diff options
| -rw-r--r-- | fs/bpf_fs_kfuncs.c | 225 | ||||
| -rw-r--r-- | include/linux/bpf_lsm.h | 18 | ||||
| -rw-r--r-- | include/uapi/linux/xattr.h | 4 | ||||
| -rw-r--r-- | kernel/bpf/bpf_lsm.c | 2 | ||||
| -rw-r--r-- | kernel/bpf/verifier.c | 21 | ||||
| -rw-r--r-- | tools/testing/selftests/bpf/bpf_kfuncs.h | 5 | ||||
| -rw-r--r-- | tools/testing/selftests/bpf/prog_tests/fs_kfuncs.c | 162 | ||||
| -rw-r--r-- | tools/testing/selftests/bpf/progs/test_get_xattr.c | 28 | ||||
| -rw-r--r-- | tools/testing/selftests/bpf/progs/test_set_remove_xattr.c | 133 |
9 files changed, 573 insertions, 25 deletions
diff --git a/fs/bpf_fs_kfuncs.c b/fs/bpf_fs_kfuncs.c index 3fe9f59ef867..08412532db1b 100644 --- a/fs/bpf_fs_kfuncs.c +++ b/fs/bpf_fs_kfuncs.c @@ -2,10 +2,12 @@ /* Copyright (c) 2024 Google LLC. */ #include <linux/bpf.h> +#include <linux/bpf_lsm.h> #include <linux/btf.h> #include <linux/btf_ids.h> #include <linux/dcache.h> #include <linux/fs.h> +#include <linux/fsnotify.h> #include <linux/file.h> #include <linux/mm.h> #include <linux/xattr.h> @@ -93,6 +95,24 @@ __bpf_kfunc int bpf_path_d_path(struct path *path, char *buf, size_t buf__sz) return len; } +static bool match_security_bpf_prefix(const char *name__str) +{ + return !strncmp(name__str, XATTR_NAME_BPF_LSM, XATTR_NAME_BPF_LSM_LEN); +} + +static int bpf_xattr_read_permission(const char *name, struct inode *inode) +{ + if (WARN_ON(!inode)) + return -EINVAL; + + /* Allow reading xattr with user. and security.bpf. prefix */ + if (strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN) && + !match_security_bpf_prefix(name)) + return -EPERM; + + return inode_permission(&nop_mnt_idmap, inode, MAY_READ); +} + /** * bpf_get_dentry_xattr - get xattr of a dentry * @dentry: dentry to get xattr from @@ -101,9 +121,10 @@ __bpf_kfunc int bpf_path_d_path(struct path *path, char *buf, size_t buf__sz) * * Get xattr *name__str* of *dentry* and store the output in *value_ptr*. * - * For security reasons, only *name__str* with prefix "user." is allowed. + * For security reasons, only *name__str* with prefixes "user." or + * "security.bpf." are allowed. * - * Return: 0 on success, a negative value on error. + * Return: length of the xattr value on success, a negative value on error. */ __bpf_kfunc int bpf_get_dentry_xattr(struct dentry *dentry, const char *name__str, struct bpf_dynptr *value_p) @@ -114,18 +135,12 @@ __bpf_kfunc int bpf_get_dentry_xattr(struct dentry *dentry, const char *name__st void *value; int ret; - if (WARN_ON(!inode)) - return -EINVAL; - - if (strncmp(name__str, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN)) - return -EPERM; - value_len = __bpf_dynptr_size(value_ptr); value = __bpf_dynptr_data_rw(value_ptr, value_len); if (!value) return -EINVAL; - ret = inode_permission(&nop_mnt_idmap, inode, MAY_READ); + ret = bpf_xattr_read_permission(name__str, inode); if (ret) return ret; return __vfs_getxattr(dentry, inode, name__str, value, value_len); @@ -139,9 +154,10 @@ __bpf_kfunc int bpf_get_dentry_xattr(struct dentry *dentry, const char *name__st * * Get xattr *name__str* of *file* and store the output in *value_ptr*. * - * For security reasons, only *name__str* with prefix "user." is allowed. + * For security reasons, only *name__str* with prefixes "user." or + * "security.bpf." are allowed. * - * Return: 0 on success, a negative value on error. + * Return: length of the xattr value on success, a negative value on error. */ __bpf_kfunc int bpf_get_file_xattr(struct file *file, const char *name__str, struct bpf_dynptr *value_p) @@ -154,6 +170,160 @@ __bpf_kfunc int bpf_get_file_xattr(struct file *file, const char *name__str, __bpf_kfunc_end_defs(); +static int bpf_xattr_write_permission(const char *name, struct inode *inode) +{ + if (WARN_ON(!inode)) + return -EINVAL; + + /* Only allow setting and removing security.bpf. xattrs */ + if (!match_security_bpf_prefix(name)) + return -EPERM; + + return inode_permission(&nop_mnt_idmap, inode, MAY_WRITE); +} + +/** + * bpf_set_dentry_xattr_locked - set a xattr of a dentry + * @dentry: dentry to get xattr from + * @name__str: name of the xattr + * @value_p: xattr value + * @flags: flags to pass into filesystem operations + * + * Set xattr *name__str* of *dentry* to the value in *value_ptr*. + * + * For security reasons, only *name__str* with prefix "security.bpf." + * is allowed. + * + * The caller already locked dentry->d_inode. + * + * Return: 0 on success, a negative value on error. + */ +int bpf_set_dentry_xattr_locked(struct dentry *dentry, const char *name__str, + const struct bpf_dynptr *value_p, int flags) +{ + + struct bpf_dynptr_kern *value_ptr = (struct bpf_dynptr_kern *)value_p; + struct inode *inode = d_inode(dentry); + const void *value; + u32 value_len; + int ret; + + value_len = __bpf_dynptr_size(value_ptr); + value = __bpf_dynptr_data(value_ptr, value_len); + if (!value) + return -EINVAL; + + ret = bpf_xattr_write_permission(name__str, inode); + if (ret) + return ret; + + ret = __vfs_setxattr(&nop_mnt_idmap, dentry, inode, name__str, + value, value_len, flags); + if (!ret) { + fsnotify_xattr(dentry); + + /* This xattr is set by BPF LSM, so we do not call + * security_inode_post_setxattr. Otherwise, we would + * risk deadlocks by calling back to the same kfunc. + * + * This is the same as security_inode_setsecurity(). + */ + } + return ret; +} + +/** + * bpf_remove_dentry_xattr_locked - remove a xattr of a dentry + * @dentry: dentry to get xattr from + * @name__str: name of the xattr + * + * Rmove xattr *name__str* of *dentry*. + * + * For security reasons, only *name__str* with prefix "security.bpf." + * is allowed. + * + * The caller already locked dentry->d_inode. + * + * Return: 0 on success, a negative value on error. + */ +int bpf_remove_dentry_xattr_locked(struct dentry *dentry, const char *name__str) +{ + struct inode *inode = d_inode(dentry); + int ret; + + ret = bpf_xattr_write_permission(name__str, inode); + if (ret) + return ret; + + ret = __vfs_removexattr(&nop_mnt_idmap, dentry, name__str); + if (!ret) { + fsnotify_xattr(dentry); + + /* This xattr is removed by BPF LSM, so we do not call + * security_inode_post_removexattr. Otherwise, we would + * risk deadlocks by calling back to the same kfunc. + */ + } + return ret; +} + +__bpf_kfunc_start_defs(); + +/** + * bpf_set_dentry_xattr - set a xattr of a dentry + * @dentry: dentry to get xattr from + * @name__str: name of the xattr + * @value_p: xattr value + * @flags: flags to pass into filesystem operations + * + * Set xattr *name__str* of *dentry* to the value in *value_ptr*. + * + * For security reasons, only *name__str* with prefix "security.bpf." + * is allowed. + * + * The caller has not locked dentry->d_inode. + * + * Return: 0 on success, a negative value on error. + */ +__bpf_kfunc int bpf_set_dentry_xattr(struct dentry *dentry, const char *name__str, + const struct bpf_dynptr *value_p, int flags) +{ + struct inode *inode = d_inode(dentry); + int ret; + + inode_lock(inode); + ret = bpf_set_dentry_xattr_locked(dentry, name__str, value_p, flags); + inode_unlock(inode); + return ret; +} + +/** + * bpf_remove_dentry_xattr - remove a xattr of a dentry + * @dentry: dentry to get xattr from + * @name__str: name of the xattr + * + * Rmove xattr *name__str* of *dentry*. + * + * For security reasons, only *name__str* with prefix "security.bpf." + * is allowed. + * + * The caller has not locked dentry->d_inode. + * + * Return: 0 on success, a negative value on error. + */ +__bpf_kfunc int bpf_remove_dentry_xattr(struct dentry *dentry, const char *name__str) +{ + struct inode *inode = d_inode(dentry); + int ret; + + inode_lock(inode); + ret = bpf_remove_dentry_xattr_locked(dentry, name__str); + inode_unlock(inode); + return ret; +} + +__bpf_kfunc_end_defs(); + BTF_KFUNCS_START(bpf_fs_kfunc_set_ids) BTF_ID_FLAGS(func, bpf_get_task_exe_file, KF_ACQUIRE | KF_TRUSTED_ARGS | KF_RET_NULL) @@ -161,6 +331,8 @@ BTF_ID_FLAGS(func, bpf_put_file, KF_RELEASE) BTF_ID_FLAGS(func, bpf_path_d_path, KF_TRUSTED_ARGS) BTF_ID_FLAGS(func, bpf_get_dentry_xattr, KF_SLEEPABLE | KF_TRUSTED_ARGS) BTF_ID_FLAGS(func, bpf_get_file_xattr, KF_SLEEPABLE | KF_TRUSTED_ARGS) +BTF_ID_FLAGS(func, bpf_set_dentry_xattr, KF_SLEEPABLE | KF_TRUSTED_ARGS) +BTF_ID_FLAGS(func, bpf_remove_dentry_xattr, KF_SLEEPABLE | KF_TRUSTED_ARGS) BTF_KFUNCS_END(bpf_fs_kfunc_set_ids) static int bpf_fs_kfuncs_filter(const struct bpf_prog *prog, u32 kfunc_id) @@ -171,6 +343,37 @@ static int bpf_fs_kfuncs_filter(const struct bpf_prog *prog, u32 kfunc_id) return -EACCES; } +/* bpf_[set|remove]_dentry_xattr.* hooks have KF_TRUSTED_ARGS and + * KF_SLEEPABLE, so they are only available to sleepable hooks with + * dentry arguments. + * + * Setting and removing xattr requires exclusive lock on dentry->d_inode. + * Some hooks already locked d_inode, while some hooks have not locked + * d_inode. Therefore, we need different kfuncs for different hooks. + * Specifically, hooks in the following list (d_inode_locked_hooks) + * should call bpf_[set|remove]_dentry_xattr_locked; while other hooks + * should call bpf_[set|remove]_dentry_xattr. + */ +BTF_SET_START(d_inode_locked_hooks) +BTF_ID(func, bpf_lsm_inode_post_removexattr) +BTF_ID(func, bpf_lsm_inode_post_setattr) +BTF_ID(func, bpf_lsm_inode_post_setxattr) +BTF_ID(func, bpf_lsm_inode_removexattr) +BTF_ID(func, bpf_lsm_inode_rmdir) +BTF_ID(func, bpf_lsm_inode_setattr) +BTF_ID(func, bpf_lsm_inode_setxattr) +BTF_ID(func, bpf_lsm_inode_unlink) +#ifdef CONFIG_SECURITY_PATH +BTF_ID(func, bpf_lsm_path_unlink) +BTF_ID(func, bpf_lsm_path_rmdir) +#endif /* CONFIG_SECURITY_PATH */ +BTF_SET_END(d_inode_locked_hooks) + +bool bpf_lsm_has_d_inode_locked(const struct bpf_prog *prog) +{ + return btf_id_set_contains(&d_inode_locked_hooks, prog->aux->attach_btf_id); +} + static const struct btf_kfunc_id_set bpf_fs_kfunc_set = { .owner = THIS_MODULE, .set = &bpf_fs_kfunc_set_ids, diff --git a/include/linux/bpf_lsm.h b/include/linux/bpf_lsm.h index aefcd6564251..643809cc78c3 100644 --- a/include/linux/bpf_lsm.h +++ b/include/linux/bpf_lsm.h @@ -48,6 +48,11 @@ void bpf_lsm_find_cgroup_shim(const struct bpf_prog *prog, bpf_func_t *bpf_func) int bpf_lsm_get_retval_range(const struct bpf_prog *prog, struct bpf_retval_range *range); +int bpf_set_dentry_xattr_locked(struct dentry *dentry, const char *name__str, + const struct bpf_dynptr *value_p, int flags); +int bpf_remove_dentry_xattr_locked(struct dentry *dentry, const char *name__str); +bool bpf_lsm_has_d_inode_locked(const struct bpf_prog *prog); + #else /* !CONFIG_BPF_LSM */ static inline bool bpf_lsm_is_sleepable_hook(u32 btf_id) @@ -86,6 +91,19 @@ static inline int bpf_lsm_get_retval_range(const struct bpf_prog *prog, { return -EOPNOTSUPP; } +static inline int bpf_set_dentry_xattr_locked(struct dentry *dentry, const char *name__str, + const struct bpf_dynptr *value_p, int flags) +{ + return -EOPNOTSUPP; +} +static inline int bpf_remove_dentry_xattr_locked(struct dentry *dentry, const char *name__str) +{ + return -EOPNOTSUPP; +} +static inline bool bpf_lsm_has_d_inode_locked(const struct bpf_prog *prog) +{ + return false; +} #endif /* CONFIG_BPF_LSM */ #endif /* _LINUX_BPF_LSM_H */ diff --git a/include/uapi/linux/xattr.h b/include/uapi/linux/xattr.h index 9854f9cff3c6..c7c85bb504ba 100644 --- a/include/uapi/linux/xattr.h +++ b/include/uapi/linux/xattr.h @@ -83,6 +83,10 @@ struct xattr_args { #define XATTR_CAPS_SUFFIX "capability" #define XATTR_NAME_CAPS XATTR_SECURITY_PREFIX XATTR_CAPS_SUFFIX +#define XATTR_BPF_LSM_SUFFIX "bpf." +#define XATTR_NAME_BPF_LSM (XATTR_SECURITY_PREFIX XATTR_BPF_LSM_SUFFIX) +#define XATTR_NAME_BPF_LSM_LEN (sizeof(XATTR_NAME_BPF_LSM) - 1) + #define XATTR_POSIX_ACL_ACCESS "posix_acl_access" #define XATTR_NAME_POSIX_ACL_ACCESS XATTR_SYSTEM_PREFIX XATTR_POSIX_ACL_ACCESS #define XATTR_POSIX_ACL_DEFAULT "posix_acl_default" diff --git a/kernel/bpf/bpf_lsm.c b/kernel/bpf/bpf_lsm.c index 967492b65185..0a59df1c550a 100644 --- a/kernel/bpf/bpf_lsm.c +++ b/kernel/bpf/bpf_lsm.c @@ -316,7 +316,9 @@ BTF_ID(func, bpf_lsm_inode_getxattr) BTF_ID(func, bpf_lsm_inode_mknod) BTF_ID(func, bpf_lsm_inode_need_killpriv) BTF_ID(func, bpf_lsm_inode_post_setxattr) +BTF_ID(func, bpf_lsm_inode_post_removexattr) BTF_ID(func, bpf_lsm_inode_readlink) +BTF_ID(func, bpf_lsm_inode_removexattr) BTF_ID(func, bpf_lsm_inode_rename) BTF_ID(func, bpf_lsm_inode_rmdir) BTF_ID(func, bpf_lsm_inode_setattr) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 9971c03adfd5..04d1d75d9ff9 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -11766,6 +11766,8 @@ enum special_kfunc_type { KF_bpf_iter_num_new, KF_bpf_iter_num_next, KF_bpf_iter_num_destroy, + KF_bpf_set_dentry_xattr, + KF_bpf_remove_dentry_xattr, }; BTF_SET_START(special_kfunc_set) @@ -11795,6 +11797,10 @@ BTF_ID(func, bpf_wq_set_callback_impl) #ifdef CONFIG_CGROUPS BTF_ID(func, bpf_iter_css_task_new) #endif +#ifdef CONFIG_BPF_LSM +BTF_ID(func, bpf_set_dentry_xattr) +BTF_ID(func, bpf_remove_dentry_xattr) +#endif BTF_SET_END(special_kfunc_set) BTF_ID_LIST(special_kfunc_list) @@ -11844,6 +11850,13 @@ BTF_ID(func, bpf_local_irq_restore) BTF_ID(func, bpf_iter_num_new) BTF_ID(func, bpf_iter_num_next) BTF_ID(func, bpf_iter_num_destroy) +#ifdef CONFIG_BPF_LSM +BTF_ID(func, bpf_set_dentry_xattr) +BTF_ID(func, bpf_remove_dentry_xattr) +#else +BTF_ID_UNUSED +BTF_ID_UNUSED +#endif static bool is_kfunc_ret_null(struct bpf_kfunc_call_arg_meta *meta) { @@ -20924,6 +20937,14 @@ static void specialize_kfunc(struct bpf_verifier_env *env, */ env->seen_direct_write = seen_direct_write; } + + if (func_id == special_kfunc_list[KF_bpf_set_dentry_xattr] && + bpf_lsm_has_d_inode_locked(prog)) + *addr = (unsigned long)bpf_set_dentry_xattr_locked; + + if (func_id == special_kfunc_list[KF_bpf_remove_dentry_xattr] && + bpf_lsm_has_d_inode_locked(prog)) + *addr = (unsigned long)bpf_remove_dentry_xattr_locked; } static void __fixup_collection_insert_kfunc(struct bpf_insn_aux_data *insn_aux, diff --git a/tools/testing/selftests/bpf/bpf_kfuncs.h b/tools/testing/selftests/bpf/bpf_kfuncs.h index 2eb3483f2fb0..8215c9b3115e 100644 --- a/tools/testing/selftests/bpf/bpf_kfuncs.h +++ b/tools/testing/selftests/bpf/bpf_kfuncs.h @@ -87,4 +87,9 @@ struct dentry; */ extern int bpf_get_dentry_xattr(struct dentry *dentry, const char *name, struct bpf_dynptr *value_ptr) __ksym __weak; + +extern int bpf_set_dentry_xattr(struct dentry *dentry, const char *name__str, + const struct bpf_dynptr *value_p, int flags) __ksym __weak; +extern int bpf_remove_dentry_xattr(struct dentry *dentry, const char *name__str) __ksym __weak; + #endif diff --git a/tools/testing/selftests/bpf/prog_tests/fs_kfuncs.c b/tools/testing/selftests/bpf/prog_tests/fs_kfuncs.c index 5a0b51157451..43a26ec69a8e 100644 --- a/tools/testing/selftests/bpf/prog_tests/fs_kfuncs.c +++ b/tools/testing/selftests/bpf/prog_tests/fs_kfuncs.c @@ -8,11 +8,12 @@ #include <unistd.h> #include <test_progs.h> #include "test_get_xattr.skel.h" +#include "test_set_remove_xattr.skel.h" #include "test_fsverity.skel.h" static const char testfile[] = "/tmp/test_progs_fs_kfuncs"; -static void test_xattr(void) +static void test_get_xattr(const char *name, const char *value, bool allow_access) { struct test_get_xattr *skel = NULL; int fd = -1, err; @@ -25,7 +26,7 @@ static void test_xattr(void) close(fd); fd = -1; - err = setxattr(testfile, "user.kfuncs", "hello", sizeof("hello"), 0); + err = setxattr(testfile, name, value, strlen(value) + 1, 0); if (err && errno == EOPNOTSUPP) { printf("%s:SKIP:local fs doesn't support xattr (%d)\n" "To run this test, make sure /tmp filesystem supports xattr.\n", @@ -48,16 +49,23 @@ static void test_xattr(void) goto out; fd = open(testfile, O_RDONLY, 0644); + if (!ASSERT_GE(fd, 0, "open_file")) goto out; - ASSERT_EQ(skel->bss->found_xattr_from_file, 1, "found_xattr_from_file"); - /* Trigger security_inode_getxattr */ - err = getxattr(testfile, "user.kfuncs", v, sizeof(v)); - ASSERT_EQ(err, -1, "getxattr_return"); - ASSERT_EQ(errno, EINVAL, "getxattr_errno"); - ASSERT_EQ(skel->bss->found_xattr_from_dentry, 1, "found_xattr_from_dentry"); + err = getxattr(testfile, name, v, sizeof(v)); + + if (allow_access) { + ASSERT_EQ(err, -1, "getxattr_return"); + ASSERT_EQ(errno, EINVAL, "getxattr_errno"); + ASSERT_EQ(skel->bss->found_xattr_from_file, 1, "found_xattr_from_file"); + ASSERT_EQ(skel->bss->found_xattr_from_dentry, 1, "found_xattr_from_dentry"); + } else { + ASSERT_EQ(err, strlen(value) + 1, "getxattr_return"); + ASSERT_EQ(skel->bss->found_xattr_from_file, 0, "found_xattr_from_file"); + ASSERT_EQ(skel->bss->found_xattr_from_dentry, 0, "found_xattr_from_dentry"); + } out: close(fd); @@ -65,6 +73,127 @@ out: remove(testfile); } +/* xattr value we will set to security.bpf.foo */ +static const char value_foo[] = "hello"; + +static void read_and_validate_foo(struct test_set_remove_xattr *skel) +{ + char value_out[32]; + int err; + + err = getxattr(testfile, skel->rodata->xattr_foo, value_out, sizeof(value_out)); + ASSERT_EQ(err, sizeof(value_foo), "getxattr size foo"); + ASSERT_EQ(strncmp(value_out, value_foo, sizeof(value_foo)), 0, "strncmp value_foo"); +} + +static void set_foo(struct test_set_remove_xattr *skel) +{ + ASSERT_OK(setxattr(testfile, skel->rodata->xattr_foo, value_foo, strlen(value_foo) + 1, 0), + "setxattr foo"); +} + +static void validate_bar_match(struct test_set_remove_xattr *skel) +{ + char value_out[32]; + int err; + + err = getxattr(testfile, skel->rodata->xattr_bar, value_out, sizeof(value_out)); + ASSERT_EQ(err, sizeof(skel->data->value_bar), "getxattr size bar"); + ASSERT_EQ(strncmp(value_out, skel->data->value_bar, sizeof(skel->data->value_bar)), 0, + "strncmp value_bar"); +} + +static void validate_bar_removed(struct test_set_remove_xattr *skel) +{ + char value_out[32]; + int err; + + err = getxattr(testfile, skel->rodata->xattr_bar, value_out, sizeof(value_out)); + ASSERT_LT(err, 0, "getxattr size bar should fail"); +} + +static void test_set_remove_xattr(void) +{ + struct test_set_remove_xattr *skel = NULL; + int fd = -1, err; + + fd = open(testfile, O_CREAT | O_RDONLY, 0644); + if (!ASSERT_GE(fd, 0, "create_file")) + return; + + close(fd); + fd = -1; + + skel = test_set_remove_xattr__open_and_load(); + if (!ASSERT_OK_PTR(skel, "test_set_remove_xattr__open_and_load")) + return; + + /* Set security.bpf.foo to "hello" */ + err = setxattr(testfile, skel->rodata->xattr_foo, value_foo, strlen(value_foo) + 1, 0); + if (err && errno == EOPNOTSUPP) { + printf("%s:SKIP:local fs doesn't support xattr (%d)\n" + "To run this test, make sure /tmp filesystem supports xattr.\n", + __func__, errno); + test__skip(); + goto out; + } + + if (!ASSERT_OK(err, "setxattr")) + goto out; + + skel->bss->monitored_pid = getpid(); + err = test_set_remove_xattr__attach(skel); + if (!ASSERT_OK(err, "test_set_remove_xattr__attach")) + goto out; + + /* First, test not _locked version of the kfuncs with getxattr. */ + + /* Read security.bpf.foo and trigger test_inode_getxattr. This + * bpf program will set security.bpf.bar to "world". + */ + read_and_validate_foo(skel); + validate_bar_match(skel); + + /* Read security.bpf.foo and trigger test_inode_getxattr again. + * This will remove xattr security.bpf.bar. + */ + read_and_validate_foo(skel); + validate_bar_removed(skel); + + ASSERT_TRUE(skel->bss->set_security_bpf_bar_success, "set_security_bpf_bar_success"); + ASSERT_TRUE(skel->bss->remove_security_bpf_bar_success, "remove_security_bpf_bar_success"); + ASSERT_TRUE(skel->bss->set_security_selinux_fail, "set_security_selinux_fail"); + ASSERT_TRUE(skel->bss->remove_security_selinux_fail, "remove_security_selinux_fail"); + + /* Second, test _locked version of the kfuncs, with setxattr */ + + /* Set security.bpf.foo and trigger test_inode_setxattr. This + * bpf program will set security.bpf.bar to "world". + */ + set_foo(skel); + validate_bar_match(skel); + + /* Set security.bpf.foo and trigger test_inode_setxattr again. + * This will remove xattr security.bpf.bar. + */ + set_foo(skel); + validate_bar_removed(skel); + + ASSERT_TRUE(skel->bss->locked_set_security_bpf_bar_success, + "locked_set_security_bpf_bar_success"); + ASSERT_TRUE(skel->bss->locked_remove_security_bpf_bar_success, + "locked_remove_security_bpf_bar_success"); + ASSERT_TRUE(skel->bss->locked_set_security_selinux_fail, + "locked_set_security_selinux_fail"); + ASSERT_TRUE(skel->bss->locked_remove_security_selinux_fail, + "locked_remove_security_selinux_fail"); + +out: + close(fd); + test_set_remove_xattr__destroy(skel); + remove(testfile); +} + #ifndef SHA256_DIGEST_SIZE #define SHA256_DIGEST_SIZE 32 #endif @@ -141,8 +270,21 @@ out: void test_fs_kfuncs(void) { - if (test__start_subtest("xattr")) - test_xattr(); + /* Matches xattr_names in progs/test_get_xattr.c */ + if (test__start_subtest("user_xattr")) + test_get_xattr("user.kfuncs", "hello", true); + + if (test__start_subtest("security_bpf_xattr")) + test_get_xattr("security.bpf.xxx", "hello", true); + + if (test__start_subtest("security_bpf_xattr_error")) + test_get_xattr("security.bpf", "hello", false); + + if (test__start_subtest("security_selinux_xattr_error")) + test_get_xattr("security.selinux", "hello", false); + + if (test__start_subtest("set_remove_xattr")) + test_set_remove_xattr(); if (test__start_subtest("fsverity")) test_fsverity(); diff --git a/tools/testing/selftests/bpf/progs/test_get_xattr.c b/tools/testing/selftests/bpf/progs/test_get_xattr.c index 66e737720f7c..54305f4c9f2d 100644 --- a/tools/testing/selftests/bpf/progs/test_get_xattr.c +++ b/tools/testing/selftests/bpf/progs/test_get_xattr.c @@ -6,6 +6,7 @@ #include <bpf/bpf_helpers.h> #include <bpf/bpf_tracing.h> #include "bpf_kfuncs.h" +#include "bpf_misc.h" char _license[] SEC("license") = "GPL"; @@ -17,12 +18,23 @@ static const char expected_value[] = "hello"; char value1[32]; char value2[32]; +/* Matches caller of test_get_xattr() in prog_tests/fs_kfuncs.c */ +static const char xattr_names[][64] = { + /* The following work. */ + "user.kfuncs", + "security.bpf.xxx", + + /* The following do not work. */ + "security.bpf", + "security.selinux" +}; + SEC("lsm.s/file_open") int BPF_PROG(test_file_open, struct file *f) { struct bpf_dynptr value_ptr; __u32 pid; - int ret; + int ret, i; pid = bpf_get_current_pid_tgid() >> 32; if (pid != monitored_pid) @@ -30,7 +42,11 @@ int BPF_PROG(test_file_open, struct file *f) bpf_dynptr_from_mem(value1, sizeof(value1), 0, &value_ptr); - ret = bpf_get_file_xattr(f, "user.kfuncs", &value_ptr); + for (i = 0; i < ARRAY_SIZE(xattr_names); i++) { + ret = bpf_get_file_xattr(f, xattr_names[i], &value_ptr); + if (ret == sizeof(expected_value)) + break; + } if (ret != sizeof(expected_value)) return 0; if (bpf_strncmp(value1, ret, expected_value)) @@ -44,7 +60,7 @@ int BPF_PROG(test_inode_getxattr, struct dentry *dentry, char *name) { struct bpf_dynptr value_ptr; __u32 pid; - int ret; + int ret, i; pid = bpf_get_current_pid_tgid() >> 32; if (pid != monitored_pid) @@ -52,7 +68,11 @@ int BPF_PROG(test_inode_getxattr, struct dentry *dentry, char *name) bpf_dynptr_from_mem(value2, sizeof(value2), 0, &value_ptr); - ret = bpf_get_dentry_xattr(dentry, "user.kfuncs", &value_ptr); + for (i = 0; i < ARRAY_SIZE(xattr_names); i++) { + ret = bpf_get_dentry_xattr(dentry, xattr_names[i], &value_ptr); + if (ret == sizeof(expected_value)) + break; + } if (ret != sizeof(expected_value)) return 0; if (bpf_strncmp(value2, ret, expected_value)) diff --git a/tools/testing/selftests/bpf/progs/test_set_remove_xattr.c b/tools/testing/selftests/bpf/progs/test_set_remove_xattr.c new file mode 100644 index 000000000000..6a612cf168d3 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/test_set_remove_xattr.c @@ -0,0 +1,133 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2024 Meta Platforms, Inc. and affiliates. */ + +#include "vmlinux.h" +#include <errno.h> +#include <bpf/bpf_tracing.h> +#include "bpf_kfuncs.h" +#include "bpf_misc.h" + +char _license[] SEC("license") = "GPL"; + +__u32 monitored_pid; + +const char xattr_foo[] = "security.bpf.foo"; +const char xattr_bar[] = "security.bpf.bar"; +static const char xattr_selinux[] = "security.selinux"; +char value_bar[] = "world"; +char read_value[32]; + +bool set_security_bpf_bar_success; +bool remove_security_bpf_bar_success; +bool set_security_selinux_fail; +bool remove_security_selinux_fail; + +char name_buf[32]; + +static inline bool name_match_foo(const char *name) +{ + bpf_probe_read_kernel(name_buf, sizeof(name_buf), name); + + return !bpf_strncmp(name_buf, sizeof(xattr_foo), xattr_foo); +} + +/* Test bpf_set_dentry_xattr and bpf_remove_dentry_xattr */ +SEC("lsm.s/inode_getxattr") +int BPF_PROG(test_inode_getxattr, struct dentry *dentry, char *name) +{ + struct bpf_dynptr value_ptr; + __u32 pid; + int ret; + + pid = bpf_get_current_pid_tgid() >> 32; + if (pid != monitored_pid) + return 0; + + /* Only do the following for security.bpf.foo */ + if (!name_match_foo(name)) + return 0; + + bpf_dynptr_from_mem(read_value, sizeof(read_value), 0, &value_ptr); + + /* read security.bpf.bar */ + ret = bpf_get_dentry_xattr(dentry, xattr_bar, &value_ptr); + + if (ret < 0) { + /* If security.bpf.bar doesn't exist, set it */ + bpf_dynptr_from_mem(value_bar, sizeof(value_bar), 0, &value_ptr); + + ret = bpf_set_dentry_xattr(dentry, xattr_bar, &value_ptr, 0); + if (!ret) + set_security_bpf_bar_success = true; + ret = bpf_set_dentry_xattr(dentry, xattr_selinux, &value_ptr, 0); + if (ret) + set_security_selinux_fail = true; + } else { + /* If security.bpf.bar exists, remove it */ + ret = bpf_remove_dentry_xattr(dentry, xattr_bar); + if (!ret) + remove_security_bpf_bar_success = true; + + ret = bpf_remove_dentry_xattr(dentry, xattr_selinux); + if (ret) + remove_security_selinux_fail = true; + } + + return 0; +} + +bool locked_set_security_bpf_bar_success; +bool locked_remove_security_bpf_bar_success; +bool locked_set_security_selinux_fail; +bool locked_remove_security_selinux_fail; + +/* Test bpf_set_dentry_xattr_locked and bpf_remove_dentry_xattr_locked. + * It not necessary to differentiate the _locked version and the + * not-_locked version in the BPF program. The verifier will fix them up + * properly. + */ +SEC("lsm.s/inode_setxattr") +int BPF_PROG(test_inode_setxattr, struct mnt_idmap *idmap, + struct dentry *dentry, const char *name, + const void *value, size_t size, int flags) +{ + struct bpf_dynptr value_ptr; + __u32 pid; + int ret; + + pid = bpf_get_current_pid_tgid() >> 32; + if (pid != monitored_pid) + return 0; + + /* Only do the following for security.bpf.foo */ + if (!name_match_foo(name)) + return 0; + + bpf_dynptr_from_mem(read_value, sizeof(read_value), 0, &value_ptr); + + /* read security.bpf.bar */ + ret = bpf_get_dentry_xattr(dentry, xattr_bar, &value_ptr); + + if (ret < 0) { + /* If security.bpf.bar doesn't exist, set it */ + bpf_dynptr_from_mem(value_bar, sizeof(value_bar), 0, &value_ptr); + + ret = bpf_set_dentry_xattr(dentry, xattr_bar, &value_ptr, 0); + if (!ret) + locked_set_security_bpf_bar_success = true; + ret = bpf_set_dentry_xattr(dentry, xattr_selinux, &value_ptr, 0); + if (ret) + locked_set_security_selinux_fail = true; + } else { + /* If security.bpf.bar exists, remove it */ + ret = bpf_remove_dentry_xattr(dentry, xattr_bar); + if (!ret) + locked_remove_security_bpf_bar_success = true; + + ret = bpf_remove_dentry_xattr(dentry, xattr_selinux); + if (ret) + locked_remove_security_selinux_fail = true; + } + + return 0; +} |