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| author | Christian Brauner <brauner@kernel.org> | 2022-10-17 17:06:35 +0200 |
|---|---|---|
| committer | Christian Brauner (Microsoft) <brauner@kernel.org> | 2022-10-18 10:09:46 +0200 |
| commit | e243e3f94c804ecca9a8241b5babe28f35258ef4 (patch) | |
| tree | fc09ac739fbc79f29e93facad741477ec38b84be /fs/attr.c | |
| parent | 11c2a8700cdcabf9b639b7204a1e38e2a0b6798e (diff) | |
| download | linux-stable-e243e3f94c804ecca9a8241b5babe28f35258ef4.tar.gz linux-stable-e243e3f94c804ecca9a8241b5babe28f35258ef4.tar.bz2 linux-stable-e243e3f94c804ecca9a8241b5babe28f35258ef4.zip | |
fs: move should_remove_suid()
Move the helper from inode.c to attr.c. This keeps the the core of the
set{g,u}id stripping logic in one place when we add follow-up changes.
It is the better place anyway, since should_remove_suid() returns
ATTR_KILL_S{G,U}ID flags.
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Diffstat (limited to 'fs/attr.c')
| -rw-r--r-- | fs/attr.c | 29 |
1 files changed, 29 insertions, 0 deletions
diff --git a/fs/attr.c b/fs/attr.c index b1162fca84a2..e508b3caae76 100644 --- a/fs/attr.c +++ b/fs/attr.c @@ -20,6 +20,35 @@ #include "internal.h" +/* + * The logic we want is + * + * if suid or (sgid and xgrp) + * remove privs + */ +int should_remove_suid(struct dentry *dentry) +{ + umode_t mode = d_inode(dentry)->i_mode; + int kill = 0; + + /* suid always must be killed */ + if (unlikely(mode & S_ISUID)) + kill = ATTR_KILL_SUID; + + /* + * sgid without any exec bits is just a mandatory locking mark; leave + * it alone. If some exec bits are set, it's a real sgid; kill it. + */ + if (unlikely((mode & S_ISGID) && (mode & S_IXGRP))) + kill |= ATTR_KILL_SGID; + + if (unlikely(kill && !capable(CAP_FSETID) && S_ISREG(mode))) + return kill; + + return 0; +} +EXPORT_SYMBOL(should_remove_suid); + /** * chown_ok - verify permissions to chown inode * @mnt_userns: user namespace of the mount @inode was found from |