nfs4acls: Use talloc_realloc()

[Samba.git] / source3 / modules / vfs_vxfs.c

/*
Unix SMB/CIFS implementation.
Wrap VxFS calls in vfs functions.
This module is for ACL handling.

Copyright (C) Symantec Corporation <www.symantec.com> 2014

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#include "includes.h"
#include "smbd/smbd.h"
#include "librpc/gen_ndr/ndr_xattr.h"
#include "../libcli/security/security.h"
#include "../librpc/gen_ndr/ndr_security.h"
#include "system/filesys.h"

#undef DBGC_CLASS
#define DBGC_CLASS DBGC_VFS

#define MODULE_NAME "vxfs"

/*
 * WARNING !! WARNING !!
 *
 * DO NOT CHANGE THIS FROM "system." space to
 * "user." space unless you are shipping a product
 * that RESTRICTS access to extended attributes
 * to smbd-only. "system." space is restricted
 * to root access only, "user." space is available
 * to ANY USER.
 *
 * If this is changed to "user." and access
 * to extended attributes is available via
 * local processes or other remote file system
 * (e.g. NFS) then the security of the system
 * WILL BE COMPROMISED. i.e. non-root users
 * WILL be able to overwrite Samba ACLs on
 * the file system.
 *
 * If you need to modify this define, do
 * so using CFLAGS on your build command
 * line.
 * e.g. CFLAGS=-DXATTR_USER_NTACL="user.NTACL"
 *
 * Added by: <jra@samba.org> 17 Sept. 2014.
 *
 */

#ifndef XATTR_USER_NTACL
#define XATTR_USER_NTACL "system.NTACL"
#endif

/* type values */
#define VXFS_ACL_UNDEFINED_TYPE  0
#define VXFS_ACL_USER_OBJ        1
#define VXFS_ACL_GROUP_OBJ       2
#define VXFS_ACL_USER            3
#define VXFS_ACL_GROUP           4
#define VXFS_ACL_OTHER           5
#define VXFS_ACL_MASK            6


/*
 * Compare aces
 * This will compare two ace entries for sorting
 * each entry contains: type, perms and id
 * Sort by type first, if type is same sort by id.
 */
static int vxfs_ace_cmp(const void *ace1, const void *ace2)
{
        int ret = 0;
        uint16_t type_a1, type_a2;
        uint32_t id_a1, id_a2;

        /* Type must be compared first */
        type_a1 = SVAL(ace1, 0);
        type_a2 = SVAL(ace2, 0);

        ret = (type_a1 - type_a2);
        if (!ret) {
                /* Compare ID under type */
                /* skip perm thus take offset as 4*/
                id_a1 = IVAL(ace1, 4);
                id_a2 = IVAL(ace2, 4);
                ret = id_a1 - id_a2;
        }

        return ret;
}

static void vxfs_print_ace_buf(char *buf, int count) {

        int i, offset = 0;
        uint16_t type, perm;
        uint32_t id;

        DEBUG(10, ("vfs_vxfs: Printing aces:\n"));
        for (i = 0; i < count; i++) {
                type = SVAL(buf, offset);
                offset += 2;
                perm = SVAL(buf, offset);
                offset += 2;
                id = IVAL(buf, offset);
                offset += 4;

                DEBUG(10, ("vfs_vxfs: type = %u, perm = %u, id = %u\n",
                          (unsigned int)type, (unsigned int)perm,
                          (unsigned int)id));
        }
}

/*
 * Sort aces so that comparing 2 ACLs will be straight forward.
 * This function will fill buffer as follows:
 * For each ace:
 *      1. ace->a_type will be filled as first 2 bytes in buf.
 *      2. ace->a_perm will be filled as next 2 bytes.
 *      3. ace->xid will be filled as next 4 bytes.
 * Thus each ace entry in buf is equal to 8 bytes.
 * Also a_type is mapped to VXFS_ACL_* so that ordering aces
 * becomes easy.
 */
static char * vxfs_sort_acl(SMB_ACL_T theacl, TALLOC_CTX *mem_ctx,
                            uint32_t o_uid,
                            uint32_t o_gid) {

        struct smb_acl_entry *smb_ace;
        int i, count;
        uint16_t type, perm;
        uint32_t id;
        int offset = 0;
        char *buf = NULL;

        count = theacl->count;

        buf = talloc_zero_size(mem_ctx, count * 8);
        if (!buf) {
                return NULL;
        }

        smb_ace = theacl->acl;

        for (i = 0; i < count; i++) {
                /* Calculate type */
                /* Map type to SMB_ACL_* to VXFS_ACL_* */
                switch(smb_ace->a_type) {
                case SMB_ACL_USER:
                        type = VXFS_ACL_USER;
                        break;
                case SMB_ACL_USER_OBJ:
                        type = VXFS_ACL_USER_OBJ;
                        break;
                case SMB_ACL_GROUP:
                        type = VXFS_ACL_GROUP;
                        break;
                case SMB_ACL_GROUP_OBJ:
                        type = VXFS_ACL_GROUP_OBJ;
                        break;
                case SMB_ACL_OTHER:
                        type = VXFS_ACL_OTHER;
                        break;
                case SMB_ACL_MASK:
                        type = VXFS_ACL_MASK;
                        break;
                default:
                        type = -1;
                        talloc_free(buf);
                        return NULL;
                }

                type = type & 0xff;

                /* Calculate id:
                 * We get owner uid and owner group gid in o_uid and o_gid
                 * Put these ids instead of -1
                 */
                switch(smb_ace->a_type) {
                case SMB_ACL_USER:
                        id = smb_ace->info.user.uid;
                        break;
                case SMB_ACL_GROUP:
                        id = smb_ace->info.group.gid;
                        break;
                case SMB_ACL_USER_OBJ:
                        id = o_uid;
                        break;
                case SMB_ACL_GROUP_OBJ:
                        id = o_gid;
                        break;
                case SMB_ACL_MASK:
                case SMB_ACL_OTHER:
                        id = -1;
                        break;
                default:
                        /* Can't happen.. */
                        id = -1;
                        break;
                }

                /* Calculate perm */
                perm = smb_ace->a_perm & 0xff;

                /* TYPE is the first 2 bytes of an entry */
                SSVAL(buf, offset, type);
                offset += 2;

                /* PERM is the next 2 bytes of an entry */
                SSVAL(buf, offset, perm);
                offset += 2;

                /* ID is the last 4 bytes of an entry */
                SIVAL(buf, offset, id);
                offset += 4;

                smb_ace++;
        }

        qsort(buf, count, 8, vxfs_ace_cmp);

        DEBUG(10, ("vfs_vxfs: Print sorted aces:\n"));
        vxfs_print_ace_buf(buf, count);

        return buf;
}

/* This function gets e_buf as an arg which is sorted and created out of
 * existing ACL. This function will compact this e_buf to c_buf where USER
 * and GROUP aces matching with USER_OBJ and GROUP_OBJ will be merged
 * respectively.
 * This is similar to what posix_acls.c does. This will make sure existing
 * acls are converted much similar to what posix_acls calculates.
 */

static char * vxfs_compact_buf(char *e_buf, int *new_count, int count,
                               TALLOC_CTX *mem_ctx)
{
        int i, e_offset = 0, c_offset = 0;
        uint16_t type, perm, o_perm;
        uint32_t id, owner_id, group_id;
        char *c_buf = NULL;


        if (count < 2) {
                return NULL;
        }

        c_buf = talloc_zero_size(mem_ctx, count * 8);
        if (!c_buf) {
                return NULL;
        }

        /*Copy first two enries from e_buf to c_buf
         *These are USER_OBJ and GROUP_OBJ
         */

        memcpy(c_buf, e_buf, 16);

        (*new_count) = 2;

        owner_id = IVAL(e_buf, 4);
        group_id = IVAL(e_buf, 12);

        c_offset = e_offset = 16;

        /* Start comparing other entries */
        for (i = 2; i < count; i++) {

                type = SVAL(e_buf, e_offset);
                e_offset += 2;
                perm = SVAL(e_buf, e_offset);
                e_offset += 2;
                id = IVAL(e_buf, e_offset);
                e_offset += 4;

                switch(type) {
                case VXFS_ACL_USER:
                        if (id == owner_id) {
                                o_perm = SVAL(c_buf, 2);
                                o_perm |= perm;
                                SSVAL(c_buf, 2, o_perm);
                                DEBUG(10, ("vfs_vxfs: merging with owner"
                                          "e_type = %u,"
                                          "e_perm = %u,"
                                          "e_id = %u\n", (unsigned int)type,
                                          (unsigned int)perm,
                                          (unsigned int)id));
                                continue;
                        }
                        break;
                case VXFS_ACL_GROUP:
                        if (id == group_id) {
                                o_perm = SVAL(c_buf, 10);
                                o_perm |= perm;
                                SSVAL(c_buf, 10, o_perm);
                                DEBUG(10, ("vfs_vxfs: merging with owner group"
                                          "e_type = %u,"
                                          "e_perm = %u,"
                                          "e_id = %u\n", (unsigned int)type,
                                          (unsigned int)perm,
                                          (unsigned int)id));
                                continue;
                        }
                        break;
                }

                SSVAL(c_buf, c_offset, type);
                c_offset += 2;

                SSVAL(c_buf, c_offset, perm);
                c_offset += 2;

                SIVAL(c_buf, c_offset, id);
                c_offset += 4;

                (*new_count)++;
        }
        DEBUG(10, ("vfs_vxfs: new_count is %d\n", *new_count));
        return c_buf;
}

/* Actually compare New ACL and existing ACL buf */
static bool vxfs_compare_acls(char *e_buf, char *n_buf, int n_count,
                              int e_count) {

        uint16_t e_type, n_type, e_perm, n_perm;
        uint32_t e_id, n_id;
        int i, offset = 0;

        if (!e_buf && !n_buf) {
                DEBUG(10, ("vfs_vxfs: Empty buffers!\n"));
                return false;
        }

        if ((e_count < 2) || (n_count < 2)) {
                return false;
        }
        /*Get type from last entry from both buffers.
         * It may or may not be ACL_MASK
         */
        n_type = SVAL(n_buf, offset + (8 * (n_count-1)));
        e_type = SVAL(e_buf, offset + (8 * (e_count-1)));

        /* Check for ACL_MASK entry properly. Handle all 4 cases*/

        /* If ACL_MASK entry is present in any of the buffers,
         * it will be always the last one. Calculate count to compare
         * based on if ACL_MASK is present on new and existing ACL
         */
        if ((n_type != VXFS_ACL_MASK) && (e_type == VXFS_ACL_MASK)){
                DEBUG(10, ("vfs_vxfs: New ACL does not have mask entry,"
                           "reduce count by 1 and compare\n"));
                e_count = e_count -1;
        }
        if ((n_type == VXFS_ACL_MASK) && (e_type != VXFS_ACL_MASK)){
                DEBUG(10, ("vfs_vxfs: new ACL to be set contains mask"
                           "existing ACL does not have mask entry\n"
                           "Need to set New ACL\n"));
                return false;
        }

        if (memcmp(e_buf, n_buf, (e_count * 8)) != 0) {
                DEBUG(10, ("vfs_vxfs: Compare with memcmp,"
                           "buffers not same!\n"));
                return false;
        }

        return true;
}

/* In VxFS, POSIX ACLs are pointed by separate inode for each file/dir.
 * However, files/dir share same POSIX ACL inode if ACLs are inherited
 * from parent.
 * To retain this behaviour, below function avoids ACL set call if
 * underlying ACLs are already same and thus saves creating extra inode.
 *
 * This function will execute following steps:
 * 1. Get existing ACL
 * 2. Sort New ACL and existing ACL into buffers
 * 3. Compact existing ACL buf
 * 4. Finally compare New ACL buf and Compact buf
 * 5. If same, return true
 * 6. Else need to set New ACL
 */

static bool vxfs_compare(connection_struct *conn, char *name, SMB_ACL_T the_acl,
                         SMB_ACL_TYPE_T the_acl_type)
{
        SMB_ACL_T existing_acl = NULL;
        bool ret = false;
        int i, count = 0;
        TALLOC_CTX *mem_ctx = talloc_tos();
        char *existing_buf = NULL, *new_buf = NULL, *compact_buf = NULL;
        struct smb_filename *smb_fname = NULL;
        int status;

        DEBUG(10, ("vfs_vxfs: Getting existing ACL for %s\n", name));
        existing_acl = SMB_VFS_SYS_ACL_GET_FILE(conn, name, the_acl_type,
                                                mem_ctx);
        if (existing_acl == NULL) {
                DEBUG(10, ("vfs_vxfs: Failed to get ACL\n"));
                goto out;
        }

        DEBUG(10, ("vfs_vxfs: Existing ACL count=%d\n", existing_acl->count));
        DEBUG(10, ("vfs_vxfs: New ACL count=%d\n", the_acl->count));

        if (existing_acl->count == 0) {
                DEBUG(10, ("vfs_vxfs: ACL count is 0, Need to set\n"));
                goto out;
        }

        smb_fname = synthetic_smb_fname(mem_ctx, name, NULL, NULL);
        if (smb_fname == NULL) {
                DEBUG(10, ("vfs_vxfs: Failed to create smb_fname\n"));
                goto out;
        }

        status = SMB_VFS_STAT(conn, smb_fname);
        if (status == -1) {
                DEBUG(10, ("vfs_vxfs: stat failed!\n"));
                goto out;
        }

        DEBUG(10, ("vfs_vxfs: Sorting existing ACL\n"));
        existing_buf = vxfs_sort_acl(existing_acl, mem_ctx,
                                     smb_fname->st.st_ex_uid,
                                     smb_fname->st.st_ex_gid);
        if (!existing_buf)
                goto out;

        DEBUG(10, ("vfs_vxfs: Sorting new ACL\n"));
        new_buf = vxfs_sort_acl(the_acl, mem_ctx, smb_fname->st.st_ex_uid,
                                smb_fname->st.st_ex_gid);
        if (!new_buf) {
                goto out;
        }

        DEBUG(10, ("vfs_vxfs: Compact existing buf\n"));
        compact_buf = vxfs_compact_buf(existing_buf, &count,
                                       existing_acl->count,
                                       mem_ctx);
        if (!compact_buf) {
                goto out;
        }

        vxfs_print_ace_buf(compact_buf, count);

        /* COmpare ACLs only if count is same or mismatch by 1 */
        if ((count == the_acl->count) ||
           (count == the_acl->count + 1) ||
           (count+1 == the_acl->count)) {

                if (vxfs_compare_acls(compact_buf, new_buf, the_acl->count,
                                     count)) {
                        DEBUG(10, ("vfs_vxfs: ACLs matched. Not setting.\n"));
                        ret = true;
                        goto out;
                } else
                        DEBUG(10, ("vfs_vxfs: ACLs NOT matched. Setting\n"));
        } else {
                DEBUG(10, ("vfs_vxfs: ACLs count does not match. Setting\n"));
        }

out:

        TALLOC_FREE(existing_acl);
        TALLOC_FREE(smb_fname);
        TALLOC_FREE(existing_buf);
        TALLOC_FREE(compact_buf);
        TALLOC_FREE(new_buf);

        return ret;
}

static int vxfs_sys_acl_set_fd(vfs_handle_struct *handle, files_struct *fsp,
                               SMB_ACL_T theacl)
{

        if (vxfs_compare(fsp->conn, fsp->fsp_name->base_name, theacl,
                         SMB_ACL_TYPE_ACCESS)) {
                return 0;
        }

        return SMB_VFS_NEXT_SYS_ACL_SET_FD(handle, fsp, theacl);
}

static int vxfs_sys_acl_set_file(vfs_handle_struct *handle,  const char *name,
                                 SMB_ACL_TYPE_T acltype, SMB_ACL_T theacl)
{
        if (vxfs_compare(handle->conn, (char *)name, theacl, acltype)) {
                return 0;
        }

        return SMB_VFS_NEXT_SYS_ACL_SET_FILE(handle, name, acltype, theacl);
}

static int vxfs_set_xattr(struct vfs_handle_struct *handle,  const char *path,
                          const char *name, const void *value, size_t size,
                          int flags){

        DEBUG(10, ("In vxfs_set_xattr\n"));

        if (strcmp(name, XATTR_NTACL_NAME) == 0) {
                return SMB_VFS_NEXT_SETXATTR(handle, path, XATTR_USER_NTACL,
                                             value, size, flags);
        }

        /* Clients can't set XATTR_USER_NTACL directly. */
        if (strcasecmp(name, XATTR_USER_NTACL) == 0) {
                errno = EACCES;
                return -1;
        }

        return SMB_VFS_NEXT_SETXATTR(handle, path, name, value, size, flags);
}

static int vxfs_fset_xattr(struct vfs_handle_struct *handle,
                           struct files_struct *fsp, const char *name,
                           const void *value, size_t size,  int flags){

        DEBUG(10, ("In vxfs_fset_xattr\n"));

        if (strcmp(name, XATTR_NTACL_NAME) == 0) {
                return SMB_VFS_NEXT_FSETXATTR(handle, fsp, XATTR_USER_NTACL,
                                              value, size, flags);
        }

        /* Clients can't set XATTR_USER_NTACL directly. */
        if (strcasecmp(name, XATTR_USER_NTACL) == 0) {
                errno = EACCES;
                return -1;
        }

        return SMB_VFS_NEXT_FSETXATTR(handle, fsp, name, value, size, flags);
}

static ssize_t vxfs_get_xattr(struct vfs_handle_struct *handle,
                              const char *path, const char *name,
                              void *value, size_t size){

        DEBUG(10, ("In vxfs_get_xattr\n"));

        if (strcmp(name, XATTR_NTACL_NAME) == 0) {
                return SMB_VFS_NEXT_GETXATTR(handle, path, XATTR_USER_NTACL,
                                             value, size);
        }

        /* Clients can't see XATTR_USER_NTACL directly. */
        if (strcasecmp(name, XATTR_USER_NTACL) == 0) {
                errno = ENOATTR;
                return -1;
        }

        return SMB_VFS_NEXT_GETXATTR(handle, path, name, value, size);
}

static ssize_t vxfs_fget_xattr(struct vfs_handle_struct *handle,
                               struct files_struct *fsp, const char *name,
                               void *value, size_t size){

        DEBUG(10, ("In vxfs_fget_xattr\n"));

        if (strcmp(name, XATTR_NTACL_NAME) == 0) {
                return SMB_VFS_NEXT_FGETXATTR(handle, fsp, XATTR_USER_NTACL,
                                              value, size);
        }

        /* Clients can't see XATTR_USER_NTACL directly. */
        if (strcasecmp(name, XATTR_USER_NTACL) == 0) {
                errno = ENOATTR;
                return -1;
        }

        return SMB_VFS_NEXT_FGETXATTR(handle, fsp, name, value, size);
}

static int vxfs_remove_xattr(struct vfs_handle_struct *handle,
                             const char *path, const char *name){

        DEBUG(10, ("In vxfs_remove_xattr\n"));

        if (strcmp(name, XATTR_NTACL_NAME) == 0) {
                return SMB_VFS_NEXT_REMOVEXATTR(handle, path, XATTR_USER_NTACL);
        }

        /* Clients can't see XATTR_USER_NTACL directly. */
        if (strcasecmp(name, XATTR_USER_NTACL) == 0) {
                errno = ENOATTR;
                return -1;
        }

        return SMB_VFS_NEXT_REMOVEXATTR(handle, path, name);
}

static int vxfs_fremove_xattr(struct vfs_handle_struct *handle,
                              struct files_struct *fsp, const char *name){

        DEBUG(10, ("In vxfs_fremove_xattr\n"));

        if (strcmp(name, XATTR_NTACL_NAME) == 0) {
                return SMB_VFS_NEXT_FREMOVEXATTR(handle, fsp, XATTR_USER_NTACL);
        }

        /* Clients can't remove XATTR_USER_NTACL directly. */
        if (strcasecmp(name, XATTR_USER_NTACL) == 0) {
                errno = ENOATTR;
                return -1;
        }

        return SMB_VFS_NEXT_FREMOVEXATTR(handle, fsp, name);
}

static size_t vxfs_filter_list(char *list, size_t size)
{
        char *str = list;

        while (str - list < size) {
                size_t element_len = strlen(str) + 1;
                if (strcasecmp(str, XATTR_USER_NTACL) == 0) {
                        memmove(str,
                                str + element_len,
                                size - (str - list) - element_len);
                        size -= element_len;
                        continue;
                }
                str += element_len;
        }
        return size;
}

static ssize_t vxfs_listxattr(vfs_handle_struct *handle, const char *path,
                              char *list, size_t size)
{
        ssize_t result;

        result = SMB_VFS_NEXT_LISTXATTR(handle, path, list, size);

        if (result <= 0) {
                return result;
        }

        /* Remove any XATTR_USER_NTACL elements from the returned list. */
        result = vxfs_filter_list(list, result);

        return result;
}

static ssize_t vxfs_flistxattr(struct vfs_handle_struct *handle,
                                struct files_struct *fsp, char *list,
                                size_t size)
{
        ssize_t result;

        result = SMB_VFS_NEXT_FLISTXATTR(handle, fsp, list, size);

        if (result <= 0) {
                return result;
        }

        /* Remove any XATTR_USER_NTACL elements from the returned list. */
        result = vxfs_filter_list(list, result);

        return result;
}

static int vfs_vxfs_connect(struct vfs_handle_struct *handle,
                            const char *service, const char *user)
{

        int ret = SMB_VFS_NEXT_CONNECT(handle, service, user);

        if (ret < 0) {
                return ret;
        }
        return 0;
}

static struct vfs_fn_pointers vfs_vxfs_fns = {
        .connect_fn = vfs_vxfs_connect,

        .sys_acl_set_file_fn = vxfs_sys_acl_set_file,
        .sys_acl_set_fd_fn = vxfs_sys_acl_set_fd,

        .getxattr_fn = vxfs_get_xattr,
        .fgetxattr_fn = vxfs_fget_xattr,
        .listxattr_fn = vxfs_listxattr,
        .flistxattr_fn = vxfs_flistxattr,
        .removexattr_fn = vxfs_remove_xattr,
        .fremovexattr_fn = vxfs_fremove_xattr,
        .setxattr_fn = vxfs_set_xattr,
        .fsetxattr_fn = vxfs_fset_xattr,
};

NTSTATUS vfs_vxfs_init(void);
NTSTATUS vfs_vxfs_init(void)
{
        return smb_register_vfs(SMB_VFS_INTERFACE_VERSION, "vxfs",
                                &vfs_vxfs_fns);
}