) { @@ -309,10 +309,10 @@ static int devcgroup_seq_show(struct seq_file *m, void *v) /** * match_exception - iterates the exception list trying to find a complete match * @exceptions: list of exceptions - * @type: device type (DEV_BLOCK or DEV_CHAR) + * @type: device type (DEVCG_DEV_BLOCK or DEVCG_DEV_CHAR) * @major: device file major number, ~0 to match all * @minor: device file minor number, ~0 to match all - * @access: permission mask (ACC_READ, ACC_WRITE, ACC_MKNOD) + * @access: permission mask (DEVCG_ACC_READ, DEVCG_ACC_WRITE, DEVCG_ACC_MKNOD) * * It is considered a complete match if an exception is found that will * contain the entire range of provided parameters. @@ -325,9 +325,9 @@ static bool match_exception(struct list_head *exceptions, short type, struct dev_exception_item *ex; list_for_each_entry_rcu(ex, exceptions, list) { - if ((type & DEV_BLOCK) && !(ex->type & DEV_BLOCK)) + if ((type & DEVCG_DEV_BLOCK) && !(ex->type & DEVCG_DEV_BLOCK)) continue; - if ((type & DEV_CHAR) && !(ex->type & DEV_CHAR)) + if ((type & DEVCG_DEV_CHAR) && !(ex->type & DEVCG_DEV_CHAR)) continue; if (ex->major != ~0 && ex->major != major) continue; @@ -344,10 +344,10 @@ static bool match_exception(struct list_head *exceptions, short type, /** * match_exception_partial - iterates the exception list trying to find a partial match * @exceptions: list of exceptions - * @type: device type (DEV_BLOCK or DEV_CHAR) + * @type: device type (DEVCG_DEV_BLOCK or DEVCG_DEV_CHAR) * @major: device file major number, ~0 to match all * @minor: device file minor number, ~0 to match all - * @access: permission mask (ACC_READ, ACC_WRITE, ACC_MKNOD) + * @access: permission mask (DEVCG_ACC_READ, DEVCG_ACC_WRITE, DEVCG_ACC_MKNOD) * * It is considered a partial match if an exception's range is found to * contain *any* of the devices specified by provided parameters. This is @@ -362,9 +362,9 @@ static bool match_exception_partial(struct list_head *exceptions, short type, struct dev_exception_item *ex; list_for_each_entry_rcu(ex, exceptions, list) { - if ((type & DEV_BLOCK) && !(ex->type & DEV_BLOCK)) + if ((type & DEVCG_DEV_BLOCK) && !(ex->type & DEVCG_DEV_BLOCK)) continue; - if ((type & DEV_CHAR) && !(ex->type & DEV_CHAR)) + if ((type & DEVCG_DEV_CHAR) && !(ex->type & DEVCG_DEV_CHAR)) continue; /* * We must be sure that both the exception and the provided @@ -647,10 +647,10 @@ static int devcgroup_update_access(struct dev_cgroup *devcgroup, } return 0; case 'b': - ex.type = DEV_BLOCK; + ex.type = DEVCG_DEV_BLOCK; break; case 'c': - ex.type = DEV_CHAR; + ex.type = DEVCG_DEV_CHAR; break; default: return -EINVAL; @@ -703,13 +703,13 @@ static int devcgroup_update_access(struct dev_cgroup *devcgroup, for (b++, count = 0; count < 3; count++, b++) { switch (*b) { case 'r': - ex.access |= ACC_READ; + ex.access |= DEVCG_ACC_READ; break; case 'w': - ex.access |= ACC_WRITE; + ex.access |= DEVCG_ACC_WRITE; break; case 'm': - ex.access |= ACC_MKNOD; + ex.access |= DEVCG_ACC_MKNOD; break; case '\n': case '\0': @@ -806,7 +806,7 @@ struct cgroup_subsys devices_cgrp_subsys = { * @type: device type * @major: device major number * @minor: device minor number - * @access: combination of ACC_WRITE, ACC_READ and ACC_MKNOD + * @access: combination of DEVCG_ACC_WRITE, DEVCG_ACC_READ and DEVCG_ACC_MKNOD * * returns 0 on success, -EPERM case the operation is not permitted */ @@ -839,13 +839,13 @@ int __devcgroup_inode_permission(struct inode *inode, int mask) short type, access = 0; if (S_ISBLK(inode->i_mode)) - type = DEV_BLOCK; + type = DEVCG_DEV_BLOCK; if (S_ISCHR(inode->i_mode)) - type = DEV_CHAR; + type = DEVCG_DEV_CHAR; if (mask & MAY_WRITE) - access |= ACC_WRITE; + access |= DEVCG_ACC_WRITE; if (mask & MAY_READ) - access |= ACC_READ; + access |= DEVCG_ACC_READ; return __devcgroup_check_permission(type, imajor(inode), iminor(inode), access); @@ -859,11 +859,11 @@ int devcgroup_inode_mknod(int mode, dev_t dev) return 0; if (S_ISBLK(mode)) - type = DEV_BLOCK; + type = DEVCG_DEV_BLOCK; else - type = DEV_CHAR; + type = DEVCG_DEV_CHAR; return __devcgroup_check_permission(type, MAJOR(dev), MINOR(dev), - ACC_MKNOD); + DEVCG_ACC_MKNOD); } -- cgit From ecf8fecb7828648cba0e42de7464a7e600c93459 Mon Sep 17 00:00:00 2001 From: Roman Gushchin Date: Sun, 5 Nov 2017 08:15:31 -0500 Subject: device_cgroup: prepare code for bpf-based device controller This is non-functional change to prepare the device cgroup code for adding eBPF-based controller for cgroups v2. The patch performs the following changes: 1) __devcgroup_inode_permission() and devcgroup_inode_mknod() are moving to the device-cgroup.h and converting into static inline. 2) __devcgroup_check_permission() is exported. 3) devcgroup_check_permission() wrapper is introduced to be used by both existing and new bpf-based implementations. Signed-off-by: Roman Gushchin Acked-by: Tejun Heo Acked-by: Alexei Starovoitov Signed-off-by: David S. Miller --- security/device_cgroup.c | 47 ++--------------------------------------------- 1 file changed, 2 insertions(+), 45 deletions(-) (limited to 'security') diff --git a/security/device_cgroup.c b/security/device_cgroup.c index 968c21557ba7..c65b39bafdfe 100644 --- a/security/device_cgroup.c +++ b/security/device_cgroup.c @@ -15,15 +15,6 @@ #include #include -#define DEVCG_ACC_MKNOD 1 -#define DEVCG_ACC_READ 2 -#define DEVCG_ACC_WRITE 4 -#define DEVCG_ACC_MASK (DEVCG_ACC_MKNOD | DEVCG_ACC_READ | DEVCG_ACC_WRITE) - -#define DEVCG_DEV_BLOCK 1 -#define DEVCG_DEV_CHAR 2 -#define DEVCG_DEV_ALL 4 /* this represents all devices */ - static DEFINE_MUTEX(devcgroup_mutex); enum devcg_behavior { @@ -810,8 +801,8 @@ struct cgroup_subsys devices_cgrp_subsys = { * * returns 0 on success, -EPERM case the operation is not permitted */ -static int __devcgroup_check_permission(short type, u32 major, u32 minor, - short access) +int __devcgroup_check_permission(short type, u32 major, u32 minor, + short access) { struct dev_cgroup *dev_cgroup; bool rc; @@ -833,37 +824,3 @@ static int __devcgroup_check_permission(short type, u32 major, u32 minor, return 0; } - -int __devcgroup_inode_permission(struct inode *inode, int mask) -{ - short type, access = 0; - - if (S_ISBLK(inode->i_mode)) - type = DEVCG_DEV_BLOCK; - if (S_ISCHR(inode->i_mode)) - type = DEVCG_DEV_CHAR; - if (mask & MAY_WRITE) - access |= DEVCG_ACC_WRITE; - if (mask & MAY_READ) - access |= DEVCG_ACC_READ; - - return __devcgroup_check_permission(type, imajor(inode), iminor(inode), - access); -} - -int devcgroup_inode_mknod(int mode, dev_t dev) -{ - short type; - - if (!S_ISBLK(mode) && !S_ISCHR(mode)) - return 0; - - if (S_ISBLK(mode)) - type = DEVCG_DEV_BLOCK; - else - type = DEVCG_DEV_CHAR; - - return __devcgroup_check_permission(type, MAJOR(dev), MINOR(dev), - DEVCG_ACC_MKNOD); - -} -- cgit