| Message ID | 20211012180624.447474-3-vgoyal@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | fuse: Send file/inode security context during creation | expand |
On 10/12/2021 11:06 AM, Vivek Goyal wrote: > When a new inode is created, send its security context to server along > with creation request (FUSE_CREAT, FUSE_MKNOD, FUSE_MKDIR and FUSE_SYMLINK). > This gives server an opportunity to create new file and set security > context (possibly atomically). In all the configurations it might not > be possible to set context atomically. > > Like nfs and ceph, use security_dentry_init_security() to dermine security > context of inode and send it with create, mkdir, mknod, and symlink requests. > > Following is the information sent to server. > > - struct fuse_secctxs. > This contains total number of security contexts being sent. > > - struct fuse_secctx. > This contains total size of security context which follows this structure. > There is one fuse_secctx instance per security context. > > - xattr name string. > This string represents name of xattr which should be used while setting > security context. As of now it is hardcoded to "security.selinux". Where is the name hardcoded? I looks as if you're getting the attribute name along with the value from security_dentry_init_security(). > > - security context. > This is the actual security context whose size is specified in fuse_secctx > struct. > > This patch is modified version of patch from > Chirantan Ekbote <chirantan@chromium.org> > > v2: > - Added "fuse_secctxs" structure where one can specify how many security > contexts are being sent. This can be useful down the line if we > have more than one security contexts being set. > > Signed-off-by: Vivek Goyal <vgoyal@redhat.com> > --- > fs/fuse/dir.c | 115 ++++++++++++++++++++++++++++++++++++-- > fs/fuse/fuse_i.h | 3 + > fs/fuse/inode.c | 4 +- > include/uapi/linux/fuse.h | 20 +++++++ > 4 files changed, 136 insertions(+), 6 deletions(-) > > diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c > index d9b977c0f38d..ce62593a61f9 100644 > --- a/fs/fuse/dir.c > +++ b/fs/fuse/dir.c > @@ -17,6 +17,9 @@ > #include <linux/xattr.h> > #include <linux/iversion.h> > #include <linux/posix_acl.h> > +#include <linux/security.h> > +#include <linux/types.h> > +#include <linux/kernel.h> > > static void fuse_advise_use_readdirplus(struct inode *dir) > { > @@ -456,6 +459,66 @@ static struct dentry *fuse_lookup(struct inode *dir, struct dentry *entry, > return ERR_PTR(err); > } > > +static int get_security_context(struct dentry *entry, umode_t mode, > + void **security_ctx, u32 *security_ctxlen) > +{ > + struct fuse_secctx *fsecctx; > + struct fuse_secctxs *fsecctxs; > + void *ctx, *full_ctx; > + u32 ctxlen, full_ctxlen; > + int err = 0; > + const char *name; > + > + err = security_dentry_init_security(entry, mode, &entry->d_name, > + &name, &ctx, &ctxlen); > + if (err) { > + if (err != -EOPNOTSUPP) > + goto out_err; > + /* No LSM is supporting this security hook. Ignore error */ > + err = 0; > + ctxlen = 0; > + } > + > + if (ctxlen > 0) { > + void *ptr; > + > + full_ctxlen = sizeof(*fsecctxs) + sizeof(*fsecctx) + > + strlen(name) + ctxlen + 1; > + full_ctx = kzalloc(full_ctxlen, GFP_KERNEL); > + if (!full_ctx) { > + err = -ENOMEM; > + kfree(ctx); > + goto out_err; > + } > + > + ptr = full_ctx; > + fsecctxs = (struct fuse_secctxs*) ptr; > + fsecctxs->nr_secctx = 1; > + ptr += sizeof(*fsecctxs); > + > + fsecctx = (struct fuse_secctx*) ptr; > + fsecctx->size = ctxlen; > + ptr += sizeof(*fsecctx); > + > + strcpy(ptr, name); > + ptr += strlen(name) + 1; > + memcpy(ptr, ctx, ctxlen); > + kfree(ctx); > + } else { > + full_ctxlen = sizeof(*fsecctxs); > + full_ctx = kzalloc(full_ctxlen, GFP_KERNEL); > + if (!full_ctx) { > + err = -ENOMEM; > + goto out_err; > + } > + } > + > + *security_ctxlen = full_ctxlen; > + *security_ctx = full_ctx; > +out_err: > + return err; > +} > + > /* > * Atomic create+open operation > * > @@ -476,6 +539,8 @@ static int fuse_create_open(struct inode *dir, struct dentry *entry, > struct fuse_entry_out outentry; > struct fuse_inode *fi; > struct fuse_file *ff; > + void *security_ctx = NULL; > + u32 security_ctxlen; > > /* Userspace expects S_IFREG in create mode */ > BUG_ON((mode & S_IFMT) != S_IFREG); > @@ -517,6 +582,18 @@ static int fuse_create_open(struct inode *dir, struct dentry *entry, > args.out_args[0].value = &outentry; > args.out_args[1].size = sizeof(outopen); > args.out_args[1].value = &outopen; > + > + if (fm->fc->init_security) { > + err = get_security_context(entry, mode, &security_ctx, > + &security_ctxlen); > + if (err) > + goto out_put_forget_req; > + > + args.in_numargs = 3; > + args.in_args[2].size = security_ctxlen; > + args.in_args[2].value = security_ctx; > + } > + > err = fuse_simple_request(fm, &args); > if (err) > goto out_free_ff; > @@ -554,6 +631,7 @@ static int fuse_create_open(struct inode *dir, struct dentry *entry, > > out_free_ff: > fuse_file_free(ff); > + kfree(security_ctx); > out_put_forget_req: > kfree(forget); > out_err: > @@ -613,13 +691,15 @@ static int fuse_atomic_open(struct inode *dir, struct dentry *entry, > */ > static int create_new_entry(struct fuse_mount *fm, struct fuse_args *args, > struct inode *dir, struct dentry *entry, > - umode_t mode) > + umode_t mode, bool init_security) > { > struct fuse_entry_out outarg; > struct inode *inode; > struct dentry *d; > int err; > struct fuse_forget_link *forget; > + void *security_ctx = NULL; > + u32 security_ctxlen = 0; > > if (fuse_is_bad(dir)) > return -EIO; > @@ -633,7 +713,29 @@ static int create_new_entry(struct fuse_mount *fm, struct fuse_args *args, > args->out_numargs = 1; > args->out_args[0].size = sizeof(outarg); > args->out_args[0].value = &outarg; > + > + if (init_security) { > + unsigned short idx = args->in_numargs; > + > + if ((size_t)idx >= ARRAY_SIZE(args->in_args)) { > + err = -ENOMEM; > + goto out_put_forget_req; > + } > + > + err = get_security_context(entry, mode, &security_ctx, > + &security_ctxlen); > + if (err) > + goto out_put_forget_req; > + > + if (security_ctxlen > 0) { > + args->in_args[idx].size = security_ctxlen; > + args->in_args[idx].value = security_ctx; > + args->in_numargs++; > + } > + } > + > err = fuse_simple_request(fm, args); > + kfree(security_ctx); > if (err) > goto out_put_forget_req; > > @@ -691,7 +793,7 @@ static int fuse_mknod(struct user_namespace *mnt_userns, struct inode *dir, > args.in_args[0].value = &inarg; > args.in_args[1].size = entry->d_name.len + 1; > args.in_args[1].value = entry->d_name.name; > - return create_new_entry(fm, &args, dir, entry, mode); > + return create_new_entry(fm, &args, dir, entry, mode, fm->fc->init_security); > } > > static int fuse_create(struct user_namespace *mnt_userns, struct inode *dir, > @@ -719,7 +821,8 @@ static int fuse_mkdir(struct user_namespace *mnt_userns, struct inode *dir, > args.in_args[0].value = &inarg; > args.in_args[1].size = entry->d_name.len + 1; > args.in_args[1].value = entry->d_name.name; > - return create_new_entry(fm, &args, dir, entry, S_IFDIR); > + return create_new_entry(fm, &args, dir, entry, S_IFDIR, > + fm->fc->init_security); > } > > static int fuse_symlink(struct user_namespace *mnt_userns, struct inode *dir, > @@ -735,7 +838,8 @@ static int fuse_symlink(struct user_namespace *mnt_userns, struct inode *dir, > args.in_args[0].value = entry->d_name.name; > args.in_args[1].size = len; > args.in_args[1].value = link; > - return create_new_entry(fm, &args, dir, entry, S_IFLNK); > + return create_new_entry(fm, &args, dir, entry, S_IFLNK, > + fm->fc->init_security); > } > > void fuse_update_ctime(struct inode *inode) > @@ -915,7 +1019,8 @@ static int fuse_link(struct dentry *entry, struct inode *newdir, > args.in_args[0].value = &inarg; > args.in_args[1].size = newent->d_name.len + 1; > args.in_args[1].value = newent->d_name.name; > - err = create_new_entry(fm, &args, newdir, newent, inode->i_mode); > + err = create_new_entry(fm, &args, newdir, newent, inode->i_mode, > + false); > /* Contrary to "normal" filesystems it can happen that link > makes two "logical" inodes point to the same "physical" > inode. We invalidate the attributes of the old one, so it > diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h > index 319596df5dc6..885f34f9967f 100644 > --- a/fs/fuse/fuse_i.h > +++ b/fs/fuse/fuse_i.h > @@ -765,6 +765,9 @@ struct fuse_conn { > /* Propagate syncfs() to server */ > unsigned int sync_fs:1; > > + /* Initialize security xattrs when creating a new inode */ > + unsigned int init_security:1; > + > /** The number of requests waiting for completion */ > atomic_t num_waiting; > > diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c > index 36cd03114b6d..343bc9cfbd92 100644 > --- a/fs/fuse/inode.c > +++ b/fs/fuse/inode.c > @@ -1152,6 +1152,8 @@ static void process_init_reply(struct fuse_mount *fm, struct fuse_args *args, > } > if (arg->flags & FUSE_SETXATTR_EXT) > fc->setxattr_ext = 1; > + if (arg->flags & FUSE_SECURITY_CTX) > + fc->init_security = 1; > } else { > ra_pages = fc->max_read / PAGE_SIZE; > fc->no_lock = 1; > @@ -1195,7 +1197,7 @@ void fuse_send_init(struct fuse_mount *fm) > FUSE_PARALLEL_DIROPS | FUSE_HANDLE_KILLPRIV | FUSE_POSIX_ACL | > FUSE_ABORT_ERROR | FUSE_MAX_PAGES | FUSE_CACHE_SYMLINKS | > FUSE_NO_OPENDIR_SUPPORT | FUSE_EXPLICIT_INVAL_DATA | > - FUSE_HANDLE_KILLPRIV_V2 | FUSE_SETXATTR_EXT; > + FUSE_HANDLE_KILLPRIV_V2 | FUSE_SETXATTR_EXT | FUSE_SECURITY_CTX; > #ifdef CONFIG_FUSE_DAX > if (fm->fc->dax) > ia->in.flags |= FUSE_MAP_ALIGNMENT; > diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h > index 2fe54c80051a..b31a0f79fde8 100644 > --- a/include/uapi/linux/fuse.h > +++ b/include/uapi/linux/fuse.h > @@ -986,4 +986,24 @@ struct fuse_syncfs_in { > uint64_t padding; > }; > > +/* > + * For each security context, send fuse_secctx with size of security context > + * fuse_secctx will be followed by security context name and this in turn > + * will be followed by actual context label. > + * fuse_secctx, name, context > + * */ > +struct fuse_secctx { > + uint32_t size; > + uint32_t padding; > +}; > + > +/* > + * Contains the information about how many fuse_secctx structures are being > + * sent. > + */ > +struct fuse_secctxs { > + uint32_t nr_secctx; > + uint32_t padding; > +}; > + > #endif /* _LINUX_FUSE_H */
On Tue, Oct 12, 2021 at 11:24:23AM -0700, Casey Schaufler wrote: > On 10/12/2021 11:06 AM, Vivek Goyal wrote: > > When a new inode is created, send its security context to server along > > with creation request (FUSE_CREAT, FUSE_MKNOD, FUSE_MKDIR and FUSE_SYMLINK). > > This gives server an opportunity to create new file and set security > > context (possibly atomically). In all the configurations it might not > > be possible to set context atomically. > > > > Like nfs and ceph, use security_dentry_init_security() to dermine security > > context of inode and send it with create, mkdir, mknod, and symlink requests. > > > > Following is the information sent to server. > > > > - struct fuse_secctxs. > > This contains total number of security contexts being sent. > > > > - struct fuse_secctx. > > This contains total size of security context which follows this structure. > > There is one fuse_secctx instance per security context. > > > > - xattr name string. > > This string represents name of xattr which should be used while setting > > security context. As of now it is hardcoded to "security.selinux". > > Where is the name hardcoded? I looks as if you're getting the attribute > name along with the value from security_dentry_init_security(). Sorry, I copied pasted this description from V1 where I was hardcoding the name to "security.selinux". But V2 got rid of that hardcoding and that's why this patch series is dependent on the other patch which modifies security_dentry_init_security() signature. https://lore.kernel.org/linux-fsdevel/YWWMO%2FZDrvDZ5X4c@redhat.com/ Thanks Vivek > > > > > - security context. > > This is the actual security context whose size is specified in fuse_secctx > > struct. > > > > This patch is modified version of patch from > > Chirantan Ekbote <chirantan@chromium.org> > > > > v2: > > - Added "fuse_secctxs" structure where one can specify how many security > > contexts are being sent. This can be useful down the line if we > > have more than one security contexts being set. > > > > Signed-off-by: Vivek Goyal <vgoyal@redhat.com> > > --- > > fs/fuse/dir.c | 115 ++++++++++++++++++++++++++++++++++++-- > > fs/fuse/fuse_i.h | 3 + > > fs/fuse/inode.c | 4 +- > > include/uapi/linux/fuse.h | 20 +++++++ > > 4 files changed, 136 insertions(+), 6 deletions(-) > > > > diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c > > index d9b977c0f38d..ce62593a61f9 100644 > > --- a/fs/fuse/dir.c > > +++ b/fs/fuse/dir.c > > @@ -17,6 +17,9 @@ > > #include <linux/xattr.h> > > #include <linux/iversion.h> > > #include <linux/posix_acl.h> > > +#include <linux/security.h> > > +#include <linux/types.h> > > +#include <linux/kernel.h> > > > > static void fuse_advise_use_readdirplus(struct inode *dir) > > { > > @@ -456,6 +459,66 @@ static struct dentry *fuse_lookup(struct inode *dir, struct dentry *entry, > > return ERR_PTR(err); > > } > > > > +static int get_security_context(struct dentry *entry, umode_t mode, > > + void **security_ctx, u32 *security_ctxlen) > > +{ > > + struct fuse_secctx *fsecctx; > > + struct fuse_secctxs *fsecctxs; > > + void *ctx, *full_ctx; > > + u32 ctxlen, full_ctxlen; > > + int err = 0; > > + const char *name; > > + > > + err = security_dentry_init_security(entry, mode, &entry->d_name, > > + &name, &ctx, &ctxlen); > > + if (err) { > > + if (err != -EOPNOTSUPP) > > + goto out_err; > > + /* No LSM is supporting this security hook. Ignore error */ > > + err = 0; > > + ctxlen = 0; > > + } > > + > > + if (ctxlen > 0) { > > + void *ptr; > > + > > + full_ctxlen = sizeof(*fsecctxs) + sizeof(*fsecctx) + > > + strlen(name) + ctxlen + 1; > > + full_ctx = kzalloc(full_ctxlen, GFP_KERNEL); > > + if (!full_ctx) { > > + err = -ENOMEM; > > + kfree(ctx); > > + goto out_err; > > + } > > + > > + ptr = full_ctx; > > + fsecctxs = (struct fuse_secctxs*) ptr; > > + fsecctxs->nr_secctx = 1; > > + ptr += sizeof(*fsecctxs); > > + > > + fsecctx = (struct fuse_secctx*) ptr; > > + fsecctx->size = ctxlen; > > + ptr += sizeof(*fsecctx); > > + > > + strcpy(ptr, name); > > + ptr += strlen(name) + 1; > > + memcpy(ptr, ctx, ctxlen); > > + kfree(ctx); > > + } else { > > + full_ctxlen = sizeof(*fsecctxs); > > + full_ctx = kzalloc(full_ctxlen, GFP_KERNEL); > > + if (!full_ctx) { > > + err = -ENOMEM; > > + goto out_err; > > + } > > + } > > + > > + *security_ctxlen = full_ctxlen; > > + *security_ctx = full_ctx; > > +out_err: > > + return err; > > +} > > + > > /* > > * Atomic create+open operation > > * > > @@ -476,6 +539,8 @@ static int fuse_create_open(struct inode *dir, struct dentry *entry, > > struct fuse_entry_out outentry; > > struct fuse_inode *fi; > > struct fuse_file *ff; > > + void *security_ctx = NULL; > > + u32 security_ctxlen; > > > > /* Userspace expects S_IFREG in create mode */ > > BUG_ON((mode & S_IFMT) != S_IFREG); > > @@ -517,6 +582,18 @@ static int fuse_create_open(struct inode *dir, struct dentry *entry, > > args.out_args[0].value = &outentry; > > args.out_args[1].size = sizeof(outopen); > > args.out_args[1].value = &outopen; > > + > > + if (fm->fc->init_security) { > > + err = get_security_context(entry, mode, &security_ctx, > > + &security_ctxlen); > > + if (err) > > + goto out_put_forget_req; > > + > > + args.in_numargs = 3; > > + args.in_args[2].size = security_ctxlen; > > + args.in_args[2].value = security_ctx; > > + } > > + > > err = fuse_simple_request(fm, &args); > > if (err) > > goto out_free_ff; > > @@ -554,6 +631,7 @@ static int fuse_create_open(struct inode *dir, struct dentry *entry, > > > > out_free_ff: > > fuse_file_free(ff); > > + kfree(security_ctx); > > out_put_forget_req: > > kfree(forget); > > out_err: > > @@ -613,13 +691,15 @@ static int fuse_atomic_open(struct inode *dir, struct dentry *entry, > > */ > > static int create_new_entry(struct fuse_mount *fm, struct fuse_args *args, > > struct inode *dir, struct dentry *entry, > > - umode_t mode) > > + umode_t mode, bool init_security) > > { > > struct fuse_entry_out outarg; > > struct inode *inode; > > struct dentry *d; > > int err; > > struct fuse_forget_link *forget; > > + void *security_ctx = NULL; > > + u32 security_ctxlen = 0; > > > > if (fuse_is_bad(dir)) > > return -EIO; > > @@ -633,7 +713,29 @@ static int create_new_entry(struct fuse_mount *fm, struct fuse_args *args, > > args->out_numargs = 1; > > args->out_args[0].size = sizeof(outarg); > > args->out_args[0].value = &outarg; > > + > > + if (init_security) { > > + unsigned short idx = args->in_numargs; > > + > > + if ((size_t)idx >= ARRAY_SIZE(args->in_args)) { > > + err = -ENOMEM; > > + goto out_put_forget_req; > > + } > > + > > + err = get_security_context(entry, mode, &security_ctx, > > + &security_ctxlen); > > + if (err) > > + goto out_put_forget_req; > > + > > + if (security_ctxlen > 0) { > > + args->in_args[idx].size = security_ctxlen; > > + args->in_args[idx].value = security_ctx; > > + args->in_numargs++; > > + } > > + } > > + > > err = fuse_simple_request(fm, args); > > + kfree(security_ctx); > > if (err) > > goto out_put_forget_req; > > > > @@ -691,7 +793,7 @@ static int fuse_mknod(struct user_namespace *mnt_userns, struct inode *dir, > > args.in_args[0].value = &inarg; > > args.in_args[1].size = entry->d_name.len + 1; > > args.in_args[1].value = entry->d_name.name; > > - return create_new_entry(fm, &args, dir, entry, mode); > > + return create_new_entry(fm, &args, dir, entry, mode, fm->fc->init_security); > > } > > > > static int fuse_create(struct user_namespace *mnt_userns, struct inode *dir, > > @@ -719,7 +821,8 @@ static int fuse_mkdir(struct user_namespace *mnt_userns, struct inode *dir, > > args.in_args[0].value = &inarg; > > args.in_args[1].size = entry->d_name.len + 1; > > args.in_args[1].value = entry->d_name.name; > > - return create_new_entry(fm, &args, dir, entry, S_IFDIR); > > + return create_new_entry(fm, &args, dir, entry, S_IFDIR, > > + fm->fc->init_security); > > } > > > > static int fuse_symlink(struct user_namespace *mnt_userns, struct inode *dir, > > @@ -735,7 +838,8 @@ static int fuse_symlink(struct user_namespace *mnt_userns, struct inode *dir, > > args.in_args[0].value = entry->d_name.name; > > args.in_args[1].size = len; > > args.in_args[1].value = link; > > - return create_new_entry(fm, &args, dir, entry, S_IFLNK); > > + return create_new_entry(fm, &args, dir, entry, S_IFLNK, > > + fm->fc->init_security); > > } > > > > void fuse_update_ctime(struct inode *inode) > > @@ -915,7 +1019,8 @@ static int fuse_link(struct dentry *entry, struct inode *newdir, > > args.in_args[0].value = &inarg; > > args.in_args[1].size = newent->d_name.len + 1; > > args.in_args[1].value = newent->d_name.name; > > - err = create_new_entry(fm, &args, newdir, newent, inode->i_mode); > > + err = create_new_entry(fm, &args, newdir, newent, inode->i_mode, > > + false); > > /* Contrary to "normal" filesystems it can happen that link > > makes two "logical" inodes point to the same "physical" > > inode. We invalidate the attributes of the old one, so it > > diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h > > index 319596df5dc6..885f34f9967f 100644 > > --- a/fs/fuse/fuse_i.h > > +++ b/fs/fuse/fuse_i.h > > @@ -765,6 +765,9 @@ struct fuse_conn { > > /* Propagate syncfs() to server */ > > unsigned int sync_fs:1; > > > > + /* Initialize security xattrs when creating a new inode */ > > + unsigned int init_security:1; > > + > > /** The number of requests waiting for completion */ > > atomic_t num_waiting; > > > > diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c > > index 36cd03114b6d..343bc9cfbd92 100644 > > --- a/fs/fuse/inode.c > > +++ b/fs/fuse/inode.c > > @@ -1152,6 +1152,8 @@ static void process_init_reply(struct fuse_mount *fm, struct fuse_args *args, > > } > > if (arg->flags & FUSE_SETXATTR_EXT) > > fc->setxattr_ext = 1; > > + if (arg->flags & FUSE_SECURITY_CTX) > > + fc->init_security = 1; > > } else { > > ra_pages = fc->max_read / PAGE_SIZE; > > fc->no_lock = 1; > > @@ -1195,7 +1197,7 @@ void fuse_send_init(struct fuse_mount *fm) > > FUSE_PARALLEL_DIROPS | FUSE_HANDLE_KILLPRIV | FUSE_POSIX_ACL | > > FUSE_ABORT_ERROR | FUSE_MAX_PAGES | FUSE_CACHE_SYMLINKS | > > FUSE_NO_OPENDIR_SUPPORT | FUSE_EXPLICIT_INVAL_DATA | > > - FUSE_HANDLE_KILLPRIV_V2 | FUSE_SETXATTR_EXT; > > + FUSE_HANDLE_KILLPRIV_V2 | FUSE_SETXATTR_EXT | FUSE_SECURITY_CTX; > > #ifdef CONFIG_FUSE_DAX > > if (fm->fc->dax) > > ia->in.flags |= FUSE_MAP_ALIGNMENT; > > diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h > > index 2fe54c80051a..b31a0f79fde8 100644 > > --- a/include/uapi/linux/fuse.h > > +++ b/include/uapi/linux/fuse.h > > @@ -986,4 +986,24 @@ struct fuse_syncfs_in { > > uint64_t padding; > > }; > > > > +/* > > + * For each security context, send fuse_secctx with size of security context > > + * fuse_secctx will be followed by security context name and this in turn > > + * will be followed by actual context label. > > + * fuse_secctx, name, context > > + * */ > > +struct fuse_secctx { > > + uint32_t size; > > + uint32_t padding; > > +}; > > + > > +/* > > + * Contains the information about how many fuse_secctx structures are being > > + * sent. > > + */ > > +struct fuse_secctxs { > > + uint32_t nr_secctx; > > + uint32_t padding; > > +}; > > + > > #endif /* _LINUX_FUSE_H */ >
On 10/12/2021 11:34 AM, Vivek Goyal wrote: > On Tue, Oct 12, 2021 at 11:24:23AM -0700, Casey Schaufler wrote: >> On 10/12/2021 11:06 AM, Vivek Goyal wrote: >>> When a new inode is created, send its security context to server along >>> with creation request (FUSE_CREAT, FUSE_MKNOD, FUSE_MKDIR and FUSE_SYMLINK). >>> This gives server an opportunity to create new file and set security >>> context (possibly atomically). In all the configurations it might not >>> be possible to set context atomically. >>> >>> Like nfs and ceph, use security_dentry_init_security() to dermine security >>> context of inode and send it with create, mkdir, mknod, and symlink requests. >>> >>> Following is the information sent to server. >>> >>> - struct fuse_secctxs. >>> This contains total number of security contexts being sent. >>> >>> - struct fuse_secctx. >>> This contains total size of security context which follows this structure. >>> There is one fuse_secctx instance per security context. >>> >>> - xattr name string. >>> This string represents name of xattr which should be used while setting >>> security context. As of now it is hardcoded to "security.selinux". >> Where is the name hardcoded? I looks as if you're getting the attribute >> name along with the value from security_dentry_init_security(). > Sorry, I copied pasted this description from V1 where I was hardcoding > the name to "security.selinux". That's what I suspected. Thanks. > But V2 got rid of that hardcoding and > that's why this patch series is dependent on the other patch which > modifies security_dentry_init_security() signature. > > https://lore.kernel.org/linux-fsdevel/YWWMO%2FZDrvDZ5X4c@redhat.com/ > > Thanks > Vivek > >>> - security context. >>> This is the actual security context whose size is specified in fuse_secctx >>> struct. >>> >>> This patch is modified version of patch from >>> Chirantan Ekbote <chirantan@chromium.org> >>> >>> v2: >>> - Added "fuse_secctxs" structure where one can specify how many security >>> contexts are being sent. This can be useful down the line if we >>> have more than one security contexts being set. >>> >>> Signed-off-by: Vivek Goyal <vgoyal@redhat.com> >>> --- >>> fs/fuse/dir.c | 115 ++++++++++++++++++++++++++++++++++++-- >>> fs/fuse/fuse_i.h | 3 + >>> fs/fuse/inode.c | 4 +- >>> include/uapi/linux/fuse.h | 20 +++++++ >>> 4 files changed, 136 insertions(+), 6 deletions(-) >>> >>> diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c >>> index d9b977c0f38d..ce62593a61f9 100644 >>> --- a/fs/fuse/dir.c >>> +++ b/fs/fuse/dir.c >>> @@ -17,6 +17,9 @@ >>> #include <linux/xattr.h> >>> #include <linux/iversion.h> >>> #include <linux/posix_acl.h> >>> +#include <linux/security.h> >>> +#include <linux/types.h> >>> +#include <linux/kernel.h> >>> >>> static void fuse_advise_use_readdirplus(struct inode *dir) >>> { >>> @@ -456,6 +459,66 @@ static struct dentry *fuse_lookup(struct inode *dir, struct dentry *entry, >>> return ERR_PTR(err); >>> } >>> >>> +static int get_security_context(struct dentry *entry, umode_t mode, >>> + void **security_ctx, u32 *security_ctxlen) >>> +{ >>> + struct fuse_secctx *fsecctx; >>> + struct fuse_secctxs *fsecctxs; >>> + void *ctx, *full_ctx; >>> + u32 ctxlen, full_ctxlen; >>> + int err = 0; >>> + const char *name; >>> + >>> + err = security_dentry_init_security(entry, mode, &entry->d_name, >>> + &name, &ctx, &ctxlen); >>> + if (err) { >>> + if (err != -EOPNOTSUPP) >>> + goto out_err; >>> + /* No LSM is supporting this security hook. Ignore error */ >>> + err = 0; >>> + ctxlen = 0; >>> + } >>> + >>> + if (ctxlen > 0) { >>> + void *ptr; >>> + >>> + full_ctxlen = sizeof(*fsecctxs) + sizeof(*fsecctx) + >>> + strlen(name) + ctxlen + 1; >>> + full_ctx = kzalloc(full_ctxlen, GFP_KERNEL); >>> + if (!full_ctx) { >>> + err = -ENOMEM; >>> + kfree(ctx); >>> + goto out_err; >>> + } >>> + >>> + ptr = full_ctx; >>> + fsecctxs = (struct fuse_secctxs*) ptr; >>> + fsecctxs->nr_secctx = 1; >>> + ptr += sizeof(*fsecctxs); >>> + >>> + fsecctx = (struct fuse_secctx*) ptr; >>> + fsecctx->size = ctxlen; >>> + ptr += sizeof(*fsecctx); >>> + >>> + strcpy(ptr, name); >>> + ptr += strlen(name) + 1; >>> + memcpy(ptr, ctx, ctxlen); >>> + kfree(ctx); >>> + } else { >>> + full_ctxlen = sizeof(*fsecctxs); >>> + full_ctx = kzalloc(full_ctxlen, GFP_KERNEL); >>> + if (!full_ctx) { >>> + err = -ENOMEM; >>> + goto out_err; >>> + } >>> + } >>> + >>> + *security_ctxlen = full_ctxlen; >>> + *security_ctx = full_ctx; >>> +out_err: >>> + return err; >>> +} >>> + >>> /* >>> * Atomic create+open operation >>> * >>> @@ -476,6 +539,8 @@ static int fuse_create_open(struct inode *dir, struct dentry *entry, >>> struct fuse_entry_out outentry; >>> struct fuse_inode *fi; >>> struct fuse_file *ff; >>> + void *security_ctx = NULL; >>> + u32 security_ctxlen; >>> >>> /* Userspace expects S_IFREG in create mode */ >>> BUG_ON((mode & S_IFMT) != S_IFREG); >>> @@ -517,6 +582,18 @@ static int fuse_create_open(struct inode *dir, struct dentry *entry, >>> args.out_args[0].value = &outentry; >>> args.out_args[1].size = sizeof(outopen); >>> args.out_args[1].value = &outopen; >>> + >>> + if (fm->fc->init_security) { >>> + err = get_security_context(entry, mode, &security_ctx, >>> + &security_ctxlen); >>> + if (err) >>> + goto out_put_forget_req; >>> + >>> + args.in_numargs = 3; >>> + args.in_args[2].size = security_ctxlen; >>> + args.in_args[2].value = security_ctx; >>> + } >>> + >>> err = fuse_simple_request(fm, &args); >>> if (err) >>> goto out_free_ff; >>> @@ -554,6 +631,7 @@ static int fuse_create_open(struct inode *dir, struct dentry *entry, >>> >>> out_free_ff: >>> fuse_file_free(ff); >>> + kfree(security_ctx); >>> out_put_forget_req: >>> kfree(forget); >>> out_err: >>> @@ -613,13 +691,15 @@ static int fuse_atomic_open(struct inode *dir, struct dentry *entry, >>> */ >>> static int create_new_entry(struct fuse_mount *fm, struct fuse_args *args, >>> struct inode *dir, struct dentry *entry, >>> - umode_t mode) >>> + umode_t mode, bool init_security) >>> { >>> struct fuse_entry_out outarg; >>> struct inode *inode; >>> struct dentry *d; >>> int err; >>> struct fuse_forget_link *forget; >>> + void *security_ctx = NULL; >>> + u32 security_ctxlen = 0; >>> >>> if (fuse_is_bad(dir)) >>> return -EIO; >>> @@ -633,7 +713,29 @@ static int create_new_entry(struct fuse_mount *fm, struct fuse_args *args, >>> args->out_numargs = 1; >>> args->out_args[0].size = sizeof(outarg); >>> args->out_args[0].value = &outarg; >>> + >>> + if (init_security) { >>> + unsigned short idx = args->in_numargs; >>> + >>> + if ((size_t)idx >= ARRAY_SIZE(args->in_args)) { >>> + err = -ENOMEM; >>> + goto out_put_forget_req; >>> + } >>> + >>> + err = get_security_context(entry, mode, &security_ctx, >>> + &security_ctxlen); >>> + if (err) >>> + goto out_put_forget_req; >>> + >>> + if (security_ctxlen > 0) { >>> + args->in_args[idx].size = security_ctxlen; >>> + args->in_args[idx].value = security_ctx; >>> + args->in_numargs++; >>> + } >>> + } >>> + >>> err = fuse_simple_request(fm, args); >>> + kfree(security_ctx); >>> if (err) >>> goto out_put_forget_req; >>> >>> @@ -691,7 +793,7 @@ static int fuse_mknod(struct user_namespace *mnt_userns, struct inode *dir, >>> args.in_args[0].value = &inarg; >>> args.in_args[1].size = entry->d_name.len + 1; >>> args.in_args[1].value = entry->d_name.name; >>> - return create_new_entry(fm, &args, dir, entry, mode); >>> + return create_new_entry(fm, &args, dir, entry, mode, fm->fc->init_security); >>> } >>> >>> static int fuse_create(struct user_namespace *mnt_userns, struct inode *dir, >>> @@ -719,7 +821,8 @@ static int fuse_mkdir(struct user_namespace *mnt_userns, struct inode *dir, >>> args.in_args[0].value = &inarg; >>> args.in_args[1].size = entry->d_name.len + 1; >>> args.in_args[1].value = entry->d_name.name; >>> - return create_new_entry(fm, &args, dir, entry, S_IFDIR); >>> + return create_new_entry(fm, &args, dir, entry, S_IFDIR, >>> + fm->fc->init_security); >>> } >>> >>> static int fuse_symlink(struct user_namespace *mnt_userns, struct inode *dir, >>> @@ -735,7 +838,8 @@ static int fuse_symlink(struct user_namespace *mnt_userns, struct inode *dir, >>> args.in_args[0].value = entry->d_name.name; >>> args.in_args[1].size = len; >>> args.in_args[1].value = link; >>> - return create_new_entry(fm, &args, dir, entry, S_IFLNK); >>> + return create_new_entry(fm, &args, dir, entry, S_IFLNK, >>> + fm->fc->init_security); >>> } >>> >>> void fuse_update_ctime(struct inode *inode) >>> @@ -915,7 +1019,8 @@ static int fuse_link(struct dentry *entry, struct inode *newdir, >>> args.in_args[0].value = &inarg; >>> args.in_args[1].size = newent->d_name.len + 1; >>> args.in_args[1].value = newent->d_name.name; >>> - err = create_new_entry(fm, &args, newdir, newent, inode->i_mode); >>> + err = create_new_entry(fm, &args, newdir, newent, inode->i_mode, >>> + false); >>> /* Contrary to "normal" filesystems it can happen that link >>> makes two "logical" inodes point to the same "physical" >>> inode. We invalidate the attributes of the old one, so it >>> diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h >>> index 319596df5dc6..885f34f9967f 100644 >>> --- a/fs/fuse/fuse_i.h >>> +++ b/fs/fuse/fuse_i.h >>> @@ -765,6 +765,9 @@ struct fuse_conn { >>> /* Propagate syncfs() to server */ >>> unsigned int sync_fs:1; >>> >>> + /* Initialize security xattrs when creating a new inode */ >>> + unsigned int init_security:1; >>> + >>> /** The number of requests waiting for completion */ >>> atomic_t num_waiting; >>> >>> diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c >>> index 36cd03114b6d..343bc9cfbd92 100644 >>> --- a/fs/fuse/inode.c >>> +++ b/fs/fuse/inode.c >>> @@ -1152,6 +1152,8 @@ static void process_init_reply(struct fuse_mount *fm, struct fuse_args *args, >>> } >>> if (arg->flags & FUSE_SETXATTR_EXT) >>> fc->setxattr_ext = 1; >>> + if (arg->flags & FUSE_SECURITY_CTX) >>> + fc->init_security = 1; >>> } else { >>> ra_pages = fc->max_read / PAGE_SIZE; >>> fc->no_lock = 1; >>> @@ -1195,7 +1197,7 @@ void fuse_send_init(struct fuse_mount *fm) >>> FUSE_PARALLEL_DIROPS | FUSE_HANDLE_KILLPRIV | FUSE_POSIX_ACL | >>> FUSE_ABORT_ERROR | FUSE_MAX_PAGES | FUSE_CACHE_SYMLINKS | >>> FUSE_NO_OPENDIR_SUPPORT | FUSE_EXPLICIT_INVAL_DATA | >>> - FUSE_HANDLE_KILLPRIV_V2 | FUSE_SETXATTR_EXT; >>> + FUSE_HANDLE_KILLPRIV_V2 | FUSE_SETXATTR_EXT | FUSE_SECURITY_CTX; >>> #ifdef CONFIG_FUSE_DAX >>> if (fm->fc->dax) >>> ia->in.flags |= FUSE_MAP_ALIGNMENT; >>> diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h >>> index 2fe54c80051a..b31a0f79fde8 100644 >>> --- a/include/uapi/linux/fuse.h >>> +++ b/include/uapi/linux/fuse.h >>> @@ -986,4 +986,24 @@ struct fuse_syncfs_in { >>> uint64_t padding; >>> }; >>> >>> +/* >>> + * For each security context, send fuse_secctx with size of security context >>> + * fuse_secctx will be followed by security context name and this in turn >>> + * will be followed by actual context label. >>> + * fuse_secctx, name, context >>> + * */ >>> +struct fuse_secctx { >>> + uint32_t size; >>> + uint32_t padding; >>> +}; >>> + >>> +/* >>> + * Contains the information about how many fuse_secctx structures are being >>> + * sent. >>> + */ >>> +struct fuse_secctxs { >>> + uint32_t nr_secctx; >>> + uint32_t padding; >>> +}; >>> + >>> #endif /* _LINUX_FUSE_H */
On Tue, 12 Oct 2021 at 20:06, Vivek Goyal <vgoyal@redhat.com> wrote: > > When a new inode is created, send its security context to server along > with creation request (FUSE_CREAT, FUSE_MKNOD, FUSE_MKDIR and FUSE_SYMLINK). > This gives server an opportunity to create new file and set security > context (possibly atomically). In all the configurations it might not > be possible to set context atomically. > > Like nfs and ceph, use security_dentry_init_security() to dermine security > context of inode and send it with create, mkdir, mknod, and symlink requests. > > Following is the information sent to server. > > - struct fuse_secctxs. > This contains total number of security contexts being sent. > > - struct fuse_secctx. > This contains total size of security context which follows this structure. > There is one fuse_secctx instance per security context. > > - xattr name string. > This string represents name of xattr which should be used while setting > security context. As of now it is hardcoded to "security.selinux". > > - security context. > This is the actual security context whose size is specified in fuse_secctx > struct. > > This patch is modified version of patch from > Chirantan Ekbote <chirantan@chromium.org> > > v2: > - Added "fuse_secctxs" structure where one can specify how many security > contexts are being sent. This can be useful down the line if we > have more than one security contexts being set. > > Signed-off-by: Vivek Goyal <vgoyal@redhat.com> > --- > fs/fuse/dir.c | 115 ++++++++++++++++++++++++++++++++++++-- > fs/fuse/fuse_i.h | 3 + > fs/fuse/inode.c | 4 +- > include/uapi/linux/fuse.h | 20 +++++++ > 4 files changed, 136 insertions(+), 6 deletions(-) > > diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c > index d9b977c0f38d..ce62593a61f9 100644 > --- a/fs/fuse/dir.c > +++ b/fs/fuse/dir.c > @@ -17,6 +17,9 @@ > #include <linux/xattr.h> > #include <linux/iversion.h> > #include <linux/posix_acl.h> > +#include <linux/security.h> > +#include <linux/types.h> > +#include <linux/kernel.h> > > static void fuse_advise_use_readdirplus(struct inode *dir) > { > @@ -456,6 +459,66 @@ static struct dentry *fuse_lookup(struct inode *dir, struct dentry *entry, > return ERR_PTR(err); > } > > +static int get_security_context(struct dentry *entry, umode_t mode, > + void **security_ctx, u32 *security_ctxlen) > +{ > + struct fuse_secctx *fsecctx; > + struct fuse_secctxs *fsecctxs; > + void *ctx, *full_ctx; > + u32 ctxlen, full_ctxlen; > + int err = 0; > + const char *name; > + > + err = security_dentry_init_security(entry, mode, &entry->d_name, > + &name, &ctx, &ctxlen); > + if (err) { > + if (err != -EOPNOTSUPP) > + goto out_err; > + /* No LSM is supporting this security hook. Ignore error */ > + err = 0; > + ctxlen = 0; > + } > + > + if (ctxlen > 0) { > + void *ptr; > + > + full_ctxlen = sizeof(*fsecctxs) + sizeof(*fsecctx) + > + strlen(name) + ctxlen + 1; > + full_ctx = kzalloc(full_ctxlen, GFP_KERNEL); > + if (!full_ctx) { > + err = -ENOMEM; > + kfree(ctx); > + goto out_err; > + } > + > + ptr = full_ctx; > + fsecctxs = (struct fuse_secctxs*) ptr; > + fsecctxs->nr_secctx = 1; > + ptr += sizeof(*fsecctxs); > + > + fsecctx = (struct fuse_secctx*) ptr; > + fsecctx->size = ctxlen; > + ptr += sizeof(*fsecctx); > + > + strcpy(ptr, name); > + ptr += strlen(name) + 1; > + memcpy(ptr, ctx, ctxlen); > + kfree(ctx); > + } else { > + full_ctxlen = sizeof(*fsecctxs); > + full_ctx = kzalloc(full_ctxlen, GFP_KERNEL); > + if (!full_ctx) { > + err = -ENOMEM; > + goto out_err; > + } > + } > + > + *security_ctxlen = full_ctxlen; > + *security_ctx = full_ctx; > +out_err: > + return err; > +} > + > /* > * Atomic create+open operation > * > @@ -476,6 +539,8 @@ static int fuse_create_open(struct inode *dir, struct dentry *entry, > struct fuse_entry_out outentry; > struct fuse_inode *fi; > struct fuse_file *ff; > + void *security_ctx = NULL; > + u32 security_ctxlen; > > /* Userspace expects S_IFREG in create mode */ > BUG_ON((mode & S_IFMT) != S_IFREG); > @@ -517,6 +582,18 @@ static int fuse_create_open(struct inode *dir, struct dentry *entry, > args.out_args[0].value = &outentry; > args.out_args[1].size = sizeof(outopen); > args.out_args[1].value = &outopen; > + > + if (fm->fc->init_security) { > + err = get_security_context(entry, mode, &security_ctx, > + &security_ctxlen); > + if (err) > + goto out_put_forget_req; > + > + args.in_numargs = 3; > + args.in_args[2].size = security_ctxlen; > + args.in_args[2].value = security_ctx; > + } > + > err = fuse_simple_request(fm, &args); > if (err) > goto out_free_ff; > @@ -554,6 +631,7 @@ static int fuse_create_open(struct inode *dir, struct dentry *entry, > > out_free_ff: > fuse_file_free(ff); > + kfree(security_ctx); > out_put_forget_req: > kfree(forget); > out_err: > @@ -613,13 +691,15 @@ static int fuse_atomic_open(struct inode *dir, struct dentry *entry, > */ > static int create_new_entry(struct fuse_mount *fm, struct fuse_args *args, > struct inode *dir, struct dentry *entry, > - umode_t mode) > + umode_t mode, bool init_security) > { > struct fuse_entry_out outarg; > struct inode *inode; > struct dentry *d; > int err; > struct fuse_forget_link *forget; > + void *security_ctx = NULL; > + u32 security_ctxlen = 0; > > if (fuse_is_bad(dir)) > return -EIO; > @@ -633,7 +713,29 @@ static int create_new_entry(struct fuse_mount *fm, struct fuse_args *args, > args->out_numargs = 1; > args->out_args[0].size = sizeof(outarg); > args->out_args[0].value = &outarg; > + > + if (init_security) { Instead of a new arg to create_new_entry(), this could check args.opcode != FUSE_LINK. > + unsigned short idx = args->in_numargs; > + > + if ((size_t)idx >= ARRAY_SIZE(args->in_args)) { > + err = -ENOMEM; > + goto out_put_forget_req; > + } > + > + err = get_security_context(entry, mode, &security_ctx, > + &security_ctxlen); > + if (err) > + goto out_put_forget_req; > + > + if (security_ctxlen > 0) { This doesn't seem right. How would the server know if this is arg is missing? I think if FUSE_SECURITY_CTX was negotiated, then the secctx header will always need to be added to the MK* requests. > + args->in_args[idx].size = security_ctxlen; > + args->in_args[idx].value = security_ctx; > + args->in_numargs++; > + } > + } > + > err = fuse_simple_request(fm, args); > + kfree(security_ctx); > if (err) > goto out_put_forget_req; > > @@ -691,7 +793,7 @@ static int fuse_mknod(struct user_namespace *mnt_userns, struct inode *dir, > args.in_args[0].value = &inarg; > args.in_args[1].size = entry->d_name.len + 1; > args.in_args[1].value = entry->d_name.name; > - return create_new_entry(fm, &args, dir, entry, mode); > + return create_new_entry(fm, &args, dir, entry, mode, fm->fc->init_security); > } > > static int fuse_create(struct user_namespace *mnt_userns, struct inode *dir, > @@ -719,7 +821,8 @@ static int fuse_mkdir(struct user_namespace *mnt_userns, struct inode *dir, > args.in_args[0].value = &inarg; > args.in_args[1].size = entry->d_name.len + 1; > args.in_args[1].value = entry->d_name.name; > - return create_new_entry(fm, &args, dir, entry, S_IFDIR); > + return create_new_entry(fm, &args, dir, entry, S_IFDIR, > + fm->fc->init_security); > } > > static int fuse_symlink(struct user_namespace *mnt_userns, struct inode *dir, > @@ -735,7 +838,8 @@ static int fuse_symlink(struct user_namespace *mnt_userns, struct inode *dir, > args.in_args[0].value = entry->d_name.name; > args.in_args[1].size = len; > args.in_args[1].value = link; > - return create_new_entry(fm, &args, dir, entry, S_IFLNK); > + return create_new_entry(fm, &args, dir, entry, S_IFLNK, > + fm->fc->init_security); > } > > void fuse_update_ctime(struct inode *inode) > @@ -915,7 +1019,8 @@ static int fuse_link(struct dentry *entry, struct inode *newdir, > args.in_args[0].value = &inarg; > args.in_args[1].size = newent->d_name.len + 1; > args.in_args[1].value = newent->d_name.name; > - err = create_new_entry(fm, &args, newdir, newent, inode->i_mode); > + err = create_new_entry(fm, &args, newdir, newent, inode->i_mode, > + false); > /* Contrary to "normal" filesystems it can happen that link > makes two "logical" inodes point to the same "physical" > inode. We invalidate the attributes of the old one, so it > diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h > index 319596df5dc6..885f34f9967f 100644 > --- a/fs/fuse/fuse_i.h > +++ b/fs/fuse/fuse_i.h > @@ -765,6 +765,9 @@ struct fuse_conn { > /* Propagate syncfs() to server */ > unsigned int sync_fs:1; > > + /* Initialize security xattrs when creating a new inode */ > + unsigned int init_security:1; > + > /** The number of requests waiting for completion */ > atomic_t num_waiting; > > diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c > index 36cd03114b6d..343bc9cfbd92 100644 > --- a/fs/fuse/inode.c > +++ b/fs/fuse/inode.c > @@ -1152,6 +1152,8 @@ static void process_init_reply(struct fuse_mount *fm, struct fuse_args *args, > } > if (arg->flags & FUSE_SETXATTR_EXT) > fc->setxattr_ext = 1; > + if (arg->flags & FUSE_SECURITY_CTX) > + fc->init_security = 1; > } else { > ra_pages = fc->max_read / PAGE_SIZE; > fc->no_lock = 1; > @@ -1195,7 +1197,7 @@ void fuse_send_init(struct fuse_mount *fm) > FUSE_PARALLEL_DIROPS | FUSE_HANDLE_KILLPRIV | FUSE_POSIX_ACL | > FUSE_ABORT_ERROR | FUSE_MAX_PAGES | FUSE_CACHE_SYMLINKS | > FUSE_NO_OPENDIR_SUPPORT | FUSE_EXPLICIT_INVAL_DATA | > - FUSE_HANDLE_KILLPRIV_V2 | FUSE_SETXATTR_EXT; > + FUSE_HANDLE_KILLPRIV_V2 | FUSE_SETXATTR_EXT | FUSE_SECURITY_CTX; > #ifdef CONFIG_FUSE_DAX > if (fm->fc->dax) > ia->in.flags |= FUSE_MAP_ALIGNMENT; > diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h > index 2fe54c80051a..b31a0f79fde8 100644 > --- a/include/uapi/linux/fuse.h > +++ b/include/uapi/linux/fuse.h I don't see why the API changes are split between the first and the second patch in the series. Please either move all API changes to 1/2 or fold 1/2 into this patch. > @@ -986,4 +986,24 @@ struct fuse_syncfs_in { > uint64_t padding; > }; > > +/* > + * For each security context, send fuse_secctx with size of security context > + * fuse_secctx will be followed by security context name and this in turn > + * will be followed by actual context label. > + * fuse_secctx, name, context > + * */ > +struct fuse_secctx { > + uint32_t size; > + uint32_t padding; > +}; > + > +/* > + * Contains the information about how many fuse_secctx structures are being > + * sent. > + */ > +struct fuse_secctxs { > + uint32_t nr_secctx; > + uint32_t padding; > +}; The name of this struct is very confusing due to similarity with fuse_secctx. How about "fuse_secctx_header"? Also I'd add the total length of the security context (including the header), otherwise further args would need to parse the security context completely to find the position of the next arg. The counterexample is null-terminated names; while parsing these is pretty trivial, in hindsight it would probably have been better to add a header to names as well. Thanks, Miklos
On Tue, Nov 02, 2021 at 03:00:30PM +0100, Miklos Szeredi wrote: > On Tue, 12 Oct 2021 at 20:06, Vivek Goyal <vgoyal@redhat.com> wrote: > > > > When a new inode is created, send its security context to server along > > with creation request (FUSE_CREAT, FUSE_MKNOD, FUSE_MKDIR and FUSE_SYMLINK). > > This gives server an opportunity to create new file and set security > > context (possibly atomically). In all the configurations it might not > > be possible to set context atomically. > > > > Like nfs and ceph, use security_dentry_init_security() to dermine security > > context of inode and send it with create, mkdir, mknod, and symlink requests. > > > > Following is the information sent to server. > > > > - struct fuse_secctxs. > > This contains total number of security contexts being sent. > > > > - struct fuse_secctx. > > This contains total size of security context which follows this structure. > > There is one fuse_secctx instance per security context. > > > > - xattr name string. > > This string represents name of xattr which should be used while setting > > security context. As of now it is hardcoded to "security.selinux". > > > > - security context. > > This is the actual security context whose size is specified in fuse_secctx > > struct. > > > > This patch is modified version of patch from > > Chirantan Ekbote <chirantan@chromium.org> > > > > v2: > > - Added "fuse_secctxs" structure where one can specify how many security > > contexts are being sent. This can be useful down the line if we > > have more than one security contexts being set. > > > > Signed-off-by: Vivek Goyal <vgoyal@redhat.com> > > --- > > fs/fuse/dir.c | 115 ++++++++++++++++++++++++++++++++++++-- > > fs/fuse/fuse_i.h | 3 + > > fs/fuse/inode.c | 4 +- > > include/uapi/linux/fuse.h | 20 +++++++ > > 4 files changed, 136 insertions(+), 6 deletions(-) > > > > diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c > > index d9b977c0f38d..ce62593a61f9 100644 > > --- a/fs/fuse/dir.c > > +++ b/fs/fuse/dir.c > > @@ -17,6 +17,9 @@ > > #include <linux/xattr.h> > > #include <linux/iversion.h> > > #include <linux/posix_acl.h> > > +#include <linux/security.h> > > +#include <linux/types.h> > > +#include <linux/kernel.h> > > > > static void fuse_advise_use_readdirplus(struct inode *dir) > > { > > @@ -456,6 +459,66 @@ static struct dentry *fuse_lookup(struct inode *dir, struct dentry *entry, > > return ERR_PTR(err); > > } > > > > +static int get_security_context(struct dentry *entry, umode_t mode, > > + void **security_ctx, u32 *security_ctxlen) > > +{ > > + struct fuse_secctx *fsecctx; > > + struct fuse_secctxs *fsecctxs; > > + void *ctx, *full_ctx; > > + u32 ctxlen, full_ctxlen; > > + int err = 0; > > + const char *name; > > + > > + err = security_dentry_init_security(entry, mode, &entry->d_name, > > + &name, &ctx, &ctxlen); > > + if (err) { > > + if (err != -EOPNOTSUPP) > > + goto out_err; > > + /* No LSM is supporting this security hook. Ignore error */ > > + err = 0; > > + ctxlen = 0; > > + } > > + > > + if (ctxlen > 0) { > > + void *ptr; > > + > > + full_ctxlen = sizeof(*fsecctxs) + sizeof(*fsecctx) + > > + strlen(name) + ctxlen + 1; > > + full_ctx = kzalloc(full_ctxlen, GFP_KERNEL); > > + if (!full_ctx) { > > + err = -ENOMEM; > > + kfree(ctx); > > + goto out_err; > > + } > > + > > + ptr = full_ctx; > > + fsecctxs = (struct fuse_secctxs*) ptr; > > + fsecctxs->nr_secctx = 1; > > + ptr += sizeof(*fsecctxs); > > + > > + fsecctx = (struct fuse_secctx*) ptr; > > + fsecctx->size = ctxlen; > > + ptr += sizeof(*fsecctx); > > + > > + strcpy(ptr, name); > > + ptr += strlen(name) + 1; > > + memcpy(ptr, ctx, ctxlen); > > + kfree(ctx); > > + } else { > > + full_ctxlen = sizeof(*fsecctxs); > > + full_ctx = kzalloc(full_ctxlen, GFP_KERNEL); > > + if (!full_ctx) { > > + err = -ENOMEM; > > + goto out_err; > > + } > > + } > > + > > + *security_ctxlen = full_ctxlen; > > + *security_ctx = full_ctx; > > +out_err: > > + return err; > > +} > > + > > /* > > * Atomic create+open operation > > * > > @@ -476,6 +539,8 @@ static int fuse_create_open(struct inode *dir, struct dentry *entry, > > struct fuse_entry_out outentry; > > struct fuse_inode *fi; > > struct fuse_file *ff; > > + void *security_ctx = NULL; > > + u32 security_ctxlen; > > > > /* Userspace expects S_IFREG in create mode */ > > BUG_ON((mode & S_IFMT) != S_IFREG); > > @@ -517,6 +582,18 @@ static int fuse_create_open(struct inode *dir, struct dentry *entry, > > args.out_args[0].value = &outentry; > > args.out_args[1].size = sizeof(outopen); > > args.out_args[1].value = &outopen; > > + > > + if (fm->fc->init_security) { > > + err = get_security_context(entry, mode, &security_ctx, > > + &security_ctxlen); > > + if (err) > > + goto out_put_forget_req; > > + > > + args.in_numargs = 3; > > + args.in_args[2].size = security_ctxlen; > > + args.in_args[2].value = security_ctx; > > + } > > + > > err = fuse_simple_request(fm, &args); > > if (err) > > goto out_free_ff; > > @@ -554,6 +631,7 @@ static int fuse_create_open(struct inode *dir, struct dentry *entry, > > > > out_free_ff: > > fuse_file_free(ff); > > + kfree(security_ctx); > > out_put_forget_req: > > kfree(forget); > > out_err: > > @@ -613,13 +691,15 @@ static int fuse_atomic_open(struct inode *dir, struct dentry *entry, > > */ > > static int create_new_entry(struct fuse_mount *fm, struct fuse_args *args, > > struct inode *dir, struct dentry *entry, > > - umode_t mode) > > + umode_t mode, bool init_security) > > { > > struct fuse_entry_out outarg; > > struct inode *inode; > > struct dentry *d; > > int err; > > struct fuse_forget_link *forget; > > + void *security_ctx = NULL; > > + u32 security_ctxlen = 0; > > > > if (fuse_is_bad(dir)) > > return -EIO; > > @@ -633,7 +713,29 @@ static int create_new_entry(struct fuse_mount *fm, struct fuse_args *args, > > args->out_numargs = 1; > > args->out_args[0].size = sizeof(outarg); > > args->out_args[0].value = &outarg; > > + > > + if (init_security) { > Hi Miklos, > Instead of a new arg to create_new_entry(), this could check > args.opcode != FUSE_LINK. Will do. > > > + unsigned short idx = args->in_numargs; > > + > > + if ((size_t)idx >= ARRAY_SIZE(args->in_args)) { > > + err = -ENOMEM; > > + goto out_put_forget_req; > > + } > > + > > + err = get_security_context(entry, mode, &security_ctx, > > + &security_ctxlen); > > + if (err) > > + goto out_put_forget_req; > > + > > + if (security_ctxlen > 0) { > > This doesn't seem right. How would the server know if this is arg is missing? > > I think if FUSE_SECURITY_CTX was negotiated, then the secctx header > will always need to be added to the MK* requests. Even for the case of FUSE_LINK request? I think I put this check because FUSE_LINK is not sending secctx header. Other requests are appending this header even if a security module is not loaded/enabled. I guess it makes more sense to add secctx header even for FUSE_LINK request. Just that header will mention 0 security contexts are following. This will interface more uniform. I will make this change. > > > + args->in_args[idx].size = security_ctxlen; > > + args->in_args[idx].value = security_ctx; > > + args->in_numargs++; > > + } > > + } > > + > > err = fuse_simple_request(fm, args); > > + kfree(security_ctx); > > if (err) > > goto out_put_forget_req; > > > > @@ -691,7 +793,7 @@ static int fuse_mknod(struct user_namespace *mnt_userns, struct inode *dir, > > args.in_args[0].value = &inarg; > > args.in_args[1].size = entry->d_name.len + 1; > > args.in_args[1].value = entry->d_name.name; > > - return create_new_entry(fm, &args, dir, entry, mode); > > + return create_new_entry(fm, &args, dir, entry, mode, fm->fc->init_security); > > } > > > > static int fuse_create(struct user_namespace *mnt_userns, struct inode *dir, > > @@ -719,7 +821,8 @@ static int fuse_mkdir(struct user_namespace *mnt_userns, struct inode *dir, > > args.in_args[0].value = &inarg; > > args.in_args[1].size = entry->d_name.len + 1; > > args.in_args[1].value = entry->d_name.name; > > - return create_new_entry(fm, &args, dir, entry, S_IFDIR); > > + return create_new_entry(fm, &args, dir, entry, S_IFDIR, > > + fm->fc->init_security); > > } > > > > static int fuse_symlink(struct user_namespace *mnt_userns, struct inode *dir, > > @@ -735,7 +838,8 @@ static int fuse_symlink(struct user_namespace *mnt_userns, struct inode *dir, > > args.in_args[0].value = entry->d_name.name; > > args.in_args[1].size = len; > > args.in_args[1].value = link; > > - return create_new_entry(fm, &args, dir, entry, S_IFLNK); > > + return create_new_entry(fm, &args, dir, entry, S_IFLNK, > > + fm->fc->init_security); > > } > > > > void fuse_update_ctime(struct inode *inode) > > @@ -915,7 +1019,8 @@ static int fuse_link(struct dentry *entry, struct inode *newdir, > > args.in_args[0].value = &inarg; > > args.in_args[1].size = newent->d_name.len + 1; > > args.in_args[1].value = newent->d_name.name; > > - err = create_new_entry(fm, &args, newdir, newent, inode->i_mode); > > + err = create_new_entry(fm, &args, newdir, newent, inode->i_mode, > > + false); > > /* Contrary to "normal" filesystems it can happen that link > > makes two "logical" inodes point to the same "physical" > > inode. We invalidate the attributes of the old one, so it > > diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h > > index 319596df5dc6..885f34f9967f 100644 > > --- a/fs/fuse/fuse_i.h > > +++ b/fs/fuse/fuse_i.h > > @@ -765,6 +765,9 @@ struct fuse_conn { > > /* Propagate syncfs() to server */ > > unsigned int sync_fs:1; > > > > + /* Initialize security xattrs when creating a new inode */ > > + unsigned int init_security:1; > > + > > /** The number of requests waiting for completion */ > > atomic_t num_waiting; > > > > diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c > > index 36cd03114b6d..343bc9cfbd92 100644 > > --- a/fs/fuse/inode.c > > +++ b/fs/fuse/inode.c > > @@ -1152,6 +1152,8 @@ static void process_init_reply(struct fuse_mount *fm, struct fuse_args *args, > > } > > if (arg->flags & FUSE_SETXATTR_EXT) > > fc->setxattr_ext = 1; > > + if (arg->flags & FUSE_SECURITY_CTX) > > + fc->init_security = 1; > > } else { > > ra_pages = fc->max_read / PAGE_SIZE; > > fc->no_lock = 1; > > @@ -1195,7 +1197,7 @@ void fuse_send_init(struct fuse_mount *fm) > > FUSE_PARALLEL_DIROPS | FUSE_HANDLE_KILLPRIV | FUSE_POSIX_ACL | > > FUSE_ABORT_ERROR | FUSE_MAX_PAGES | FUSE_CACHE_SYMLINKS | > > FUSE_NO_OPENDIR_SUPPORT | FUSE_EXPLICIT_INVAL_DATA | > > - FUSE_HANDLE_KILLPRIV_V2 | FUSE_SETXATTR_EXT; > > + FUSE_HANDLE_KILLPRIV_V2 | FUSE_SETXATTR_EXT | FUSE_SECURITY_CTX; > > #ifdef CONFIG_FUSE_DAX > > if (fm->fc->dax) > > ia->in.flags |= FUSE_MAP_ALIGNMENT; > > diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h > > index 2fe54c80051a..b31a0f79fde8 100644 > > --- a/include/uapi/linux/fuse.h > > +++ b/include/uapi/linux/fuse.h > > I don't see why the API changes are split between the first and the > second patch in the series. Please either move all API changes to > 1/2 or fold 1/2 into this patch. I guess I will fold first patch into this one, so that there is only one patch. > > > @@ -986,4 +986,24 @@ struct fuse_syncfs_in { > > uint64_t padding; > > }; > > > > +/* > > + * For each security context, send fuse_secctx with size of security context > > + * fuse_secctx will be followed by security context name and this in turn > > + * will be followed by actual context label. > > + * fuse_secctx, name, context > > + * */ > > +struct fuse_secctx { > > + uint32_t size; > > + uint32_t padding; > > +}; > > + > > +/* > > + * Contains the information about how many fuse_secctx structures are being > > + * sent. > > + */ > > +struct fuse_secctxs { > > + uint32_t nr_secctx; > > + uint32_t padding; > > +}; > > The name of this struct is very confusing due to similarity with > fuse_secctx. How about "fuse_secctx_header"? Sounds good. Will do. > > Also I'd add the total length of the security context (including the > header), otherwise further args would need to parse the security > context completely to find the position of the next arg. The > counterexample is null-terminated names; while parsing these is pretty > trivial, in hindsight it would probably have been better to add a > header to names as well. Agreed. Will add total length also to "fuse_secctx_header". That will act as a strong check/verification mechanism as well as allow to quickly skip to next args if one does not want to parse security contexts for whatever reason. Thanks Vivek
On Tue, 2 Nov 2021 at 16:30, Vivek Goyal <vgoyal@redhat.com> wrote: > > On Tue, Nov 02, 2021 at 03:00:30PM +0100, Miklos Szeredi wrote: > > On Tue, 12 Oct 2021 at 20:06, Vivek Goyal <vgoyal@redhat.com> wrote: > > > @@ -633,7 +713,29 @@ static int create_new_entry(struct fuse_mount *fm, struct fuse_args *args, > > > args->out_numargs = 1; > > > args->out_args[0].size = sizeof(outarg); > > > args->out_args[0].value = &outarg; > > > + > > > + if (init_security) { > > > > Hi Miklos, > > > Instead of a new arg to create_new_entry(), this could check > > args.opcode != FUSE_LINK. > > Will do. > > > > > > + unsigned short idx = args->in_numargs; > > > + > > > + if ((size_t)idx >= ARRAY_SIZE(args->in_args)) { > > > + err = -ENOMEM; > > > + goto out_put_forget_req; > > > + } > > > + > > > + err = get_security_context(entry, mode, &security_ctx, > > > + &security_ctxlen); > > > + if (err) > > > + goto out_put_forget_req; > > > + > > > + if (security_ctxlen > 0) { > > > > This doesn't seem right. How would the server know if this is arg is missing? > > > > I think if FUSE_SECURITY_CTX was negotiated, then the secctx header > > will always need to be added to the MK* requests. > > Even for the case of FUSE_LINK request? I think I put this check because > FUSE_LINK is not sending secctx header. Other requests are appending > this header even if a security module is not loaded/enabled. No, FUSE_LINK wouldn't even get this far. > I guess it makes more sense to add secctx header even for FUSE_LINK > request. Just that header will mention 0 security contexts are > following. This will interface more uniform. I will make this change. Why? FUSE_LINK is not an inode creation op, it just shares the instantiation part with creation. Thanks, Miklos
On Tue, Nov 02, 2021 at 04:38:06PM +0100, Miklos Szeredi wrote: > On Tue, 2 Nov 2021 at 16:30, Vivek Goyal <vgoyal@redhat.com> wrote: > > > > On Tue, Nov 02, 2021 at 03:00:30PM +0100, Miklos Szeredi wrote: > > > On Tue, 12 Oct 2021 at 20:06, Vivek Goyal <vgoyal@redhat.com> wrote: > > > > > @@ -633,7 +713,29 @@ static int create_new_entry(struct fuse_mount *fm, struct fuse_args *args, > > > > args->out_numargs = 1; > > > > args->out_args[0].size = sizeof(outarg); > > > > args->out_args[0].value = &outarg; > > > > + > > > > + if (init_security) { > > > > > > > Hi Miklos, > > > > > Instead of a new arg to create_new_entry(), this could check > > > args.opcode != FUSE_LINK. > > > > Will do. > > > > > > > > > + unsigned short idx = args->in_numargs; > > > > + > > > > + if ((size_t)idx >= ARRAY_SIZE(args->in_args)) { > > > > + err = -ENOMEM; > > > > + goto out_put_forget_req; > > > > + } > > > > + > > > > + err = get_security_context(entry, mode, &security_ctx, > > > > + &security_ctxlen); > > > > + if (err) > > > > + goto out_put_forget_req; > > > > + > > > > + if (security_ctxlen > 0) { > > > > > > This doesn't seem right. How would the server know if this is arg is missing? > > > > > > I think if FUSE_SECURITY_CTX was negotiated, then the secctx header > > > will always need to be added to the MK* requests. > > > > Even for the case of FUSE_LINK request? I think I put this check because > > FUSE_LINK is not sending secctx header. Other requests are appending > > this header even if a security module is not loaded/enabled. > > No, FUSE_LINK wouldn't even get this far. You are right. My bad. So looks like this check will always be true given the current code. get_security_context() will either all headers with security context or just return zeroed "struct fuse_secctxs", indicating there are no security context. If that's the case, I should be able to get rid of this check. I will do some more testing. > > > I guess it makes more sense to add secctx header even for FUSE_LINK > > request. Just that header will mention 0 security contexts are > > following. This will interface more uniform. I will make this change. > > Why? FUSE_LINK is not an inode creation op, it just shares the > instantiation part with creation. Ok, got it. Makes sense. So no sending of zeroed security context header with FUSE_LINK. Vivek
diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c index d9b977c0f38d..ce62593a61f9 100644 --- a/fs/fuse/dir.c +++ b/fs/fuse/dir.c @@ -17,6 +17,9 @@ #include <linux/xattr.h> #include <linux/iversion.h> #include <linux/posix_acl.h> +#include <linux/security.h> +#include <linux/types.h> +#include <linux/kernel.h> static void fuse_advise_use_readdirplus(struct inode *dir) { @@ -456,6 +459,66 @@ static struct dentry *fuse_lookup(struct inode *dir, struct dentry *entry, return ERR_PTR(err); } +static int get_security_context(struct dentry *entry, umode_t mode, + void **security_ctx, u32 *security_ctxlen) +{ + struct fuse_secctx *fsecctx; + struct fuse_secctxs *fsecctxs; + void *ctx, *full_ctx; + u32 ctxlen, full_ctxlen; + int err = 0; + const char *name; + + err = security_dentry_init_security(entry, mode, &entry->d_name, + &name, &ctx, &ctxlen); + if (err) { + if (err != -EOPNOTSUPP) + goto out_err; + /* No LSM is supporting this security hook. Ignore error */ + err = 0; + ctxlen = 0; + } + + if (ctxlen > 0) { + void *ptr; + + full_ctxlen = sizeof(*fsecctxs) + sizeof(*fsecctx) + + strlen(name) + ctxlen + 1; + full_ctx = kzalloc(full_ctxlen, GFP_KERNEL); + if (!full_ctx) { + err = -ENOMEM; + kfree(ctx); + goto out_err; + } + + ptr = full_ctx; + fsecctxs = (struct fuse_secctxs*) ptr; + fsecctxs->nr_secctx = 1; + ptr += sizeof(*fsecctxs); + + fsecctx = (struct fuse_secctx*) ptr; + fsecctx->size = ctxlen; + ptr += sizeof(*fsecctx); + + strcpy(ptr, name); + ptr += strlen(name) + 1; + memcpy(ptr, ctx, ctxlen); + kfree(ctx); + } else { + full_ctxlen = sizeof(*fsecctxs); + full_ctx = kzalloc(full_ctxlen, GFP_KERNEL); + if (!full_ctx) { + err = -ENOMEM; + goto out_err; + } + } + + *security_ctxlen = full_ctxlen; + *security_ctx = full_ctx; +out_err: + return err; +} + /* * Atomic create+open operation * @@ -476,6 +539,8 @@ static int fuse_create_open(struct inode *dir, struct dentry *entry, struct fuse_entry_out outentry; struct fuse_inode *fi; struct fuse_file *ff; + void *security_ctx = NULL; + u32 security_ctxlen; /* Userspace expects S_IFREG in create mode */ BUG_ON((mode & S_IFMT) != S_IFREG); @@ -517,6 +582,18 @@ static int fuse_create_open(struct inode *dir, struct dentry *entry, args.out_args[0].value = &outentry; args.out_args[1].size = sizeof(outopen); args.out_args[1].value = &outopen; + + if (fm->fc->init_security) { + err = get_security_context(entry, mode, &security_ctx, + &security_ctxlen); + if (err) + goto out_put_forget_req; + + args.in_numargs = 3; + args.in_args[2].size = security_ctxlen; + args.in_args[2].value = security_ctx; + } + err = fuse_simple_request(fm, &args); if (err) goto out_free_ff; @@ -554,6 +631,7 @@ static int fuse_create_open(struct inode *dir, struct dentry *entry, out_free_ff: fuse_file_free(ff); + kfree(security_ctx); out_put_forget_req: kfree(forget); out_err: @@ -613,13 +691,15 @@ static int fuse_atomic_open(struct inode *dir, struct dentry *entry, */ static int create_new_entry(struct fuse_mount *fm, struct fuse_args *args, struct inode *dir, struct dentry *entry, - umode_t mode) + umode_t mode, bool init_security) { struct fuse_entry_out outarg; struct inode *inode; struct dentry *d; int err; struct fuse_forget_link *forget; + void *security_ctx = NULL; + u32 security_ctxlen = 0; if (fuse_is_bad(dir)) return -EIO; @@ -633,7 +713,29 @@ static int create_new_entry(struct fuse_mount *fm, struct fuse_args *args, args->out_numargs = 1; args->out_args[0].size = sizeof(outarg); args->out_args[0].value = &outarg; + + if (init_security) { + unsigned short idx = args->in_numargs; + + if ((size_t)idx >= ARRAY_SIZE(args->in_args)) { + err = -ENOMEM; + goto out_put_forget_req; + } + + err = get_security_context(entry, mode, &security_ctx, + &security_ctxlen); + if (err) + goto out_put_forget_req; + + if (security_ctxlen > 0) { + args->in_args[idx].size = security_ctxlen; + args->in_args[idx].value = security_ctx; + args->in_numargs++; + } + } + err = fuse_simple_request(fm, args); + kfree(security_ctx); if (err) goto out_put_forget_req; @@ -691,7 +793,7 @@ static int fuse_mknod(struct user_namespace *mnt_userns, struct inode *dir, args.in_args[0].value = &inarg; args.in_args[1].size = entry->d_name.len + 1; args.in_args[1].value = entry->d_name.name; - return create_new_entry(fm, &args, dir, entry, mode); + return create_new_entry(fm, &args, dir, entry, mode, fm->fc->init_security); } static int fuse_create(struct user_namespace *mnt_userns, struct inode *dir, @@ -719,7 +821,8 @@ static int fuse_mkdir(struct user_namespace *mnt_userns, struct inode *dir, args.in_args[0].value = &inarg; args.in_args[1].size = entry->d_name.len + 1; args.in_args[1].value = entry->d_name.name; - return create_new_entry(fm, &args, dir, entry, S_IFDIR); + return create_new_entry(fm, &args, dir, entry, S_IFDIR, + fm->fc->init_security); } static int fuse_symlink(struct user_namespace *mnt_userns, struct inode *dir, @@ -735,7 +838,8 @@ static int fuse_symlink(struct user_namespace *mnt_userns, struct inode *dir, args.in_args[0].value = entry->d_name.name; args.in_args[1].size = len; args.in_args[1].value = link; - return create_new_entry(fm, &args, dir, entry, S_IFLNK); + return create_new_entry(fm, &args, dir, entry, S_IFLNK, + fm->fc->init_security); } void fuse_update_ctime(struct inode *inode) @@ -915,7 +1019,8 @@ static int fuse_link(struct dentry *entry, struct inode *newdir, args.in_args[0].value = &inarg; args.in_args[1].size = newent->d_name.len + 1; args.in_args[1].value = newent->d_name.name; - err = create_new_entry(fm, &args, newdir, newent, inode->i_mode); + err = create_new_entry(fm, &args, newdir, newent, inode->i_mode, + false); /* Contrary to "normal" filesystems it can happen that link makes two "logical" inodes point to the same "physical" inode. We invalidate the attributes of the old one, so it diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h index 319596df5dc6..885f34f9967f 100644 --- a/fs/fuse/fuse_i.h +++ b/fs/fuse/fuse_i.h @@ -765,6 +765,9 @@ struct fuse_conn { /* Propagate syncfs() to server */ unsigned int sync_fs:1; + /* Initialize security xattrs when creating a new inode */ + unsigned int init_security:1; + /** The number of requests waiting for completion */ atomic_t num_waiting; diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c index 36cd03114b6d..343bc9cfbd92 100644 --- a/fs/fuse/inode.c +++ b/fs/fuse/inode.c @@ -1152,6 +1152,8 @@ static void process_init_reply(struct fuse_mount *fm, struct fuse_args *args, } if (arg->flags & FUSE_SETXATTR_EXT) fc->setxattr_ext = 1; + if (arg->flags & FUSE_SECURITY_CTX) + fc->init_security = 1; } else { ra_pages = fc->max_read / PAGE_SIZE; fc->no_lock = 1; @@ -1195,7 +1197,7 @@ void fuse_send_init(struct fuse_mount *fm) FUSE_PARALLEL_DIROPS | FUSE_HANDLE_KILLPRIV | FUSE_POSIX_ACL | FUSE_ABORT_ERROR | FUSE_MAX_PAGES | FUSE_CACHE_SYMLINKS | FUSE_NO_OPENDIR_SUPPORT | FUSE_EXPLICIT_INVAL_DATA | - FUSE_HANDLE_KILLPRIV_V2 | FUSE_SETXATTR_EXT; + FUSE_HANDLE_KILLPRIV_V2 | FUSE_SETXATTR_EXT | FUSE_SECURITY_CTX; #ifdef CONFIG_FUSE_DAX if (fm->fc->dax) ia->in.flags |= FUSE_MAP_ALIGNMENT; diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h index 2fe54c80051a..b31a0f79fde8 100644 --- a/include/uapi/linux/fuse.h +++ b/include/uapi/linux/fuse.h @@ -986,4 +986,24 @@ struct fuse_syncfs_in { uint64_t padding; }; +/* + * For each security context, send fuse_secctx with size of security context + * fuse_secctx will be followed by security context name and this in turn + * will be followed by actual context label. + * fuse_secctx, name, context + * */ +struct fuse_secctx { + uint32_t size; + uint32_t padding; +}; + +/* + * Contains the information about how many fuse_secctx structures are being + * sent. + */ +struct fuse_secctxs { + uint32_t nr_secctx; + uint32_t padding; +}; + #endif /* _LINUX_FUSE_H */
When a new inode is created, send its security context to server along with creation request (FUSE_CREAT, FUSE_MKNOD, FUSE_MKDIR and FUSE_SYMLINK). This gives server an opportunity to create new file and set security context (possibly atomically). In all the configurations it might not be possible to set context atomically. Like nfs and ceph, use security_dentry_init_security() to dermine security context of inode and send it with create, mkdir, mknod, and symlink requests. Following is the information sent to server. - struct fuse_secctxs. This contains total number of security contexts being sent. - struct fuse_secctx. This contains total size of security context which follows this structure. There is one fuse_secctx instance per security context. - xattr name string. This string represents name of xattr which should be used while setting security context. As of now it is hardcoded to "security.selinux". - security context. This is the actual security context whose size is specified in fuse_secctx struct. This patch is modified version of patch from Chirantan Ekbote <chirantan@chromium.org> v2: - Added "fuse_secctxs" structure where one can specify how many security contexts are being sent. This can be useful down the line if we have more than one security contexts being set. Signed-off-by: Vivek Goyal <vgoyal@redhat.com> --- fs/fuse/dir.c | 115 ++++++++++++++++++++++++++++++++++++-- fs/fuse/fuse_i.h | 3 + fs/fuse/inode.c | 4 +- include/uapi/linux/fuse.h | 20 +++++++ 4 files changed, 136 insertions(+), 6 deletions(-)