1 /* vfs_vnops.c 4.32 82/12/31 */ 2 3 #include "../machine/reg.h" 4 5 #include "../h/param.h" 6 #include "../h/systm.h" 7 #include "../h/dir.h" 8 #include "../h/user.h" 9 #include "../h/fs.h" 10 #include "../h/file.h" 11 #include "../h/conf.h" 12 #include "../h/inode.h" 13 #include "../h/acct.h" 14 #include "../h/mount.h" 15 #include "../h/socket.h" 16 #include "../h/socketvar.h" 17 #include "../h/proc.h" 18 #include "../h/nami.h" 19 20 /* 21 * Openi called to allow handler 22 * of special files to initialize and 23 * validate before actual IO. 24 */ 25 openi(ip, mode) 26 register struct inode *ip; 27 { 28 dev_t dev = (dev_t)ip->i_rdev; 29 register u_int maj = major(dev); 30 31 switch (ip->i_mode&IFMT) { 32 33 case IFCHR: 34 if (maj >= nchrdev) 35 return (ENXIO); 36 return ((*cdevsw[maj].d_open)(dev, mode)); 37 38 case IFBLK: 39 if (maj >= nblkdev) 40 return (ENXIO); 41 return ((*bdevsw[maj].d_open)(dev, mode)); 42 } 43 return (0); 44 } 45 46 /* 47 * Check mode permission on inode pointer. 48 * Mode is READ, WRITE or EXEC. 49 * In the case of WRITE, the 50 * read-only status of the file 51 * system is checked. 52 * Also in WRITE, prototype text 53 * segments cannot be written. 54 * The mode is shifted to select 55 * the owner/group/other fields. 56 * The super user is granted all 57 * permissions. 58 */ 59 access(ip, mode) 60 register struct inode *ip; 61 int mode; 62 { 63 register m; 64 register int *gp; 65 66 m = mode; 67 if (m == IWRITE) { 68 if (ip->i_fs->fs_ronly != 0) { 69 if ((ip->i_mode & IFMT) != IFCHR && 70 (ip->i_mode & IFMT) != IFBLK) { 71 u.u_error = EROFS; 72 return (1); 73 } 74 } 75 if (ip->i_flag&ITEXT) /* try to free text */ 76 xrele(ip); 77 if (ip->i_flag & ITEXT) { 78 u.u_error = ETXTBSY; 79 return (1); 80 } 81 } 82 if (u.u_uid == 0) 83 return (0); 84 if (u.u_uid != ip->i_uid) { 85 m >>= 3; 86 for (gp = u.u_groups; gp < &u.u_groups[NGROUPS]; gp++) 87 if (ip->i_gid == *gp) 88 goto found; 89 m >>= 3; 90 found: 91 ; 92 } 93 if ((ip->i_mode&m) != 0) 94 return (0); 95 u.u_error = EACCES; 96 return (1); 97 } 98 99 /* 100 * Look up a pathname and test if 101 * the resultant inode is owned by the 102 * current user. 103 * If not, try for super-user. 104 * If permission is granted, 105 * return inode pointer. 106 */ 107 struct inode * 108 owner(follow) 109 int follow; 110 { 111 register struct inode *ip; 112 113 ip = namei(uchar, LOOKUP, follow); 114 if (ip == NULL) 115 return (NULL); 116 if (u.u_uid == ip->i_uid) 117 return (ip); 118 if (suser()) 119 return (ip); 120 iput(ip); 121 return (NULL); 122 } 123 124 /* 125 * Test if the current user is the 126 * super user. 127 */ 128 suser() 129 { 130 131 if (u.u_uid == 0) { 132 u.u_acflag |= ASU; 133 return (1); 134 } 135 u.u_error = EPERM; 136 return (0); 137 } 138