diff options
Diffstat (limited to 'fs/inode.c')
| -rw-r--r-- | fs/inode.c | 32 |
1 files changed, 28 insertions, 4 deletions
diff --git a/fs/inode.c b/fs/inode.c index e1b4b5f7f4ca..a0554434f225 100644 --- a/fs/inode.c +++ b/fs/inode.c @@ -2101,10 +2101,6 @@ void inode_init_owner(struct inode *inode, const struct inode *dir, /* Directories are special, and always inherit S_ISGID */ if (S_ISDIR(mode)) mode |= S_ISGID; - else if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP) && - !in_group_p(inode->i_gid) && - !capable_wrt_inode_uidgid(dir, CAP_FSETID)) - mode &= ~S_ISGID; } else inode->i_gid = current_fsgid(); inode->i_mode = mode; @@ -2360,3 +2356,31 @@ int vfs_ioc_fssetxattr_check(struct inode *inode, const struct fsxattr *old_fa, return 0; } EXPORT_SYMBOL(vfs_ioc_fssetxattr_check); + +/** + * mode_strip_sgid - handle the sgid bit for non-directories + * @dir: parent directory inode + * @mode: mode of the file to be created in @dir + * + * If the @mode of the new file has both the S_ISGID and S_IXGRP bit + * raised and @dir has the S_ISGID bit raised ensure that the caller is + * either in the group of the parent directory or they have CAP_FSETID + * in their user namespace and are privileged over the parent directory. + * In all other cases, strip the S_ISGID bit from @mode. + * + * Return: the new mode to use for the file + */ +umode_t mode_strip_sgid(const struct inode *dir, umode_t mode) +{ + if ((mode & (S_ISGID | S_IXGRP)) != (S_ISGID | S_IXGRP)) + return mode; + if (S_ISDIR(mode) || !dir || !(dir->i_mode & S_ISGID)) + return mode; + if (in_group_p(dir->i_gid)) + return mode; + if (capable_wrt_inode_uidgid(dir, CAP_FSETID)) + return mode; + + return mode & ~S_ISGID; +} +EXPORT_SYMBOL(mode_strip_sgid); |