| Message ID | 20171009222028.13096-6-chenbofeng.kernel@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Mon, 2017-10-09 at 15:20 -0700, Chenbo Feng wrote: > From: Chenbo Feng <fengc@google.com> > > 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. > The information stored inside the file security struct is the same as > the information in bpf object security struct. > > Signed-off-by: Chenbo Feng <fengc@google.com> > --- > include/linux/bpf.h | 3 +++ > include/linux/lsm_hooks.h | 17 +++++++++++++ > include/linux/security.h | 9 +++++++ > kernel/bpf/syscall.c | 4 ++-- > security/security.c | 8 +++++++ > security/selinux/hooks.c | 61 > +++++++++++++++++++++++++++++++++++++++++++++++ > 6 files changed, 100 insertions(+), 2 deletions(-) > > diff --git a/include/linux/bpf.h b/include/linux/bpf.h > index 225740688ab7..81d6c01b8825 100644 > --- a/include/linux/bpf.h > +++ b/include/linux/bpf.h > @@ -285,6 +285,9 @@ int bpf_prog_array_copy_to_user(struct > bpf_prog_array __rcu *progs, > #ifdef CONFIG_BPF_SYSCALL > DECLARE_PER_CPU(int, bpf_prog_active); > > +extern const struct file_operations bpf_map_fops; > +extern const struct file_operations bpf_prog_fops; > + > #define BPF_PROG_TYPE(_id, _ops) \ > extern const struct bpf_verifier_ops _ops; > #define BPF_MAP_TYPE(_id, _ops) \ > diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h > index 7161d8e7ee79..517dea60b87b 100644 > --- a/include/linux/lsm_hooks.h > +++ b/include/linux/lsm_hooks.h > @@ -1385,6 +1385,19 @@ > * @bpf_prog_free_security: > * Clean up the security information stored inside bpf prog. > * > + * @bpf_map_file: > + * When creating a bpf map fd, set up the file security > information with > + * the bpf security information stored in the map struct. So > when the map > + * fd is passed between processes, the security module can > directly read > + * the security information from file security struct rather > than the bpf > + * security struct. > + * > + * @bpf_prog_file: > + * When creating a bpf prog fd, set up the file security > information with > + * the bpf security information stored in the prog struct. So > when the prog > + * fd is passed between processes, the security module can > directly read > + * the security information from file security struct rather > than the bpf > + * security struct. > */ > union security_list_options { > int (*binder_set_context_mgr)(struct task_struct *mgr); > @@ -1726,6 +1739,8 @@ union security_list_options { > void (*bpf_map_free_security)(struct bpf_map *map); > int (*bpf_prog_alloc_security)(struct bpf_prog_aux *aux); > void (*bpf_prog_free_security)(struct bpf_prog_aux *aux); > + void (*bpf_map_file)(struct bpf_map *map, struct file > *file); > + void (*bpf_prog_file)(struct bpf_prog_aux *aux, struct file > *file); > #endif /* CONFIG_BPF_SYSCALL */ > }; > > @@ -1954,6 +1969,8 @@ struct security_hook_heads { > struct list_head bpf_map_free_security; > struct list_head bpf_prog_alloc_security; > struct list_head bpf_prog_free_security; > + struct list_head bpf_map_file; > + struct list_head bpf_prog_file; > #endif /* CONFIG_BPF_SYSCALL */ > } __randomize_layout; > > diff --git a/include/linux/security.h b/include/linux/security.h > index 18800b0911e5..57573b794e2d 100644 > --- a/include/linux/security.h > +++ b/include/linux/security.h > @@ -1740,6 +1740,8 @@ extern int security_bpf_map_alloc(struct > bpf_map *map); > extern void security_bpf_map_free(struct bpf_map *map); > extern int security_bpf_prog_alloc(struct bpf_prog_aux *aux); > extern void security_bpf_prog_free(struct bpf_prog_aux *aux); > +extern void security_bpf_map_file(struct bpf_map *map, struct file > *file); > +extern void security_bpf_prog_file(struct bpf_prog_aux *aux, struct > file *file); > #else > static inline int security_bpf(int cmd, union bpf_attr *attr, > unsigned int size) > @@ -1772,6 +1774,13 @@ static inline int > security_bpf_prog_alloc(struct bpf_prog_aux *aux) > > static inline void security_bpf_prog_free(struct bpf_prog_aux *aux) > { } > + > +static inline void security_bpf_map_file(struct bpf_map *map, struct > file *file) > +{ } > + > +static inline void security_bpf_prog_file(struct bpf_prog_aux *aux, > + struct file *file) > +{ } > #endif /* CONFIG_SECURITY */ > #endif /* CONFIG_BPF_SYSCALL */ > > diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c > index 1cf31ddd7616..b144181d3f3a 100644 > --- a/kernel/bpf/syscall.c > +++ b/kernel/bpf/syscall.c > @@ -313,7 +313,7 @@ static ssize_t bpf_dummy_write(struct file *filp, > const char __user *buf, > return -EINVAL; > } > > -static const struct file_operations bpf_map_fops = { > +const struct file_operations bpf_map_fops = { > #ifdef CONFIG_PROC_FS > .show_fdinfo = bpf_map_show_fdinfo, > #endif > @@ -964,7 +964,7 @@ static void bpf_prog_show_fdinfo(struct seq_file > *m, struct file *filp) > } > #endif > > -static const struct file_operations bpf_prog_fops = { > +const struct file_operations bpf_prog_fops = { > #ifdef CONFIG_PROC_FS > .show_fdinfo = bpf_prog_show_fdinfo, > #endif > diff --git a/security/security.c b/security/security.c > index 1cd8526cb0b7..dacf649b8cfa 100644 > --- a/security/security.c > +++ b/security/security.c > @@ -1734,4 +1734,12 @@ void security_bpf_prog_free(struct > bpf_prog_aux *aux) > { > call_void_hook(bpf_prog_free_security, aux); > } > +void security_bpf_map_file(struct bpf_map *map, struct file *file) > +{ > + call_void_hook(bpf_map_file, map, file); > +} > +void security_bpf_prog_file(struct bpf_prog_aux *aux, struct file > *file) > +{ > + call_void_hook(bpf_prog_file, aux, file); > +} > #endif /* CONFIG_BPF_SYSCALL */ > diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c > index 41aba4e3d57c..fea88655e0ee 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_file_check(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_file_check(file, cred_sid(cred)); > + if (rc) > + goto out; > +#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_file_check(file, sid); > + if (rc) > + return rc; > +#endif > + > if (unlikely(IS_PRIVATE(d_backing_inode(dentry)))) > return 0; > > @@ -6288,6 +6304,33 @@ 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_file_check(struct file *file, u32 sid) > +{ > + struct file_security_struct *fsec = file->f_security; > + int ret; > + > + if (file->f_op == &bpf_map_fops) { > + ret = avc_has_perm(sid, fsec->sid, SECCLASS_BPF_MAP, > + bpf_map_fmode_to_av(file- > >f_mode), NULL); > + if (ret) > + return ret; > + } else if (file->f_op == &bpf_prog_fops) { > + ret = avc_has_perm(sid, fsec->sid, > SECCLASS_BPF_PROG, > + BPF_PROG__USE, NULL); > + if (ret) > + return ret; > + } > + return 0; > +} > + > static int selinux_bpf_map(struct bpf_map *map, fmode_t fmode) > { > u32 sid = current_sid(); > @@ -6351,6 +6394,22 @@ static void selinux_bpf_prog_free(struct > bpf_prog_aux *aux) > aux->security = NULL; > kfree(bpfsec); > } > + > +static void selinux_bpf_map_file(struct bpf_map *map, struct file > *file) > +{ > + struct bpf_security_struct *bpfsec = map->security; > + struct file_security_struct *fsec = file->f_security; > + > + fsec->sid = bpfsec->sid; > +} > + > +static void selinux_bpf_prog_file(struct bpf_prog_aux *aux, struct > file *file) > +{ > + struct bpf_security_struct *bpfsec = aux->security; > + struct file_security_struct *fsec = file->f_security; > + > + fsec->sid = bpfsec->sid; I could be wrong, but isn't it the case that fsec->sid already will equal bpfsec->sid, because they are both created by the same thread during the same system call, and they each inherit the SID of the current task? What I expected you to do was to add and set a flags field in the file_security_struct to indicate that this is a bpf map or prog, and then test for that in your bpf_file_check() function instead of having to export and test the fops structures. > +} > #endif > > static struct security_hook_list selinux_hooks[] __lsm_ro_after_init > = { > @@ -6581,6 +6640,8 @@ static struct security_hook_list > selinux_hooks[] __lsm_ro_after_init = { > 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), > + LSM_HOOK_INIT(bpf_map_file, selinux_bpf_map_file), > + LSM_HOOK_INIT(bpf_prog_file, selinux_bpf_prog_file), > #endif > }; > -- To unsubscribe from this list: send the line "unsubscribe linux-security-module" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, Oct 10, 2017 at 7:24 AM, Stephen Smalley <sds@tycho.nsa.gov> wrote: > On Mon, 2017-10-09 at 15:20 -0700, Chenbo Feng wrote: >> From: Chenbo Feng <fengc@google.com> >> >> 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. >> The information stored inside the file security struct is the same as >> the information in bpf object security struct. >> >> Signed-off-by: Chenbo Feng <fengc@google.com> >> --- >> include/linux/bpf.h | 3 +++ >> include/linux/lsm_hooks.h | 17 +++++++++++++ >> include/linux/security.h | 9 +++++++ >> kernel/bpf/syscall.c | 4 ++-- >> security/security.c | 8 +++++++ >> security/selinux/hooks.c | 61 >> +++++++++++++++++++++++++++++++++++++++++++++++ >> 6 files changed, 100 insertions(+), 2 deletions(-) >> >> diff --git a/include/linux/bpf.h b/include/linux/bpf.h >> index 225740688ab7..81d6c01b8825 100644 >> --- a/include/linux/bpf.h >> +++ b/include/linux/bpf.h >> @@ -285,6 +285,9 @@ int bpf_prog_array_copy_to_user(struct >> bpf_prog_array __rcu *progs, >> #ifdef CONFIG_BPF_SYSCALL >> DECLARE_PER_CPU(int, bpf_prog_active); >> >> +extern const struct file_operations bpf_map_fops; >> +extern const struct file_operations bpf_prog_fops; >> + >> #define BPF_PROG_TYPE(_id, _ops) \ >> extern const struct bpf_verifier_ops _ops; >> #define BPF_MAP_TYPE(_id, _ops) \ >> diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h >> index 7161d8e7ee79..517dea60b87b 100644 >> --- a/include/linux/lsm_hooks.h >> +++ b/include/linux/lsm_hooks.h >> @@ -1385,6 +1385,19 @@ >> * @bpf_prog_free_security: >> * Clean up the security information stored inside bpf prog. >> * >> + * @bpf_map_file: >> + * When creating a bpf map fd, set up the file security >> information with >> + * the bpf security information stored in the map struct. So >> when the map >> + * fd is passed between processes, the security module can >> directly read >> + * the security information from file security struct rather >> than the bpf >> + * security struct. >> + * >> + * @bpf_prog_file: >> + * When creating a bpf prog fd, set up the file security >> information with >> + * the bpf security information stored in the prog struct. So >> when the prog >> + * fd is passed between processes, the security module can >> directly read >> + * the security information from file security struct rather >> than the bpf >> + * security struct. >> */ >> union security_list_options { >> int (*binder_set_context_mgr)(struct task_struct *mgr); >> @@ -1726,6 +1739,8 @@ union security_list_options { >> void (*bpf_map_free_security)(struct bpf_map *map); >> int (*bpf_prog_alloc_security)(struct bpf_prog_aux *aux); >> void (*bpf_prog_free_security)(struct bpf_prog_aux *aux); >> + void (*bpf_map_file)(struct bpf_map *map, struct file >> *file); >> + void (*bpf_prog_file)(struct bpf_prog_aux *aux, struct file >> *file); >> #endif /* CONFIG_BPF_SYSCALL */ >> }; >> >> @@ -1954,6 +1969,8 @@ struct security_hook_heads { >> struct list_head bpf_map_free_security; >> struct list_head bpf_prog_alloc_security; >> struct list_head bpf_prog_free_security; >> + struct list_head bpf_map_file; >> + struct list_head bpf_prog_file; >> #endif /* CONFIG_BPF_SYSCALL */ >> } __randomize_layout; >> >> diff --git a/include/linux/security.h b/include/linux/security.h >> index 18800b0911e5..57573b794e2d 100644 >> --- a/include/linux/security.h >> +++ b/include/linux/security.h >> @@ -1740,6 +1740,8 @@ extern int security_bpf_map_alloc(struct >> bpf_map *map); >> extern void security_bpf_map_free(struct bpf_map *map); >> extern int security_bpf_prog_alloc(struct bpf_prog_aux *aux); >> extern void security_bpf_prog_free(struct bpf_prog_aux *aux); >> +extern void security_bpf_map_file(struct bpf_map *map, struct file >> *file); >> +extern void security_bpf_prog_file(struct bpf_prog_aux *aux, struct >> file *file); >> #else >> static inline int security_bpf(int cmd, union bpf_attr *attr, >> unsigned int size) >> @@ -1772,6 +1774,13 @@ static inline int >> security_bpf_prog_alloc(struct bpf_prog_aux *aux) >> >> static inline void security_bpf_prog_free(struct bpf_prog_aux *aux) >> { } >> + >> +static inline void security_bpf_map_file(struct bpf_map *map, struct >> file *file) >> +{ } >> + >> +static inline void security_bpf_prog_file(struct bpf_prog_aux *aux, >> + struct file *file) >> +{ } >> #endif /* CONFIG_SECURITY */ >> #endif /* CONFIG_BPF_SYSCALL */ >> >> diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c >> index 1cf31ddd7616..b144181d3f3a 100644 >> --- a/kernel/bpf/syscall.c >> +++ b/kernel/bpf/syscall.c >> @@ -313,7 +313,7 @@ static ssize_t bpf_dummy_write(struct file *filp, >> const char __user *buf, >> return -EINVAL; >> } >> >> -static const struct file_operations bpf_map_fops = { >> +const struct file_operations bpf_map_fops = { >> #ifdef CONFIG_PROC_FS >> .show_fdinfo = bpf_map_show_fdinfo, >> #endif >> @@ -964,7 +964,7 @@ static void bpf_prog_show_fdinfo(struct seq_file >> *m, struct file *filp) >> } >> #endif >> >> -static const struct file_operations bpf_prog_fops = { >> +const struct file_operations bpf_prog_fops = { >> #ifdef CONFIG_PROC_FS >> .show_fdinfo = bpf_prog_show_fdinfo, >> #endif >> diff --git a/security/security.c b/security/security.c >> index 1cd8526cb0b7..dacf649b8cfa 100644 >> --- a/security/security.c >> +++ b/security/security.c >> @@ -1734,4 +1734,12 @@ void security_bpf_prog_free(struct >> bpf_prog_aux *aux) >> { >> call_void_hook(bpf_prog_free_security, aux); >> } >> +void security_bpf_map_file(struct bpf_map *map, struct file *file) >> +{ >> + call_void_hook(bpf_map_file, map, file); >> +} >> +void security_bpf_prog_file(struct bpf_prog_aux *aux, struct file >> *file) >> +{ >> + call_void_hook(bpf_prog_file, aux, file); >> +} >> #endif /* CONFIG_BPF_SYSCALL */ >> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c >> index 41aba4e3d57c..fea88655e0ee 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_file_check(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_file_check(file, cred_sid(cred)); >> + if (rc) >> + goto out; >> +#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_file_check(file, sid); >> + if (rc) >> + return rc; >> +#endif >> + >> if (unlikely(IS_PRIVATE(d_backing_inode(dentry)))) >> return 0; >> >> @@ -6288,6 +6304,33 @@ 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_file_check(struct file *file, u32 sid) >> +{ >> + struct file_security_struct *fsec = file->f_security; >> + int ret; >> + >> + if (file->f_op == &bpf_map_fops) { >> + ret = avc_has_perm(sid, fsec->sid, SECCLASS_BPF_MAP, >> + bpf_map_fmode_to_av(file- >> >f_mode), NULL); >> + if (ret) >> + return ret; >> + } else if (file->f_op == &bpf_prog_fops) { >> + ret = avc_has_perm(sid, fsec->sid, >> SECCLASS_BPF_PROG, >> + BPF_PROG__USE, NULL); >> + if (ret) >> + return ret; >> + } >> + return 0; >> +} >> + >> static int selinux_bpf_map(struct bpf_map *map, fmode_t fmode) >> { >> u32 sid = current_sid(); >> @@ -6351,6 +6394,22 @@ static void selinux_bpf_prog_free(struct >> bpf_prog_aux *aux) >> aux->security = NULL; >> kfree(bpfsec); >> } >> + >> +static void selinux_bpf_map_file(struct bpf_map *map, struct file >> *file) >> +{ >> + struct bpf_security_struct *bpfsec = map->security; >> + struct file_security_struct *fsec = file->f_security; >> + >> + fsec->sid = bpfsec->sid; >> +} >> + >> +static void selinux_bpf_prog_file(struct bpf_prog_aux *aux, struct >> file *file) >> +{ >> + struct bpf_security_struct *bpfsec = aux->security; >> + struct file_security_struct *fsec = file->f_security; >> + >> + fsec->sid = bpfsec->sid; > > I could be wrong, but isn't it the case that fsec->sid already will > equal bpfsec->sid, because they are both created by the same thread > during the same system call, and they each inherit the SID of the > current task? > This is true when bpf object is created by the same process that obtains the fd. But there are other ways of getting a bpf object fd from the kernel such as bpf_obj_get and bpf_get_obj_fd_by_id. These action will ask the kernel to allocate a new file for the bpf object and the file sid would be the process ask for fd while the bpfsec->sid is the sid when bpf object get created. These two could be different. > What I expected you to do was to add and set a flags field in the > file_security_struct to indicate that this is a bpf map or prog, and > then test for that in your bpf_file_check() function instead of having > to export and test the fops structures. > > >> +} >> #endif >> >> static struct security_hook_list selinux_hooks[] __lsm_ro_after_init >> = { >> @@ -6581,6 +6640,8 @@ static struct security_hook_list >> selinux_hooks[] __lsm_ro_after_init = { >> 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), >> + LSM_HOOK_INIT(bpf_map_file, selinux_bpf_map_file), >> + LSM_HOOK_INIT(bpf_prog_file, selinux_bpf_prog_file), >> #endif >> }; >> -- To unsubscribe from this list: send the line "unsubscribe linux-security-module" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, 2017-10-10 at 10:48 -0700, Chenbo Feng wrote: > On Tue, Oct 10, 2017 at 7:24 AM, Stephen Smalley <sds@tycho.nsa.gov> > wrote: > > On Mon, 2017-10-09 at 15:20 -0700, Chenbo Feng wrote: > > > From: Chenbo Feng <fengc@google.com> > > > > > > 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. > > > The information stored inside the file security struct is the > > > same as > > > the information in bpf object security struct. > > > > > > Signed-off-by: Chenbo Feng <fengc@google.com> > > > --- > > > include/linux/bpf.h | 3 +++ > > > include/linux/lsm_hooks.h | 17 +++++++++++++ > > > include/linux/security.h | 9 +++++++ > > > kernel/bpf/syscall.c | 4 ++-- > > > security/security.c | 8 +++++++ > > > security/selinux/hooks.c | 61 > > > +++++++++++++++++++++++++++++++++++++++++++++++ > > > 6 files changed, 100 insertions(+), 2 deletions(-) > > > > > > diff --git a/include/linux/bpf.h b/include/linux/bpf.h > > > index 225740688ab7..81d6c01b8825 100644 > > > --- a/include/linux/bpf.h > > > +++ b/include/linux/bpf.h > > > @@ -285,6 +285,9 @@ int bpf_prog_array_copy_to_user(struct > > > bpf_prog_array __rcu *progs, > > > #ifdef CONFIG_BPF_SYSCALL > > > DECLARE_PER_CPU(int, bpf_prog_active); > > > > > > +extern const struct file_operations bpf_map_fops; > > > +extern const struct file_operations bpf_prog_fops; > > > + > > > #define BPF_PROG_TYPE(_id, _ops) \ > > > extern const struct bpf_verifier_ops _ops; > > > #define BPF_MAP_TYPE(_id, _ops) \ > > > diff --git a/include/linux/lsm_hooks.h > > > b/include/linux/lsm_hooks.h > > > index 7161d8e7ee79..517dea60b87b 100644 > > > --- a/include/linux/lsm_hooks.h > > > +++ b/include/linux/lsm_hooks.h > > > @@ -1385,6 +1385,19 @@ > > > * @bpf_prog_free_security: > > > * Clean up the security information stored inside bpf prog. > > > * > > > + * @bpf_map_file: > > > + * When creating a bpf map fd, set up the file security > > > information with > > > + * the bpf security information stored in the map struct. So > > > when the map > > > + * fd is passed between processes, the security module can > > > directly read > > > + * the security information from file security struct rather > > > than the bpf > > > + * security struct. > > > + * > > > + * @bpf_prog_file: > > > + * When creating a bpf prog fd, set up the file security > > > information with > > > + * the bpf security information stored in the prog struct. So > > > when the prog > > > + * fd is passed between processes, the security module can > > > directly read > > > + * the security information from file security struct rather > > > than the bpf > > > + * security struct. > > > */ > > > union security_list_options { > > > int (*binder_set_context_mgr)(struct task_struct *mgr); > > > @@ -1726,6 +1739,8 @@ union security_list_options { > > > void (*bpf_map_free_security)(struct bpf_map *map); > > > int (*bpf_prog_alloc_security)(struct bpf_prog_aux *aux); > > > void (*bpf_prog_free_security)(struct bpf_prog_aux *aux); > > > + void (*bpf_map_file)(struct bpf_map *map, struct file > > > *file); > > > + void (*bpf_prog_file)(struct bpf_prog_aux *aux, struct file > > > *file); > > > #endif /* CONFIG_BPF_SYSCALL */ > > > }; > > > > > > @@ -1954,6 +1969,8 @@ struct security_hook_heads { > > > struct list_head bpf_map_free_security; > > > struct list_head bpf_prog_alloc_security; > > > struct list_head bpf_prog_free_security; > > > + struct list_head bpf_map_file; > > > + struct list_head bpf_prog_file; > > > #endif /* CONFIG_BPF_SYSCALL */ > > > } __randomize_layout; > > > > > > diff --git a/include/linux/security.h b/include/linux/security.h > > > index 18800b0911e5..57573b794e2d 100644 > > > --- a/include/linux/security.h > > > +++ b/include/linux/security.h > > > @@ -1740,6 +1740,8 @@ extern int security_bpf_map_alloc(struct > > > bpf_map *map); > > > extern void security_bpf_map_free(struct bpf_map *map); > > > extern int security_bpf_prog_alloc(struct bpf_prog_aux *aux); > > > extern void security_bpf_prog_free(struct bpf_prog_aux *aux); > > > +extern void security_bpf_map_file(struct bpf_map *map, struct > > > file > > > *file); > > > +extern void security_bpf_prog_file(struct bpf_prog_aux *aux, > > > struct > > > file *file); > > > #else > > > static inline int security_bpf(int cmd, union bpf_attr *attr, > > > unsigned int size) > > > @@ -1772,6 +1774,13 @@ static inline int > > > security_bpf_prog_alloc(struct bpf_prog_aux *aux) > > > > > > static inline void security_bpf_prog_free(struct bpf_prog_aux > > > *aux) > > > { } > > > + > > > +static inline void security_bpf_map_file(struct bpf_map *map, > > > struct > > > file *file) > > > +{ } > > > + > > > +static inline void security_bpf_prog_file(struct bpf_prog_aux > > > *aux, > > > + struct file *file) > > > +{ } > > > #endif /* CONFIG_SECURITY */ > > > #endif /* CONFIG_BPF_SYSCALL */ > > > > > > diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c > > > index 1cf31ddd7616..b144181d3f3a 100644 > > > --- a/kernel/bpf/syscall.c > > > +++ b/kernel/bpf/syscall.c > > > @@ -313,7 +313,7 @@ static ssize_t bpf_dummy_write(struct file > > > *filp, > > > const char __user *buf, > > > return -EINVAL; > > > } > > > > > > -static const struct file_operations bpf_map_fops = { > > > +const struct file_operations bpf_map_fops = { > > > #ifdef CONFIG_PROC_FS > > > .show_fdinfo = bpf_map_show_fdinfo, > > > #endif > > > @@ -964,7 +964,7 @@ static void bpf_prog_show_fdinfo(struct > > > seq_file > > > *m, struct file *filp) > > > } > > > #endif > > > > > > -static const struct file_operations bpf_prog_fops = { > > > +const struct file_operations bpf_prog_fops = { > > > #ifdef CONFIG_PROC_FS > > > .show_fdinfo = bpf_prog_show_fdinfo, > > > #endif > > > diff --git a/security/security.c b/security/security.c > > > index 1cd8526cb0b7..dacf649b8cfa 100644 > > > --- a/security/security.c > > > +++ b/security/security.c > > > @@ -1734,4 +1734,12 @@ void security_bpf_prog_free(struct > > > bpf_prog_aux *aux) > > > { > > > call_void_hook(bpf_prog_free_security, aux); > > > } > > > +void security_bpf_map_file(struct bpf_map *map, struct file > > > *file) > > > +{ > > > + call_void_hook(bpf_map_file, map, file); > > > +} > > > +void security_bpf_prog_file(struct bpf_prog_aux *aux, struct > > > file > > > *file) > > > +{ > > > + call_void_hook(bpf_prog_file, aux, file); > > > +} > > > #endif /* CONFIG_BPF_SYSCALL */ > > > diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c > > > index 41aba4e3d57c..fea88655e0ee 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_file_check(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_file_check(file, cred_sid(cred)); > > > + if (rc) > > > + goto out; > > > +#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_file_check(file, sid); > > > + if (rc) > > > + return rc; > > > +#endif > > > + > > > if (unlikely(IS_PRIVATE(d_backing_inode(dentry)))) > > > return 0; > > > > > > @@ -6288,6 +6304,33 @@ 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_file_check(struct file *file, u32 sid) > > > +{ > > > + struct file_security_struct *fsec = file->f_security; > > > + int ret; > > > + > > > + if (file->f_op == &bpf_map_fops) { > > > + ret = avc_has_perm(sid, fsec->sid, > > > SECCLASS_BPF_MAP, > > > + bpf_map_fmode_to_av(file- > > > > f_mode), NULL); > > > > > > + if (ret) > > > + return ret; > > > + } else if (file->f_op == &bpf_prog_fops) { > > > + ret = avc_has_perm(sid, fsec->sid, > > > SECCLASS_BPF_PROG, > > > + BPF_PROG__USE, NULL); > > > + if (ret) > > > + return ret; > > > + } > > > + return 0; > > > +} > > > + > > > static int selinux_bpf_map(struct bpf_map *map, fmode_t fmode) > > > { > > > u32 sid = current_sid(); > > > @@ -6351,6 +6394,22 @@ static void selinux_bpf_prog_free(struct > > > bpf_prog_aux *aux) > > > aux->security = NULL; > > > kfree(bpfsec); > > > } > > > + > > > +static void selinux_bpf_map_file(struct bpf_map *map, struct > > > file > > > *file) > > > +{ > > > + struct bpf_security_struct *bpfsec = map->security; > > > + struct file_security_struct *fsec = file->f_security; > > > + > > > + fsec->sid = bpfsec->sid; > > > +} > > > + > > > +static void selinux_bpf_prog_file(struct bpf_prog_aux *aux, > > > struct > > > file *file) > > > +{ > > > + struct bpf_security_struct *bpfsec = aux->security; > > > + struct file_security_struct *fsec = file->f_security; > > > + > > > + fsec->sid = bpfsec->sid; > > > > I could be wrong, but isn't it the case that fsec->sid already will > > equal bpfsec->sid, because they are both created by the same thread > > during the same system call, and they each inherit the SID of the > > current task? > > > > This is true when bpf object is created by the same process that > obtains the fd. But there are other ways of getting a bpf object fd > from the kernel such as bpf_obj_get and bpf_get_obj_fd_by_id. These > action will ask the kernel to allocate a new file for the bpf object > and the file sid would be the process ask for fd while the bpfsec- > >sid > is the sid when bpf object get created. These two could be different. Oh, in that case you shouldn't change the fsec->sid; you'll need to use the bpfsec->sid in your checks instead. But you can still do what I described below. > > What I expected you to do was to add and set a flags field in the > > file_security_struct to indicate that this is a bpf map or prog, > > and > > then test for that in your bpf_file_check() function instead of > > having > > to export and test the fops structures. > > > > > > > +} > > > #endif > > > > > > static struct security_hook_list selinux_hooks[] > > > __lsm_ro_after_init > > > = { > > > @@ -6581,6 +6640,8 @@ static struct security_hook_list > > > selinux_hooks[] __lsm_ro_after_init = { > > > 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), > > > + LSM_HOOK_INIT(bpf_map_file, selinux_bpf_map_file), > > > + LSM_HOOK_INIT(bpf_prog_file, selinux_bpf_prog_file), > > > #endif > > > }; > > > -- To unsubscribe from this list: send the line "unsubscribe linux-security-module" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, Oct 10, 2017 at 12:23 PM, Stephen Smalley <sds@tycho.nsa.gov> wrote: > On Tue, 2017-10-10 at 10:48 -0700, Chenbo Feng wrote: >> On Tue, Oct 10, 2017 at 7:24 AM, Stephen Smalley <sds@tycho.nsa.gov> >> wrote: >> > On Mon, 2017-10-09 at 15:20 -0700, Chenbo Feng wrote: >> > > From: Chenbo Feng <fengc@google.com> >> > > >> > > 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. >> > > The information stored inside the file security struct is the >> > > same as >> > > the information in bpf object security struct. >> > > >> > > Signed-off-by: Chenbo Feng <fengc@google.com> >> > > --- >> > > include/linux/bpf.h | 3 +++ >> > > include/linux/lsm_hooks.h | 17 +++++++++++++ >> > > include/linux/security.h | 9 +++++++ >> > > kernel/bpf/syscall.c | 4 ++-- >> > > security/security.c | 8 +++++++ >> > > security/selinux/hooks.c | 61 >> > > +++++++++++++++++++++++++++++++++++++++++++++++ >> > > 6 files changed, 100 insertions(+), 2 deletions(-) >> > > >> > > diff --git a/include/linux/bpf.h b/include/linux/bpf.h >> > > index 225740688ab7..81d6c01b8825 100644 >> > > --- a/include/linux/bpf.h >> > > +++ b/include/linux/bpf.h >> > > @@ -285,6 +285,9 @@ int bpf_prog_array_copy_to_user(struct >> > > bpf_prog_array __rcu *progs, >> > > #ifdef CONFIG_BPF_SYSCALL >> > > DECLARE_PER_CPU(int, bpf_prog_active); >> > > >> > > +extern const struct file_operations bpf_map_fops; >> > > +extern const struct file_operations bpf_prog_fops; >> > > + >> > > #define BPF_PROG_TYPE(_id, _ops) \ >> > > extern const struct bpf_verifier_ops _ops; >> > > #define BPF_MAP_TYPE(_id, _ops) \ >> > > diff --git a/include/linux/lsm_hooks.h >> > > b/include/linux/lsm_hooks.h >> > > index 7161d8e7ee79..517dea60b87b 100644 >> > > --- a/include/linux/lsm_hooks.h >> > > +++ b/include/linux/lsm_hooks.h >> > > @@ -1385,6 +1385,19 @@ >> > > * @bpf_prog_free_security: >> > > * Clean up the security information stored inside bpf prog. >> > > * >> > > + * @bpf_map_file: >> > > + * When creating a bpf map fd, set up the file security >> > > information with >> > > + * the bpf security information stored in the map struct. So >> > > when the map >> > > + * fd is passed between processes, the security module can >> > > directly read >> > > + * the security information from file security struct rather >> > > than the bpf >> > > + * security struct. >> > > + * >> > > + * @bpf_prog_file: >> > > + * When creating a bpf prog fd, set up the file security >> > > information with >> > > + * the bpf security information stored in the prog struct. So >> > > when the prog >> > > + * fd is passed between processes, the security module can >> > > directly read >> > > + * the security information from file security struct rather >> > > than the bpf >> > > + * security struct. >> > > */ >> > > union security_list_options { >> > > int (*binder_set_context_mgr)(struct task_struct *mgr); >> > > @@ -1726,6 +1739,8 @@ union security_list_options { >> > > void (*bpf_map_free_security)(struct bpf_map *map); >> > > int (*bpf_prog_alloc_security)(struct bpf_prog_aux *aux); >> > > void (*bpf_prog_free_security)(struct bpf_prog_aux *aux); >> > > + void (*bpf_map_file)(struct bpf_map *map, struct file >> > > *file); >> > > + void (*bpf_prog_file)(struct bpf_prog_aux *aux, struct file >> > > *file); >> > > #endif /* CONFIG_BPF_SYSCALL */ >> > > }; >> > > >> > > @@ -1954,6 +1969,8 @@ struct security_hook_heads { >> > > struct list_head bpf_map_free_security; >> > > struct list_head bpf_prog_alloc_security; >> > > struct list_head bpf_prog_free_security; >> > > + struct list_head bpf_map_file; >> > > + struct list_head bpf_prog_file; >> > > #endif /* CONFIG_BPF_SYSCALL */ >> > > } __randomize_layout; >> > > >> > > diff --git a/include/linux/security.h b/include/linux/security.h >> > > index 18800b0911e5..57573b794e2d 100644 >> > > --- a/include/linux/security.h >> > > +++ b/include/linux/security.h >> > > @@ -1740,6 +1740,8 @@ extern int security_bpf_map_alloc(struct >> > > bpf_map *map); >> > > extern void security_bpf_map_free(struct bpf_map *map); >> > > extern int security_bpf_prog_alloc(struct bpf_prog_aux *aux); >> > > extern void security_bpf_prog_free(struct bpf_prog_aux *aux); >> > > +extern void security_bpf_map_file(struct bpf_map *map, struct >> > > file >> > > *file); >> > > +extern void security_bpf_prog_file(struct bpf_prog_aux *aux, >> > > struct >> > > file *file); >> > > #else >> > > static inline int security_bpf(int cmd, union bpf_attr *attr, >> > > unsigned int size) >> > > @@ -1772,6 +1774,13 @@ static inline int >> > > security_bpf_prog_alloc(struct bpf_prog_aux *aux) >> > > >> > > static inline void security_bpf_prog_free(struct bpf_prog_aux >> > > *aux) >> > > { } >> > > + >> > > +static inline void security_bpf_map_file(struct bpf_map *map, >> > > struct >> > > file *file) >> > > +{ } >> > > + >> > > +static inline void security_bpf_prog_file(struct bpf_prog_aux >> > > *aux, >> > > + struct file *file) >> > > +{ } >> > > #endif /* CONFIG_SECURITY */ >> > > #endif /* CONFIG_BPF_SYSCALL */ >> > > >> > > diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c >> > > index 1cf31ddd7616..b144181d3f3a 100644 >> > > --- a/kernel/bpf/syscall.c >> > > +++ b/kernel/bpf/syscall.c >> > > @@ -313,7 +313,7 @@ static ssize_t bpf_dummy_write(struct file >> > > *filp, >> > > const char __user *buf, >> > > return -EINVAL; >> > > } >> > > >> > > -static const struct file_operations bpf_map_fops = { >> > > +const struct file_operations bpf_map_fops = { >> > > #ifdef CONFIG_PROC_FS >> > > .show_fdinfo = bpf_map_show_fdinfo, >> > > #endif >> > > @@ -964,7 +964,7 @@ static void bpf_prog_show_fdinfo(struct >> > > seq_file >> > > *m, struct file *filp) >> > > } >> > > #endif >> > > >> > > -static const struct file_operations bpf_prog_fops = { >> > > +const struct file_operations bpf_prog_fops = { >> > > #ifdef CONFIG_PROC_FS >> > > .show_fdinfo = bpf_prog_show_fdinfo, >> > > #endif >> > > diff --git a/security/security.c b/security/security.c >> > > index 1cd8526cb0b7..dacf649b8cfa 100644 >> > > --- a/security/security.c >> > > +++ b/security/security.c >> > > @@ -1734,4 +1734,12 @@ void security_bpf_prog_free(struct >> > > bpf_prog_aux *aux) >> > > { >> > > call_void_hook(bpf_prog_free_security, aux); >> > > } >> > > +void security_bpf_map_file(struct bpf_map *map, struct file >> > > *file) >> > > +{ >> > > + call_void_hook(bpf_map_file, map, file); >> > > +} >> > > +void security_bpf_prog_file(struct bpf_prog_aux *aux, struct >> > > file >> > > *file) >> > > +{ >> > > + call_void_hook(bpf_prog_file, aux, file); >> > > +} >> > > #endif /* CONFIG_BPF_SYSCALL */ >> > > diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c >> > > index 41aba4e3d57c..fea88655e0ee 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_file_check(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_file_check(file, cred_sid(cred)); >> > > + if (rc) >> > > + goto out; >> > > +#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_file_check(file, sid); >> > > + if (rc) >> > > + return rc; >> > > +#endif >> > > + >> > > if (unlikely(IS_PRIVATE(d_backing_inode(dentry)))) >> > > return 0; >> > > >> > > @@ -6288,6 +6304,33 @@ 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_file_check(struct file *file, u32 sid) >> > > +{ >> > > + struct file_security_struct *fsec = file->f_security; >> > > + int ret; >> > > + >> > > + if (file->f_op == &bpf_map_fops) { >> > > + ret = avc_has_perm(sid, fsec->sid, >> > > SECCLASS_BPF_MAP, >> > > + bpf_map_fmode_to_av(file- >> > > > f_mode), NULL); >> > > >> > > + if (ret) >> > > + return ret; >> > > + } else if (file->f_op == &bpf_prog_fops) { >> > > + ret = avc_has_perm(sid, fsec->sid, >> > > SECCLASS_BPF_PROG, >> > > + BPF_PROG__USE, NULL); >> > > + if (ret) >> > > + return ret; >> > > + } >> > > + return 0; >> > > +} >> > > + >> > > static int selinux_bpf_map(struct bpf_map *map, fmode_t fmode) >> > > { >> > > u32 sid = current_sid(); >> > > @@ -6351,6 +6394,22 @@ static void selinux_bpf_prog_free(struct >> > > bpf_prog_aux *aux) >> > > aux->security = NULL; >> > > kfree(bpfsec); >> > > } >> > > + >> > > +static void selinux_bpf_map_file(struct bpf_map *map, struct >> > > file >> > > *file) >> > > +{ >> > > + struct bpf_security_struct *bpfsec = map->security; >> > > + struct file_security_struct *fsec = file->f_security; >> > > + >> > > + fsec->sid = bpfsec->sid; >> > > +} >> > > + >> > > +static void selinux_bpf_prog_file(struct bpf_prog_aux *aux, >> > > struct >> > > file *file) >> > > +{ >> > > + struct bpf_security_struct *bpfsec = aux->security; >> > > + struct file_security_struct *fsec = file->f_security; >> > > + >> > > + fsec->sid = bpfsec->sid; >> > >> > I could be wrong, but isn't it the case that fsec->sid already will >> > equal bpfsec->sid, because they are both created by the same thread >> > during the same system call, and they each inherit the SID of the >> > current task? >> > >> >> This is true when bpf object is created by the same process that >> obtains the fd. But there are other ways of getting a bpf object fd >> from the kernel such as bpf_obj_get and bpf_get_obj_fd_by_id. These >> action will ask the kernel to allocate a new file for the bpf object >> and the file sid would be the process ask for fd while the bpfsec- >> >sid >> is the sid when bpf object get created. These two could be different. > > Oh, in that case you shouldn't change the fsec->sid; you'll need to use > the bpfsec->sid in your checks instead. But you can still do what I > described below. > Okay, I will add a bpf flag and a bpf sid in the file security struct to store the flag and sid for selinux checking when fd get transfered. >> > What I expected you to do was to add and set a flags field in the >> > file_security_struct to indicate that this is a bpf map or prog, >> > and >> > then test for that in your bpf_file_check() function instead of >> > having >> > to export and test the fops structures. >> > >> > >> > > +} >> > > #endif >> > > >> > > static struct security_hook_list selinux_hooks[] >> > > __lsm_ro_after_init >> > > = { >> > > @@ -6581,6 +6640,8 @@ static struct security_hook_list >> > > selinux_hooks[] __lsm_ro_after_init = { >> > > 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), >> > > + LSM_HOOK_INIT(bpf_map_file, selinux_bpf_map_file), >> > > + LSM_HOOK_INIT(bpf_prog_file, selinux_bpf_prog_file), >> > > #endif >> > > }; >> > > -- To unsubscribe from this list: send the line "unsubscribe linux-security-module" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 225740688ab7..81d6c01b8825 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -285,6 +285,9 @@ int bpf_prog_array_copy_to_user(struct bpf_prog_array __rcu *progs, #ifdef CONFIG_BPF_SYSCALL DECLARE_PER_CPU(int, bpf_prog_active); +extern const struct file_operations bpf_map_fops; +extern const struct file_operations bpf_prog_fops; + #define BPF_PROG_TYPE(_id, _ops) \ extern const struct bpf_verifier_ops _ops; #define BPF_MAP_TYPE(_id, _ops) \ diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h index 7161d8e7ee79..517dea60b87b 100644 --- a/include/linux/lsm_hooks.h +++ b/include/linux/lsm_hooks.h @@ -1385,6 +1385,19 @@ * @bpf_prog_free_security: * Clean up the security information stored inside bpf prog. * + * @bpf_map_file: + * When creating a bpf map fd, set up the file security information with + * the bpf security information stored in the map struct. So when the map + * fd is passed between processes, the security module can directly read + * the security information from file security struct rather than the bpf + * security struct. + * + * @bpf_prog_file: + * When creating a bpf prog fd, set up the file security information with + * the bpf security information stored in the prog struct. So when the prog + * fd is passed between processes, the security module can directly read + * the security information from file security struct rather than the bpf + * security struct. */ union security_list_options { int (*binder_set_context_mgr)(struct task_struct *mgr); @@ -1726,6 +1739,8 @@ union security_list_options { void (*bpf_map_free_security)(struct bpf_map *map); int (*bpf_prog_alloc_security)(struct bpf_prog_aux *aux); void (*bpf_prog_free_security)(struct bpf_prog_aux *aux); + void (*bpf_map_file)(struct bpf_map *map, struct file *file); + void (*bpf_prog_file)(struct bpf_prog_aux *aux, struct file *file); #endif /* CONFIG_BPF_SYSCALL */ }; @@ -1954,6 +1969,8 @@ struct security_hook_heads { struct list_head bpf_map_free_security; struct list_head bpf_prog_alloc_security; struct list_head bpf_prog_free_security; + struct list_head bpf_map_file; + struct list_head bpf_prog_file; #endif /* CONFIG_BPF_SYSCALL */ } __randomize_layout; diff --git a/include/linux/security.h b/include/linux/security.h index 18800b0911e5..57573b794e2d 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -1740,6 +1740,8 @@ extern int security_bpf_map_alloc(struct bpf_map *map); extern void security_bpf_map_free(struct bpf_map *map); extern int security_bpf_prog_alloc(struct bpf_prog_aux *aux); extern void security_bpf_prog_free(struct bpf_prog_aux *aux); +extern void security_bpf_map_file(struct bpf_map *map, struct file *file); +extern void security_bpf_prog_file(struct bpf_prog_aux *aux, struct file *file); #else static inline int security_bpf(int cmd, union bpf_attr *attr, unsigned int size) @@ -1772,6 +1774,13 @@ static inline int security_bpf_prog_alloc(struct bpf_prog_aux *aux) static inline void security_bpf_prog_free(struct bpf_prog_aux *aux) { } + +static inline void security_bpf_map_file(struct bpf_map *map, struct file *file) +{ } + +static inline void security_bpf_prog_file(struct bpf_prog_aux *aux, + struct file *file) +{ } #endif /* CONFIG_SECURITY */ #endif /* CONFIG_BPF_SYSCALL */ diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 1cf31ddd7616..b144181d3f3a 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -313,7 +313,7 @@ static ssize_t bpf_dummy_write(struct file *filp, const char __user *buf, return -EINVAL; } -static const struct file_operations bpf_map_fops = { +const struct file_operations bpf_map_fops = { #ifdef CONFIG_PROC_FS .show_fdinfo = bpf_map_show_fdinfo, #endif @@ -964,7 +964,7 @@ static void bpf_prog_show_fdinfo(struct seq_file *m, struct file *filp) } #endif -static const struct file_operations bpf_prog_fops = { +const struct file_operations bpf_prog_fops = { #ifdef CONFIG_PROC_FS .show_fdinfo = bpf_prog_show_fdinfo, #endif diff --git a/security/security.c b/security/security.c index 1cd8526cb0b7..dacf649b8cfa 100644 --- a/security/security.c +++ b/security/security.c @@ -1734,4 +1734,12 @@ void security_bpf_prog_free(struct bpf_prog_aux *aux) { call_void_hook(bpf_prog_free_security, aux); } +void security_bpf_map_file(struct bpf_map *map, struct file *file) +{ + call_void_hook(bpf_map_file, map, file); +} +void security_bpf_prog_file(struct bpf_prog_aux *aux, struct file *file) +{ + call_void_hook(bpf_prog_file, aux, file); +} #endif /* CONFIG_BPF_SYSCALL */ diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index 41aba4e3d57c..fea88655e0ee 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_file_check(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_file_check(file, cred_sid(cred)); + if (rc) + goto out; +#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_file_check(file, sid); + if (rc) + return rc; +#endif + if (unlikely(IS_PRIVATE(d_backing_inode(dentry)))) return 0; @@ -6288,6 +6304,33 @@ 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_file_check(struct file *file, u32 sid) +{ + struct file_security_struct *fsec = file->f_security; + int ret; + + if (file->f_op == &bpf_map_fops) { + ret = avc_has_perm(sid, fsec->sid, SECCLASS_BPF_MAP, + bpf_map_fmode_to_av(file->f_mode), NULL); + if (ret) + return ret; + } else if (file->f_op == &bpf_prog_fops) { + ret = avc_has_perm(sid, fsec->sid, SECCLASS_BPF_PROG, + BPF_PROG__USE, NULL); + if (ret) + return ret; + } + return 0; +} + static int selinux_bpf_map(struct bpf_map *map, fmode_t fmode) { u32 sid = current_sid(); @@ -6351,6 +6394,22 @@ static void selinux_bpf_prog_free(struct bpf_prog_aux *aux) aux->security = NULL; kfree(bpfsec); } + +static void selinux_bpf_map_file(struct bpf_map *map, struct file *file) +{ + struct bpf_security_struct *bpfsec = map->security; + struct file_security_struct *fsec = file->f_security; + + fsec->sid = bpfsec->sid; +} + +static void selinux_bpf_prog_file(struct bpf_prog_aux *aux, struct file *file) +{ + struct bpf_security_struct *bpfsec = aux->security; + struct file_security_struct *fsec = file->f_security; + + fsec->sid = bpfsec->sid; +} #endif static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = { @@ -6581,6 +6640,8 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = { 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), + LSM_HOOK_INIT(bpf_map_file, selinux_bpf_map_file), + LSM_HOOK_INIT(bpf_prog_file, selinux_bpf_prog_file), #endif };