sendmail, 4th Edition

-d44.4

Trace safefile( ) Debug command-line switch

The V8 sendmail program tries to be extra careful about file permissions, and the key to checking them is the internal safefile( ) function. The -d44.4 debugging switch^[228] prints the parameters passed to the safefile( ) function:

safefile(fname, uid=uid, gid=gid, flags=sff_flags, mode=wantmode)

Here, the file named fname is being checked to determine whether the user identified by the uid, with the group gid, is allowed to find or use the file. The range of checking is determined by the hexadecimal sff_flags, described in Table 15-11. Where a file’s permissions are required, the mode printed in wantmode will be used.

Table 15-11. safefile( ) access flags

Mnemonic	Hex flag	Description
SFF_ANYFILE	0x00000000	No special restrictions
SFF_MUSTOWN	0x00000001	User must own this file
SFF_NOSLINK	0x00000002	File cannot be a symbolic link
SFF_ROOTOK	0x00000004	OK for root to own this file
SFF_RUNASREALUID	0x00000008	If no controlling user, run as real user-id
SFF_NOPATHCHECK	0x00000010	Don’t bother checking directory path
SFF_SETUIDOK	0x00000020	Set-user-id files are OK.
SFF_CREAT	0x00000040	OK to create file if necessary
SFF_REGONLY	0x00000080	Regular files only
SFF_SAFEDIRPATH	0x00000100	No writable directories (also check owner)
SFF_NOHLINK	0x00000200	File cannot have hard links
SFF_NOWLINK	0x00000400	Links only in nonwritable directories
SFF_NOGWFILES	0x00000800	Disallow group-writable files
SFF_NOWWFILES ...