7.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Paul Moore commit 77d499e61d36e883a6ad1f10afe05f556aa7e0cc upstream. Avoid multiple lookups of the bpffs creator SID using the token's file descriptor when the same information can be found via the resolved path/dentry (in selinux_bpf_token_create()) or the token itself (in selinux_bpf_map_create() and selinux_bpf_prog_load()). Not only does this simplify the code, it avoids potential TOCTOU issues if the user changes the token file descriptor passed into the kernel. Cc: stable@vger.kernel.org Fixes: 5473a722f782 ("selinux: add support for BPF token access control") Reviewed-by: Stephen Smalley Tested-by: Stephen Smalley Signed-off-by: Paul Moore Signed-off-by: Greg Kroah-Hartman --- security/selinux/hooks.c | 36 ++++++++++-------------------------- 1 file changed, 10 insertions(+), 26 deletions(-) --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -7382,24 +7382,6 @@ static int selinux_bpf_prog(struct bpf_p BPF__PROG_RUN, NULL); } -static u32 selinux_bpffs_creator_sid(u32 fd) -{ - struct path path; - struct super_block *sb; - struct superblock_security_struct *sbsec; - - CLASS(fd, f)(fd); - - if (fd_empty(f)) - return SECSID_NULL; - - path = fd_file(f)->f_path; - sb = path.dentry->d_sb; - sbsec = selinux_superblock(sb); - - return sbsec->creator_sid; -} - static int selinux_bpf_map_create(struct bpf_map *map, union bpf_attr *attr, struct bpf_token *token, bool kernel) { @@ -7412,7 +7394,7 @@ static int selinux_bpf_map_create(struct if (!token) ssid = bpfsec->sid; else - ssid = selinux_bpffs_creator_sid(attr->map_token_fd); + ssid = selinux_bpf_token_security(token)->grantor_sid; return avc_has_perm(ssid, bpfsec->sid, SECCLASS_BPF, BPF__MAP_CREATE, NULL); @@ -7430,7 +7412,7 @@ static int selinux_bpf_prog_load(struct if (!token) ssid = bpfsec->sid; else - ssid = selinux_bpffs_creator_sid(attr->prog_token_fd); + ssid = selinux_bpf_token_security(token)->grantor_sid; return avc_has_perm(ssid, bpfsec->sid, SECCLASS_BPF, BPF__PROG_LOAD, NULL); @@ -7444,12 +7426,14 @@ static int selinux_bpf_token_create(stru const struct path *path) { struct bpf_security_struct *bpfsec; - u32 sid = selinux_bpffs_creator_sid(attr->token_create.bpffs_fd); + struct superblock_security_struct *sbsec; int err; + sbsec = selinux_superblock(path->dentry->d_sb); + bpfsec = selinux_bpf_token_security(token); bpfsec->sid = current_sid(); - bpfsec->grantor_sid = sid; + bpfsec->grantor_sid = sbsec->creator_sid; bpfsec->perms = 0; /** @@ -7458,15 +7442,15 @@ static int selinux_bpf_token_create(stru * in the allowed_cmds bitmap. */ if (bpf_token_cmd(token, BPF_MAP_CREATE)) { - err = avc_has_perm(bpfsec->sid, sid, SECCLASS_BPF, - BPF__MAP_CREATE_AS, NULL); + err = avc_has_perm(bpfsec->sid, bpfsec->grantor_sid, + SECCLASS_BPF, BPF__MAP_CREATE_AS, NULL); if (err) return err; bpfsec->perms |= BPF__MAP_CREATE; } if (bpf_token_cmd(token, BPF_PROG_LOAD)) { - err = avc_has_perm(bpfsec->sid, sid, SECCLASS_BPF, - BPF__PROG_LOAD_AS, NULL); + err = avc_has_perm(bpfsec->sid, bpfsec->grantor_sid, + SECCLASS_BPF, BPF__PROG_LOAD_AS, NULL); if (err) return err; bpfsec->perms |= BPF__PROG_LOAD;