linux/kernel/bpf/token.c
Haiyue Wang 6668e818f9 bpf,token: Use BIT_ULL() to convert the bit mask
Replace the '(1ULL << *)' with the macro BIT_ULL(nr).

Signed-off-by: Haiyue Wang <haiyue.wang@intel.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20240127134901.3698613-1-haiyue.wang@intel.com
2024-01-29 20:04:55 -08:00

279 lines
6.5 KiB
C

#include <linux/bpf.h>
#include <linux/vmalloc.h>
#include <linux/fdtable.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/kernel.h>
#include <linux/idr.h>
#include <linux/namei.h>
#include <linux/user_namespace.h>
#include <linux/security.h>
static bool bpf_ns_capable(struct user_namespace *ns, int cap)
{
return ns_capable(ns, cap) || (cap != CAP_SYS_ADMIN && ns_capable(ns, CAP_SYS_ADMIN));
}
bool bpf_token_capable(const struct bpf_token *token, int cap)
{
struct user_namespace *userns;
/* BPF token allows ns_capable() level of capabilities */
userns = token ? token->userns : &init_user_ns;
if (!bpf_ns_capable(userns, cap))
return false;
if (token && security_bpf_token_capable(token, cap) < 0)
return false;
return true;
}
void bpf_token_inc(struct bpf_token *token)
{
atomic64_inc(&token->refcnt);
}
static void bpf_token_free(struct bpf_token *token)
{
security_bpf_token_free(token);
put_user_ns(token->userns);
kfree(token);
}
static void bpf_token_put_deferred(struct work_struct *work)
{
struct bpf_token *token = container_of(work, struct bpf_token, work);
bpf_token_free(token);
}
void bpf_token_put(struct bpf_token *token)
{
if (!token)
return;
if (!atomic64_dec_and_test(&token->refcnt))
return;
INIT_WORK(&token->work, bpf_token_put_deferred);
schedule_work(&token->work);
}
static int bpf_token_release(struct inode *inode, struct file *filp)
{
struct bpf_token *token = filp->private_data;
bpf_token_put(token);
return 0;
}
static void bpf_token_show_fdinfo(struct seq_file *m, struct file *filp)
{
struct bpf_token *token = filp->private_data;
u64 mask;
BUILD_BUG_ON(__MAX_BPF_CMD >= 64);
mask = BIT_ULL(__MAX_BPF_CMD) - 1;
if ((token->allowed_cmds & mask) == mask)
seq_printf(m, "allowed_cmds:\tany\n");
else
seq_printf(m, "allowed_cmds:\t0x%llx\n", token->allowed_cmds);
BUILD_BUG_ON(__MAX_BPF_MAP_TYPE >= 64);
mask = BIT_ULL(__MAX_BPF_MAP_TYPE) - 1;
if ((token->allowed_maps & mask) == mask)
seq_printf(m, "allowed_maps:\tany\n");
else
seq_printf(m, "allowed_maps:\t0x%llx\n", token->allowed_maps);
BUILD_BUG_ON(__MAX_BPF_PROG_TYPE >= 64);
mask = BIT_ULL(__MAX_BPF_PROG_TYPE) - 1;
if ((token->allowed_progs & mask) == mask)
seq_printf(m, "allowed_progs:\tany\n");
else
seq_printf(m, "allowed_progs:\t0x%llx\n", token->allowed_progs);
BUILD_BUG_ON(__MAX_BPF_ATTACH_TYPE >= 64);
mask = BIT_ULL(__MAX_BPF_ATTACH_TYPE) - 1;
if ((token->allowed_attachs & mask) == mask)
seq_printf(m, "allowed_attachs:\tany\n");
else
seq_printf(m, "allowed_attachs:\t0x%llx\n", token->allowed_attachs);
}
#define BPF_TOKEN_INODE_NAME "bpf-token"
static const struct inode_operations bpf_token_iops = { };
static const struct file_operations bpf_token_fops = {
.release = bpf_token_release,
.show_fdinfo = bpf_token_show_fdinfo,
};
int bpf_token_create(union bpf_attr *attr)
{
struct bpf_mount_opts *mnt_opts;
struct bpf_token *token = NULL;
struct user_namespace *userns;
struct inode *inode;
struct file *file;
struct path path;
struct fd f;
umode_t mode;
int err, fd;
f = fdget(attr->token_create.bpffs_fd);
if (!f.file)
return -EBADF;
path = f.file->f_path;
path_get(&path);
fdput(f);
if (path.dentry != path.mnt->mnt_sb->s_root) {
err = -EINVAL;
goto out_path;
}
if (path.mnt->mnt_sb->s_op != &bpf_super_ops) {
err = -EINVAL;
goto out_path;
}
err = path_permission(&path, MAY_ACCESS);
if (err)
goto out_path;
userns = path.dentry->d_sb->s_user_ns;
/*
* Enforce that creators of BPF tokens are in the same user
* namespace as the BPF FS instance. This makes reasoning about
* permissions a lot easier and we can always relax this later.
*/
if (current_user_ns() != userns) {
err = -EPERM;
goto out_path;
}
if (!ns_capable(userns, CAP_BPF)) {
err = -EPERM;
goto out_path;
}
/* Creating BPF token in init_user_ns doesn't make much sense. */
if (current_user_ns() == &init_user_ns) {
err = -EOPNOTSUPP;
goto out_path;
}
mnt_opts = path.dentry->d_sb->s_fs_info;
if (mnt_opts->delegate_cmds == 0 &&
mnt_opts->delegate_maps == 0 &&
mnt_opts->delegate_progs == 0 &&
mnt_opts->delegate_attachs == 0) {
err = -ENOENT; /* no BPF token delegation is set up */
goto out_path;
}
mode = S_IFREG | ((S_IRUSR | S_IWUSR) & ~current_umask());
inode = bpf_get_inode(path.mnt->mnt_sb, NULL, mode);
if (IS_ERR(inode)) {
err = PTR_ERR(inode);
goto out_path;
}
inode->i_op = &bpf_token_iops;
inode->i_fop = &bpf_token_fops;
clear_nlink(inode); /* make sure it is unlinked */
file = alloc_file_pseudo(inode, path.mnt, BPF_TOKEN_INODE_NAME, O_RDWR, &bpf_token_fops);
if (IS_ERR(file)) {
iput(inode);
err = PTR_ERR(file);
goto out_path;
}
token = kzalloc(sizeof(*token), GFP_USER);
if (!token) {
err = -ENOMEM;
goto out_file;
}
atomic64_set(&token->refcnt, 1);
/* remember bpffs owning userns for future ns_capable() checks */
token->userns = get_user_ns(userns);
token->allowed_cmds = mnt_opts->delegate_cmds;
token->allowed_maps = mnt_opts->delegate_maps;
token->allowed_progs = mnt_opts->delegate_progs;
token->allowed_attachs = mnt_opts->delegate_attachs;
err = security_bpf_token_create(token, attr, &path);
if (err)
goto out_token;
fd = get_unused_fd_flags(O_CLOEXEC);
if (fd < 0) {
err = fd;
goto out_token;
}
file->private_data = token;
fd_install(fd, file);
path_put(&path);
return fd;
out_token:
bpf_token_free(token);
out_file:
fput(file);
out_path:
path_put(&path);
return err;
}
struct bpf_token *bpf_token_get_from_fd(u32 ufd)
{
struct fd f = fdget(ufd);
struct bpf_token *token;
if (!f.file)
return ERR_PTR(-EBADF);
if (f.file->f_op != &bpf_token_fops) {
fdput(f);
return ERR_PTR(-EINVAL);
}
token = f.file->private_data;
bpf_token_inc(token);
fdput(f);
return token;
}
bool bpf_token_allow_cmd(const struct bpf_token *token, enum bpf_cmd cmd)
{
if (!token)
return false;
if (!(token->allowed_cmds & BIT_ULL(cmd)))
return false;
return security_bpf_token_cmd(token, cmd) == 0;
}
bool bpf_token_allow_map_type(const struct bpf_token *token, enum bpf_map_type type)
{
if (!token || type >= __MAX_BPF_MAP_TYPE)
return false;
return token->allowed_maps & BIT_ULL(type);
}
bool bpf_token_allow_prog_type(const struct bpf_token *token,
enum bpf_prog_type prog_type,
enum bpf_attach_type attach_type)
{
if (!token || prog_type >= __MAX_BPF_PROG_TYPE || attach_type >= __MAX_BPF_ATTACH_TYPE)
return false;
return (token->allowed_progs & BIT_ULL(prog_type)) &&
(token->allowed_attachs & BIT_ULL(attach_type));
}